Homeostasis and Response

Question 1

What is Homeostasis?

Answer 1

The regulation of the conditions inside your body to maintain a stable internal environment, in response to changes in both internal and external conditions.

Question 2

Why is Homeostasis important?

Answer 2

Cells and enzymes inside the body need the right conditions in order to function properly

Question 3

What is negative feedback?

Answer 3

When the level of something gets too high or too low, your body uses negative feedback to bring it back to normal.

Question 4

What is a stimulus?

Answer 4

A change in the environment

Question 5

What do receptors do?

Answer 5

Receptors are the cells that detect a stimulus

Question 6

What does the coordination centre do?

Answer 6

It receives and processes the information, then organises a response.

Question 7

What does the effector do?

Answer 7

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

Question 8

What does the nervous system do?

Answer 8

It means that humans can react to their surroundings and coordinate their behaviour.

Question 9

What are some examples of receptors?

Answer 9

• Taste receptors on the tongue

- Sound receptors in the ears

Question 10

What are some examples of effectors?

Answer 10

Muscles and glands - They respond in different ways

Question 11

What are sensory neurones?

Answer 11

The neurones that carry information as electrical impulses from the receptors to the CNS

Question 12

What are motor neurones?

Answer 12

The neurones that carry electrical impulses from the CNS to the effectors

Question 13

What are relay neurones?

Answer 13

They connect sensory neurones to motor neurones

Question 14

What is the Central Nervous System?

Answer 14

It is a coordination centre - it receives information from the receptors and then coordinates a response (decides what to do about it). The response is carried out by effectors.

Question 15

What is a synapse?

Answer 15

The gap between two neurones is called a synapse

Question 16

How is information transferred through the synapse?

Answer 16

The nerve signal is transferred by chemicals which diffuse across the gap. These chemicals then set off a new electrical signal in the next neurone.

Question 17

What are reflexes?

Answer 17

They are rapid, automatic responses to certain stimuli that do not involve the conscious part of the brain

Question 18

What are some examples of reflexes?

Answer 18

• I someone shines a bright light in your eyes, your pupils automatically get smaller so that less light gets into your eye, to stop it from getting damaged
• If you get a shock, your body releases the hormone adrenaline automatically

Question 19

What does the body do when you are too hot?

Answer 19

1) Sweat is produced by sweat glands and evaporates from the skin
2) Blood vessels supplying the skin dilate so more blood flows close to the surface of the skin

Question 20

What does the body do when you are too cold?

Answer 20

1) Hairs stand up to trap an insulating layer of air
2) No sweat is produced
3) Blood vessels supplying skin capillaries constrict to close off the skin’s blood supply. This is called vasoconstriction
4) Shivering contracts your muscles. This needs respiration which transfers some energy to warm the body

Question 21

What are hormones?

Answer 21

Hormones are chemical molecules released directly into the blood. They only affect particular cells in particular organs.

Question 22

What is the pituitary gland?

Answer 22

Produces many hormones that regulate body conditions

Question 23

What is the Thyroid?

Answer 23

This produces thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature

Question 24

What is the adrenal gland?

Answer 24

This produces adrenaline, which is used to prepare the body for a ‘fight or flight’ response

Question 25

What are the ovaries?

Answer 25

Found only in females, these produce oestrogen which is involved in the menstrual cycle

Question 26

What are the testes?

Answer 26

Found only in males, they control testosterone which controls puberty and sperm production

Question 27

What is the pancreas?

Answer 27

This produces insulin, which is used to regulate the blood glucose level

Question 28

What is the difference between hormones and nerves?

Answer 28

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