Neuromuscular etc

Question 1

What is a tendon Golgi?

Answer 1

Junction between tendon and muscle that monitors tension

Question 2

What is the structure of a tendon Golgi?

Answer 2

Afferent nerve endings surrounding the collagen bundles in tendon

Question 3

What does a muscle spindle do?

Answer 3

Monitors length of muscle

Question 4

Structure of muscle spindle?

Answer 4

Afferent nerve endings surrounding muscle fibres

Question 5

Intrafusal/Extrafusal?

Answer 5

Intrafusal - within spindle

Extrafusal - outside spindle

Question 6

Name reflexes

Answer 6

Stretch
Withdrawal
Inverse stretch
Clasp knife reflexes

Question 7

What is a stretch reflex?

Answer 7

A muscle contraction in response to stretch

Eg postural control
Lean to far to one side muscles contract to correct it

Question 8

What is a withdrawal reflex

Answer 8

Protects body from damaging stimuli

Eg withdrawing hand from hot object

Question 9

What is a inverse stretch reflex?

Answer 9

Also called Golgi tendon reflex

Causes relaxation before the tendon tension becomes high enough to cause damage

Question 10

What is a clasp-knife reflex?

Answer 10

When a limb resists passive resistance but then suddenly gives way when more pressure is applied

Question 11

What causes upper motor neuron weakness?

Answer 11

Corticospinal tract lesions

Question 12

What causes lower motor neuron lesions?

Answer 12

Peripheral neuropathies

Anterior horn cell lesions

Question 13

What causes weakness at neuromuscular junctions?

Answer 13

Myasthenia gravis

Question 14

Where are upper motor neurons?

Answer 14

Motor neurons within the CNS (brain & spinal cord)

Above anterior horn cell

Question 15

Where are lower motor neurons?

Answer 15

In PNS
From spinal cord to the rest of the body

Below anterior horn cell

Question 16

Signs of upper motor neuron lesion?

Answer 16

Increased tone (spasticity)
Hyperreflexia

Question 17

Signs of lower motor neuron lesion?

Answer 17

Decreased tone (flaccidity)
Hyporeflexia
Fasciculations & atrophy

Question 18

What happens at a neuromuscular junction?

Answer 18

1. Action potential arrives at the presynaptic terminal causing Ca channels to open and Ca to go into the presynaptic bulb
2. The Ca ions cause vesicles to release Ach from synaptic vesicles into the presynaptic cleft
3. Ach diffuses across and binds to the ACH receptors on postsynaptic muscle fibre membrane
4. Na ions go into postsynaptic terminal and K ions leave it
5. This muscle cell results in depolarisation of membrane. An action potential is generated and propagates over muscle cell membrane
6. Causes Ca to be released from sarcoplasmic reticulum and muscle contracts

Question 19

What happens to the Ach after it has bound to the receptors?

Answer 19

It is broken down into acetic acid and choline by acetlycholinesterase

Reabsorbed back into presynaptic bulb and combines to form more Ach

Question 20

What is a motor end plate?

Answer 20

The bit on the muscle where an axon of a motor neuron establishes synaptic contact with it