Miscellaneous

Question 0

What is denervation hypersensitivity

Answer 0

As a result of denervation, the ACh receptors are rearranged away from the motor end plate, thereby increasing sensitivity right along the muscle fibre

Question 1

What are the effects of muscle denervation?

Answer 1

Flaccid paralysis - inability to contact muscle, neither voluntarily nor involuntarily

Fasciculations - initial involuntary muscle twitching as a result of denervation hypersensitivity

Atrophy of affected muscle

Question 2

How many heavy chains and light chains does myosin have?

Answer 2

2 heavy chains & 4 light chains

Question 3

What are the three subunits of the troponin complex?

Answer 3

I - inhibitory subunit (binds to actin)
C - calcium binding subunit
T - tropomyosin binding subunit

Question 4

How do the ryanodine and dihydropyridine receptors work?

Answer 4

The ryanodine receptor is on the sarcoplasmic reticulum membrane while the dihydropyridine receptor is on the t-tubule membrane.

The depolarisation of the t-tubule triggers a conformational change in the dihydropyridine receptor, which then causes the dihydropyridine receptor to be physically coupled with the ryanodine receptor, thereby triggering a conformational change in the ryanodine receptor, leading to the release of calcium ions into the cytoplasm

Question 5

In the formation of creatine phosphate, what enzyme phosphorylates creatine?

Answer 5

Creatine kinase

Question 6

What is a DXA (or DEXA) scan and what is it used for?

Answer 6

DXA = Dual-Energy X-Ray Absorbtiometry

It is used to diagnose osteoporosis