Special Senses: Smell and Taste
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Questions and Answers

Which region of the nasal cavity is responsible for detecting chemicals for the sense of smell?

  • Olfactory bulb
  • Olfactory epithelium (correct)
  • Paranasal sinus
  • Nasal septum

What are the specialized neurons that detect odorants in the nasal cavity called?

  • Basal cells
  • Receptor proteins
  • Olfactory bulb neurons
  • Olfactory sensory neurons (correct)

What do odorants bind to in order to produce smell sensations?

  • Basal cells
  • Support cells
  • Olfactory receptor proteins (correct)
  • Nasal tissue

Which cells in the olfactory epithelium are responsible for replacing damaged olfactory sensory neurons?

<p>Basal cells (A)</p> Signup and view all the answers

What type of sensations do general senses detect?

<p>Large area sensations (D)</p> Signup and view all the answers

What aspect of special senses makes them different from general senses?

<p>Special senses are localized to specific organs (D)</p> Signup and view all the answers

What type of ions cause the salty taste sensation when they enter gustatory cells?

<p>Na+ ions (D)</p> Signup and view all the answers

What triggers the sour taste sensation in gustatory cells?

<p>Presence of H+ ions (C)</p> Signup and view all the answers

Which molecules activate the sweet taste receptors in gustatory cells?

<p>Glucose and its analogs (C)</p> Signup and view all the answers

Which type of molecules are primarily responsible for bitter taste sensations?

<p>Alkaloids (C)</p> Signup and view all the answers

What is the primary substance that activates umami taste receptors?

<p>L-glutamate (C)</p> Signup and view all the answers

Which cranial nerve is responsible for carrying taste sensations from the anterior third of the tongue?

<p>Facial nerve (C)</p> Signup and view all the answers

What happens to taste sensations over time?

<p>They often decrease due to adaptation and dilution (A)</p> Signup and view all the answers

Which accessory structure is primarily responsible for protecting the eye from foreign particles?

<p>Eyelids (D)</p> Signup and view all the answers

What is conjunctivitis commonly referred to as?

<p>Pink eye (B)</p> Signup and view all the answers

What structures produce tears that wash away foreign particles from the eye?

<p>Lacrimal glands (A)</p> Signup and view all the answers

Where do excess tears flow after washing over the surface of the eye?

<p>Lacrimal punctum (B)</p> Signup and view all the answers

Which cranial nerve connects to taste buds located in the posterior two-thirds of the tongue?

<p>Glossopharyngeal nerve (A)</p> Signup and view all the answers

Which taste sensation might stimulate a gag reflex to avoid poisons?

<p>Bitters (B)</p> Signup and view all the answers

What structure do the lacrimal puncta lead to?

<p>Lacrimal canaliculus (C)</p> Signup and view all the answers

Which muscle is responsible for moving the eye upwards?

<p>Superior rectus (A)</p> Signup and view all the answers

What feature helps the oblique muscles to rotate the eye effectively?

<p>Trochlea (B)</p> Signup and view all the answers

What is the outermost layer of the eye called?

<p>Fibrous tunic (D)</p> Signup and view all the answers

What does the cornea do?

<p>Allows light to enter the eye (A)</p> Signup and view all the answers

What structure connects the lens to the ciliary body?

<p>Suspensory ligaments (C)</p> Signup and view all the answers

What part of the eye is responsible for photoreception?

<p>Retina (D)</p> Signup and view all the answers

What is the role of the iris in the eye?

<p>To adjust the pupil size (B)</p> Signup and view all the answers

Where is the fovea located?

<p>In the retina (A)</p> Signup and view all the answers

What is the main function of the lacrimal sac?

<p>To drain tears into the nasal cavity (D)</p> Signup and view all the answers

Which muscle is NOT involved in rotating the eye?

<p>Sternocleidomastoid (D)</p> Signup and view all the answers

What happens when the superior oblique muscle contracts?

<p>Eye rotates laterally (C)</p> Signup and view all the answers

What is the primary role of the ciliary body?

<p>To change the shape of the lens (B)</p> Signup and view all the answers

What structure acts as a transition between the sclera and cornea?

<p>Corneal limbus (C)</p> Signup and view all the answers

What is the outermost layer of the retina primarily composed of?

<p>Photoreceptor cells (C)</p> Signup and view all the answers

What condition is characterized by damage to the blood vessels in the retina due to diabetes?

<p>Diabetic retinopathy (A)</p> Signup and view all the answers

Which cavity of the eye is filled with vitreous humor?

<p>Posterior cavity (B)</p> Signup and view all the answers

What is the primary function of the aqueous humor in the anterior cavity?

<p>To maintain intraocular pressure (B)</p> Signup and view all the answers

What is the process called that allows the lens to change its shape for focusing?

<p>Accommodation (A)</p> Signup and view all the answers

What occurs when light is not properly focused on the retina due to the shape of the eye?

<p>Myopia (B)</p> Signup and view all the answers

What happens to the lens as a person ages that can impair vision?

<p>Becomes stiffer (B)</p> Signup and view all the answers

Which layer of the retina contains ganglion cells?

<p>Ganglion layer (C)</p> Signup and view all the answers

What causes the bending of light as it enters the eye?

<p>The cornea (A)</p> Signup and view all the answers

What distinguishes emmetropia from other vision states?

<p>It implies perfect clarity. (D)</p> Signup and view all the answers

What is a common consequence of high intraocular pressure?

<p>Glaucoma (A)</p> Signup and view all the answers

What role do the ciliary muscles play in vision?

<p>They control the shape of the lens. (D)</p> Signup and view all the answers

What condition may result from changes in the vitreous humor?

<p>Retinal detachment (B)</p> Signup and view all the answers

What causes blur and distortions in vision associated with astigmatism?

<p>Irregularity in the cornea. (B)</p> Signup and view all the answers

What is the main consequence of bacteria invading the middle ear?

<p>Middle ear infection (C)</p> Signup and view all the answers

What treatment is typically necessary to address otitis media in babies?

<p>Antibiotics (C)</p> Signup and view all the answers

What type of ear infection is often referred to as swimmer's ear?

<p>Otitis externa (B)</p> Signup and view all the answers

What protective response reduces the movement of ossicles in response to loud sounds?

<p>Tympanic reflex (B)</p> Signup and view all the answers

What structure in the inner ear contains the receptors for hearing?

<p>Spiral organ (B)</p> Signup and view all the answers

What is the role of the basilar membrane in the cochlea?

<p>To separate different sound frequencies (D)</p> Signup and view all the answers

What happens when the inner hair cells of the basilar membrane are vibrated?

<p>They release neurotransmitters (B)</p> Signup and view all the answers

Which ions influx into hair cells during depolarization due to sound vibrations?

<p>Calcium and potassium (C)</p> Signup and view all the answers

How does the auditory system localize sound in space?

<p>By timing comparisons of sound arrival (D)</p> Signup and view all the answers

What is the primary fluid within the membranous labyrinth?

<p>Endolymph (D)</p> Signup and view all the answers

What does the cochlear nucleus in the pons project to next?

<p>Superior olivary nucleus (C)</p> Signup and view all the answers

Which characteristics of sound are determined by the frequency of hair cell firing?

<p>Pitch and loudness (C)</p> Signup and view all the answers

What structure acts as a protective element against loud sounds by partially immobilizing ossicles?

<p>Tensor tympani muscle (D)</p> Signup and view all the answers

What is the role of the inferior colliculus in the auditory pathway?

<p>It transmits signals to the auditory cortex. (B), It controls auditory reflexes. (D)</p> Signup and view all the answers

In the vestibular system, what do the maculae detect?

<p>Linear acceleration and head position. (A)</p> Signup and view all the answers

What causes hair cells in the maculae to bend when the head tilts?

<p>Gravity on the otoliths within the gelatinous membrane. (C)</p> Signup and view all the answers

What is the primary function of the semicircular canals in the vestibular system?

<p>Detect rotational movement. (C)</p> Signup and view all the answers

How does the vestibular system help maintain gaze during head movement?

<p>Through the vestibulo-ocular reflex (VOR). (A)</p> Signup and view all the answers

What happens to sensations after spinning around and then stopping?

<p>The brain misinterprets continued spinning. (B)</p> Signup and view all the answers

What type of membrane do hair cells in the cristae of the semicircular canals reside within?

<p>Gelatinous membrane called the cupula. (B)</p> Signup and view all the answers

What physiological reaction occurs when hair cells bend in response to movement?

