A reflex arc

Question 1

What is the simplest type of nervous resonse to a stimulus?

Answer 1

A reflex arc

Question 2

What are the two divisions of the nervous system?

Answer 2

• CNS
• PNS

Question 3

What is CNS stand for?

Answer 3

Central Nervous System

Question 4

What is CNS made up of?

Answer 4

The brain and the spinal cord

Question 5

What does PNS stand for?

Answer 5

Peripheral nervous system

Question 6

What is the PNS made up of?

Answer 6

Pairs of nerves that originate from either the brain or the spinal cord

Question 7

What is the PNS divided into?

Answer 7

Sensory and motor nerounes

Question 8

What is the sensory neruone carry?

Answer 8

Nerve impulses (electrical signals) from receptors towards the CNS

Question 9

What do the motor neruone carry?

Answer 9

Carry nerve impulses away from the CNS to the effectors

Question 10

What is the motor neurone further divided into?

Answer 10

Voluntary nervous system

and

automatic nervous system

Question 11

What is the voluntary nervous system?

Answer 11

Carries nerve impulses to the body muscles and under voluntary (conscious) control

Question 12

What is the autonomic nervous sytem?

Answer 12

Carries nerve impulses to glands, smooth muscle and cardiac muscle and is not unver voluntary control , it is involuntary (subconscious)

Question 13

What is a spinal cord?

Answer 13

A column of nervous tissue that runs along the back and lies inside the vertebral column for protection

Question 14

Diagram of reflex arc

Answer 14

Question 15

What is a reflex?

Answer 15

It is a rapid response to a stimulus without conscious control

Question 16

What is a reflex arc?

Answer 16

A pathway of neurones involved in a reflex

Question 17

What is spinal reflex?

Answer 17

One of the neurones in the spinal cord

Question 18

Sequence of reflex arc

Answer 18

1. stimulus
2. receptor
3. Sensory neurone
4. Coordinate/intermediate neurone
5. Motor neurone
6. Effector
7. Response

Question 19

Example of withdrawing hand from hot object

Answer 19

1. Stimulus - heat from hot object
2. Receptor - Temperature receptor in the skin on the back of hand, generates nerve impulses in the sensory neurone
3. Sensory neurone - Passes nerve impulses to spinal cord
4. Coordinate(intermediate neurone) - links to the sensory neruone to the motor neurone in the spinal cord
5. Motor neurone- carries nerve impulses from the spinal cord to the muscle in upper arm
6. Effector - muscle in upper arm which is stimulated to contract
7. Response - pulling the hand away from hot object

Question 20

Why is it important that reflexes are involuntary

Answer 20

• They do not require the decision of making powers of the brain
• Free to carry out more complex responses
• Brain is not overloaded with situations in which the response is same
• (if some impulses sent to brain and informed what is happening , override reflex)

Question 21

Why is reflexes important for our body?

Answer 21

They protect the body from harm

Effective from bith and not have to learn

e.g infants

Question 22

Why is it important that reflexes are fast?

Answer 22

• Fast - neurone pathway is short and very few synpases where neurones communicate with each other (synpases are slowest link in a neurone pathway)
• Important in withdrawl reflexes
• Absence of decision making process means action is rapid