13.2 Neurones

Question 1

What is the role of neurones?

Answer 1

Transmit electrical impulses rapidly around the body so that the organism can respond to changes in its internal or external environment

Question 2

What are the three types of neurone?

Answer 2

Sensory, Motor, Relay

Question 3

What is the structure and function of a sensory neurone?

Answer 3

-Transmit impulses from a sensory receptor cell
-Short dendrites
-One long dendron which carries impulse to the cell body
-One axon which which carries impulse away from the cell body (to the CNS)

Question 4

What is the structure and function of a motor neurone?

Answer 4

-Transmit impulses to an effector such as a muscle or gland
-Many short dendrites which carry nerve impulses to the cell body
-One long axon that carries nerve impulse to effector cell

Question 5

What is the structure and function of a relay neurone?

Answer 5

-Transmit impulses between neurones, between sensory and motor neurones
-Many short dendrites that transmit impulses to the cell body
-One axon that carries nerve impulses from the cell body to motor neurones

Question 6

What is the function of the CNS

Answer 6

processes the information, decides what to do and sends impulses along motor neurones to an effector

Question 7

What is the typical pathway an electrical impulse follows?

Answer 7

Stimulus → Receptor → Sensory Neurone → Relay Neurone → Motor Neurone → Effector Cell → Response

Question 8

What are the common features of all mammalian neurones?

Answer 8

Cell body, Dendrons, Axons

Question 9

What is the purpose and structure of the cell body?

Answer 9

-Contain a nucleus surrounded by cytoplasm
-Large amounts of endoplasmic reticulum and mitochondria involved in the production of neurotransmitters

Question 10

What is the purpose and structure of the dendrons?

Answer 10

-Short extensions which come from the cell body
-Divide into small branches called dendrites
-Responsible for transmitting electrical impulses towards the cell body

Question 11

What is the purpose and structure of the axons?

Answer 11

-Singular, elongated nerve fibres that transmit impulses away from the cell body

Question 12

What is the function of Schwann cells?

Answer 12

To produce layers of membrane for the myelin sheath by growing around the axon many times

Question 13

What is the myelin sheath made out of?

Answer 13

Layers of plasma membrane

Question 14

What is the purpose of the myelin sheath?

Answer 14

Acts as an insulating layer and allows neurones to conduct an electrical impulse at a faster speed

Question 15

What are the nodes of Ranvier?

Answer 15

The gaps between adjacent Schwann cells

Question 16

How does the myelin sheath allow electrical impulses to travel faster?

Answer 16

Impulse can be transmitted to travel much quicker, as it jumps from one node to the next rather then continuously along the axon