<p>Opening of potassium channels and depolarization. (C)</p> Signup and view all the answers

Which region of the brain coordinates movement based on vestibular information?

<p>Cerebellum. (C)</p> Signup and view all the answers

What happens as a result of extensive decussation in the auditory pathway?

<p>Equal processing of sounds in both cortices. (C)</p> Signup and view all the answers

What type of cells connect the photoreceptors to the retinal ganglion cells (RGCs) in the retina?

<p>Bipolar cells (D)</p> Signup and view all the answers

Which structure in the ear contains hair cells that transduce sound stimuli?

<p>Organ of Corti (C)</p> Signup and view all the answers

What controls the shape of the lens in the eye?

<p>Ciliary body (B)</p> Signup and view all the answers

What is the function of basal cells in the olfactory sensory neuron system?

<p>To replace damaged olfactory neurons (A)</p> Signup and view all the answers

Which component of the auditory system is involved in equilibrium?

<p>Semicircular canals (D)</p> Signup and view all the answers

How does the sensitivity of the sense of olfaction change with age?

<p>It gradually becomes less sensitive (C)</p> Signup and view all the answers

What membrane in the cochlea marks the end of the scala tympani?

<p>Round window (C)</p> Signup and view all the answers

What type of muscle is responsible for the elevation of the upper eyelid?

<p>Levator palpebrae superioris (B)</p> Signup and view all the answers

Which of the following cranial nerves is associated with the olfactory system?

<p>Olfactory nerve (I) (D)</p> Signup and view all the answers

What role does cAMP play in olfactory signal transduction?

<p>It opens cation channels (A)</p> Signup and view all the answers

Which structure contains the calcium carbonate crystals involved in balance in the inner ear?

<p>Otolithic membrane (D)</p> Signup and view all the answers

What is the process called that allows the olfactory system to become less responsive to a continuous odor?

<p>Olfactory adaptation (B)</p> Signup and view all the answers

What is the function of the retinal ganglion cells (RGCs)?

<p>Project visual signals to the brain (B)</p> Signup and view all the answers

What component of the inner ear is responsible for interpreting sound waves?

<p>Organ of Corti (D)</p> Signup and view all the answers

Which brain region is primarily involved in processing olfactory information?

<p>Temporal lobe (D)</p> Signup and view all the answers

Which part of the retina is responsible for the highest visual acuity?

<p>Fovea (A)</p> Signup and view all the answers

Which type of cells in taste buds are responsible for the detection of tastants?

<p>Gustatory receptor cells (C)</p> Signup and view all the answers

What are the five known primary tastes recognized in gustation?

<p>Sweet, sour, salty, bitter, and umami (A)</p> Signup and view all the answers

What type of receptor cells are responsible for the sense of taste?

<p>Gustatory receptor cells (B)</p> Signup and view all the answers

How do salty and sour tastes trigger gustatory receptor cells?

<p>Through ion channels that leak cations (C)</p> Signup and view all the answers

What does the suprachiasmatic nucleus help establish in the body?

<p>Circadian rhythm (B)</p> Signup and view all the answers

What is the average lifespan of gustatory receptor cells?

<p>10 days (C)</p> Signup and view all the answers

What type of sensory system is associated with specific organ structures like vision and hearing?

<p>Special sense (A)</p> Signup and view all the answers

What structure is referred to as the white of the eye?

<p>Sclera (B)</p> Signup and view all the answers

What happens to olfactory receptor neurons when they are damaged?

<p>They are replaced by new ones (D)</p> Signup and view all the answers

What mechanism allows gustatory receptor cells to increase their detection of chemicals?

<p>Gustatory hairs (B)</p> Signup and view all the answers

How do olfactory signals differ from other sensory signals?

<p>They do not synapse with the thalamus (D)</p> Signup and view all the answers

What is the relationship between olfaction and memory/emotion?

<p>Smells can trigger strong emotional memories (C)</p> Signup and view all the answers

What is the primary function of the fovea centralis in vision?

<p>It provides high cone density for detailed vision. (A)</p> Signup and view all the answers

How does binocular vision enhance our perception?

<p>It combines the visual fields of both eyes for depth perception. (D)</p> Signup and view all the answers

What is the role of the optic chiasm in visual processing?

<p>To separate visual information from both eyes. (A)</p> Signup and view all the answers

What primarily makes up the outer ear?

<p>The pinna and external auditory canal. (A)</p> Signup and view all the answers

What determines the pitch of a sound?

<p>The frequency of the sound waves. (B)</p> Signup and view all the answers

What is the main function of the tympanic membrane?

<p>To vibrate in response to sound waves. (C)</p> Signup and view all the answers

Which structure connects the middle ear to the throat for pressure equalization?

<p>Eustachian tube. (B)</p> Signup and view all the answers

What is the consequence of conductive hearing loss?

<p>Impairment of soundwave transmission to the inner ear. (D)</p> Signup and view all the answers

What initiates the process of hearing?

<p>The vibration of air molecules. (D)</p> Signup and view all the answers

In terms of vision, how is information processed in the brain?

<p>In a lateralized manner across the brain hemispheres. (C), Sequentially from the retina to various brain regions. (D)</p> Signup and view all the answers

What is the function of the auditory ossicles?

<p>To amplify and transmit vibrations to the oval window. (A)</p> Signup and view all the answers

Which part of the brain primarily receives and processes visual information?

<p>Occipital lobe. (B)</p> Signup and view all the answers

What type of equilibrium does the inner ear help to detect?

<p>Static and dynamic equilibrium. (A)</p> Signup and view all the answers

Which of the following is NOT a consequence of improper functioning of the tympanic membrane?

<p>Loss of balance. (D)</p> Signup and view all the answers

What typically causes myopia?

<p>An eye length that is too long (A)</p> Signup and view all the answers

What is hyperopia commonly referred to as?

<p>Far-sightedness (A)</p> Signup and view all the answers

Which type of visual aid can correct myopia and hyperopia?

<p>Glasses that add layers to refract light (D)</p> Signup and view all the answers

What occurs during the dark current in photoreceptor cells?

<p>Cells remain depolarized (D)</p> Signup and view all the answers

What happens to retinal when it absorbs a photon?

<p>It converts to trans-retinal (B)</p> Signup and view all the answers

What is the role of retinal isomerase after photobleaching?

<p>To convert trans-retinal back to cis-retinal (B)</p> Signup and view all the answers

Why are rods more sensitive to light than cones?

<p>Rods can continuously photobleach (D)</p> Signup and view all the answers

What happens to photoreceptors in bright light conditions?

<p>They become hyperpolarized (D)</p> Signup and view all the answers

What is the typical duration for rods to reach full sensitivity in darkness?

<p>30 to 40 minutes (A)</p> Signup and view all the answers

What symptom do individuals experience upon waking up in bright conditions?

<p>Photobleaching of rod receptors (D)</p> Signup and view all the answers

Which of the following proteins do rods use to detect light?

<p>Rhodopsin (A)</p> Signup and view all the answers

How does phototransduction primarily occur in rods and cones?

<p>Via chemical reactions triggered by light (C)</p> Signup and view all the answers

What is primarily responsible for the repolarization of photoreceptor cells in light conditions?

<p>Closure of sodium channels (C)</p> Signup and view all the answers

What is the primary function of olfactory sensory neurons?

<p>To detect odorants in the nasal cavity (C)</p> Signup and view all the answers

Which term describes the molecules that activate our sensations of smell?

<p>Odorants (D)</p> Signup and view all the answers

Which part of the olfactory system contains the olfactory sensory neurons?

<p>Olfactory epithelium (A)</p> Signup and view all the answers

What type of cells within the olfactory epithelium support the structure of the tissue?

<p>Supporting cells (C)</p> Signup and view all the answers

In which area of the body are olfactory receptor proteins mainly located?

<p>Dendrites of olfactory sensory neurons (A)</p> Signup and view all the answers

What causes the salty taste sensation in gustatory cells?

<p>Dissociation of NaCl into Na+ and Cl- ions (C)</p> Signup and view all the answers

How do sweet, bitter, and umami tastes primarily differ from salty and sour tastes?

<p>They bind to protein receptors without entering the cells (B)</p> Signup and view all the answers

What type of molecules typically activate umami receptors in gustatory cells?

<p>Amino acids, particularly L-glutamate (D)</p> Signup and view all the answers

What is the role of the facial and glossopharyngeal cranial nerves in taste sensation?

