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Receptors are spread throughout the body


receptors are concentrated in specific location


Examples of types of somatic sences

temperature, pressure,, pain, and proprioceptors

What is a proprioceptor?

awareness of position in space

Examples of sensory sences

vision, hearing and equilibrium, gustatory, smell

Theese are the complex sensory organs

eyes, ears

Sensory inputs with localized clusters of receptors

taste buds, olfactory epithelium of nose

What is the retina?

single region of delicate white nervous tissue

What is the lens?

not a layer of the eye wall, but is a transparent structure suspended from the ciliary body by suspensory ligaments

What does the suspensory ligaments do?

holds the lens in place.

What is the cornea?

Where light enters

There are many nerve endings here


This is transparent and contains no blood vessells, can be transplanted


What is the function of the sclera?

protects and gives shape to eye

This is the white, tough, connective tissue


What covers 5/6 of the eyeball


This is the most anterior portion of the eye


This is the hole in the center of the iris


Theese act like the diaphragm on camera

radial smooth muscles, and circular smooth muscles

The radial smooth muscles do what?

make the pupil larger

Dialation is for what kinda vision and light?

Long distance and dim light

The circular smooth muscles do what?

Make pupil smaller

Constriction is for what kinda vision and light?

close vision, and bright light

What is the cicilary body?

Smooth muscle to which the lens is attached

What is the thickest area of the vascular tunic?

the ciliary body

What is the darkly pigmented layer of the posterior eye?


Why is the choroid pigmented darkly?

So it can absorb the excess light entering eye.

What is the largest portion of vascular coat?


What is the optic disk?

blind spot where the optic nerve emerges from the eye

What is the macula lutea?

a yellow spot on the retina: lateral to the optic disk

What is the fovea centralis?

depression in center of the macula lutea containing cones

Where is the point of sharpest vision?

fovea centralis

Caused by a lack of cones

color blindness

Deficiancy in vitamin a caused by malfunction of the rods?

Night Blindness

What are celiary glands?

modified sweat glands that are btw eyelids

Theese carry tears down toward the nasal cavity

Lacrimal glands

What is the conjuctiva?

membrane on front of the eye and lining eyelid

What is the function of the conjuctiva?

lubricates with mucus and keeps eye moist.

Where is the anterior cavity?

Space between back of the cornea and front of the lens

Where is the anterior chamber?

posterior cornea to anterior iris

Where is the posterior chamber?

posterior iris to the anterior len

What is aqueous humor?

Watery fluid filling anterio cavity which mantains presure, nourishes, and refracts light

What produces the aqueous humor?

The epithelial cells of the cilliary body

Describe the pathway of the aqueous humor

ciliary body, to the posterior chamber, then the pupil, then the anterior chamber,, the the scleral venous sinus aka canal of schlemm

What is the canal of schlemm?

Permealble blood vessel at junction of cornea and sclera that reabsorbs aqueous humore

Where is the posterior cavity?

Between the posterior lens and the retina

What keeps the eyeball from collapsing?

vitreous humor

What is the function of the vitous humor?

Holds the fragile retina in place

this humor helps maintain intraocular pressure


What is the function of the rods, and what do they contain?

outline black and white vision at night, and provide peripheral vision

What is the function of the cones?

they are for sharp color vision

describe the pathway of light

cornea>aqueous humor of the anterior chamber>pupil>aqueous humor of the posterior chamber>lens>victreous humor>retina>optic disk>optic neve>cerebrum

What is refraction?

when light rays bend as they pass from one transparent substance to another with varrying density

Theese have constant light bending power

cornea and aqueous humor

How does the lens refract light?

by varrying and making itself less or more convex greater convexity the more the light bends, the flatter the lens, the less the lens bends

What do convex transparent structures do to light?

bend rays together

What do concave transparent structures do?

spread rays apart

This contracts the lens to become more or less convex

ciliary body

What are the convex structures within the eye that converge light?

the cornea and lens

What is the real image?

image found on the retina as a result of the bending activity of the lens

What happens if the eyeball is to short?

light rays converge behind the retina and results in far sightedness

What happens if the eyeball is too long?

light rays converge in front of the retina and results in near sightedness

what is distance vision?

when the object is 20 feet or more from the eye

What should happen in distance vision?

light rays will be parrallel lines to the eye, there is less refraction to focus on retina

What is close vision?

less than 20 feet from object to the eye

What should happen in close vision?

light rays will spread apart as they enter the eye, more refraction is needed to focus on retina

What does the ciliary body muscle do during each type of vision?

distance it relaxes, close it contracts

What happens to the suspensory ligaments during each type of vision?

distance they are taut, close they are relaxed

What happens to the lins during each type of vision?

distance the lens is less convex, and close the lens is more convex

Define photopupillary reflex

eyes are exposed to brith light and the pupil constrict.

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