Special Senses Lecture 2022-2023 PDF

MC_101_: ANATOMY AND PHYSIOLOGY LECTURE LECTURE #2: SPECIAL SENSES PROFESSOR: Prof. Celisse Esguerra, MD 1ST SEMESTER | A.Y 2022-2023 ` OBJECTIVES...

MC_101_: ANATOMY AND PHYSIOLOGY LECTURE LECTURE #2: SPECIAL SENSES PROFESSOR: Prof. Celisse Esguerra, MD 1ST SEMESTER | A.Y 2022-2023 ` OBJECTIVES RECEPTORS FUNCTION I. Distinguish between general and special senses Mechanoreceptors Mechanical Stimuli II. List and describe the 5 sensory receptors Bending, III. List the general senses and its receptor type Stretching, etc. IV. Define and describe pain and referred pain Movement of V. Describe olfactory neurons and olfactory pathway muscles VI. Outline the structure and function of a taste bud and Chemoreceptors Chemicals describe the neuronal pathways for gustation Odor molecules VII. Describe the accessory structures of the eye and Taste molecules their functions VIII. Name the tunic of the eye, its parts and functions Photoreceptors Light IX. Explain the difference between rods and cones Thermoreceptors Temperature changes X. Describe the chambers of the eye and the fluids they Nociceptors Pain contain Noci - to injure XI. Explain how images are registered on the retina Free nerve ending XII. Discuss the visual pathway XIII. Describe the structures of the outer, middle and inner Table 1. Types of Receptors ear, and their functions XIV. Describe the anatomy of the cochlea and explain how FREE NERVE ENDINGS sounds are detected Simplest and most common receptors XV. Explain how the vestibule and semicircular canals Attached to the skin function in balance ○ Cold receptors - decreasing temperature Stops responding at BELOW SENSES 12°C The ability to perceive stimuli ○ Warm receptors - increasing temperature SENSORY RECEPTORS Stops responding at ABOVE Sensory nerve endings that respond to stimuli by developing action potential. 47°C TYPES OF TOUCH RECEPTORS SENSATION Process initiated by stimulating these sensory MERKEL DISKS receptors Small, superficial nerve endings that detects light, ○ Perception - conscious awareness of touch and superficial pressure stimuli received by sensory neurons Cell that interact with the free nerve endings GENERAL SENSES HAIR FOLLICLE RECEPTORS Have receptors distributed over the body Light touch Senses in skin, muscle, joints, internal organ Sensitive More diffused than special senses Not discriminative and Not localized SOMATIC SENSES bodily function Provide sensory info about the body and the MEISSNER CORPUSCLES environment Deep receptor; between epidermis and dermis ○ Touch, Pressure, Pain, Temperature, and Fine, discriminative touch. Localizing tactile Proprioception sensation Superficial; papillary dermis VISCERAL SENSES internal organs - Provide information about the internal organs RUFFINI CORPUSCLES ○ Pain and Pressure Deep receptor; deeper than meissner Detects continuous touch and pressure ○ Example: Shaking hands, Holding Hands SPECIAL SENSES Localized to different parts of the body PACINIAN CORPUSCLES ○ Smell, Taste, Sight, Hearing, and Balance Deepest receptors; associated with tendons and joints Detects deep pressure. vibration, position ○ Proprioception - position changes MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 1  PAIN REFERRED PAIN Unpleasant, perceptual and emotional experiences Perceived pain that originated somewhere in the body TWO TYPES OF PAIN SENSATION Mostly felt when the internal organs are damaged or inflamed LOCALIZED PAIN the sensory neurons from the superficial area to Also known as “Superficial Pain” which the pain is referred, and the neurons from the Sharp, pricking, cutting pain deeper, visceral area where the pain stimulation Rapidly conducted action potential originates, converge onto the same ascending neurons in the spinal cord; thus the brain can’t distinguish DIFFUSE PAIN Also known as “Deep/Visceral Pain” OLFACTION No tactile receptors Sense of smell ; reacts to chemoreceptors Burning aching pain At Least 400 olfactory receptors; 10,000 different Slower action potentials smells ODORANTS PAIN CONTROL Airborne molecules iscent Anesthesia - removal of the sensation Enters through the nostrils; dissolved in a specialized cilia that lies within a thin mucous on the LOCAL ANESTHESIA epithelial surface Action potentials suppressed from pain Receptors in local areas OLFACTORY NEURONS Chemicals are injected near sensory nerve Bipolar neurons within the olfactory epithelium Minor Operations OLFACTORY EPITHELIUM Lines the superior part of the