A&P Chapter 17: The Special Senses
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What are the different parts of the olfactory epithelia?
- 1. Olfactory receptor cells: contain cilia suspended in mucus that have receptors for ordorants
- 2. Supporting cells
- 3. Basal cells: can develop into olfactory receptor cells
How do molecules bind to olfactory receptor cells?
- 1. Olfactory gland secrete mucus that coats olfactory epithelia
- 2. Chemical odorants are dissolved in the mucus before they are able to bind to the receptors
- 3. When odorants bind to receptors, chemically gated Na+ channels open and depolarize the membrane
What are the 3 types of papillae found on the tongue?
- 1. Filiform papillae: smallest, no taste buds, provides friction that helps tongue move objects around in the mouth
- 2. Fungiform papillae: medium, 5 taste buds
- 3. Circumvallate papillae: largest, 100 taste buds, form V near posterior margin of the tongue
What are the primary taste sensations?
- 1. Sweet
- 2. Salty
- 3. Sour
- 4. Bitter
What are the 2 new taste sensations?
- 1. Umami - savory taste
- 2. Water - water receptors in pharynx
Know the primary structures of the eye that we talked about!
What structure produces tears?
- The lacrimal apparatus:
- 1. Lacrimal gland: produces volume and key ingredients for tears, lysozome
- 2. Lacrimal canaliculi: where tears drain, near the medial canthus
- 3. Lacrimal sac: sits in the lacrimal sulcus of the orbit, receives tears from lacrimal canaliculi
- 4. Nasolacrimal duct: passes through the nasolacrimal canal which delivers tears to nasal cavity
Describe the path of light from the cornea to ganglion cells.
- Anterior cavity:
- 1. Cornea
- 2. Pupil (size controlled by the iris)
- 3. Lens (size controlled by the ciliary body contractions)
- 4. Ora serrata (separates the anterior and posterior cavity)
- Posterior Cavity:
- 5. through the vitreous body
- 6. Fovea
- 7. Rods/cones
- 8. Bipolar cells
- 9. Ganglion cells
- 10. Optic disc
- 11. Optic Nerve
- 12. Optic chiasm
- 13. Visual cortex
What is the function of the 2 humors?
- 1. Aqueous humor: Fluid that circulates in the anterior cavity, nutrient and waste transport, fluid pressure helps retain eye's shape, replaced
- 2. Vitreous humor: gelatinous mass in the posterior cavity, stabilize the shape of the eye, helps hold retina in place, not replaced
What is the fovea?
- 1. Contains the highest concentration of cones
- 2. Site of our sharpest vision on the retina
Why do we have a blind spot?
- 1. Because there are no photoreceptors in the optic disc
- 2. This is where all the ganglion cells collect and form the optic nerve
How do we dilate or constrict our pupils?
- 1. Dilate: pupillary dilator muscles extend radially away from the pupil, contraction enlarges the pupil
- 2. Constrict: pupillary constrictor muscles form concentric circles around the pupil, sphincter muscles contract making pupil smaller
Describe the circulation of aqueous humor?
- 1. Secreted into the posterior chamber through the ciliary body
- 2. Enters anterior chamber through the pupil
- 3.Collects in the canal of Schlemm and circulates to the veins in the sclera
What are the most important features and functions of the lens?
- 1. Transparent so light can pass through
- 2. Held in place by suspensory ligaments of the ciliary body
- 3. Function is to focus the visual image on the photoreceptors
- 4. When ciliary body contracts,suspensory ligaments moves towards the lens and lens fattens up (focus on nearby object)
- 5. When ciliary body relaxes, suspensory ligaments move away from the lens and lens flattens out (distan objects)
How does the shape of the eyeball affect our vision?
- 1. Emmetropia: normal vision, lens fattens and flattens and image is focused on retina's surface
- 2. Myopia: nearsightedness, eyeball is too deep or resting curvature of lens is too great, image is projected in front of the retina
- 3. Hyperopia: Farsightedness, eyeball is too shallow or lens is too flat, image is focused deeper than the retina
What is the difference between rods and cones?
- 1. Rods: respond to all wavelengths, highly sensitive to light
- 2. Cones: absorb red, green and blue light, concentrated in the fovea
What are the 3 sections of the ear?
- 1. Outer ear: auricle, external acoustic meatus, ceruminous glands, tympanic membrane
- 2. Middle ear: auditory ossicles (malleus, incus, and stapes), auditory tube, tensor tympani muscle and stapedius muscle
- 3. Internal ear: bony labyrinth (semicircular canals, vestibule, cochlea, cochlear duct), oval window and round window
What are the functions of the structures of the outer ear?
- 1. Auricle: protects the opening of the canal and provides directional sensitivity to sound
- 2. External acoustic meatus: funnels sound from the auricle to the tympanic membrane
- 3. Ceruminous glands: integumentary glands that secrete cerumin (wax) into the external acoustic meatus
- 4. Tympanic membrane: separates external ear from middle ear, thin semitransparent sheet
What are the functions and structures of the middle ear?
- 1. Auditory ossicles: connect the tympanic membrane with the receptor complexes of the internal ear, conduct vibrations of sound
- 2. Auditory tube: connects with the nasopharynx, equalizes the pressure on both sides of the tympanic membrane
- 3. Tensor tympani muscle: contracts with loud noise stimuli which pulls malleus medially and stiffens the tympanic membrane
- 4. Stapedius muscle: contracts with loud noises, pulls the stapes to reduce movement at the oval window
What are the functions of the structures of the internal ear?
- 1. Semicircular canals: receptors stimulated by rotation of the head, 3D balance
- 2. Vestibule: provide sensations of gravity and linear movement, 2D
- 3. Coclea: superior scala vestibuli and inferior scala tympani, and cochlear duct, vibrations on the oval window make waves in the scala vestibuli which cause the basilar membrane ti rub hair cells agains the tectorial membrane which depolarizes the hair cells and sends AP to the brain
- 4. Oval window: covered by the stapes
- 5. Round window: thin membranous partition that separates the middle ear from the perilymph of the scala tympani
A sound wave strikes the tympanic membrane, how does the sound travel to the vestibulochoclear nerve?
- 1. Vibration of the tympanic membrane causes auditory ossicles to move
- 2. Movement of the stapes puts pressure on the oval window
- 3. Pressure from the oval window causes waves in the perilymph of the scala vestibuli
- 4. Waves in the scala vestibuli cause the basement membrane of the cochlear duct to rub hair cells against the tectorial membrane
- 5. Hair cells depolarize sending AP on nerve fibers to the vestibulocochlear nerve
- 6. Perilymph waves continue to the scala tympani and release on the round window
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