<p>They transmit taste sensations from the tongue to the brain (B)</p> Signup and view all the answers

What protective function do the eyelids serve for the eye?

<p>They block particles and prevent abrasions (B)</p> Signup and view all the answers

What is the role of the lacrimal canaliculus?

<p>It drains tears into the lacrimal sac. (A)</p> Signup and view all the answers

Which muscle is primarily responsible for elevating and retracting the upper eyelid?

<p>Levator palpebrae superioris (A)</p> Signup and view all the answers

What structure is responsible for the adjustment of the lens to focus light on the retina?

<p>Ciliary body (C)</p> Signup and view all the answers

Which part of the eye is primarily involved in photoreception?

<p>Retina (A)</p> Signup and view all the answers

What is the primary function of the iris?

<p>To adjust light entering the eye (C)</p> Signup and view all the answers

Which layer of the eye is primarily vascularized and supplies blood to the eyeball?

<p>Vascular tunic (D)</p> Signup and view all the answers

What is the primary function of basal cells in the olfactory sensory neurons?

<p>To regenerate and replace olfactory sensory neurons (D)</p> Signup and view all the answers

Which cranial nerve carries olfactory information to the olfactory bulb?

<p>Olfactory nerve (A)</p> Signup and view all the answers

What phenomenon explains the initial strong perception of an odor that diminishes over time?

<p>Negative feedback mechanisms (A)</p> Signup and view all the answers

Which taste sensation is activated by sodium ions entering the gustatory receptor cells?

<p>Salty (B)</p> Signup and view all the answers

What role do gustatory receptor cells in taste buds play?

<p>Responding to chemical stimuli and activating sensory nerves (C)</p> Signup and view all the answers

What are the primary components of the retina?

<p>Photoreceptors, ganglion cells, bipolar cells (C)</p> Signup and view all the answers

What condition may result from diabetes affecting the retina?

<p>Diabetic retinopathy (A)</p> Signup and view all the answers

What is the role of the ciliary body in vision?

<p>To change the shape of the lens for focusing (B)</p> Signup and view all the answers

What happens to the lens as a person ages?

<p>It becomes stiffer and less responsive (D)</p> Signup and view all the answers

What condition results from the retinal detachment?

<p>Permanent blindness (A)</p> Signup and view all the answers

Which substance primarily fills the posterior cavity of the eye?

<p>Vitreous humor (C)</p> Signup and view all the answers

What phenomenon occurs when light is not properly focused on the retina?

<p>Refraction error (A)</p> Signup and view all the answers

What is the role of the vitreous humor in the eye?

<p>Keeps the retina pressed against the walls of the eye (C)</p> Signup and view all the answers

What is the primary cause of myopia?

<p>The eye is too long from anterior to posterior (C)</p> Signup and view all the answers

Which condition is characterized by difficulty focusing on near objects due to an eye that is too short?

<p>Hyperopia (A)</p> Signup and view all the answers

What is the role of retinal isomerase in phototransduction?

<p>To convert trans-retinal back to cis-retinal (B)</p> Signup and view all the answers

What does photobleaching lead to in the context of rod function?

<p>Cessation of the dark current (D)</p> Signup and view all the answers

During the dark current, what is the membrane potential of receptor cells?

<p>-30mV (C)</p> Signup and view all the answers

What type of visual system operates during high light intensity conditions?

<p>Photopic system (C)</p> Signup and view all the answers

What does the term 'dark current' refer to?

<p>The flow of sodium ions into the photoreceptor cells (D)</p> Signup and view all the answers

What is the function of the rods in the retina compared to cones?

<p>More sensitive to light and best for low-light conditions (A)</p> Signup and view all the answers

What happens to the rods in bright light conditions?

<p>They are continuously photobleached and inactive (B)</p> Signup and view all the answers

What part of the nasal cavity is primarily responsible for detecting odors?

<p>Olfactory epithelium (A)</p> Signup and view all the answers

What role do olfactory sensory neurons play in the sense of smell?

<p>They detect odorants through their dendrites. (D)</p> Signup and view all the answers

What types of cells in the olfactory epithelium are responsible for maintaining its structure?

<p>Supporting cells (B)</p> Signup and view all the answers

Which term refers to chemicals that cause sensations of smells and odors?

<p>Odorants (D)</p> Signup and view all the answers

What happens to olfactory sensory neurons when they are damaged?

<p>They are replaced by basal cells. (D)</p> Signup and view all the answers

What causes the depolarization of gustatory receptor cells in response to salty taste?

<p>Sodium ions (Na+) (A)</p> Signup and view all the answers

Which molecule specifically activates umami taste receptors?

<p>L-glutamate (A)</p> Signup and view all the answers

What type of proteins are activated by sweet, bitter, and umami tastants in gustatory cells?

<p>G proteins (B)</p> Signup and view all the answers

What role do the cranial nerves VII and IX play in taste sensation?

<p>They carry taste signals to the brain. (C)</p> Signup and view all the answers

What structure does each lacrimal punctum lead to?

<p>Lacrimal canaliculus (C)</p> Signup and view all the answers

Which muscle is responsible for laterally rotating the eye in opposition to the superior oblique muscle?

<p>Inferior oblique (D)</p> Signup and view all the answers

What part of the eye adjusts the amount of light entering by controlling the pupil size?

<p>Iris (A)</p> Signup and view all the answers

What is the main function of the ciliary body in the eye?

<p>Adjusting lens shape for focus (B)</p> Signup and view all the answers

Which layer of the eye contains the blood vessels that supply nutrients to the eyeball?

<p>Vascular tunic (D)</p> Signup and view all the answers

What is the function of the suspensory ligaments of the eye?

<p>Holding the lens in place and shaping it (B)</p> Signup and view all the answers

Which layer of the retina is responsible for photoreception?

<p>Neural layer (C)</p> Signup and view all the answers

What is the primary function of the aqueous humor in the anterior cavity of the eye?

<p>Maintaining intraocular pressure (B)</p> Signup and view all the answers

What occurs to the sensitivity of the sense of olfaction as a person ages?

<p>It gradually becomes less sensitive due to decreased turnover of olfactory neurons. (A)</p> Signup and view all the answers

Which condition results from the stiffening of the lens with age?

<p>Presbyopia (B)</p> Signup and view all the answers

Which type of feedback mechanism occurs in olfactory neurons after action potentials are generated?

<p>Inhibition that blocks the ion channels contributing to action potentials. (B)</p> Signup and view all the answers

What does the ciliary body control in the lens of the eye?

<p>The thickness and shape of the lens (C)</p> Signup and view all the answers

What major visually impairing condition may result from high intraocular pressure?

<p>Glaucoma (C)</p> Signup and view all the answers

How do gustatory receptor cells communicate the presence of different tastes?

<p>By responding to specific chemicals that stimulate them. (D)</p> Signup and view all the answers

Which structure converts light stimulation into action potentials in the retina?

<p>Photoreceptors (A)</p> Signup and view all the answers

What is the lifespan of gustatory receptor cells?

<p>Approximately 10 days, after which they regenerate. (A)</p> Signup and view all the answers

Which response correctly identifies the known primary tastes?

<p>Salty, bitter, sweet, sour, savory. (D)</p> Signup and view all the answers

How does light refract as it enters the eye?

<p>It is refracted at each interface between different substances. (A)</p> Signup and view all the answers

What happens when there is a retinal detachment?

<p>The retina falls away from the walls of the eye. (D)</p> Signup and view all the answers

Which layer of the retina contains the first-order sensory neurons?

<p>Inner nuclear layer (A)</p> Signup and view all the answers

What visual effect does emmetropia describe?

<p>Normal, clear vision without defects (D)</p> Signup and view all the answers

What condition results from an eye that is too long from anterior to posterior?

<p>Myopia (C)</p> Signup and view all the answers

Which visual aid is commonly used to correct myopia?

<p>Contact lenses (C)</p> Signup and view all the answers

What happens to sodium channels in photoreceptor cells when light is detected?

<p>They close, preventing an influx of Na+ and Ca2+ (A)</p> Signup and view all the answers

What is the process called when the retinal molecule detaches from the opsin pigment?

<p>Photobleaching (B)</p> Signup and view all the answers

Which protein do rods use to detect light?

<p>Rhodopsin (C)</p> Signup and view all the answers

What is the primary role of guanylyl cyclase (GC) in the phototransduction cascade?

<p>To synthesize cGMP (B)</p> Signup and view all the answers

What adaptation occurs in the visual system during prolonged exposure to bright light?

