13 Neuronal Communication

Question 1

What are “dendrites”?

Answer 1

Smaller, extending branches of neurones responsible for directing impulses TOWARDS the cell body

Question 2

What are “axons”?

Answer 2

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

Question 3

What makes a sensory neurone different to other types of neurones?

Answer 3

Sensory neurones have a cell body IN THE MIDDLE of the axon

REMEMBER: Dendrites carry information towards the cell body

Question 4

What makes a relay neurone different to other neurones?

Answer 4

Non-myelinated axon

Question 5

What makes a motor neurone different to other neurones?

Answer 5

Cell body is at end of neurone

Question 6

What are Schwann cells?

Answer 6

Cells making up the myelin sheath

LAYERS of Schwann cells make up myelin sheath

Question 7

How does a Pacinian corpuscle work?

Answer 7

Converts mechanical pressure into a nervous impulse by generating a generator potential that is used to generate an action potential

Question 8

What are the steps involved in the Pacinian corpuscle?

Answer 8

1. RESTING STATE
   Stretch-mediated Na+ ion channels in sensory neurone’s membrane are too narrow to allow sodium ions to pass through them. = Neurone at RESTING POTENTIAL.
2. PRESSURE applied —> corpuscle CHANGES SHAPE —> membrane surrounding it STRETCHES
3. As the membrane stretches, Na+ ion channels can now OPEN WIDE —> Na+ DIFFUSES INTO neurone.
4. DEPOLARISATION - Influx of positive Na+ ions changes potential of MEMBRANE and depolarises it —> Results in GENERATOR POTENTIAL.
5. Generator potential creates an ACTION POTENTIAL that passes along sensory neurone.
6. Action potential is then transmitted along neurones to the CNS.