reflexes 1

Question 1

what is the basic principle of a reflex arc?

Answer 1

a sensory receptor receives sensory information from the periphery and synapses on a motor neurone in the anterior horn of the spinal cord, the motor neurone then relays this information to a muscle

Question 2

what are the principal differences in nerve axons which contribute to speed of transmission?

Answer 2

diameter and myelination

Question 3

what is the conduction velocity of a type Aα fibre?

Answer 3

70-120 m/s

Question 4

what is the conduction velocity of a type Aβ fibre?

Answer 4

30-70 m/s

Question 5

what is the conduction velocity of a type Aγ fibre?

Answer 5

15-30 m/s

Question 6

what is the conduction velocity of type Aδ fibres?

Answer 6

12-30m/s

Question 7

what is the conduction velocity of type B fibres?

Answer 7

3-15m/s

Question 8

what is the conduction velocity of type C fibres?

Answer 8

0.5-2 m/s

Question 9

what is the diameter of a type Aα fibre?

Answer 9

12-20μm

Question 10

what is the diameter of a type Aβ fibre?

Answer 10

5-12μm

Question 11

what is the diameter of a type Aγ fibre?

Answer 11

3-6μm

Question 12

what is the diameter of a type Aδ fibre?

Answer 12

2-5μm

Question 13

what is the diameter of a type B fibre?

Answer 13

1-3μm

Question 14

what is the diameter of a type C fibre?

Answer 14

0.1-2μm

Question 15

what is the function of Aα fibres?

Answer 15

proprioception, somatic motor neurons

Question 16

what is the function of Aβ fibres?

Answer 16

touch and pressure

Question 17

what is the function of Aγ fibres?

Answer 17

motor to muscle spindles

Question 18

what is the function of Aδ fibres?

Answer 18

pain and temperature

Question 19

what is the function of B fibres?

Answer 19

preganglionic autonomic

Question 20

what is the function of C fibres?

Answer 20

postganglionic sympathetic, pain and possibly heat, cold and pressure

Question 21

where do IA fibres originate?

Answer 21

muscle spindles Alpha motor neurons

Question 22

where do IB fibres originate?

Answer 22

in the golgi tendon organs Aα

Question 23

where do II fibres originate?

Answer 23

in muscle spindles, touch and pressure receptors (Aβ and Aγ)

Question 24

where do III fibres originate?

Answer 24

pain and temperature receptors (Aδ)

Question 25

where do IV fibres originate?

Answer 25

pain and other receptors (C fibres)

Question 26

what does a motor unit consist of?

Answer 26

a motor neuron and the muscle fibres it innervates

Question 27

what type of motor neurone fibres form smaller motor unit?

Answer 27

small motor neurones

Question 28

what type of motor neurones form large motor units?

Answer 28

large motor neurones

Question 29

which type of motor neurones is easiest to activate?

Answer 29

small motor neurones

Question 30

what type of muscle fibres are innervated by small motor neurones?

Answer 30

slow oxidative fibres

Question 31

what type of muscle fibres are innervated by large motor neurones?

Answer 31

fast glycolytic muscle fibres

Question 32

why are larger motor neurones harder to activate?

Answer 32

smaller motor neurones have a resting membrane potential closer to the threshold