<p>Rods become less sensitive (C)</p> Signup and view all the answers

Which of the following describes the initial change of retinal when it absorbs a photon?

<p>It converts from 11-cis-retinal to 11-trans-retinal (C)</p> Signup and view all the answers

How long does it typically take for rods to regain full light sensitivity after exposure to darkness?

<p>30 to 40 minutes (D)</p> Signup and view all the answers

Which part of the nasal cavity contains olfactory sensory neurons?

<p>Olfactory epithelium (B)</p> Signup and view all the answers

What is the function of basal cells in the olfactory epithelium?

<p>They replace damaged olfactory sensory neurons. (C)</p> Signup and view all the answers

What stimulates the sense of taste in gustatory cells?

<p>Chemical molecules (A)</p> Signup and view all the answers

Which statement accurately describes olfactory receptor proteins?

<p>They bind to odorants on sensory neuron dendrites. (C)</p> Signup and view all the answers

What type of ions causes depolarization in gustatory cells for a salty taste sensation?

<p>Na+ ions (B)</p> Signup and view all the answers

Which taste is primarily recognized through the binding of L-glutamate to specific receptors?

<p>Umami (D)</p> Signup and view all the answers

What structure is responsible for carrying taste sensations from the posterior two-thirds of the tongue?

<p>Glossopharyngeal nerve (D)</p> Signup and view all the answers

Which type of cells do sweet, bitter, and umami tastes primarily activate through their binding mechanisms?

<p>Gustatory receptor cells (A)</p> Signup and view all the answers

What is commonly referred to as pink eye, which affects the inner surface of the eyelids?

<p>Conjunctivitis (D)</p> Signup and view all the answers

What structure do the lacrimal canaliculi drain into?

<p>Lacrimal sac (B)</p> Signup and view all the answers

Which muscle is responsible for laterally rotating the eye?

<p>Lateral rectus (B)</p> Signup and view all the answers

What is the primary function of the iris in the eye?

<p>To regulate the amount of light entering the eye (D)</p> Signup and view all the answers

What is the relationship between the superior and inferior oblique muscles during vertical eye movements?

<p>They move in opposite directions to counteract vertical movement (B)</p> Signup and view all the answers

Which part of the eye transitions between the sclera and the cornea?

<p>Corneal limbus (A)</p> Signup and view all the answers

Which layer of the eye is responsible for supplying blood to the eyeball?

<p>Vascular tunic (D)</p> Signup and view all the answers

What structure is primarily responsible for the drainage of tears from the eye?

<p>Nasolacrimal duct (A)</p> Signup and view all the answers

What is the condition characterized by damage to the blood vessels in the retina due to diabetes?

<p>Diabetic retinopathy (B)</p> Signup and view all the answers

What fluid fills the anterior cavity of the eye?

<p>Aqueous humor (C)</p> Signup and view all the answers

Which process allows the lens to change shape for proper focusing?

<p>Accommodation (C)</p> Signup and view all the answers

What is the potential consequence of high intraocular pressure in the eye?

<p>Glaucoma (C)</p> Signup and view all the answers

What happens to the lens fibers as an individual ages?

<p>They become discolored and cloudy. (D)</p> Signup and view all the answers

What is the inner layer of the retina primarily composed of?

<p>Ganglion cells (A)</p> Signup and view all the answers

What is the function of basal cells in the olfactory system?

<p>They replace damaged olfactory sensory neurons. (B)</p> Signup and view all the answers

What causes distortions or blurriness in vision known as astigmatism?

<p>Irregular shape of the cornea (C)</p> Signup and view all the answers

Which part of the eye is responsible for maintaining its overall shape and preventing distortion?

<p>Vitreous humor (B)</p> Signup and view all the answers

Which mechanism is responsible for the detection of salty tastes by gustatory receptor cells?

<p>Ion channels that leak cations into cells. (A)</p> Signup and view all the answers

What type of vision is described by the term emmetropia?

<p>Normal vision (B)</p> Signup and view all the answers

How does age affect the olfactory system's sensitivity?

<p>It decreases the ability of basal cells to replace neurons. (A)</p> Signup and view all the answers

Which taste sensation is not among the five known primary tastes?

<p>Fruity (C)</p> Signup and view all the answers

What happens to olfactory receptor response over time when exposed to a constant odor?

<p>The receptor cells lose responsiveness and may stop firing. (D)</p> Signup and view all the answers

What condition occurs when the eye is too long from anterior to posterior, causing blurriness at the retina?

<p>Nearsightedness (D)</p> Signup and view all the answers

What effect does hyperopia (far-sightedness) have on vision?

<p>Close objects are out of focus (B)</p> Signup and view all the answers

What is the role of phototransduction in the vision process?

<p>Converting light into electrical signals (A)</p> Signup and view all the answers

Which protein is used by rods to detect purple light?

<p>Rhodopsin (A)</p> Signup and view all the answers

What happens to retinal when it undergoes photobleaching?

<p>It becomes 11-trans-retinal (D)</p> Signup and view all the answers

What is the primary function of retinal isomerase in the photoreceptor cells?

<p>It converts trans-retinal back to cis-retinal (A)</p> Signup and view all the answers

How long does it typically take for the rods to regain full sensitivity in darkness?

<p>30 to 40 minutes (C)</p> Signup and view all the answers

What is the reason cones are less useful in low light conditions compared to rods?

<p>They are less sensitive to light (D)</p> Signup and view all the answers

What happens to sodium channels in the absence of light?

<p>They open, causing depolarization (A)</p> Signup and view all the answers

What type of taste sensation is primarily associated with the presence of L-glutamate?

<p>Umami (D)</p> Signup and view all the answers

Which mechanism is responsible for salty and sour taste sensations in gustatory cells?

<p>Direct entry of ions through specific channels (C)</p> Signup and view all the answers

Which type of receptors are activated when sweet, bitter, or umami tastants bind to gustatory receptor cells?

<p>G protein-coupled receptors (A)</p> Signup and view all the answers

What is a potential evolutionary reason for the bitterness taste response in humans?

<p>To recognize poisonous substances (B)</p> Signup and view all the answers

Which cranial nerve is NOT involved in carrying taste sensations?

<p>Optic nerve (II) (B)</p> Signup and view all the answers

What do olfactory sensory neurons primarily detect?

<p>Chemical odorants (A)</p> Signup and view all the answers

Which cells in the olfactory epithelium assist in maintaining its structure?

<p>Supporting cells (B)</p> Signup and view all the answers

How are sensations of smell activated?

<p>By chemicals inhaled through the nasal cavity (A)</p> Signup and view all the answers

What is the main function of olfactory receptor proteins?

<p>To bind with odorants (B)</p> Signup and view all the answers

What role do basal cells play in the olfactory sensory neurons?

<p>They serve as stem cells to replace damaged olfactory neurons. (C)</p> Signup and view all the answers

How does the sense of smell differ from the other senses in terms of brain processing?

<p>It bypasses thalamic filtering and connects directly to the cerebral cortex. (B)</p> Signup and view all the answers

What is the primary mechanism for detecting salty tastes in gustatory receptor cells?

<p>Leaking of cations through ion channels. (A)</p> Signup and view all the answers

What happens to the olfactory sensory neurons as a person ages?

<p>Their rate of replacement decreases, reducing sensitivity. (A)</p> Signup and view all the answers

How are gustatory receptor cells structured to enhance their function?

<p>They have taste hairs that increase surface area for chemical detection. (C)</p> Signup and view all the answers

What is the role of the lacrimal canaliculus in tear drainage?

<p>It conducts tears to the lacrimal sac. (D)</p> Signup and view all the answers

Which layer of the eye is primarily responsible for photoreception?

<p>Neural tunic (B)</p> Signup and view all the answers

What is the primary function of the ciliary body?

<p>To adjust the lens for focusing. (C)</p> Signup and view all the answers

What part of the eye forms the border between the sclera and cornea?

<p>Corneal limbus (C)</p> Signup and view all the answers

How does the iris control the amount of light entering the eye?

<p>By constricting or dilating the pupil. (D)</p> Signup and view all the answers

Which anatomical structure leads excess tears into the nasal cavity?

<p>Nasolacrimal duct (D)</p> Signup and view all the answers

What is the primary substance found in the anterior cavity of the eye?

<p>Aqueous humor (D)</p> Signup and view all the answers

What is the condition resulting from diabetic damage to the retina's blood vessels?

