13.2 Neurones

Question 1

What is the role of the nervous system?

Answer 1

detect, process & respond

to stimuli

Question 2

What is the structure of a general neurone?

Answer 2

• CELL BODY
  
  • many mitochondria + endoplasmic reticulum for neurotransmitter synthesis
• DENDRON
  
  • nerve fibres transmitting electrical impulses towards cell body.
  • divide into smaller dendrites
• AXON
  
  • nerve fibres transmitting electrical impulses away from cell body

Question 3

What are the 3 types of neurones from longest to shortest?

Answer 3

(longest)

sensory

motor

relay

(shortest)

Question 4

Where does the sensory neurone transmit electrical impulses to and from?

Answer 4

from receptor ⟶ relay/motor/brain

Question 5

Where do motor neurones transmit electrical impulses to and from?

Answer 5

from relay/sensory ⟶ effector

Question 6

Where do relay neurones transmit electrical impulses to and from?

Answer 6

between neurones

Question 7

What is the general pathway of electrical impulses through neurones?

Answer 7

Question 8

What is a myelinated neurone?

Answer 8

neurone with myelin sheath around axon

Question 9

How do Schwann cells increase the rate of electrical impulse transmission along the axon?

Answer 9

• Schwann cells wrap around axon, adding phospholipid bilayer
  
  • wrap around many times, adding many phospholipid bilayers
• High lipid content acts as insulator
  
  • Electrical impulse forced to “jump” between Nodes of Ranvier, (as opposed to continuous transmission)
    
    • increases impulse transmission

Question 10

What is the difference in structure of the 3 types of neurone?

Answer 10

• Sensory:
  
  • 1 long dendron + shorter axon (cell body further along neurone)
• Motor:
  
  • 1 long axon + many short dendrons (cell body @ end)
• Relay:
  
  • many short axons + dendrons

Question 11

What is this type of neurone?

Answer 11

Sensory neurone

Question 12

What is this type of neurone?

Answer 12

Relay neurone

Question 13

What is this type of neurone?

Answer 13

Relay neurone

Question 14

What makes the myelin sheath a good electrical insulator?

Answer 14

Made from layers of phospholipid bilayer,

so high lipid content,

so good electrical insulator.

Question 15

What type of neurone is this?

Answer 15

(myelinated) sensory

Question 16

What type of neurone is this?

Answer 16

(myelinated) motor

Question 17

What is this part of a neurone?

Answer 17

Node of Ranvier

Question 18

What is a Node of Ranvier?

Answer 18

Gap in the myelin sheath of a nerve

between adjacent Schwann cells

Question 19

What is this part of a neurone?

Answer 19

Cell body

(contains nucleus + many mitochondria + endoplasmic reticulum for neurotransmitter synthesis)

Question 20

How is the cell body of a neurone specialised?

Answer 20

contains many mitochondria + endoplasmic reticulum

for neurotransmitter synthesis

Question 21

What is this part of a neurone?

Answer 21

Schwann cell/myelin sheath

Question 22

What is the difference in function between axons and dendrons?

Answer 22

axons carry electrical impulses away from cell body

dendrons carry electrical impulses towards cell body

Question 23

What is this part of a neurone?

Answer 23

dendrite

Question 24

What is this part of a neurone?

Answer 24

dendron

Question 25

What is this part of a neurone?

Answer 25

axon