Control And Coordination

Question 1

What changes do animals respond to?

And why?

Answer 1

-changes in their external environment
-changes in their internal environment(to make sure conditions are always right)
To increase their chance of survival

Question 2

What changes do plants respond to?

Answer 2

They increase their chance of survival by responding to changes in their environment

Question 3

What’s a stimulus?

Answer 3

Any change in the internal or external environment is called a stimulus.

Question 4

What do receptors do?

Answer 4

Receptors detect stimuli.

Receptors in the sense organs are groups of cells that detect external stimulus.

Question 5

What are the sense organs?

Answer 5

Eyes, ears, nose, tongue, skin

Question 6

What do effectors do?

And what’re examples of effectors?

Answer 6

Effectors are cells that bring about a response to stimuli.
E.g.
Muscle cells contract
Glands secrete hormones

Question 7

How do receptors communicate with effectors?

Answer 7

They communicate via the nervous system or the hormonal system or both

Question 8

What’s the nervous system made up of?

Answer 8

Neurones (nerve cells)

Question 9

What are the three main types of neurones?

Answer 9

• sensory neurone
• relay neurone
• motor neurone

Question 10

What’s the CNS made up of?

And what’s its function?

Answer 10

CNS- Central Nervous System
-consists of the brain and spinal cord only
Function- to coordinate the response, coordinated responses always need a stimulus, receptor and an effector

Question 11

What detects a stimulus, and what happens once a stimulus is detected?

Answer 11

receptors detect a stimulus

• they send electrical impulses along sensory neurones to the CNS
• the CNS then sends electrical impulses to an effector along a motor neurone, the effector then responds accordingly

Question 12

Why is the nervous system able to bring about very rapid responses?

Answer 12

Because neurones transmit information using high speed electrical impulses

Question 13

What’s a synapse?

Answer 13

The connection between two neurones is a synapse

Question 14

How do synapses work?

Answer 14

• the nerve signal is transmitted by chemicals called neurotransmitters which diffuse across the gap
• these chemicals then set off a new electrical signal in the next neurone

Question 15

What’re reflexes?

Answer 15

Reflexes are automatic responses to certain stimuli

-they can reduce the chances of being injured

Question 16

What’s a reflex arc?

Answer 16

The route taken by the information in a reflex(from receptor to effector)

Question 17

What’s the sequence of a reflex arc?

Answer 17

Stimulus 
Receptor
Sensory neurone
CNS
Motor neurone
Effector
Response

Question 18

What coordinates the response in a reflex?

Answer 18

The spinal cord or an unconscious part of the brain

Question 19

What’s the process that goes on in a reflex action?

Answer 19

• a stimulus is detected by receptors and an impulse is sent along a sensory neurone to the CNS
• the CNS then passes on the message to a relay neurone
• the relay neurones relay the impulse to a motor neurone
• the impulse then travels along the motor neurone to the effector
• then the response happens

Question 20

What’s the difference between nerve and hormonal responses?

Answer 20

Nerves
-fast message, act for a very short time, on a very precise area
Hormones
-slower message, for a long time, act in a more general way

Question 21

Define homeostasis:

Answer 21

Homeostasis is the maintenance of a constant internal environment

Question 22

What’re two examples of homeostasis?

Answer 22

Body water content

Body temperature

Question 23

How is body water content an example of homeostasis?

Answer 23

You need to keep a balance between the water you lose and the water you gain

Question 24

How is body temperature an example of homeostasis?

Answer 24

You need to get rid of excess body heat when you’re hot, but retain heat when the environment is cold