<p>Diabetic retinopathy (C)</p> Signup and view all the answers

What is the process called that enables the lens to change shape for focusing?

<p>Accommodation (D)</p> Signup and view all the answers

What is the term for normal vision with no refractive errors?

<p>Emmetropia (D)</p> Signup and view all the answers

Which humor in the eye is responsible for maintaining its shape and preventing distortion?

<p>Vitreous humor (A)</p> Signup and view all the answers

What condition can occur if the cornea is not perfectly rounded?

<p>Astigmatism (C)</p> Signup and view all the answers

What is a common effect of aging on the lens of the eye?

<p>Clouding of the lens (B)</p> Signup and view all the answers

Which structure helps to protect the eye from foreign particles?

<p>Conjunctiva (B)</p> Signup and view all the answers

What occurs when light is refracted by the cornea and lens?

<p>The image appears upside-down (C)</p> Signup and view all the answers

What condition is characterized by the focus of an image falling short of the retina?

<p>Myopia (A)</p> Signup and view all the answers

What structure in the retina is responsible for sensory transduction of light?

<p>Rods and cones (C)</p> Signup and view all the answers

What is the effect of dark current on photoreceptor cells?

<p>Depolarization of photoreceptor cells (D)</p> Signup and view all the answers

What happens to the retinal molecule during photobleaching?

<p>It detaches from rhodopsin (A)</p> Signup and view all the answers

What enzyme is responsible for converting trans-retinal back to cis-retinal?

<p>Retinal isomerase (A)</p> Signup and view all the answers

How long does it typically take for rods to fully adapt to darkness?

<p>30 to 40 minutes (A)</p> Signup and view all the answers

What is the main reason rods are often inactive during the day?

<p>They are continuously photobleached (C)</p> Signup and view all the answers

What type of protein do cones use to detect color in vision?

<p>Photopsin (A)</p> Signup and view all the answers

How does the sense of smell uniquely differ from other special senses?

<p>It does not undergo thalamic filtering before reaching the brain (D)</p> Signup and view all the answers

What happens to the sensitivity of olfactory neurons as a person ages?

<p>Sensitivity decreases due to a lower turnover rate of neurons (A)</p> Signup and view all the answers

Which type of cells in the taste buds are responsible for sensing different primary tastes?

<p>Gustatory receptor cells (B)</p> Signup and view all the answers

What is the lifespan of gustatory receptor cells in the taste buds?

<p>10 days (A)</p> Signup and view all the answers

What primary mechanism is responsible for the salty taste sensation?

<p>Dissociation of NaCl into Na+ and Cl- ions (B)</p> Signup and view all the answers

Which taste sensation is specifically activated by the amino acid L-glutamate?

<p>Umami (A)</p> Signup and view all the answers

What role do the facial and glossopharyngeal cranial nerves play in taste perception?

<p>They carry taste sensations to the brain. (D)</p> Signup and view all the answers

What is the function of bitter taste in relation to food intake?

<p>To avoid the ingestion of potentially toxic substances (B)</p> Signup and view all the answers

How does the presence of saliva affect taste sensations over time?

<p>It dilutes and washes away taste compounds. (B)</p> Signup and view all the answers

What role do olfactory receptor proteins play in the sense of smell?

<p>They detect chemicals and produce sensations of smell. (D)</p> Signup and view all the answers

Which of the following describes the olfactory sensory neurons?

<p>They are specialized neurons embedded in the olfactory epithelium. (B)</p> Signup and view all the answers

What type of cells in the olfactory epithelium support the structure and function of olfactory sensory neurons?

<p>Supporting cells (B)</p> Signup and view all the answers

What substances are considered stimulants for our chemical senses of smell and taste?

<p>Odorants and molecules from food (B)</p> Signup and view all the answers

Which of the following accurately describes the general senses?

<p>They provide sensation throughout multiple areas of the body. (D)</p> Signup and view all the answers

What is the function of the lacrimal canaliculus?

<p>To drain tears from the eye to the lacrimal sac (D)</p> Signup and view all the answers

What structure is responsible for controlling the amount of light entering the eye?

<p>Iris (A)</p> Signup and view all the answers

How do the oblique muscles assist in eye movement?

<p>They rotate the eye in coordination with the rectus muscles (C)</p> Signup and view all the answers

Where are the rods and cones located within the eye?

<p>Retina (A)</p> Signup and view all the answers

What does the ciliary body primarily do?

<p>Adjusts the shape of the lens (B)</p> Signup and view all the answers

What occurs in myopia?

<p>The eye is too long, causing images to blur at the retina. (D)</p> Signup and view all the answers

In hyperopia, which of the following is true?

<p>The eye is too short, leading to poor near vision. (D)</p> Signup and view all the answers

During sensory transduction in the retina, what happens to sodium channels in the presence of light?

<p>Sodium channels close causing repolarization of photoreceptor cells. (D)</p> Signup and view all the answers

What is the significance of photobleaching in phototransduction?

<p>It leads to the formation of trans-retinal which initiates signaling. (B)</p> Signup and view all the answers

What role does retinal isomerase play after photobleaching?

<p>It converts trans-retinal back to cis-retinal. (A)</p> Signup and view all the answers

Which statement describes the scotopic and photopic systems?

<p>Scotopic vision is suited for low light conditions using rods. (C)</p> Signup and view all the answers

What is the resting membrane potential of photoreceptor cells in the absence of light?

<p>-30mV (B)</p> Signup and view all the answers

How long does it typically take for rods to reach full light sensitivity after moving from bright light to darkness?

<p>30 to 40 minutes (A)</p> Signup and view all the answers

Which fluid in the anterior cavity of the eye helps maintain its shape?

<p>Aqueous humor (C)</p> Signup and view all the answers

What condition is characterized by the loss of vision due to damage to retinal blood vessels linked with diabetes?

<p>Diabetic retinopathy (B)</p> Signup and view all the answers

What is the result of high intraocular pressure within the eye?

<p>Glaucoma (A)</p> Signup and view all the answers

What happens to the lens of the eye as a person ages that affects vision?

<p>It becomes cloudier (C)</p> Signup and view all the answers

Which layer of the retina contains the photoreceptor cells?

<p>Outermost layer (B)</p> Signup and view all the answers

What causes light to be bent as it enters the eye?

<p>Cornea and lens (C)</p> Signup and view all the answers

What condition may develop if the vitreous humor changes and the retina detaches?

<p>Retinal detachment (A)</p> Signup and view all the answers

Which term describes normal, clear vision without defects in focus or refraction?

<p>Emmetropia (C)</p> Signup and view all the answers

Flashcards

Olfaction

The sense of smell, detected by chemicals inhaled through the nasal cavity.

Olfactory Sensory Neurons

Specialized neurons that detect odorants in the nose.

Odorants

Chemicals that cause smells.

Olfactory Epithelium

The area in the nasal cavity containing olfactory sensory neurons and regenerative cells.

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Special Senses

Senses localized in specific areas of the body.

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Olfactory Receptor Proteins

Proteins on the neurons that detect odorants.

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Cribriform Plate

Bone structure through which olfactory neurons pass to the brain.

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Olfactory Bulb

Brain region receiving signals from olfactory neurons.

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Basal Cells

Stem cells that replace olfactory sensory neurons.

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Olfactory Nerve

Axons of olfactory sensory neurons that carry smell signals to the brain.

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Olfactory Pathway

The route smell signals take through the brain.

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Primary Olfactory Cortex

Brain region processing initial smell information.

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Limbic System

Brain region linked to emotions and memories.

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Olfactory Discrimination

Ability to differentiate between different smells.

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Gustation

The sense of taste.

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Papillae

Bumpy structures on the tongue containing taste buds.

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Taste Buds

Structures containing taste receptors.

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Gustatory Receptor Cells

Specialized cells that detect taste stimuli.

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Gustatory Receptor

Taste receptor proteins that identify different tastes.

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Primary Tastes

Basic tastes recognized by humans (sour, salty, sweet, bitter, savory).

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Generator potential

Changes in membrane potential that can trigger action potentials.

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Salty Taste Mechanism

Sodium ions (Na+) entering gustatory cells through Na+ channels causing depolarization.

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Sour Taste Mechanism

Hydrogen ions (H+) entering gustatory cells through H+ channels causing depolarization.

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Sweet Taste Mechanism

Tastants bind to protein receptors, triggering signal transduction and depolarization, not entering the cells.

