Nerves

Question 1

Classification of nerves

Answer 1

By diameter - A alpha, beta, gamma, delta, B and C (A is biggest)
By speed - same classification, A alpha is fastest

Question 2

A alpha nerves

Answer 2

Motor nerve
Responsible for proprioception, motor neurones
Diameter 12-20 µm
Conduction velocity 70-120 m/s

Question 3

A beta nerves

Answer 3

Sensory nerve
Responsible for touch, pressure
Diameter 5-12 µm
Conduction velocity 30-70 m/s

Question 4

A gamma nerves

Answer 4

Motor nerve
Motor to muscle spindles
Diameter 3-6 µm
Conduction velocity 15-30 m/s

Question 5

A delta nerves

Answer 5

Sensory nerve
Pain, touch, cold
Diameter 2-5 µm
Conduction velocity 12-30 m/s

Question 6

B nerves

Answer 6

Motor nerve
Preganglionic autonomic
Diameter <3 µm
Conduction velocity 3-15 m/s

Question 7

C nerves

Answer 7

Sensory nerve
Pain, temperature, postganglionic sympathetics
Diameter 0.3-1.3 µm
Conduction velocity 0.5-2.3 m/s

Question 8

Glia

Answer 8

Responsible for supporting and nurturing neurones

Types include microglia, Schwann cells (form myelin sheath), astrocytes and oligodendrocytes

Question 9

Microglia

Answer 9

Scavenger cells of CNS - activated by infection or brain injury

Question 10

Fibrous astrocytes

Answer 10

Form the white matter of the brain, support neurones

Question 11

Protoplasmic astrocytes

Answer 11

Maintain electrolyte balance

Question 12

Blood-brain barrier

Answer 12

Created by astrocytes which ensure capillaries cannot leak (forms after birth so neonates are at risk of developing brain damage in neonatal jaundice)