nasal cavity GENERAL ANESTHESIA Loss of consciousness NOTE: Chemicals affect the reticular formation The threshold for the detection of odor is low, so (Sleep-wake cycle) only a few receptors can initiate action potentials Major Operations The receptors desensitizes once it is already bound to an odorant GATE CONTROL THEORY Inhibits action potentials carried to the brain by NEURONAL PATHWAY spinothalamic tract OLFACTORY BULB Synapse of olfactory neurons and interneurons takes place OLFACTORY TRACTS Relays the action potentials to the brain OLFACTORY CORTEX -frontal and temporal Where each olfactory tract terminates FEEDBACK LOOP Inhibit the transmission of action potentials resulting from prolonged exposure to a given deodorant Results to Adaptation ↳ When nerves get desensitized TASTE TASTE BUDS Detects taste stimuli ○ Supporting Cells - specialized epithelial cells located in the exterior ○ Taste Cells - located in the interior Taste Hair receptors · Taste Pore PAPILLAE Enlargements on the surface of the tongue Protuberance from an organ Can be found in the palate, root of the tongue, root of the epiglottis MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 2  5 GENERAL TASTE SENSATIONS Sour Salty (defense mechanism ( Bitter most poisonous · plants are bitter Sweet Umami (Savory) VISION Sense of sight; reacts to photoreceptors ORBIT Bony cavities where the eyes are housed NOTE: 1 When you burn your tongue, your taste buds die. They regenerate in about 2 weeks. NEURAL PATHWAYS FOR TASTE 1. FACIAL NERVE (7) anterior 213 · Transmits taste sensations from the anterior of the tongue 2. GLOSSOPHARYNGEAL NERVE (9) posterior /3 Carries taste sensations form the posterior of the tongue ACCESSORY STRUCTURES OF THE EYE Protect, lubricate, and move the eye 3. VAGUS NERVE (10) root Carries some taste sensations from the root of the EYEBROW protection against eye and sweat tongue Works like an umbrella Prevents sweat from the forehead and shade from 4. GUSTATORY PORTION OF THE BRAINSTEM NUCLEI the sun Axons from three cranial nerves synapse EYELIDS protection from foreignObject (dust 5. THALAMUS Protect eyes from foreign objects Axons of neuron in brain stem extend and synapse Works along with the lashes in thalamus ○ Blinking reflex - occurs about 20 times/min, spreads the tears in the eyes to keep it 6. TASTE AREA (INSULA) lubricated Located in the cerebrum CONJUNCTIVA spreads mucous to the eyes thin, transparent mucous that covers the inner surface and the anterior surface of the eye ○ Conjunctivitis - inflammation of the conjunctival; Sore Eyes MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 3 LACRIMAL APPARATUS ANATOMY OF THE EYE Lacrimal gland - produces tears EYEBALL ○ Lacrimal canaliculi - small ducts where Hollow, fluid-filled sphere tears are collected ○ Lacrimal sac - enlargement of WALL (TUNICS) nasolacrimal duct Fibrous Tunic(outer) ○ Nasolacrimal duct - opens the nasal ○ Sclera - helps maintain the shape of the cavity eye ○ Cornea - is the transparent anterior sixth of the eye, which permits the light to enter -rends and refracts light Vascular Tunic(middle) - contains most of the blood vessels of the eye ○ Choroid - very thin; black; consists of a vascular network and many melanin-containing pigment cells ○ Ciliary Body - continuous with the anterior margin of the choroid Suspensory Ligaments - attached to the perimeter of the lens Lens - flexible, biconvex. Transparent disc ○ Iris - the colored part of the eye, regulates the diameter of the pupil Pupil - controls the amount of light entering the eye EXTRINSIC EYE MUSCLES opening Responsible for each eyeball movement Nervous Tunic(inner) - innermost tunic and consists 4 quadrants of retina ○ Superior rectus muscles - upwards ○ Outer Pigmented Retina - keeps light ○ Inferior rectus muscles - downward reflecting back into the eye ○ Medial rectus muscles - inward ○ Inner Sensory Retina - contains ○ Lateral rectus muscles - outward photoreceptor cells Photoreceptor cells - respond to Light Rods and Cones - REGIONS OF THE RETINA MACULA LUTEA Small, yellow spot near the center of the posterior retina OPTIC DISC photoreceptor no White spot medial to the eye; number of blood vessels enter the eye ○ Blind Spot of the eye - no photoreceptors SUPERIOR & INFERIOR OBLIQUE MUSCLES Located at an angle to the long axis of the eyeball Superior - Counterclockwise CHAMBERS OF THE EYE Inferior - Clockwise MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 4 CHAMBER OF THE EYE Lateral geniculate nucleus - neurons in thalamus ANTERIOR CHAMBER ○ Forms optic radiation which POSTERIOR CHAMBER sends signals to the visual cortex. ○ between the cornea and lens ○ separated by the iris but it continues in the pupil. DIPLOPIA Problem with depth perception. - AQUENOUS HUMOR produced by cilliary bodies DOUBLE VISION Watery fluid,helps maintain pressure within the The extraocular muscles have problems that lead to eye.refracts light,provide nutrients the misalignment of the eyes. GLACUMA VISUAL DEFECTS Disease of older people all of these visual defects require glasses. compression of the retina and may cause blindness,because that compression does not allow MYOPIA near - the blood vessels to circulate in the retina. (cause nearsightedness tissue damage or “ischemia”) image is in front of retina (supposedly in the retina, doesn't reach the retina that much) VITREOUS CHAMBER gelating - HYPEROPIA far · Located posterior to the lens and is filled with farsightedness jelly-like substance. image is behind retina Does not circulate. eyeball is shorter Vitreous body also refract lights. ASTIGMATISM irregular curvature of lens glasses or contacts required to correct FOCUSING BY EYE LIGHT REFRACTION HEARING AND BALANCE FOCAL POINT - Crossing point Ear is responsible for hearing and balance FOCUSING - Causes light to converge Divided into three; EXTERNAL, MIDDLE, AND INNER FOCUSING IMAGES ON THE RETINA Accomodation - greater fraction of light; also EXTERNAL EAR enables the eyes to focus on images Environment up to the eardrum (tympanic membrane) PHOTORECEPTORS Rods - periphery AURICLE ○ Rhodopsin - photosensitive pigment Cartilaginous part in the ear that collects sound Opsin - colorless waves to the external auditory canal Retinal - yellow (needs vitamin A) ○ Night blindness - retinal detachment ↳ Retino EXTERNAL AUDITORY CANAL Canal that leads the sound waves from your auricle to the eardrum. Cones - found mostly in the center of the retina ○ Ceruminous Glands - produces cerumen ○ Sensitive to blue, red, and green or earwax. ○ Color Blindness - mostly seen in men due Both earwax and the hair inside to X linked of the external auditory canal prevent foreign objects from reaching the eardrum. NEURONAL PATHWAY/VISUAL PATHWAY TYMPANIC MEMBRANE (EARDRUM) Thin layer of connective tissue 1. Light passes through CORNEA through the Separates external and middle ear AQUEOUS HUMOR, through the LENS, through the VITREOUS HUMOR, image forms on photoreceptors in RETINA, breakdown of RHODOPSIN, and signals BIPOLAR CELLS. MIDDLE EAR air-filled chamber medial to the eardrum. 2. OPTIC NERVE, enters the CRANIAL CAVITY, the to smallest bones in body connects via the OPTIC CHIASM where two optic 3 Auditory ossicles or bone - amplify vibrations nerves connect, it becomes the OPTIC TRACT. ○ Malleus - Looks like a hammer ○ Incus - Looks like an anvil. It connects 3. The axons of these optic tracts terminate in the malleus and stapes together. THALAMUS.. MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 5  ○ Stapes - Looks like a sterup, covers the Scala tympani - Stretches from the apex to the oval window oval window but parallel to your scala vestibuli. Technically it goes to your round window. Considered as the smallest bones ○ contains perilymph in the body transmit vibrations to the oval VESTIBULE window from your tympanic Balance membrane. ○ Auditory/Eustachian Tube - enables SEMICIRCULAR CANALS pressure to be equalized Balance Enables a person to detect the movements in any direction. INNER EAR fluid-filled chamber medial to the middle ear. Both for auditory and balance SPIRAL ORGAN Labyrinth - maze Fixed in your basilar membrane and it contains hair cells. ○ Hair Cells - hair-like microvilli or stereo cilia BONY LABYRINTH interconnecting tunnel and chambers located in Microvilli - Stiffened by actin filaments your temporal lobe. It has a membranous labyrinth Tectorial membrane - cellular gelatinous shell attached to the spiral lamina ○ Covers microvilli, doesn't move, holds the embedded hair tips, and vibrates against the hair cells. ○ Forms action potential when the hair bends. HEARING PROCESS BONY LABYRINTH 2 Major Process Filled with endolymph (clear fluid). 