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Bitter Taste Mechanism

Bitter compounds bind to protein receptors, either depolarizing or hyperpolarizing gustatory cells.

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Umami Taste Mechanism

L-glutamate binds to protein receptors, causing depolarization, relating to savory/protein-rich foods.

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Facial Nerve (VII)

Cranial nerve carrying taste information from the anterior tongue.

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Glossopharyngeal Nerve (IX)

Cranial nerve carrying taste information from the posterior tongue.

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Vagus Nerve

Cranial nerve carrying some posterior taste and gag reflex information.

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Conjunctiva

Thin membrane lining inner eyelid surface and covering the white of eye.

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Lacrimal Apparatus

Structure producing and draining tears, washing away foreign objects.

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Pink Eye

Inflammation of the conjunctiva, often viral or bacterial.

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Eyelids

Protective coverings of the eye, preventing dust and debris.

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Depolarization

Change in electrical potential causing a change in neurons, triggering nerve signaling.

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Lacrimal Punctum

A tiny opening at the inner corner of each eyelid where tears drain into the lacrimal canaliculus.

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Lacrimal Canaliculus

A tiny channel that carries tears from the lacrimal punctum to the lacrimal sac.

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Lacrimal Sac

A small pouch that collects tears from the lacrimal canaliculi before they flow into the nasolacrimal duct.

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Nasolacrimal Duct

A duct carrying tears from the lacrimal sac to the nasal cavity.

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Extrinsic Eye Muscles

Muscles located outside the eye that control eye movement and focus.

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Superior Rectus Muscle

An extrinsic eye muscle that rotates the eye upward.

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Inferior Rectus Muscle

An extrinsic eye muscle that rotates the eye downward.

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Lateral Rectus Muscle

An extrinsic eye muscle that rotates the eye outward (away from the nose).

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Medial Rectus Muscle

An extrinsic eye muscle that rotates the eye inward (towards the nose).

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Superior Oblique Muscle

An extrinsic eye muscle that rotates the eye downward and outward, helping with specific eye movements.

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Inferior Oblique Muscle

An extrinsic eye muscle that rotates the eye upward and outward, helping with specific eye movements.

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Trochlea

A pulley-like piece of cartilage that guides the tendon of the superior oblique muscle.

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Levator Palpebrae Superioris Muscle

A muscle located in the orbit that elevates and retracts the upper eyelid.

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Fibrous Tunic

The outermost layer of the eye, consisting of the sclera and cornea.

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Sclera

The white, opaque part of the fibrous tunic that covers most of the eye.

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Cornea

The transparent front part of the fibrous tunic that allows light to enter the eye.

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Myopia

Nearsightedness, a condition where distant objects appear blurry because the eye focuses images in front of the retina.

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Hyperopia

Farsightedness, a condition where nearby objects appear blurry because the eye focuses images behind the retina.

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Astigmatism

A vision defect where the eye's cornea or lens has an irregular shape, causing distorted vision.

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Phototransduction

The process by which light energy is converted into electrical signals in the retina.

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Dark Current

The continuous release of neurotransmitter glutamate from photoreceptor cells in the absence of light.

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Photobleaching

The process where light causes retinal to detach from opsin, resulting in a breakdown of cGMP.

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Retinal Isomerase

An enzyme that converts trans-retinal back to cis-retinal, resetting the photoreceptor for light detection.

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Photopic System

The visual system responsible for high-intensity light vision, primarily using cones.

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Scotopic System

The visual system responsible for low-intensity light vision, primarily using rods.

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Rods

Photoreceptor cells in the retina responsible for detecting light and motion, particularly in low light.

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Retinal

A light-sensitive molecule derived from vitamin A, essential for vision.

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Opsin

A protein that binds to retinal, forming a light-sensitive pigment in photoreceptor cells.

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cGMP

Cyclic guanosine monophosphate, a molecule that keeps sodium channels open in photoreceptor cells, allowing the dark current.

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Photoreceptors

Specialized cells in the retina that convert light into electrical signals.

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Retina Layers

The retina is organized into three layers: the photoreceptor layer, the bipolar/horizontal cell layer, and the ganglion cell layer.

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Diabetic Retinopathy

A complication of diabetes affecting the blood vessels in the retina, potentially leading to vision loss.

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Rods and Cones

Two types of photoreceptor cells: Rods detect light intensity (dim light) and cones detect color.

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Bipolar Cells

First-order sensory neurons in the retina that receive signals from photoreceptors and transmit them to ganglion cells.

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Ganglion Cells

Neurons in the retina that receive signals from bipolar cells and send their axons to the brain.

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Optic Nerve

Bundle of axons from ganglion cells that transmits visual information to the brain.

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Aqueous Humor

Clear, watery fluid in the anterior cavity of the eye that maintains eye shape and provides nutrition.

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Vitreous Humor

Thick, jelly-like substance filling the posterior cavity of the eye, helping maintain eye shape and hold the retina in place.

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Intraocular Pressure

Pressure within the eye, related to the amount of aqueous humor.

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Glaucoma

A condition causing damage to the optic nerve due to high intraocular pressure, leading to vision loss.

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Retinal Detachment

Condition where the retina pulls away from the back of the eye, potentially causing vision loss.

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Accommodation

The process of changing the lens shape to focus on objects at different distances.

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Presbyopia

Age-related loss of accommodation, making it difficult to focus on near objects.

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Fovea Centralis

A small region in the center of the retina with a high density of cones, responsible for sharp central vision.

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Binocular Vision

The ability to perceive depth and distance using both eyes, where the visual fields overlap.

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Nasal Retina

The medial half of the retina, receiving light from the opposite visual field.

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Temporal Retina

The lateral half of the retina, receiving light from the same visual field.

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Optic Chiasm

The point where the optic nerves from each eye cross over, allowing information from the opposite visual field to reach the brain.

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Lateral Geniculate Nucleus (LGN)

A structure in the thalamus that receives visual information from the optic nerve and processes it before sending it to the cortex.

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Optic Radiations

Axons of the LGN neurons that project to the primary visual cortex in the occipital lobe.

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Primary Visual Cortex

The area in the occipital lobe where conscious perception of vision occurs.

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Static Equilibrium

The sense of head position relative to gravity.

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Dynamic Equilibrium

The sense of linear and rotational movement.

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Auditory Ossicles

Three tiny bones in the middle ear (malleus, incus, stapes) that transmit vibrations from the eardrum to the oval window.

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Oval Window

A membrane-covered opening separating the middle ear from the inner ear, receiving vibrations from the stapes.

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Perilymph

Fluid in the inner ear that transmits sound vibrations from the oval window.

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Conduction Hearing Loss

Hearing loss caused by problems in the outer or middle ear, preventing sound vibrations from reaching the inner ear efficiently.

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Eustachian Tube

A tube connecting the middle ear to the throat, equalizing pressure on both sides of the eardrum.

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Otitis Media

Infection of the middle ear, often caused by bacteria entering through the Eustachian tube. It can cause pain, fever, and hearing loss.

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Tympanic Membrane

The eardrum separating the outer ear from the middle ear, vibrating to transmit sound.

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Ossicles

Three tiny bones in the middle ear (malleus, incus, stapes) that amplify sound vibrations.

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What are the three ossicles?

The three bones in the middle ear are the malleus, incus, and stapes. They are connected in a chain and transmit sound vibrations from the tympanic membrane to the oval window.

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Tympanic Reflex

Muscular contraction that partially immobilizes the ossicles to protect the inner ear from loud sounds.

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Bony Labyrinth

Hollow space in the temporal bone filled with perilymph fluid, containing the structures of the inner ear.

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Membranous Labyrinth

Hollow membranous structure within the bony labyrinth, filled with endolymph fluid and containing receptor cells.

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Organ of Corti

The structure on the basilar membrane within the cochlea where sound is detected.

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Vestibular Duct

The space in the cochlea where perilymph vibrates, traveling around the cochlea.

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Helicotrema

The structure where the vestibular duct joins the tympanic duct, at the apex of the cochlea.

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Basilar Membrane

Membrane within the cochlea that vibrates in response to specific frequencies of sound.

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Tonotopic Arrangement

Organisation of the auditory system where specific frequencies of sound are processed in specific locations.

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Auditory Cortex

The area of the brain that receives and processes sound information.

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What are the auditory reflexes controlled by?

Auditory reflexes are controlled by the inferior colliculus in the midbrain.

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What structure receives auditory information from the inferior colliculus?

