Homeostasis and response

Question 1

What is homeostasis?

Answer 1

Maintaining a stable internal environment controlled by automatic nervous and hormonal control systems.

Question 2

What is negative feedback?

Answer 2

A mechanism that keeps internal conditions stable. When a level of something (eg. water, blood sugar, temperature) gets too high or too low, your body uses negative feedback to bring it back to the normal level.

Question 3

What does the nervous system do?

Answer 3

Detects and reacts to stimuli

Question 4

What are stimuli?

Answer 4

Changes in environment

Question 5

What is the nervous system made up of?

Answer 5

Central Nervous System CNS (brain and spinal cord)
Sensory Neurones
Motor neurones
Effectors

Question 6

What are receptors?

Answer 6

The cells that detect stimuli.

They can form part of larger organisms.

Question 7

What are effectors?

Answer 7

Effectors respond to nervous impulses and bring about a change.
They’re either muscles or glands.

Question 8

What are synapses?

Answer 8

The connection between two neurones.

Question 9

What are reflexes?

Answer 9

Rapid, automatic responses to certain stimuli that do not require the conscious part of the brain.

Question 10

What is the reflex arc?

Answer 10

Stimulus
Receptors
Sensory neurone
Relay neurone
Motor neurone
Effector
Response

Question 11

What is the function of the cerebral cortex?

Answer 11

The part of the brain responsible for consciousness, memory, intelligence and language.

Question 12

What is the function of the medulla?

Answer 12

The part of the brain that controls unconscious activities eg. breathing and heartbeat

Question 13

What is the function of the cerebellum?

Answer 13

The part of the brain responsible for muscle coordination.

Question 14

How do scientists study the brain?

Answer 14

• Studying patients with brain damage
• Electrically stimulating the brain
• MRI scans

Question 15

What are the disadvantages of studying the brain?

Answer 15

It is difficult.

There is a risk of physical damage or increased problems involving the brain.

Question 16

What is the sclera?

Answer 16

Tough, supporting wall of the eye

Question 17

What is the cornea?

Answer 17

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

Question 18

What is the iris?

Answer 18

The coloured part of the eye that contains muscles which control the diameter of the pupil and therefore how much light enters the eye.

Question 19

What is the pupil?

Answer 19

Hole in the middle of the eye which light enters through

Question 20

What is the lens?

Answer 20

The part of the eye that focuses the light.

Question 21

What is the retina?

Answer 21

The part of the eye that contains receptor cells sensitive to light intensity and colour.

Question 22

What is the function of the ciliary muscles and suspensory muscles?

Answer 22

Control the shape of the lens

Question 23

What is the function of the optic nerve?

Answer 23

Carries impulses from the receptors on the retina of the eye to the brain

Question 24

What happens to the eye in bright light?

Answer 24

Pupil constricts (goes smaller)
Circular muscles contract
Radial muscles relax

Question 25

What happens to the eye in dim light?

Answer 25

Pupil dilates (gets bigger) Circular muscles relax Radial muscles contract

Question 26

What happens to the eye to look at near objects?

Answer 26

Ciliary muscles contract which slacken the suspensory ligaments Lens becomes fat (more curved) Increases amount by which it refracts light

Question 27

What happens to the eye to look at distant objects?

Answer 27

Ciliary muscles relax which allow the suspensory ligaments to pull tight Lens becomes thins (less curved) Refracts light by smaller amount

Question 28

What is hyperopia?

Answer 28

Long sightedness | Being unable to focus on near objects

Question 29

What is myopia?

Answer 29

Short sightedness | Being unable to focus on far objects

Question 30

What treatments are there for vision defects?

Answer 30

glasses contact lenses laser eye surgery replacement lens surgery

Question 31

How does hyperopia happen?

Answer 31

Being long sighted happens when: the lens is the wrong shape and doesn't refract enough light or the eyeball is too short images of near objects are brought to focus behind the retina instead of on it

Question 32

How does myopia happen?

Answer 32

Being short sighted happens when: the lens is the wrong shape and refracts too much light or the eyeball is too long images of far objects are brought to focus in front of the retina instead of on it

Question 33

Where is body temperature controlled?

Answer 33

thermoregulatory centre in the brain | contains receptors sensitive to blood temperature and receives impulses from receptors in the skin

Question 34

What are antagonistic effectors?

Answer 34

effectors that oppose each other's actions | eg. one effector heats and the other cools at the same time so that together they reach the correct temperature

Question 35

What does your body do when you're too hot?

Answer 35

hairs lie flat sweat is produced (by sweat glands) and then evaporates from the skin, which transfers energy to the environment vasodilation - blood vessels supplying the skin dilate so more blood flows closer to the skin so that more enegy transfers to the environment

Question 36

What does your body do when you're too hot?

Answer 36

hairs stand up, which creates an insulating layer of air vasoconstriction - bloos vessels supplying the skin capillaries constrict to cloe of the skin's blood supply so that less heat is transferred to the surroundingd shivering (muscles contract quickly), which needs respiration which transfers some energy to the body

Question 37

What are hormones?

Answer 37

Chemical molecules released directly into the blood, which are produced and secreted by endocrine glands (that make up the endocrine system)

Question 38

What is the role of the pituitary gland?

Answer 38

Produces many hormones that regulate body conditions

Question 39

What is the role of the thyroid?

Answer 39

Produces thyroxine, which regulates things like the rate of metabolism, heart rate and temperature

Question 40

What is the role of the adrenal gland?

Answer 40

Produces adrenaline, the hormone in control of the fight or flight response

Question 41

What is the role of the pancreas?

Answer 41

Produces insulin, which regulates the blood glucose level

Question 42

What is the role of the ovaries (in women)?

Answer 42

Produce oestrogen, which is involvd in the menstrual cycle

Question 43

What is the role of the testes (in men)?

Answer 43

Produce testosterone, which controls puberty and sperm production

Question 44

What are the differences between nerves and hormones?

Answer 44

``` NERVES: -very fast action -act for a very short time -act on a very precise area HORMONES: -slower action -act for a long time -act in a more general way ```

Question 45

What happens when your blood glucose level is too high?

Answer 45

The pancreas secretes insulin into the blood The insulin and glucose move into the liver The insulin makes the liver turn glucose into glycogen so that it can be stored

Question 46

What happens when your blood glucose level is too low?

Answer 46

The pancreas secretes glucagon into the blood The glucagon makes the liver turn glycogen into glucose Glucose is released into the blood

Question 47

What is diabetes?

Answer 47

Condition where your body can't control your blood sugar level

Question 48

What is type 1 diabetes?

Answer 48

Where the pancreas produces little or no insulin. This means the person's blood glucose levels can easily get to a dangerous level. People with type 1 glucose need to have insulin therapy (eg. insulin injections) Developed at young age/born with it

Question 49

What is type 2 diabetes?

Answer 49

Where someone's body becomes resistant to their own insulin. This means the person's blood glucose levels can easily get to a dangerous level. Can be controlled by eating a carbohydrate controlled diet or by regular exercise. Being overweight and unfit can increase chances of developing type 2 diabetes.