chapter 8 special senses Flashcards
what are the special senses?
1) smell
2) taste
3) sight
4) hearing
5) equilibrium
where are 70% of sensory receptors?
eyes
how many nerve fibers does each eye contain?
over 1 million
what are the accessory structures of the eyes
1) extrinsic eye muscles
2) eyelids
3) eye lashes
4) conjuctiva
5) lacrimal apparatus
what glands are located in the eye lashes?
1) tarsal glands
2) ciliary glands
what do tarsal glands secrete?
oily secretions that lubricate eyes
what is conjuctiva?
what is its function?
1) membrane that lines the eyelids and eyeballs
2) secretes mucus to lubricate eye
what does the lacrimal apparatus consist of?
lacrimal glands and ducts
what is the pathway of lacrimal fluid?
1) fluid secreted by gland
2) drains to lacrimal sac
3) travels through nasolacrimal duct and empties into nasal cavity
what does lacrimal fluid consist of?
1) salt solution
2) mucus
3) antibodies
4) lysozyme
what is lysozyme?
an enzyme that destroys bacteria
what is the function of lacrimal fluid?
1) cleanse
2) protect
3) moisten
4) lubricate
what are the 3 layers of the eye wall?
1) fibrous tunic
2) vascular tunic
3) retina
what does the fibrous tunic of the eye wall consist of?
1) sclera
2) cornea
what does the vascular tunic of the eye wall consist of?
1) iris
2) ciliary body
3) choroid
what are the names of the layers in the retina?
1) pigmented layer
2) neural layer
the cornea is avascular, so where does it get its nutrients and oxygen from?
1) lacrimal fluid
2) aqueous humor
what part of the eye does the majority of the focusing?
the cornea
what makes up the majority of the fibrous tunic of the eye wall? what part of the eye is this?
the sclera (the white part of the eye)
what are the functions of the sclera?
1) provides shape
2) protects internal parts
3) attachment site for muscles
what does the choroid contain?
a vast network of capillaries that supply oxygen and nutrients to the retina
what part of the eye is the iris and what does it control?
the pigmented part of the eye
it controls the amount of light that enters the eye by controlling the size of the pupil
what is the ciliary body composed of?
1) ciliary muscles
2) ciliary processes
what is the function of the ciliary body?
changes the shape of the lense to adjust the focal point
what is the pigmented layer of retina attached to and what does it absorb?
its attached to the choroid and absorbs light that passes through the retina
what type of tissue is the pigmented layer of retina made of?
simple cuboidal epithelial tissue
what does the neural layer of retina house?
1) photoreceptors
2) associated neurons
what happens when the neural layer of retina recieves light?
it converts the energy from the light into nerve impulses
how are the neurons arranged in the neural layer of retina?
in 3 layers of bipolar neurons
what is the center of the eyes sharpest vision and why?
fovea centralis because it has the highest proportion of cones with almost no rods
in the neural layer of retina, what are the 3 cell types in order from superficial to deep?
1) photoreceptor cells (rods and cones)
2) bipolar cells
3) ganglion cells
the ganglion cells in the neural layer of the retina have axons that form what?
the optic nerve (CN2)
the aqueous humor has fluid inside with what type of consistancy?
watery consistancy
the vitreous humor has fluid inside with what type of consistancy?
gel- like consistancy
ophthalmoscope =
an instrument used to illuminate the interior of the eyeball and fundus (posterior wall)
what can an ophthalmoscope detect?
1) diabettes
2) arteriosclerosis
3) optic nerve or retina degeneration
optic nerve =
a bundle of axons that exit the back of the eye. carries impulses from the retina