Topic 5 - Homeostasis and Response

Question 1

What is homeostasis?

Answer 1

Homeostasis is all about the regulation of the conditions inside your body (and cells) to maintain a stable internal environment, in response to changes in both internal and external conditions.

Question 2

Why is homeostasis important?

Answer 2

Our cells need the right conditions in order to function properly, including the right conditions for enzyme action.

Question 3

What are nervous and hormonal communication also known as and what is their job?

Answer 3

They are also known as automatic control systems, and their job is to maintain our body temperature, blood glucose level and water content.

Question 4

What are the three main components that our automatic control systems are made of?

Answer 4

Receptors, coordination centres (including the brain, spinal cord, and pancreas) and effectors.

Question 5

What is negative feedback used for?

Answer 5

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

Question 6

What component of a control system detects stimuli?

Answer 6

Receptor

Question 7

What is a stimulus?

Answer 7

A change in the environment.

Question 8

What happens when the coordination centres receive the information?

Answer 8

They organise a response through an effector.

Question 9

Role of the effector?

Answer 9

To counteract the change and restore the optimum level - if the level was too high, the effector will decrease it and if the level was too low, the effector will increase it.

Question 10

What does the nervous system do?

Answer 10

It reacts to stimuli, allowing humans to react to their surroundings and coordinate their behaviour.

Question 11

State the different parts of the nervous system.

Answer 11

CNS (central nervous system), sensory neurones, motor neurones, effectors.

Question 12

What is the CNS?

Answer 12

In vertebrates (animals with backbones), this consists of the brain and spinal cord only. In mammals the CNS is connected to the body by sensory neurones and motor neurones.

Question 13

What are the sensory neurones?

Answer 13

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

Question 14

What are the motor neurones?

Answer 14

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

Question 15

What are the effectors?

Answer 15

All our muscles and glands that respond to nervous impulses.

Question 16

Name some examples of different receptors.

Answer 16

Taste receptors on the tongue and sound receptors in the ears. Receptors can also form part of larger, complex organs, e.g. the retina of the eye is covered in light receptor cells.

Question 17

What do the effectors do?

Answer 17

They respond to nervous impulses and bring about a change.

Question 18

How do muscles (as effectors) respond?

Answer 18

Muscles contract.

Question 19

How do glands (as effectors) respond?

Answer 19

Glands secrete hormones.

Question 20

How does the CNS work?

Answer 20

It receives information from the receptors and then coordinates a response (which is carried out by the effectors).

Question 21

What is a synapse?

Answer 21

The connection between two neurones.

Question 22

How is the nerve signal transported via a synapse?

Answer 22

It is transferred by chemicals which diffuse across the gap and and set off a new electrical signal in the next neurone.

Question 23

What are reflexes?

Answer 23

They are rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain - they can reduce the chances of being injured.

Question 24

What is a reflex arc?

Answer 24

It is the passage of information in a reflex (from receptor to effector).

Question 25

What part of the Central Nervous System does the reflex arc go through?

Answer 25

The spinal cord or an unconscious part of the brain.