Special Senses Flashcards
(35 cards)
Gustatory cells are
Epithelial cells
Alkaloids excite gustatory hairs mostly at the
back of the tongue and circumvallate papillae
cranial nerves that are part of the gustatory pathway include
Facial & glossopharyngeal
This cranial nerve controls contractions of the circular smooth muscle of the iris
Oculomotor
The cornea is nourished by
aqueous humor
In focusing for far vision
The lens is at its thinnest; the light rays are nearly parallel
Convergence
Requires contraction of the medial rectus muscles of both eyes
These are paired correctly
Vestibule-Macula
Semicircular duct-ampulla
Movement of the ____ membrane triggers bending of hairs of the hair cells in the spiral organ of Corti
Tectorial
Sounds entering the external acoustic meatus are eventually converted to nerve impulses via a chain of events including
- vibration of the eardrum
- vibratory motion of the ossicles against the oval window
- stimulation of hair cells in the spiral organ of Corti
Name 3 accessory eye structures that help to lubricate the eyeball, and name the secretion of each.
-Lacrimal Glands: Saline solution & lysosomes
-Tarsal & Ciliary glands: Oily secretion
-Conjuctiva: Mucous
Why do you often have to blow your nose after crying?
The lacrimal secretions drain via the nasolacrimal duct into the nasal cavities
Diagram & label the internal sturctures of the eye & give the major function of each strucuture.
- —Internal Structures
- Lens: Major focusing apparatus of the eye
- Retina: Light (photoreceptive) sensitive area
- Choroid: The nutritive (vascular) coat of the eye
- Ciliary Body & Ciliary Zonule: Smooth muscle structure that regulates the shape of the lens for focusing.
- Iris: Smooth muscle structure that controls the amount of light entering the eye
- Sclera: Protective (fibrous) coat
- Cornea: Transparant part of the sclera that allows light to enter the eye
- Pupil: Opening through which light passes
- Aqueous Humor: Helps maintain interocular pressure & provide nutrients to the lens & cornea
- Scleral venous sinus: Reabsorbs aqueous humor in the bloodstream
- Vitreous humor: Helps prevent the eyeball from collasping inward
- Fovea Centralis: Contains only cones & is the area w/the greatest visual acuity
- Optic Nerve: Transmits nerve impulses to the optic cortex
- Optic Disc: Blind spot where nerve leaves eyeball
- Central Artery & Vein of the retina”: Provides nutrients & removes waste products
Name the extrinsic eye muscles that allow you to direct your eyes
Superior, Inferior, lateral, & medial rectus muscles; & the superior & inferior oblique muscles
Describe the 2 humors of the eye
- Vitreous Humor: Posterior to the lens; Reinforces eyeball
- Aqueous Humor: Anterior to lens; Reinforces eyeball & provide nutrients to the avascular lens & cornea
What is the “blind spot” and why is it called this?
The portion of the retina w/no photoreceptors bcuz it is the site at which the optic nerve leaves the eyeball. Light focused on this spot is not converted into vision or photoreception.
The structure that controls light entry into the eye
Iris
What is the fovea centralis & why is it important?
A small pit in the retinal layer that contains cones only is located lateral to the optic disk in each eye. Anything that must be viewed (discriminative vision) is focused on the fovea bcuz its the area of greatest visual acuity.
Trace the pathway of light from the time it hits the cornea until it excites the rods & cons
Cornea to aqueous humor, through pupil to aqueous humor to lens to vitreous humor to retina. The path of light goes through the ganglion cells 1st, then the bipolar cells before stimulating the rods & cones.
Trace the pathway of nerve impulses from the photoreceptors in the retina to the visual cortex of the brain
Photoreceptors (rods & cones) to bipolar cells to ganglion cells to optic nerve through the optic chiasm to optic tract to thalamus to visual cortex in the occipital lobe via the optic radiation
Define: Hyperopia; Myopia;
- Hyperopia: Farsightedness; The individ. has no problem with distance vision, which requires no accomadation; In near vision the image is focused behind the retina bcuz of a lazy lens or foreshortened eyeball
- Myopia: Nearsightedness; The individ has no problem with near vision, but in distance vision the image is focused anterior to the retina bcuz of an overly strong lens, an elongated eyeball, or a cornea that’s too curved.
- Emmetropia: Normal vision
Why do most people develop presbyopia as they age? Which of the conditions in quest 21 does it resemble?
As we age the lens loose their elasticity, causing it to focus less acutly for close vision; Hyperopia
There are only 3 types of cones. How can you explain the fact that we see many more colors?
When 2/more different cone types are stimulated simultaneously the color perceived is intermediate (in wavelength/light) btw them. Thus the stimulation of red & green cones produces the sensation of yellow; when all cones are simultaneously excited, we perceive white (white= all colors).
why are ophthalmoscopic exams important?
they allow the examiner to determine the condition of the retina, as well as the the optic disc & internal vessels. Many blood vessel problems (ex: high bp, diabetes mellitus) and degeneration of the optic nerve and/or retina can be detected early from this exam. Its extremly import. in diagnosis.
