The eye Flashcards
cornea
transparent area on the anterior surface of the eye
Where are the two eyelids connected?
The lateral angle of the eye
How does light enter the eye?
It passes through the cornea and the pupil
What is the lacrimal caruncle?
- what does it do?
- small, reddish body at the medial angle of the eye
- produces thick secretion that cause gritty deposits that appear after sleep
What is the palpebral fissure?
The gap that separates the free margins of the upper and lower eyelids
What is conjunctiva, and what is it made of?
- mucous covered specialized, stratified squamous epithelium
- covers the inner surfaces of the eyelids and the outer surface of the eye
What are tarsal glands?
- on inner margin of the eye lid
- secrete lipid rich product that keeps the eyelids from sticking together
What is palpebral conjunctiva?
covers the inner surface of the eyelids
bulbar conjunctiva
covers the anterior surface of the eye
fornix
a pocket created when the palpebral conjunctiva becomes continuous with the bulbar conjunctiva
What does the lacrimal apparatus do and what does it consist of?
- produces, distributes, and removes tears
1) lacrimal gland
2) paired lacrimal canaliculi
3) lacrimal sac
4) nasolacrimal duct
What are the three layers of the wall of the eye?
1) outer fibrous layer
2) intermediate vascular layer
3) deep inner layer
What does the fibrous layer of the eye consist of? What is its function?
- cornea and white sclera (continuous and connect at the corneoscleral junction)
- protect the eye, attach to extrinsic eye muscles, contains cornea
What does the vascular layer consist of?
What is its function?
- blood vessels, lymphatic vessels, intrinsic muscles of eye (iris, ciliary body, choroid)
- route for bv’s and lymphatic supply, regulate amount of light that enters, secreting and absorbing aqueous humor, controlling the shape of the lense
What does the inner layer of the eye consist of? What is its function?
- retina
- absorbs light, photoreceptors
What is the ciliary body?
Thickened region that bulges into the interior of the eye
- a ring of fibres holds the lens in place behind the pupil
What does the body of the iris consist of?
Highly vascular, pigmented loose connective tissue
- anterior surface has no epithelial covering; instead, incomplete layer of fibroblasts and melanocytes
What is the ciliary zonule?
Attaches to the tips of the ciliary processes
- connective tissue fibres hold the lens posterior to the iris and cantered on the pupil
What is the ora serrata?
Jagged anterior edge of the neural layer of the retina
- outer pigmented layer of the retina continues anteriorly across the posterior surface of the iris
Where is the highest concentration of photoreceptors?
Fovea central is (at the macula)
What is accommodation?
We focus images on the retina by changing the shape of the lens to keep the focal distance constant and give us clear vision
What is the near point of vision?
The inner limit of clear vision for close objects, determined by the degree of elasticity in the lensw
What is the near point of vision?
The inner limit of clear vision for close objects, determined by the degree of elasticity in the lensw
What is the function fo the pigmented layer of the retina?
- prevents light from bouncing back and producing visual “echoes”
What is in the neural layer of the retina?
Photoreceptors, supporting cells and neurons that do preliminary processing (ganglion cells)
Where do the axons of ganglion cells converge at?
The optic disc (aka the blind spot)
Which cells are for seeming dimly lit rooms/black and white?Which are for colour/more intense light?
Rods, cones
Where are the bipolar cells located?
Rods and cones synapse with neurons called bipolar cells
What do amacrine cells do?
Inhibit communication between photoreceptors and ganglion cells thereby altering the sensitivity of the retina
What is the visual pigment a derivative of?
Rhodopsin (visual purple)
- consists of opsin bound to the pigment retinal
What colour wavelength is rod opsin most sensitive to? What are the three different colours of cones?
Blue-green, blue green and red
How are photoreceptor gated channels kept open?
(cGMP) cyclic guanosine monophosphate, because channel is open, the membrane potential is approximately -40mV and constantly releasing neurotransmitters/sodium across synapses to bipolar cells
Where do the optic nerves reach the diencephalon?
The optic chiasm
Where does visual information travel from the diencephalon through the projection fibres?
The occipital cortex
