Nervous System

Question 1

Definition of a receptor cell

Answer 1

Specialised cells that detect a stimulus (change in environment)

Question 2

Definition of a coordination centre

Answer 2

Receive and process information from receptors

Question 3

Definition of an effector

Answer 3

A muscle or a gland in the body that produces a response to restore optimum levels in the body.

Question 4

Function of neurones

Answer 4

Specialised to transmit messages in the form of an electrical impulse.

Question 5

Definition of the axon

Answer 5

A long extension of a neurone that carries nerve impulses away from the body of the cell.

Question 6

Definition of axon terminals

Answer 6

Hair like ends of the axon

Question 7

Definition of the cell body

Answer 7

The cell body of the neurone, containing the soma (nucleus)

Question 8

Definition of dendrites

Answer 8

The branching structure of a neurone that receives messages from other neurones.

Question 9

Definition of the myelin sheath

Answer 9

The fatty substance that surrounds and protects some nerve fibres.

Question 10

Definition of rode of Ranvier

Answer 10

A gap in the myelin sheath where the action potential occurs during saltatory conduction along the axon

Question 11

Definition of the nucleus

Answer 11

The organelle in the cell body of the neurone that contains the genetic material of the cell.

Question 12

Definition of the Schwann’s cells

Answer 12

Cells that produce myelin.

Question 13

What do sensory neurones do?

Answer 13

They carry signals from the receptors to the CNS

Question 14

What do motor neurones do?

Answer 14

They carry signals from the CNS to effectors.

Question 15

Explain the response produced by a human after smelling tea

Answer 15

1. The olfactory receptors in the nose sense the stimulus (smell of tea)
2. An electrical impulse travels from the receptor cells to the brain via the sensory neurones.
3. An electrical impulse travels from the brain to the muscles in the hand via the motor neurones.
4. The hand moves to pick up the tea.

Question 16

Flow chart for production of a response

Answer 16

Stimulus
Receptor
(Sensory neurone)
Coordination centre
(Motor neurone)
Effector
Response

Question 17

Describe how an electrical impulse travels from one neurone to another.

Answer 17

1. An impulse arrives at the synapse, vesicles containing neurotransmitters move to the membrane.
2. The vesicles release the neurotransmitters into the gap
3. The neurotransmitter crosses the synapse and binds to receptors in the end of the next neurone, beginning a new electrical impulse along the next neurone.
4. The neurotransmitter is broken down by enzymes made by the second neurone

Question 18

Explain the response when a someone touches a drawing pin

Answer 18

1. A hand touches a drawing pin which is picked up by a sensory neurone.
2. An impulse in the sensory neurone travels to the grey matter of the spinal cord.
3. Neurotransmitters are released into the synapse between the sensory and relay neurones
4. An impulse travels along the relay neurone to the next synapse.
5. Neurotransmitters released into the synapse trigger an impulse in the motor neurone.
6. An impulse travels out of the spinal cord, along a motor neurone to an effector muscle.
7. Neurotransmitters are released in the effector (a muscle in the arm)
8. The muscle contracts, moving the hand away.