Unit 3: Eyes And Hormonal Coordination

Question 1

What is the function of the cornea?

Answer 1

Refract the light as it enters the eye

Question 2

What is the function of the iris?

Answer 2

Controls how much light enters the eye

Question 3

Hat is the function of the lens?

Answer 3

Further refract light onto retina

Question 4

What is the function of the retina?

Answer 4

Contains light receptors

Question 5

What is the function of the optic nerve?

Answer 5

Carries electrical impulses from eye to brain

Question 6

What are cones and rods?

Answer 6

Light receptors:
Cones = colour, bright light
Rods = black and white, dim light

Question 7

How does the eye adjust to bright light?

Answer 7

Circular muscles contract
Radial muscles relax
Pupil is constricted
Allows less light into the eye

Question 8

How does the eye adjust to dim light?

Answer 8

Circular muscles relax
Radial muscles contract
Pupil is dilated
Allows more light into the eye

Question 9

What is accommodation?

Answer 9

Process of changing the shape of the lens to focus on near or distant objects

Question 10

How does the eye adjust to focus on distant objects?

Answer 10

Ciliary muscles relax
Suspensory ligaments tighten
Lens is pulled thin
Slight refraction
Light rays focused onto retina

Question 11

How does the eye adjust to focus on near objects?

Answer 11

Ciliary muscles contract
Suspensory ligaments loosen
Lens is thicker
Strong refraction
Light rays focused onto retina

Question 12

What is myopia?

Answer 12

Shortsightedness

Question 13

What is hyperopia?

Answer 13

Longsightedness

Question 14

What are some of the causes of myopia?

Answer 14

Eyeball too long
Cornea too curved
Light rays focused before the retina

Question 15

What is the treatment for myopia?

Answer 15

Concave lens

Question 16

What are the causes of hyperopia?

Answer 16

Lens is too weak
Eyeball too short
Cornea not curved enough
Light rays focused after retina

Question 17

What is the treatment for hyperopia?

Answer 17

Convex lens

Question 18

What is the optimum human body temperature?

Answer 18

37ºC

Question 19

Where in the brain is body temperature controlled?

Answer 19

Thermoregulatory centre, hypothalamus

Question 20

How does your body cool itself down?

Answer 20

Vasodilation - Blood vessels on surface become wider so more energy radiated away
Sweating - evaporates, taking energy with it

Question 21

How does your body keep warm?

Answer 21

Vasoconstriction - blood vessels on surface get smaller so less heat is lost
Shivering - Skeletal muscles contract and relax rapidly requiring respiration which produces energy

Question 22

What are the 6 glands?

Answer 22

Thyroid gland - neck - thyroxine - basal metabolic rate
Pituitary gland - brain - all other glands
Adrenal gland - kidneys - adrenaline - fight or flight
Pancreas - insulin & glucagon - blood sugar levels
Testes (biological males) - testosterone
Ovaries (biological females) - oestrogen

Question 23

What happens when blood glucose levels are too high?

Answer 23

Insulin is released by pancreas
Causes body & liver cells to take in glucose
Store as glycogen

Question 24

What happens when the blood glucose levels get too low?

Answer 24

Glucagon is released by pancreas
Causes body & liver cells to break down glycogen into glucose ad release it back into the bloodstream

Question 25

What is type 1 diabetes?

Answer 25

Pancreas doesn’t produce insulin

Question 26

What are the symptoms of type 1 diabetes?

Answer 26

Sticky urine Produce lots of urine Lack energy Lose weight

Question 27

What is type 2 diabetes?

Answer 27

Body cells no longer respond to insulin

Question 28

What can people with type 1 diabetes do to control blood glucose levels?

Answer 28

Inject insulin Monitor blood glucose levels Eat low-sugar foods Excercise

Question 29

What can people with type 2 diabetes do to help control blood glucose levels?

Answer 29

Carbohydrate controlled diet Regular excercise

Question 30

What is osmoregulation?

Answer 30

Control of water levels and mineral salts in blood

Question 31

Explain hypertonic cells

Answer 31

Too little water in blood Blood is concentrated Water leaves cells by osmosis Cells shrivel

Question 32

Explain isotonic cells

Answer 32

Equal concentration of water inside and outside of the cell

Question 33

Explain hypotonic cells

Answer 33

Too much water in blood Blood is too dilute Water enters cells b osmosis Cells swell & burst

Question 34

What are the 3 ways that water can be lost from the body?

Answer 34

Urine Sweat Water vapour

Question 35

How does the body remove excess amino acids?

Answer 35

Deaminated into ammonia (toxic) Ammonia converted to urea Exits in urine

Question 36

What are the 3 processes that occur in the kidneys to produce urine?

Answer 36

_Filtration:_ high pressure, small molecules (urea/water/ions/glucose) go into kidneys, larger molecules (proteins) remain in blood _Selective Reabsorption:_ useful substances (glucose, some ions, some water) re-absorbed into the bloodstream _Urine Formation:_ not useful substances (urea, excess water, excess ions) pass to bladder

Question 37

What is ADH?

Answer 37

Hormone that controls permeability of kidney tubules, produced by pituitary gland

Question 38

What does ADH do?

Answer 38

Increases permeability of kidney tubules and causes more water to be re-absorbed when you are dehydrated causing a small volume of concentrated urine

Question 39

What are the two methods of treating kidney failure?

Answer 39

Dialysis Kidney transplant

Question 40

What is dialysis?

Answer 40

Long-term treatment Dialysis machine filters patients blood by diffusion 3 times a week 4 hour sessions

Question 41

What is a diner transplant?

Answer 41

Receive a single, healthy kidney from a donor Immunosuppressant drugs

Question 42

What is negative feedback

Answer 42

Mechanism of negative correlation to restore homeostasis

Question 43

What is the function of adrenaline?

Answer 43

Prepare body for action by: - increasing breathing rate = more oxygen - increasing heart rate = more blood to muscles - dilate pupils = more light - blood diverted from digestive system to skeletal muscles - increase of oxygen & glucose to brain