Eyes Flashcards
The eye is compose of how many tunics
Fibrous,vascular ,and nervous tunics
Fibrous tunic
The outer most layer of the eyes consisting of sclera and cornea
Vascular tunic
Underneath the fibrous tunic, rich in supply of blood very vasculrized and some pigment (choroid)
Nervous tunic
The inner layer of the eyes underneath the vascular tunic, the retina lies here with it photoreceptors cells rods and cones
The cavities of the eye
There are two eye cavities, posterior cavity and anterior cavity
The anterior cavity has two chamber.
Anterior chamber and posterior chamber
Anterior chamber
Located in front of the iris and its filled with aqueous humor
Posterior chamber
This is behind the iris
Accommodation
The process of focusing light to the retina
Explain the process of accommodation
Suspensory ligament is attached to the ciliary muscle, the ciliary muscle
Presbyopia
The thicken of the eye lens, causing the weaken of the suspensory ligament attached to the lens
Relaxation of the muscle make the lens ……. and contracting makes the lens …….
Thicker and thinner
The ciliary muscle is controlled by the
Cranial nerve 3 ocular motor nerve
The three layer of the retina are
Photoreceptors cells(rods and cones), bipolar cells, ganglion cells
Describe the direction of the signal sent when light hits the eyes
Light hits the photoreceptor cells and send the signal in one direction to the brain and the signal reacting to the stimulus travels in the opposite direction
The image of the outside world is perceived as upside down but the brain
Flips the image receive form the outside world
What is the function of the iris
The iris controls the amount of light that goes through by relaxing and contracting
Posterior cavity
Filled with vitreous liquid which is very gel like located located behind the lens
Suspensory ligament
Attaches lens to ciliary muscle. It has a thing layer around it can make the eye lens thinner or thicker
Ciliary muscle
Pulls on the suspension ligament to focus light into the retina by changing the thickness of the lens
Crystalline lens
The lens, it is a transparent structure along with the cornea helps with refracting light to be be focused in the retina
Cranial nerve 3 ( ocular motor nerve) controls the
Ciliary muscles
The retina is part of what tunic
Nervous tunic
Photo transduction occurs in what tunic
In the nervous tunic in the retina
Horizontal cells and amacrince cells
Are specialized interneurons that ends up in the ganglion cells
Photo transduction converting light waves to nerve signals occurs at the
Ganglion cells
The transmition of the nerve signal away from the retina is after the ganglion cell by the
Optic nerve ( cranial nerve 2)
Rhodopsin
Found in the outer most part of the rods and there are two parts scotopsin and retinal
Photoisomerization
When light changes the configuration of cis-retinal to trans-retinal
Rhodopsin form is
Csi retinal and scotopsin
Retinal isomerase
Converts trans retinal into cis retinal when there is no light
Describe what happens at the outer segment of the rod cell
At the surface of the rod cells there are Na channels opened by cyclic GMP, Na goes into the cell making it more positive. After light hits then cyclic GMP is converted to GMP thus closing the Na channels making it more negative leading to hyper polarization
Describe the closing of Na channels
After light hits rhodopsin activates the G protein transducin, producing GTP, GTP activates phosphodiesterase. It then convert cyclic GMP to GMP thus closing the sodium channel
Cones uses what opsin
Photopsin
Tri color vision
It is based on the fact we see color base on the absorption of three color receptors blue red and green. And the color we see is due to the percentage of the different color cones
We see white light because
All the color cones are activated
Color blindness is caused by
The absence of different color cone, it is a x linked recessive gene that is generally found males
The neurotransmitter released by the photoreceptors at the base of the retinal is
Glutamate
Horizontal cells
Transmit signal horizontally and participates in lateral inhibition. The end result is usually inhibitory.. Have graded potential or electronic potential
Bipolar cells
There two types the on cells and off cells, the on cells hyper polarize glutamate is inhibitory and the off cells depolarize where glutamate is excitort…it has very short graded potentials
Ganglion cells
Carries signal to the optic nerv, has action potential not graded potential, they are self propagating, and there are three types x, y,and w
Amacrine cells
Found between bipolar cell, can transmit vertically and horizontally, can interact with bipolar and ganglion cells.
The neurotransmitter released by amacrine are cells are
GABA, glycine, dopamine, acetylcholine, and endolamine
In the ganglion cells, the frequency of action potential increase significantly
When there is light stimulus
W ganglion cells
Linked to rods activates in dim light. It is the least population of the gang lions..diameter is smaller thus does not conduct rapidly
X ganglion
Most of ganglion are x, larger diameter, and it is involved with refine structure of light ,associated with cones
Y ganglion
Second large rest , involves determination of rapid change in the visual field
Retinal ganglion cells has two functions
Participating in the visual function of the eye
Deploys SCN in the hypothalamus
SNC
Biological clock controlled in the hypothalamus region of the brain. Which controls the light dark period involving the pigment melonopsin
Optic chiasma
The cross over effect to the ociptal lobe
