Anatomy of the eye

Question 1

how does light enter the eye?

Answer 1

• light enters through the cornea
• progresses trough the pupil
• light is then bent by the lens
• this light continues through the vitreous humour
• light is then projected onto the retina

Question 2

What is lens accomodation?

Answer 2

The process of the lens being flexible to allow us to see from close and far away

The lens is flexible and controlled by ciliary muscles thru zonules.

to see at shorter focal distances= ciliary muscles contract causing zonules to loosen creating a rounder shaped lense and higher refractive power

to see at longer distances= ciliary muscles relax causing zonules to contract creating a flatter lense increasing focal distances (also lower refractive power)

lens accomodation and age= as we get older our lense beocmes stiffer so less able to adjust lens shape (why we need to wear glasses)

Question 3

Retina structure-

Answer 3

Photoreceptor layer= converts light energy into neural activity

bipolar cells- transmit info to ganglion cells

ganglion cells= intergrate info and send AP to brain

horizontal and amacrine cells= lateral neutrites influence cell close by

Question 4

explain the role of photo receptors

Answer 4

rods= 92 million
cones= 4.6 million

rods= found in the peripheral retina and are very sensitive to light providing monochromatic information (no info oncolour) Rods provide poor acuity

cones= most prevalent in fovea- less sensitive to light/ provide info on hue. Cones have high acuity

Question 5

what is transduction?

Answer 5

A process that converts external stimulus into an internal stimulus

• transduction of light energy into changes in membrane potential
• transduction of light is responsible by photopigment

Question 6

What is the receptive field?

Answer 6

the area of visual space in which stimulus has to be presented to change the activity of a neuron