Physiology: sight - anatomy

Question 1

Is the cornea avascular?
Implications of this?

Answer 1

Yes, the cornea is avascular.
Enables it to be transparent, however it can’t oxygenate itself. Instead, it gets oxygen from tears (the lacrimal glands)

Question 2

Does the iris contain muscles controlling pupil diameter?

Answer 2

Yes

Question 3

Does the sclera enable attachment for extraocular muscles?
The sclera is usually white, why might it turn red?

Answer 3

Yes
Disease, drugs, trauma

Question 4

Where are the anterior, posterior and vitreous chambers located?
Where is the aqueous and vitreous humour located?

Answer 4

Aqueous humour: anterior and posterior chamber
Vitreous humour: vitreous chamber

Question 5

Does the aqueous humour turn over?
How about the vitreous humour?

Answer 5

Yes - continually refreshed
Turns over so slowly that it’s effectively static

Question 6

Lens
- What 2 components is it made of?

Answer 6

Cells (lens fibres) and proteins (crystallins)

Question 7

LENS
- What is a key characteristic of mature lens fibre cells?
- Why is this important?
- What process enables the cells to be this way?

Answer 7

They lack organelles.
Helps maintain transparency
Cells burn glucose by anaerobic respiration - doesn’t need organelles.

Question 8

RETINA
What are the 5 cell types of the retina?

Answer 8

Question 9

RETINA
What are the 2 layers of the retina?
And sub layers?

Answer 9

Retinal pigment epithelium
Neural retina

Question 10

FOVEA
- What is it?
- Contains the highest density of which type of photoreceptor?
- Are bipolar and ganglion cells pushed aside, giving light less obstacles in its path to the cones?
- Is it in line with the visual axis?

Answer 10

Pit in the retina
Cones
Yes
Yes

Question 11

CHOROID
What is it?
Is it densely pigmented?

Answer 11

Contains a vascular netework that nourishes the outer layers of the retina
Yes

Question 12

Retinogram
- Label the following

Answer 12

Question 13

Retinogram
- Differentiate the macula and the fovea
- Why is the macula yellow?

Answer 13

The macula is the yellow area, which contains the fovea.
Because it contains fewer blood vessels

Question 14

Retinogram
- Are BV’s normally found in the periphery, but not near the macula?
- Condition involving vascularisation of the macula?
- Way around this?

Answer 14

Yes
Macular degeneration: vascularisation of macula lutea (due to irritation or damage) –> disrupted light transmission into the fovea –> vision impairment
Can wear dark glasses - makes light coming in darker, can take advantage of dark sensitive rods

Question 15

PUPILLARY LIGHT REFLEX
What is it?
Is it consensual in healthy people?

Answer 15

When light is shone into an eye, and the pupil constricts.
Yes - other eye should also constrict.

Question 16

PUPILLARY LIGHT REFLEX
Describe the pathway

Answer 16

Question 17

PUPILLARY LIGHT REFLEX
What is it?
Is it consensual in healthy people?

Answer 17

When light is shone into an eye, and the pupil constricts.
Yes - other eye should also constrict.