1. Conduction of Sound Waves (External, Middle, and inner) 2. Stimulation of the hearing receptors. PERILYMPH (Inner) The space between the bony and the membranous tunnels Sound waves cause EARDRUMS to vibrate, amplified by AUDITORY OSSICLES, then vibrates 3 REGIONS OF LABYRINTH OVAL WINDOW. It sends vibrate to the fluid-filled chamber medial to the middle ear. PERILYMPH (disrupts the fluid). Waves travel to the ROUND WINDOW The Vibration also causes the VESTIBULAR MEMBRANE and the ENDOLYMPH COCHLEA MEMBRANE. Hearing shell -like It moves the BASILAR MEMBRANE, causing the HAIR CELLS to move with it. However, the tectorial Scala vestibuli - Stretches from the oval window to membrane doesn’t move but it bends creating the apex of the cochlear. action potentials sending it to the COCHLEAR ○ contains perilymph NERVE via your sensory nerve axons associated with the hair cells. Cochlear duct - Is the space between the vestibular membrane and the basilar membrane. PITCH ○ filled with endolymph Frequency or the wavelength of the sound. - spiral ligament The shorter the wavelength = higher pitch - organ of corti MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 6  Longer wavelength = lower pitch ○ Otoliths - particles containing proteins, and calcium carbonate. VOLUME ○ These structures respond to movements in Related to the amplitude of the soundwave. regard to gravity. Louder sound = louder amplitude Detects movement about linear acceleration. The Like pitch, it distorts the basilar membrane more utricle is for the vertical plane, while the saccule is intensely. More action potentials go to the auditory for the horizontal plane. pathway. ○ Utricle - looking up and down ○ Saccule - looking left and right NOTE: Everything in the pitch and volume, it depends on the hair cells that are being activated and where they're located. SEMICIRCULAR CANALS Balance Enables a person to detect the movements in any HEARING IMPAIRMENTS direction bcs it has 3 canals; placed 90° to each other to detect movements. CONDUCTION DEAFNESS The base of each canal has dilated, and is called an Problem in conduction of soundwaves. Usually ampullae. mechanical. Inside each ampullae you have the crista Ex: ampullaris. ○ impacted cerumen (covers external This is a specialized epithelium, it also contains auditory canal) hair-like microvilli. This is embedded in the curved ○ destruction of the ligaments of your gelatinous mass called cupula (light blue). malleus and incus (won't be able to conduct air waves) ○ cupula (looks like a cup) - gelatinous mass found in semicircular canals. SENSORINEURAL DEAFNESS It is suspended over the crest and Caused by deficiencies in your spiral organ. Defects displaced by movement of in spinal nerve or microvilli of the hair cells. endolymph within the semicircular Ex: canals. ○ hearing an explosion ○ front of booming loud speaker How it works with Dynamic Equilibrium - the canals have endolymph which remains stationary after the AUDITORY NEURONAL PATHWAY movement of the head (cupula) but then it catches up or it reacts late. Cochlear nerve is for hearing, while the vestibular nerve is for balance. Once it merges, it becomes vestibulocochlear nerve. The vestibulocochlear nerve and cell bodies in the cochlear nucleus in the brain stem. Cochlear nucleus then project to other areas of your brainstem, such as inferior colliculus in the midbrain that sends signals to your superior colliculus and thalamus. Once it reaches the thalamus, it senses the action potentials to your auditory cortex (temporal lobe), where the sound is recognized. BALANCE (EQUILIBRIUM) 2 COMPONENTS OF BALANCE Static equilibrium associated with vestibule evaluates position of head relative to gravity Dynamic equilibrium changes associated with semicircular canals evaluates changes in direction and rate of head movement VESTIBULE 2 Chambers (Utricle & Saccule) ○ Both contains a maculae ○ Maculae - specialized patches of sensory epithelium that contain hair cells (has NEURAL PATHWAY FOR BALANCE otolithic membrane) The axons from the vestibular portion of the vestibulocochlear nerve goes to the vestibular MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 7  nucleus (this is also found in your brain stem). And then it ascends to other areas of your CNS (cerebral cortex) This nucleus also receives inputs from proprioceptive neurons in your limbs, and from your visual system. NOTE: if there is conflicting information from the sensory sources, like the eyes and the semicircular canals of the ear, then you'll manifest with vertigo or nausea (basically feel dizziness). RESOURCES: Special Senses Lecture 2022 - Dr. Esguerra Seeley’s Essentials of Anatomy and Physiology 11th Ed. Tabanao, K.’s Senses Transes MENESES, M., PAREDES, J., PAREDES, S., PINO, R., PLURAD, N, QUIÑONES, M., RAMOS, A., REPE, A. | 1NU02 8