Eyes lecture Flashcards
Why isn’t the cornea ever rejected in a transplant.
The lack of vascularization mean then there is no immune response.
How does constricting the pupil to focus on close objects work?
It help keep light rays parallel to prevent divergence.
What is the function of the lens in focusing
It fine tunes the image between humors
Which types of cells in the eye send an action potential?
Ganglion Cells
What is the plate of protective connective tissues in the eyelids? and where is it locate?
The tarsal plate on both upper an lower eyelids.
Ho may bi-polar cells and ganglion cells are there per cone?
One bi-polar cells, One ganglion cells.
What muscle causes constriction of pupil? What system control its?
The circular muscles (pupil constrictor muscle). Controlled by the parasympathetic system.
What is the sclera made out? What is is function?
Dense irregular connective tissue. Keeps the shape of the eyeball.
How does the cornea get oxygen?
It diffuses in from outside air.
Can vitreous humor be regenerated?
No. You only have what you are born with
Median caruncle
.
What are the medial and lateral commissures of the eyes?
The place where the eyelids meet.
What are 4 functions of tears.
The acidity helps keep bacterial count down. They Contain lysosomes to break down bacteria and fungal wall. they Wash the eye clean, and they keep it wet allow the cornea to be oxygenated.
What causes the cornea to be cloudy?
Problems with the sodium pumps that changes the shape of the fibroblasts.
Where do the nutrients for the cornea come from?
The aqueous humor.
What is the cause of cataracts?
problems the regular arrangement of the lens. Sometimes modified and sometimes removed to correct the cataracts.
How many pigments are the for eye color? What are other causes of eye color?
The is one pigment for brown. Other colors are caused by melanin quantity and refraction.
What produces the Aqueous humor, and how much is produced per day?
The Ciliary process. It produces about 1/2 liter per day
Describe the location of the conjunctiva.
The conductiva is a membrane that covers the font of the slcera and the eyelids.
What kind of tissue composes the cornea and what make it so clear.
It is highly regularly arranged college fibers. The hexagonal arrangement make is clear.
What organ is of primary importance for focus and how does it work?
The cornea. It becomes more of less convex depending on the distance of the object to make sure that the light it still refracted onto the fovea
What muscle causes dilation of pupil? What system control its?
The radial muscles (pupil dilator muscle). Controlled by the sympathetic system.
What is accommodation and when does it occur?
When the lens increases its curvature to view near objects. At distance close than 6 feet
What is the function of tarsal glands (Meibomian Glands)
Produce and secrete an oil that helps keep the eyeball wet and coats particles to prevent scratching
What are the parts of the fibrous Tunic?
The sclera and the cornea
What is the Ora Serrata?
It connects the retina and the ciliary body
What kind of tissue composes the cornea and what make it so clear.
It is highly regularly arranged college fibers. The hexagonal arrangement of the fibroblasts make is clear.
What are the folks above and below the eyes called?
The superior and inferior palpebral suclus (sulci)
What is the shape of the lens when focusing up close?
Rounder
About how many rods converge onto one ganglion cell?
About 500-600
What type of eye cell divides more rapidly than any cell in the body?
Corneal epithelium
What pigment gives color the choroid and what is its function?
Melanin. The black color absorbs photons to they don’t cause interference in vision.
What can be an effect of damage to the conjunctiva and why?
Infections that can reach to CNS due to the fact the eye is an invagination from the brain.
What cranial nerve control the lateral rectus?
Aducens
What is the photopupilary reflex?
Dilation of pupils after bright light
When the lens is flattened what is happening with the suspensory ligament and the ciliary muscle?
The suspensory ligament is shortened. The Ciliary muscle is contracted.
What happens when the production of Aqueous humor exceeds the draining?
It leads to excess pressure which causes glaucoma
What is presbyopia, what causes it?
the lens and ligaments hardening over time so that they can’t fully relax
What is horizontal cell in the retina?
An an-axonic cell that causes lateral inhibittion to adjacent rod cells in the presence of a photon increase accuity
What cranial nerve controls the superior oblique
Trochlear
What is the visible spectrum for people
about 400-750NM
What is an Amacrine cell?
It is a cell that excites the bi-polar cells in different conditions (i.e. direction-specific motion)
Macula Lutea
Area of sharp vision surrounding fovea centralis
What is the direction of flow of the aqueous humor?
From the posterior chamber of the anterior cavity through the pupil and out the canal of Schlemm
What are functions of the aqueous humor?
To maintain eye shape and provide Nutrients for cornea and lens.
Review 46 minute mark
Where is the lacrimal gland?
Superior lateral side of the eye in eye in the frontal bone
Lacrimal caruncle
.
What percent of all sensory receptors are in the eyes?
Over 80%
What are the 4 extrinsic eye muscles controlled by the oculomotor nerve?
The superior, median, and inferior rectus and the inferior oblique.
What is the configuration of the lens when the Ciliary muscle is contracted?
round
Describe the Fovea Centralis
Central area at back of eye Highest concentration of cones
What is in the nervous tunic?
The retina, the optic disc, the optic nerve, and the retina blood vessels
What is a tapetum?
The reflective part in the eye in animals that can see in the dark.
Where does Aqueous humor drain?
Canal of Schlemm
What are the parts are the vascular tunic?
Choroid, iris, and pupil, lens and Ciliary body.
What causes a detached retina and why can it lead to blindness or blind spots?
A blow to the head (boxer’s), lack of vitreous fluid.. When it detached it loses blood supply and the neurons die.
Describe the Lacrimal Apparatus following the parts of tears.
Tears are formed in the lacrimal gland. They drain medially into the lateral puctum, which is the entrance to the lacrimal canal. The panel drains in the nasolacrimal duct and into the nose from there.
What is convergence?
Moving eyes (crossing eyes slightly)
What is the shape of the lens when focusing farther away?
Flatter.