The medial geniculate nucleus (MGN) of the thalamus receives auditory information from the inferior colliculus.

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What is the role of the primary auditory cortex?

The primary auditory cortex in the temporal lobe is responsible for our conscious awareness of sounds.

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How does the vestibular system detect static equilibrium?

Static equilibrium, or the position of the head relative to gravity, is detected by the maculae within the utricle and saccule.

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What detects rotational movements in the vestibular system?

Rotational movements are detected by the cristae within the ampullae of the semicircular canals.

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What is the role of the vestibular nuclei?

The vestibular nuclei in the pons and medulla receive information from the vestibular system and project to various areas, including the cerebellum, cranial nerve nuclei, and the spinal cord.

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What is the vestibular ocular reflex (VOR)?

The vestibular ocular reflex (VOR) is a reflex that allows us to maintain gaze on an object even when our head is moving.

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What is nystagmus?

Nystagmus is a rapid back and forth movement of the eyes that can occur due to sensory adaptation in the vestibular system, as seen after spinning.

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How does the vestibular system contribute to our sense of body position?

The vestibular nuclei project to the sensory cortices, combining information from the vestibular system, proprioception, and vision to provide a sense of body position.

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What is an alkaloid?

A substance, often from plants, that's chemically basic (alkaline) and makes things taste bitter.

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Amacrine cell

A type of cell in the retina that helps process early images by connecting to bipolar cells.

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Ampulla

The base of a semicircular canal in the ear where hair cells detect head rotation.

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Pinna

The fleshy, outer part of the ear that catches sound waves.

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What is a bipolar cell?

A cell in the retina that connects photoreceptors to the ganglion cells, passing visual information.

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Choroid

Highly vascular tissue in the eye supplying the outer retina with blood.

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Ciliary body

A smooth muscle structure in the eye that controls the lens shape for focusing.

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What is the cochlea?

The auditory part of the inner ear, containing structures that convert sound vibrations into electrical signals.

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Cochlear duct

A space inside the cochlea containing the organ of Corti, surrounded by fluid.

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Contralateral

Meaning 'on the opposite side,' like nerve fibers crossing the midline of the brain.

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Cupula

A structure in the ear that bends hair cells when the head rotates, triggering balance.

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What is the definition of 'equilibrium'?

The sense of balance that tells you about your head's position and movement.

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Extraocular muscle

One of six muscles that control eye movement by attaching to the eye's surface.

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What is olfaction?

Olfaction is the sense of smell, which is triggered by chemicals inhaled through the nasal cavity.

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What is the olfactory epithelium?

The olfactory epithelium is a specialized area in the nasal cavity that contains sensory neurons, basal cells, and supporting cells, all of which are crucial for detecting smells.

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How do odorants trigger smell?

Odorants are chemicals that bind to receptor proteins on the dendrites of olfactory sensory neurons, triggering a signal that travels to the brain.

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What are the main parts of the olfactory system?

The olfactory system includes the olfactory epithelium in the nose, the olfactory bulb in the brain, and the olfactory nerve connecting them.

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What is the role of the olfactory bulb?

The olfactory bulb is a structure in the brain that receives signals from the olfactory sensory neurons and processes them into a recognizable smell.

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Salty Taste

Caused by Na+ ions entering gustatory cells through Na+ channels, leading to depolarization.

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Sour Taste

Caused by H+ ions entering gustatory cells through H+ channels, leading to depolarization.

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Sweet, Bitter, and Umami Taste

Tastants bind to protein receptors on gustatory cells, triggering signal transduction and depolarization, without entering the cells.

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Bitter Taste Function

May have evolved to protect us from poisons by triggering a gag reflex.

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Umami Taste

Caused by L-glutamate binding to protein receptors on gustatory cells, triggering depolarization.

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What happens when coffee molecules bind to olfactory receptor proteins?

They activate a G protein, which in turn activates adenylyl cyclase to produce cAMP, a second messenger. cAMP then opens cation channels, allowing Na+ and Ca2+ to enter the cell, causing depolarization and triggering action potentials in the olfactory neuron.

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What is olfactory discrimination?

The ability to differentiate between different odorants or smells. The human nose can detect a vast range of scents.

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How does our sense of smell adapt to odors?

Once generator and action potentials occur in an olfactory neuron, negative feedback mechanisms block the ion channels involved, reducing the signal. This is why a strong odor might fade over time, even if it's still present.

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What are the five primary tastes?

Sour, salty, sweet, bitter, and umami (savory). Each taste is detected by specialized gustatory receptor cells on the tongue.

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How are salty and sour tastes detected?

Salty and sour tastes are detected by gustatory receptor cells that have ion channels that leak cations into cells. Salty tastes are due to the presence of sodium ions (Na+), while sour tastes are caused by hydrogen ions (H+).

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Vascular Tunic

The middle layer of the eye, containing the choroid, ciliary body, and iris, supplying blood and regulating light.

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What are the three layers of the retina?

The retina is composed of three layers: the outermost layer containing photoreceptor cells (rods and cones), the middle layer with bipolar cells and horizontal cells, and the innermost layer consisting of ganglion cells.

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What is diabetic retinopathy?

Diabetic retinopathy is a complication of diabetes that damages the blood vessels in the retina, potentially leading to vision loss.

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What is aqueous humor?

Aqueous humor is a clear, watery fluid that fills the anterior cavity of the eye, maintaining its shape and providing nutrients.

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What is vitreous humor?

Vitreous humor is a thick, jelly-like substance that fills the posterior cavity of the eye, maintaining its shape and holding the retina in place.

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What is accommodation?

Accommodation is the process of changing the lens shape to focus on objects at different distances.

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What is presbyopia?

Presbyopia is an age-related loss of accommodation, making it difficult to focus on near objects.

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What is emmetropia?

Emmetropia describes normal, clear vision with no defects in focus or refraction.

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What is astigmatism?

Astigmatism is a vision defect where the cornea or lens has an irregular shape, causing distorted vision.

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What are special senses?

Senses localized to specific organs and tissues, like taste, smell, sight, balance, and hearing.

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What does the olfactory epithelium contain?

It contains olfactory sensory neurons (smell detectors), basal cells (to replace damaged neurons), and supporting cells for structure.

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What are odorants?

Chemicals that trigger the sensation of smell when they bind to olfactory receptor proteins.

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What is the function of the cribriform plate?

It is a bone structure that allows olfactory neurons to pass from the nasal cavity into the brain.

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Olfactory Sensory Neuron Turnover

Olfactory sensory neurons are constantly replaced by new ones from basal cells, but this process slows down with age, leading to reduced sense of smell.

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What is the olfactory tract?

The olfactory tract is a bundle of axons that connect the olfactory bulb to various brain regions, carrying smell information.

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Unique Olfactory Pathway

Olfaction is unique because it bypasses the thalamus, directly connecting to the cerebral cortex, explaining how smells trigger strong memories and emotions.

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Olfactory Receptor Protein Activation

When odorants bind to olfactory receptor proteins, they activate a G protein, which then activates an enzyme to produce cAMP, opening ion channels and causing depolarization.

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Taste Buds and Gustatory Receptor Cells

Taste buds are small structures on the tongue containing gustatory receptor cells, which detect chemicals in the oral cavity and send taste signals to the brain.

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What are the five basic tastes?

The five basic tastes are sweet, sour, salty, bitter, and umami. Each of these tastes is detected by specific receptor cells on the tongue and palate, and each responds to a different type of chemical stimulus.

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How do sweet, bitter, and umami tastes work?

Sweet, bitter, and umami tastes are initiated by tastant molecules binding to specific protein receptors on the membranes of gustatory cells. The binding triggers signal transduction pathways, leading to depolarization of the gustatory cell and the sensation of taste.

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How are salty and sour tastes different from sweet, bitter, and umami?

Salty and sour tastes rely on ions entering the gustatory cells. Na+ ions for salty and H+ ions for sour. These ions cause depolarization and initiate the taste signal.

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What is the function of the lacrimal apparatus?

The lacrimal apparatus is responsible for producing and draining tears. Tears protect the eye by washing away foreign particles and debris, keeping the surface of the eye moist and preventing infections.

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Eyebrows and eyelids

Eyebrows and eyelids are protective structures surrounding the eye. Eyebrows help prevent sweat and debris from entering the eye, while eyelids protect the eye from abrasions and block light.

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What are the special senses?

Special senses are highly specialized senses that rely on specific organs and tissues for detection. They include smell, taste, vision, hearing, and equilibrium.

