4.5.2.1 Structure and Function

Question 1

What does the nervous system enable?

Answer 1

• humans to react to their surroundings and coordinate their behaviours

Question 2

What does the nervous system consist of?

Answer 2

• CNS (central nervous system), brain and spinal cord
• PNS (peripheral nervous system), nerve cells that carry information

Question 3

What are neurones?

Answer 3

• nerve cells
• adapted to carry electrical impulses from one place to another
• a bundle is called a nerve

Question 4

What are the three main types of neurones?

Answer 4

• sensory
• relay
• motor

Question 5

What is the function of a sensory neurone?

Answer 5

• carry information as electrical impulses from receptors to CNS

Question 6

What is the function of a relay neurone?

Answer 6

• allows sensory and motor neurones to communicate

Question 7

What is the function of a motor neurone?

Answer 7

• carry electrical impulses from CNS to effectors

Question 8

What are receptors?

Answer 8

• groups of specialised cells that detect a stimulus
• stimulate electrical impulses in response

Question 9

What do sense organs contain?

Answer 9

• groups of receptors that respond to specific stimuli

Question 10

What are examples of sense organs?

Answer 10

• skin
• tongue
• nose
• eye
• ear

Question 11

What stimulus does skin respond to?

Answer 11

• touch
• temperature
• pain

Question 12

What stimulus does the tongue respond to?

Answer 12

• chemicals (in food and drink)

Question 13

What stimulus does the nose respond to?

Answer 13

• chemicals (in air)

Question 14

What stimulus does the eye respond to?

Answer 14

• light

Question 15

What stimulus does the ear respond to?

Answer 15

• sound
• position of head

Question 16

What are effectors?

Answer 16

• organs/cells that produce a specific response to a detected stimulus
• muscles or glands

Question 17

What are examples of effectors?

Answer 17

• muscle contracting to move an arm
• muscle squeezing saliva from salivary gland
• gland released a hormone into blood

Question 18

How are electrical impulses passed from receptor to effector?

Answer 18

• stimulus
• receptor
• sensory neurone
• relay neurone (CNS)
• motor neurone
• effector
• response

Question 19

What is a reflex action?

Answer 19

• an automatic/rapid response to a stimulus
• minimises any damage to body from potentially harmful conditions

Question 20

What is a reflex arc?

Answer 20

• nerve pathway followed by a reflex action
• e.g. a simple reflex arc happens if accidentally touching something hot
• goes to unconscious part of brain

Question 21

What is the general sequence of a reflex arc?

Answer 21

• receptor in skin detects a stimulus
• sensory neurone sends electrical impulses to relay neurone (in spinal cord) which connect sensory neurones to motor neurones
• motor neurone sends electrical impulses to an effector
• effector produces a response

Question 22

What is a synapse?

Answer 22

• small gap where two neurones meet

Question 23

What happens at a synapse?

Answer 23

• electrical impulse travels along first axon
• triggers nerve-endings to release neurotransmitters
• chemicals diffuse across synapse and bind with receptor molecules on membrane of second neurone
• bind only to specific neurotransmitters released, stimulates second neurone to transmit electrical impulse