Topic 13: coordination (eye structure and hormones)

Question 1

role of iris

Answer 1

control pupil size

Question 2

role of pupil

Answer 2

allows light to enter the eye

Question 3

role of lens

Answer 3

refract light onto the retina

Question 4

role of cornea

Answer 4

allows light to enter the eye while refracting it a little

Question 5

role of conjunctiva

Answer 5

• lubricate the eye by producing mucus and tears
• provide protection against external irritants

Question 6

role of sclera

Answer 6

• keeps eye in shape
• provides shape for muscle to attach

Question 7

role of retina

Answer 7

contains light intensive receptor cells that converts light into electrical impulses

Question 8

what is the fovea

Answer 8

an area of the retina which is densely packed with light receptor cells (choroids). allows vision to be clear, detailed and in good colour

Question 9

role of ciliary muscle

Answer 9

controls and changes the shape of lens

Question 10

role of suspensory ligaments

Answer 10

attaches the ciliary muscles with the lens

Question 11

role of optic nerve

Answer 11

transfers electrical impulses from the retina to the brain

Question 12

what is the blind spot

Answer 12

where the electrical impulses leaves the eye, doesn’t contain light receptor cells

Question 13

focusing on close objects

Answer 13

• ciliary muscles contracts
• suspensory ligaments slackens
• lens gets thicker
• more light is refracted

Question 14

focusing on distant objects

Answer 14

• ciliary muscles relax
• suspensory ligaments tightens
• lens gets thinner
• less light is refracted

Question 15

response to dim light

Answer 15

• circular muscle relax
• radial muscle contract
• pupil dilates, so more light enters the eye

Question 16

response to bright light

Answer 16

• circular muscles contract
• radial muscles relaxes
• pupil constricts, so less light enters the eye

Question 17

source, role and effect of adrenaline

Answer 17

• adrenal gland
• readies the body for ‘fight or flight’
• decrease reaction time and pain sensitivity
• increase heart rate, blood flow and blood sugar levels
• vessels dilates in muscles so more blood reaches active muscles
• break down of glycogen into glucose in liver & muscle

Question 18

source, role and effect of testosterone

Answer 18

• male testes
• stimulate development of male reproductive organs
• male secondary sexual characteristics: facial hair, voice deepening, increase muscle mass, increase bone density
• sperm production

Question 19

source, role and effect of progesterone

Answer 19

• corpus luteum
• regulation of menstrual cycle and supports pregnancy
• maintains thick uterus lining
• prevents further ovulation

Question 20

source, role and effect of oestrogen

Answer 20

• female ovaries
• regulation of menstrual cycle + development of female reproductive organs
• female secondary sexual characteristics: hips widening, development of breast, start of periods, body hair
• repairs uterus lining

Question 21

source, role and effect of FSH

Answer 21

• pituitary gland
• cause egg to to start maturing in the ovary
• stimulate releasing of oestrogen

Question 22

source, role and effect of LH

Answer 22

• pituitary gland
• cause ovulation to occur
• stimulate releasing of progesterone