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NS exam > Eye Physiology > Flashcards

Eye Physiology Flashcards

1
Q

Eyes are an extension of the

A

brain

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2
Q

Eyes are physiologically formed by

A

A system of lenses
A receptor layer
A system of axons

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3
Q

What for has the eye a system of lenses?

A

For focusing the image

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4
Q

What for has the eye a system of axons?

A

For transmitting action potentials to the brain

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5
Q

Functions of sclera?

A

Keep eye shape
Protection
Insertion of eye muscles

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6
Q

Tapetum lucidum

A

A layer of highly reflective tissue in the choroid

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7
Q

Pupil

A

A hole in the choroid

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8
Q

What is the function of tapetum lucidum?

A

Night vision

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9
Q

Choroid

A

Highly vascular and pigmented layer of the eye

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10
Q

What is the pigment of choroid?

A

melanin

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11
Q

The front of the choroid is called?

A

Iris

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12
Q

Functions of the vascular tunic?

A
  • Supply of nutrients
  • Storage of vitamin A
  • Excess of light
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13
Q

Functions of the iris?

A

Light regulation

Acting as a diaphragm

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14
Q

What is the pupillary reflex?

A

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

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15
Q

Miosis

A

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

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16
Q

Mydriasis

A

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

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17
Q

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

A

Both pupils will react and constrict

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18
Q

For what is the pupillary reflex important?

A

As a diagnostic tool.

19
Q

What can be assessed by the pupillary reflex?

A

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

Brain stem function

20
Q

What is included in the retina?

A

The photoreceptor cells

21
Q

What are the photoreceptor cells?

A

Rods and cones

22
Q

To what is the retina connected to?

A

To CN II aka optic nerve.

23
Q

Optic disc

A

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

24
Q

Fovea centralis

A

Small, central pit composed of closely packed cones.

25
Q

What is the function of fovea centralis?

A

Sharp central vision (visual details).

26
Q

Neural tunic

A

Internal tunic/retina

27
Q

Functions of the neural tunic

A

Luminic sensibility
Signal transduction
Sentive transmission

28
Q

Cells of the vertebrate retina?

A 
Pigmented cells
Neurons (5 main types)
Supporting cells (2 types)
29
Q

Pigmented cells

A

Retinal cells:

30
Q

Functions of the pigmented cells

A

Photoreceptor metabolism
Absorption of extra light
Storage of vitamin A

31
Q

Neurons of the retina

A 
Photoreceptors
Bipolar cells
Horizontal cells
Amacrine cells
Ganglion cells
32
Q

Supporting cells of the retina

A

Astrocytes and Muller cells

33
Q

Rod functions

A

Black and white vision in dim light

34
Q

Where are rods concentrated?

A

In the periphery

35
Q

Cone functions

A

Color vision in bright light

High visual acuity (sharpness)

36
Q

Where are cones concentrated?

A

In the centre of the eye (fovea)

37
Q

How many rods and cones humans approximately have?

A

120 million rods and 6 million cones

38
Q

What is the convergence of fovea?

A

1:1

39
Q

What does the 1:1 convergence of fovea mean?

A

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

40
Q

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

A

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

41
Q

Explain why is vision so good in fovea?

A

The photoreceptor cells are not covered by other neurons.

42
Q

What are the main regions of the photoreceptor cells?

A

Outer segment OS
Inner segment IS
Synaptic terminal

43
Q

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

A

They are phagocytized by the pigment cells.

NS exam (5 decks)

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