Special Senses and Vision Quiz

Special Senses

• Senses are general capabilities to detect stimuli, categorized into general and special senses.
• Special senses involve specific organs and complex processing for vision, hearing, balance/equilibrium, taste, and smell.

Sensory Receptors

• Sensory receptors are microscopic detectors that translate stimuli into signals for the nervous system.
• Types of sensory receptors include mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, and chemoreceptors.

Sense of Vision

Eye's Accessory Structures

• Eyelashes: prevent foreign matter from entering the eyes.
• Eyelids (palpebrae): continuation of skin that close to protect the eye, blinking lubricates the surface and clears debris.
• Medial angle of the eye: inner corner.
• Lateral angle of the eye: outer corner.
• Palpebral fissure: gap between upper and lower eyelids.
• Lacrimal caruncle: small fleshy bump located at the medial angle of the eye.
• Conjunctiva: mucous membrane and epithelium covering the anterior of eye
• Palpebral Conjunctiva: lining the eyelids.
• Bulbar conjunctiva: lining the anterior surface of eye.
• Fornix: area connecting palpebral to bulbar conjunctiva
• Conjunctivitis: inflammation of the conjunctiva
• Eye muscles: help move the eyeball
• Lacrimal apparatus: produces tears that lubricate, nourish, and oxygenate the cornea; contain lysozyme and antibodies; includes the lacrimal gland, tear ducts, lacrimal puncta, lacrimal canaliculi, lacrimal sac, and nasolacrimal duct.

Layers of the Eye

• Fibrous Tunic: outermost layer
  • Cornea: transparent structure covering the iris and pupil, allows light to enter and focus light.
  • Sclera: a firm, white outer part, helps maintain eye shape, provides attachment sites and protects internal structures.
• Vascular Tunic: middle layer
  • Choroid: vascular layer underlying the sclera.
  • Ciliary body: helps hold the lens in place.
  • Iris: colored part surrounding the pupil, regulates amount of light entering.
  • Pupil: opening in the center of iris that regulates light entering; constricted or dilated.
  • Lens: flexible disk that focuses light onto Retina.
• Nervous Tunic: innermost layer
  • Retina: most inner layer of eyeball; outer pigmented layer absorbs light, inner sensory/neural layer contains photoreceptors rods & cones.
  • Rods: sensitive to low light; low visual acuity.
  • Cones sensitive to bright light; provide high visual acuity.
  • Posterior region:
    • Macula: surrounds the fovea centralis for central vision.
    • Fovea centralis: sharpest visual and fine details located at center of the macula.
    • Optic disc: white spot medial to macula; no photoreceptors.

Eye Cavities

• Anterior cavity: extends from cornea to lens, contains aqueous humor.
• Posterior cavity: filled with vitreous body fluid, includes vitreous humor.

Visual Pathway

• Retina:
• Optic nerve:
• Optic chiasm:
• Optic tracts:
• Lateral Geniculate Nucleus (LGN):
• Optic radiations:
• Primary visual cortex (occipital lobe):

Sense of Equilibrium & Hearing

• The External Ear:

  • Auricle (pinna): collects sound waves.
  • External auditory meatus (auditory canal): directs sound waves to the middle ear.

• The Middle Ear

  • Tympanic membrane (eardrum): vibrates in response to sound waves.
  • Auditory ossicles (malleus, incus, stapes): amplify and transmit vibrations.
  • Eustachian or auditory tube: connects the middle ear to the pharynx.

• The Inner Ear

  • Bony labyrinth: shell of dense bone, surrounding/protecting membranous labyrinth.
  • Membranous labyrinth: inside bony labyrinth. houses receptors for hearing and equilibrium.
    • Filled with perilymph
    • Contains fluid called endolymph.
      • Regions: cochlea, vestibule, semicircular canals.
    • Cochlea :snail shell structure where hearing takes place. contains 3 regions;
      • Scala vestibuli (vestibular duct), filled with perilymph
      • Scala tympani (tympanic duct), filled with perilymph
      • Cochlear duct (scala media), filled with endolymph.
      • Spiral organ/Organ of Corti: located in cochlear duct. contains hair cells.
      • Tectorial membrane: vibrates against hair cells.

Hearing Pathway

• Sound wave capture:

• Mechanical transmission:

• Oval window movement:

• Fluid waves propagation:

• Basilar membrane activation:

• Hair cell stimulation:

• Signal Transmission

• Superior olivary nucleus :

• Thalamic relay

• Primary auditory cortex:

Balance (Equilibrium)

• Equilibrium: refers to the body's ability to maintain balance, stability, and orientation.
  • Static equilibrium: maintains balance when stationary.
  • Dynamic equilibrium: maintains balance during motion.
• Vestibular system:
  • Semicircular canals: detect rotational or angular movements.
    • Crista ampullaris: a swelling at base, responsible for detecting rotational acceleration.
  • Otolith organs: detect linear movements and gravitational pull.
    • Utricle, Saccule, and otoliths: detect linear acceleration and position of head.

Physiology of Dynamic Equilibrium

• Head Rotation
• Cupula Bends
• Hair Cell Stimulation
• Signal Generation
• Signal Transmission
• Brain Interpretation

Physiology of Static Equilibrium

• Head Tilts or Body Moves Linearly
• Otolith Movement
• Hair Cell Bending
• Nerve Impulses
• Signal Transmission
• Brain Interpretation

Sense of Smell

Olfactory System

• Olfactory Epithelium
  • Olfactory receptor cells: specialized neurons that detect odors.
  • Supporting cells: provide structure and nourishment.
  • Basal cells: stem cells that regenerate receptor cells.
• Olfactory Bulb
  • Receives signals from receptor cells. Processes them.
• Olfactory Tract
  • Transmits processed signals from the olfactory bulb to the brain.

Olfactory Pathway

• Odor detection
• Olfactory cilia of olfactory receptor cells
• Olfactory bulb
• Olfactory tract
• Olfactory cortex (frontal lobe)

Sense of Taste

Gustatory System

• Taste buds: found in papillae on tongue.
• Types of Papillae:
  • Fungiform
  • Circumvallate
  • Foliate
  • Filiform
• Gustatory cells: specialized receptor cells within taste buds. have microvilli (taste hairs) that extend into the taste pore to detect tastants.
• Cranial nerves:
  • Facial nerve (CN VII)
  • Glossopharyngeal nerve (CN IX)
  • Vagus nerve (CN X)
• Brain regions:
  • Gustatory cortex
  • Thalamus

Gustatory Pathway

• Taste detection
• Taste buds
• Signal generation
• Signal Transmission (Cranial nerves)
• Brainstem processing
• Thalamic relay
• Perception in the Gustatory Cortex

Types of Taste Sensations

• Sweet
• Sour
• Salty
• Bitter
• Umami

Test your knowledge on special senses, focusing on the mechanisms of vision. This quiz covers the types of sensory receptors and the eye's accessory structures. Understand how these components work together to facilitate perception.