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What causes salty taste?

Sodium ions (Na+) enter gustatory cells through Na+ channels, causing depolarization, leading to a salty sensation.

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What causes sour taste?

Hydrogen ions (H+) enter gustatory cells through H+ channels, causing depolarization, leading to a sour sensation.

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Why are bitter tastes important?

Bitter tastes can signal toxins, triggering the gag reflex to prevent ingestion of harmful substances.

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What is umami taste?

Umami, or savory taste, is triggered by the amino acid L-glutamate binding to protein receptors in gustatory cells.

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What are taste buds?

Taste buds are small structures on the tongue and palate that contain specialized cells called gustatory receptor cells.

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How do we taste salty and sour?

Salty and sour tastes are detected by gustatory receptor cells that have ion channels. Sodium ions (Na+) for salty, and Hydrogen ions (H+) for sour, enter the cells, causing depolarization.

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What are gustatory receptor cells?

Specialized cells within taste buds that detect the presence of chemicals dissolved in saliva.

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What does it mean for olfactory neurons to have 'constant turnover'?

Olfactory sensory neurons are constantly being replaced by new neurons. Basal cells, which function as stem cells, divide and differentiate to replace damaged or dead olfactory neurons.

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What are rods and cones?

Rods and cones are photoreceptor cells found in the retina. Rods are responsible for detecting light intensity and are essential for vision in low light conditions. Cones are responsible for detecting color and provide sharp central vision.

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What is the function of aqueous humor?

Aqueous humor is a clear, watery fluid found in the anterior cavity of the eye. It helps maintain the shape of the eye, provides nutrients to the cornea and lens, and removes waste products.

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What is myopia?

Myopia, or nearsightedness, is a refractive error where the eye focuses light in front of the retina, causing distant objects to appear blurry. This is due to an elongated eyeball.

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What is hyperopia?

Hyperopia, or farsightedness is a refractive error where the eye focuses light behind the retina, causing near objects to appear blurry. This is due to a shorter eyeball.

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What are the basic tastes we can detect?

Humans can identify five primary tastes: sour, salty, sweet, bitter, and savory (umami).

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How Olfactory Receptors Work

When odorants bind to olfactory receptor proteins, they activate a G protein, which in turn activates adenylyl cyclase to produce cAMP. cAMP then opens cation channels, allowing Na+ and Ca2+ into the cell, causing depolarization and triggering action potentials.

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Taste Buds: Sensory Structures of Gustation

Small structures on the tongue, containing taste receptor cells (gustatory receptor cells) that are exposed to chemicals in the oral cavity through tiny openings. They have taste hairs (gustatory hairs) that increase their surface area for chemical detection.

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What are the 5 basic tastes?

The 5 basic tastes are salty, sour, sweet, bitter, and umami.

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What are the mechanisms of salty and sour tastes?

Salty taste occurs when sodium ions (Na+) enter through channels in taste receptor cells, while sour taste is triggered by hydrogen ions (H+) entering through their respective channels, both causing depolarization.

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How are sweet, bitter, and umami tastes different?

Sweet, bitter, and umami tastes involve tastant molecules binding to specific protein receptors on the taste receptor cell membranes, triggering signal transduction pathways, instead of entering the cell.

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What is the function of bitter taste?

Bitter taste likely evolved to protect us from ingesting toxins, often found in plants. It can trigger the gag reflex to avoid swallowing harmful substances.

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What causes umami taste?

Umami, or savory, is triggered by the binding of the amino acid L-glutamate to protein receptors. It's associated with protein-rich foods like meat, mushrooms, and tomatoes.

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What are the differences between rods and cones?

Cones are responsible for color vision and work best in bright light, while rods are more sensitive to light and allow us to see in dim light. Hence, cones are responsible for the photopic system and rods are responsible for scotopic system.

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What is the olfactory bulb?

The olfactory bulb is a region in the brain that receives signals from olfactory sensory neurons. It's involved in processing and interpreting smell information.

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Olfactory Turnover

The constant replacement of damaged or dead olfactory sensory neurons by new ones, a process that slows down with age.

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How does smell trigger memories?

Smell signals reach the limbic system and hypothalamus, areas associated with long-term memory and emotional responses.

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Gustatory Hairs

Small microvilli on gustatory receptor cells that increase surface area for detecting chemicals in the mouth.

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Five Primary Tastes

Sour, salty, sweet, bitter, and umami. Each taste is detected by a specific type of gustatory receptor cell.

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How do sour tastes work?

Acidic hydrogen ions (H+) enter gustatory cells through H+ channels, causing depolarization, leading to a sour sensation.

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Sweet, bitter, umami taste mechanism

These tastes involve tastant molecules binding to specific protein receptors on gustatory cell membranes, triggering signal transduction and depolarization without entering the cells.

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What is umami taste caused by?

Umami, or savory taste, is caused by the binding of the amino acid L-glutamate to protein receptors on gustatory cells.

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Taste nerve pathways

Facial (VII) and glossopharyngeal (IX) cranial nerves carry taste information to the brain, with the vagus nerve also playing a role in gag reflexes.

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Emmetropia

Normal, clear vision with no defects in focus or refraction.

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Study Notes

Special Senses

  • Stars are spies of heaven (Hawaiian proverb)
  • Special senses are localized to specific organs/tissues, unlike general senses
  • Smell (olfaction) and taste (gustation) are chemical senses
  • Olfaction occurs in the olfactory region of the nasal cavity, containing olfactory sensory neurons
  • Olfactory sensory neurons detect odorants via olfactory receptor proteins
  • Olfactory pathway includes olfactory nerves, bulb, and tracts connecting to primary olfactory cortex and limbic system
  • Olfactory discrimination is the ability to distinguish between different odors, genes code for receptor proteins
  • Olfactory pathway is unique as it does not use thalamus
  • Gustation involves chemical detection in the oral cavity
  • Tongue contains papillae with taste buds containing gustatory receptor cells
  • Gustatory receptor cells have taste hairs (microvilli) to detect chemicals
  • Gustatory receptor cells have lifespan of 10 days, replaced by basal cells
  • Five primary tastes: sour, salty, sweet, bitter, and umami (savory)
  • Salty and sour tastes are detected by ion channels, while sweet, bitter, and umami tastes involve binding to protein receptors
  • Taste sensations gradually decrease due to dilution and adaptation
  • Olfaction and Gustation work together

Vision

  • Eyes are located within the bony orbits of the skull
  • Accessory structures like eyelids, eyebrows, and lacrimal apparatus protect the eye
  • Tears produced by lacrimal glands wash away foreign particles
  • Extrinsic muscles move the eye for focus
  • Eye has three layers: fibrous tunic, vascular tunic, and neural tunic
  • Fibrous tunic includes sclera (white of eye) and cornea (transparent)
  • Vascular tunic includes choroid (vascular layer), ciliary body (changes lens shape), and iris (controls pupil size)
  • Lens, in conjunction with ciliary body, accommodates for focusing
  • Anterior cavity contains aqueous humor to maintain eye shape
  • Posterior cavity contains vitreous humor to maintain eye shape
  • Refraction of light occurs as it passes through cornea, aqueous humor, lens, and vitreous humor
  • Myopia ("nearsightedness") occurs when eye is too long, hyperopia ("farsightedness") when eye is too short
  • Retina contains photoreceptors (rods and cones)
  • Rods are more sensitive to light, cones detect color
  • Phototransduction converts light into neural signals (action potentials)
  • Image is inverted and projected onto retina

Hearing and Equilibrium

  • Ear detects sound, static, and dynamic equilibrium
  • Outer ear funnels sound waves to tympanic membrane
  • Middle ear has auditory ossicles (malleus, incus, stapes) to transmit vibrations to oval window
  • Inner ear contains bony labyrinth (filled with perilymph) and membranous labyrinth (filled with endolymph)
  • Cochlea detects sound via hair cells on basilar membrane
  • Hair cell movement triggers action potentials in vestibulocochlear nerve
  • Vestibular system detects static and dynamic equilibrium in utricle, saccule, and semicircular canals
  • Static equilibrium in vestibule detected via maculae
  • Dynamic equilibrium (rotation) detected in semicircular canals via cristae
  • Hearing loss can be conductive or sensorineural

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Description

Explore the fascinating world of special senses, focusing on olfaction and gustation. Learn how the olfactory and gustatory systems function, from the detection of odors and tastes to the unique pathways involved. Test your knowledge on the chemical senses and their specific organs.

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