Activity 2: Internal Anatomy of the Eye and Identifying Internal Structures of the Eye
The wall of the eye is constructed of what 3 layers?
1. Fibrous layer
2. Vascular layer
3. Inner layer
How are the photoreceptor cells distributed on the neural retina?
Distributed over the entire neural retina, except where the optic nerve leaves the eyeball.
The site on the neural retina where there is no photoreceptor distribution at all is called what?
Optic disc (aka blind spot)
Where is the optic disc located?
In a weak spot in the fundus
Lateral to each blind spot and directly posterior to the lens is an area referred to as what?
The macula lutea is dense in what type of photoreceptor cell?
In the center of the macula lutea is what structure?
The fovea centralis contains only what type of photoreceptor cell?
The fovea centralis is the area of greatest what?
Area of greatest visual acuity
Focusing for detailed color vision occurs where in the eye?
The lens divides the eye into which 2 segments?
1. Anterior segment
2. Posterior segment
The anterior segment contains what fluid?
The posterior segment contains what gel-like substance?
The anterior segment is further divided into what 2 chambers?
1. Anterior chamber
2. Posterior chamber
1. What separates the anterior and posterior chambers in the anterior segment?
2. How are the anterior and posterior chambers positioned in regard to the iris?
1. The iris.
2. The anterior chamber lies in front of the iris, and the posterior chamber lies behind the iris.
The aqueous humor is continually formed by what?
The ciliary processes of the ciliary body.
What are the 2 functions of the aqueous humor?
1. Maintain intraocular pressure of the eye.
2. Provides nutrients for the avascular lens and cornea.
The aqueous humor drains into what what?
The scleral venous sinus.
What are the 2 functions of the vitreous humor?
1. Provide internal reinforcement to the posterior part of the eyeball.
2. Keep the retina pressed against the wall of the eyeball.
When is the vitreous humor formed, and is it renewable like the aqueous humor (i.e. continually produced)?
Only formed before birth and is not renewable.
What are the 4 light-bending media of the eye?
3. Aqueous humor
4. Vitreous humor
Anything that interferes with drainage of the aqueous humor increases what type of pressure?
What 2 things happen when intraocular pressure reaches dangerously high levels?
1. The retina is compressed
2. The optic nerve is compressed
The compressing of the retina and optic nerve due to high intraocular pressure results in pain and what condition?
Glaucoma can lead to what permanent disability?
Cells of the retina include what 2 groups of cells (and also name their associated layers)?
1. Pigment cells of the outer pigment layer
2. Neurons of the neural layer
The inner neural layer is composed of how many major populations of cells?
In the inner layer, from outer to inner aspect, what are the 3 major populations of cells?
2. Bipolar cells
3. Ganglion cells
What are the specialized receptors for dim light?
Visual interpretation of rod activity is in what type of tones?
The cones are what type of receptors?
The cones permit high levels of what, and function only under what type of conditions?
Permit high levels of visual acuity, but they function only under conditions of high light intensity.
Due to the fact that cones only function under conditions of high light intensity, what is the consequence in moonlight?
No color vision.
The fovea centralis contains only cones, the macula lutea contains mostly cones, and from the edge of the macula lutea to the retina periphery, what happens to cone density?
It declines gradually.
What photoreceptors are most numerous in the retina periphery, and how is their density affected as the macula lutea is approached?
Rods are most numerous in the retina periphery, and their density decreases as the macula lutea is approached.
Light must pass through which 2 cell layers to reach and excite the rods and cones?
1. Ganglion cell layer
2. Bipolar cell layer
Receiving a light stimulus, describe what happens to the photoreceptors and the bipolar neurons?
Receiving a light stimulus, the photoreceptors undergo changes in their membrane potential that influence the bipolar neurons.
Once the bipolar neurons are stimulated by the changed membrane potential of the photoreceptors, which group of cells is activated next?
The axons of ganglion cells leave the retina through what nerve?
The optic nerve is composed of what?
In addition to the three major types of cells/neurons (i.e. photoreceptor cells, bipolar cells, and ganglion cells), the retina also contains which 2 other types of cells/neurons?
1. Horizontal cells
2. Amacrine cells
Horizontal and amacrine cells are both what type of neuron?
The horizontal and amacrine cells/neurons play a roll in what type of processing?