Eye Physiology

Question 1

Eyes are an extension of the

Answer 1

brain

Question 2

Eyes are physiologically formed by

Answer 2

A system of lenses
A receptor layer
A system of axons

Question 3

What for has the eye a system of lenses?

Answer 3

For focusing the image

Question 4

What for has the eye a system of axons?

Answer 4

For transmitting action potentials to the brain

Question 5

Functions of sclera?

Answer 5

Keep eye shape
Protection
Insertion of eye muscles

Question 6

Tapetum lucidum

Answer 6

A layer of highly reflective tissue in the choroid

Question 7

Pupil

Answer 7

A hole in the choroid

Question 8

What is the function of tapetum lucidum?

Answer 8

Night vision

Question 9

Choroid

Answer 9

Highly vascular and pigmented layer of the eye

Question 10

What is the pigment of choroid?

Answer 10

melanin

Question 11

The front of the choroid is called?

Answer 11

Iris

Question 12

Functions of the vascular tunic?

Answer 12

• Supply of nutrients
• Storage of vitamin A
• Excess of light

Question 13

Functions of the iris?

Answer 13

Light regulation

Acting as a diaphragm

Question 14

What is the pupillary reflex?

Answer 14

Control of the diameter of the pupil in response to the intensity of light.

Question 15

Miosis

Answer 15

Constriction of the pupil in response to a greater intensity of light.

Question 16

Mydriasis

Answer 16

Dilation of the pupil in response to a lower intensity of light.

Question 17

What happens if a light is shown to one eye only?

Answer 17

Both pupils will react and constrict

Question 18

For what is the pupillary reflex important?

Answer 18

As a diagnostic tool.

Question 19

What can be assessed by the pupillary reflex?

Answer 19

The integrity of the motor and sensory functions of the eye.

Brain stem function

Question 20

What is included in the retina?

Answer 20

The photoreceptor cells

Question 21

What are the photoreceptor cells?

Answer 21

Rods and cones

Question 22

To what is the retina connected to?

Answer 22

To CN II aka optic nerve.

Question 23

Optic disc

Answer 23

A blind spot where the retinal vessels enter and leave the optic nerve.

Question 24

Fovea centralis

Answer 24

Small, central pit composed of closely packed cones.

Question 25

What is the function of fovea centralis?

Answer 25

Sharp central vision (visual details).

Question 26

Neural tunic

Answer 26

Internal tunic/retina

Question 27

Functions of the neural tunic

Answer 27

Luminic sensibility Signal transduction Sentive transmission

Question 28

Cells of the vertebrate retina?

Answer 28

``` Pigmented cells Neurons (5 main types) Supporting cells (2 types) ```

Question 29

Pigmented cells

Answer 29

Retinal cells:

Question 30

Functions of the pigmented cells

Answer 30

Photoreceptor metabolism Absorption of extra light Storage of vitamin A

Question 31

Neurons of the retina

Answer 31

``` Photoreceptors Bipolar cells Horizontal cells Amacrine cells Ganglion cells ```

Question 32

Supporting cells of the retina

Answer 32

Astrocytes and Muller cells

Question 33

Rod functions

Answer 33

Black and white vision in dim light

Question 34

Where are rods concentrated?

Answer 34

In the periphery

Question 35

Cone functions

Answer 35

Color vision in bright light | High visual acuity (sharpness)

Question 36

Where are cones concentrated?

Answer 36

In the centre of the eye (fovea)

Question 37

How many rods and cones humans approximately have?

Answer 37

120 million rods and 6 million cones

Question 38

What is the convergence of fovea?

Answer 38

1:1

Question 39

What does the 1:1 convergence of fovea mean?

Answer 39

1 cone communicates with 1 bipolar cell and this one with 1 ganglion cell etc so the most direct transmission of the signal in all retina

Question 40

What is the implication of the most direct transmission of the signal in the fovea?

Answer 40

The fovea centralis has the highest acuity of the vision regions but quite a low sensitivity.

Question 41

Explain why is vision so good in fovea?

Answer 41

The photoreceptor cells are not covered by other neurons.

Question 42

What are the main regions of the photoreceptor cells?

Answer 42

Outer segment OS Inner segment IS Synaptic terminal

Question 43

What happens to the old disks at the tip of the outer pigment?

Answer 43

They are phagocytized by the pigment cells.