Homeostasis-PAPER2

Question 1

What is homeostasis?

Answer 1

Scientists describe it as maintaining a stable internal environment.

Question 2

Why is homeostasis important?

Answer 2

Homeostasis is how the body keeps conditions inside it the same. Things it keeps the same are
body temperature at 37°C
the amount of water inside our body
and blood glucose levels

Question 3

Describe common features of all control systems

Answer 3

Negative feedback ensures that, in any control system, changes are reversed and returned back to the set level.

Question 4

What is the role of negative feedback?

Answer 4

When something becomes too high or too low, negative feedback brings it back to normal.

Question 5

What does negative feedback do if we are too hot?

Answer 5

blood vessels in our skin vasodilate (become larger) and we lose heat and cool down.
sweat is produced and evaporates from the skin. This transfers energy into the environment.

Question 6

what does negative feedback do if we are too cold?

Answer 6

blood vessels in our skin vasoconstrict (become smaller), we lose less heat and our body warms up.
Hairs stand up to trap an insulating layer of air.
You shiver meaning your muscles automatically contract which needs respiration which transfers some energy to warm up the body.

Question 7

why do internal conditions in our body need to be regulated?

Answer 7

So cells are in the correct conditions to function properly and for enzyme reactions.

Question 8

All automatic control systems are made up of one of these 3.

Answer 8

Receptors, coordination centres and effectors.

Question 9

What does a receptor do?

Answer 9

Detects the stimulus

Question 10

What does the coordination centre do?

Answer 10

receives and processes the information then organises a response.

Question 11

What does an effector do?

Answer 11

Produces the response which counteracts the change and restores the optimum level

Question 12

What is a stimulus?

Answer 12

A change in environment

Question 13

What is a reflex action?

Answer 13

A rapid automatic response that doesn’t involve the conscious brain

Question 14

What does a relay neurone do?

Answer 14

Connects sensory neurones to motor neurones.

Question 15

What is the cerebellum responsible for?

Answer 15

muscle coordination

Question 16

What part of the brain controls consciousness memory, and intelligence?

Answer 16

Cerebral cortex

Question 17

What does the medulla do?

Answer 17

Controls unconscious activities e.g. breathing and heartbeat.

Question 18

What makes up the central nervous system?

Answer 18

spinal cord and the brain

Question 19

What 3 methods do scientists use to study the brain?

Answer 19

MRI Scans, Electrically stimulating the brain or studying people which brain damage.

Question 20

How do MRI scans work?

Answer 20

By showing a detailed picture of the brain’s structures so you can see which areas of the brain are active whilst doing certain activities.

Question 21

How does electrically stimulating the brain work?

Answer 21

Pushing a tiny electrode into the tissue and zapping it with electricity. By observing what stimulating different areas of the brain does you can see what their function is.

Question 22

What consequences are there from messing with the brain?

Answer 22

Electric stimulation has resulted in a treatment for nervous system disorders e.g. muscle tremors caused by parkinsons disease.
However it risks physical damage to the brain or brain function e.g. difficulties with speech.

Question 23

Name all treatments for vision defects

Answer 23

Glasses
Contact lenses
Laser eye surgery
replacement lens surgery

Question 24

What does being long sighted mean about you eye?

Answer 24

The eyeball is too short or the lens doesn’t refract the light enough

Question 25

What does being short sighted mean about your eye?

Answer 25

The eyeball is too long or the lens refracts too much light.

Question 26

Medical term for long sightedness?

Answer 26

Hyperopia

Question 27

Medical term for short sightedness?

Answer 27

Myopia

Question 28

What is the Cornea?

Answer 28

The transparent outer layer at the front of your eye. This refracts light into the eye.

Question 29

What is the sclera?

Answer 29

A tough supporting wall for the eye.

Question 30

What is the Lens?

Answer 30

The lens focuses the light onto the RETINA

Question 31

What does the retina contain?

Answer 31

Receptor cells sensitive to light intensity and colour

Question 32

What is the iris?

Answer 32

The iris contains muscles that control the diameter of the pupil, and therefore how much light enters.

Question 33

How is the shape of the lens controlled?

Answer 33

By the ciliary muscles and suspensory ligaments

Question 34

What does the optic nerve do?

Answer 34

Carries impulses from the receptors on the retina to the brain.

Question 35

Why do you have an iris reflex?

Answer 35

As very bright light can damage the retina to the reflex protects it

Question 36

What happens to your eye when you look at something near?

Answer 36

The ciliary muscles contract which slackens he suspensory ligaments and this makes the lens fat which increases the amount by which it refracts light

Question 37

What happens to your eye when you look at something distant?

Answer 37

The ciliary muscles relax, which allows the suspensory ligaments to tighten which makes the lens thin and means that less light is refracted by a smaller amount.

Question 38

How does vasodilation cool you down?

Answer 38

As it allows more energy to transfer from the skin to the environment.

Question 39

How does shivering keep you warm?

Answer 39

As it requires respiration which transfers some energy to warm the body.

Question 40

Some effectors work antagonistically- what does this mean?

Answer 40

They work together to achieve a very precise response. an example is one effector does heats one cools to get a very accurate temperature

Question 41

How do hairs standing on end keep us warm?

Answer 41

They stand up and trap an insulating layer of air

Question 42

How do humans cool down except vasodilation

Answer 42

Sweat evaporates from the skin which transfers energy to the environment.

Question 43

What does insulin do?

Answer 43

Triggers body cells to take up glucose and triggers muscle cells and the liver to STORE excess glucose. (glycogen)