Lecture 3- How We See 2

Question 1

What is phototransduction

Answer 1

Conversion of light energy to an electrochemical response by the photoreceptors (rods and cones)

Question 2

What do the phtotransduced rods and cones activate

Answer 2

Optic nerve cells to generate and action potential

Question 3

Where are the rods and cones located

Answer 3

Deep in the retina

Question 4

What is more present cones or rods

Answer 4

Rods

Question 5

What is integrated into the cell membrane of the lamellae that surrounds rods and cones

Answer 5

Visual pigment- Rhodopsin in rods

Opsins in cones

Question 6

What happen when light rays hit rods

Answer 6

The vitamin A compound reacts to from an isomer (from 11-cis to all trans retinal)
Because it goes from bent to straight it cannot fit and rhodopsin splits and bleaches purple
It then activates a cascade or reaction which closes the sodium channel and leads to hyper polarisation and becomes an action potential directed to the brain

Question 7

What is Rhodopsin made of

Answer 7

Opsin + 11-cis Retinal

Question 8

What happens to the remaining trans-retinal

Answer 8

Converted to cis-retinol and used with opsin to reform Rhodopsin

Question 9

What type of deficiency can affect vision

Answer 9

Vitamin A
Night blindness
Abnormal conjunctiva and corneal epithelium