Pathophysiology Of Skeletal Muscle

Question 1

Endurance exercise responds to?

Answer 1

Total contractile activity

Question 2

Resistance training responds to?

Answer 2

Loading and stretch

Question 3

Biceps brachii have how many fibres?

Answer 3

200,000

Question 4

Hypertrophy is what?

Answer 4

Synthesis of myofilaments
Addition of sarcomeres
satellite cell activation
Angiogenesis and vascularisation

Question 5

Muscles can enlarge between?

Answer 5

15-50%

Question 6

Effect of endurance exercise?

Answer 6

Increased fibre diameter 
Increased blood supply 
Mitochondrial content increase 
Increase in oxidative enzymes 
Fibres become slower 

Transformation from type IIX to IIA or type I

Question 7

Resistance training transformation happens from?

Answer 7

Type IIA to IIX

To get greater muscle force and strength
Increase in sarcomeres and myofilaments

Results in larger muscles bulk

Question 8

After a sports injury what should you use?

Answer 8

Ice and aspirin

Question 9

Mechanism of aspirin?

Answer 9

Inhibit COX, REDUCING SYNTHESIS OF PROSTAGLANDINS

Question 10

High levels of aspirin can cause?

Answer 10

Gastrointestinal adverse effects, stomach bleeding and ulcers

Question 11

Steroid abuse can cause?

Answer 11

Testes atrophy, baldness, sterility, breast and uterus atrophy, menstrual changes, facial hair

Question 12

What is the effect of spacefight?

Answer 12

Reduction in weight bearing muscles, transition from type 1 to type 2 x/2a fibres

All muscles undergo atrophy

Question 13

Effect of bed rest?

Answer 13

Type 1 to type 2a, decrease in protein synthesis, myofibrillar breakdown, loss of strength

Question 14

What happens in contracture?

Answer 14

Immobilisation cause removal of sarcomeres, so shorter muscle

Question 15

Skeletal muscle cells appear?

Answer 15

Multinucleate, start as myoblasts which are mono nucleate and then fuse, moving nuclei to periphery, multinucleate cells can’t divide

Question 16

Muscle regeneration happens?

Answer 16

Quiescent myogenic satellite cells are activated by HGF by proliferating differentiating and fuse onto extant fibres onto muscle cell. They reform elements of muscle (multinucleate myofibres)

Question 17

Myalgia can be associated with?

Answer 17

Rhamdomyolsis

Question 18

Dystrophies?

Answer 18

Incorrect muscle growth, familial and progressive

Muscle stuck in degeneration and regeneration cycle, regenerative ability is lost

Question 19

Paresis?

Answer 19

Weakness of voluntary movement or partial loss

Question 20

Fasciculations?

Answer 20

Involuntary twitches in single motor units, common in lower motor neuron disease seen in ALS/ polio, look like ripples

Question 21

Fibrillations?

Answer 21

Involuntary spontaneous contraction of individual muscle fibres , myogenic, invisible to eye

Question 22

Rhabdomyolysis?

Answer 22

Rapid breakdown of skeletal muscle, risk of kidney failure, myoglobin can clog glomeruli

Urine looks tea coloured, no urine produced after 12 hours

Causes hyperkalaemia, high K

Question 23

Rhabdomyolysis treatment?

Answer 23

IV fluid

Haemodialysis

Question 24

Causes of rhambdomyolysis?

Answer 24

Trauma crush injury
Hyperthermia
Ischaemia to local skeletal muscle (compartment syndrome, thrombosis)
Drugs, statins or fibrates

Question 25

Symptoms and signs of rhambdo?

Answer 25

Muscle pains, Vomiting and confusion Dark urine

Question 26

Diagnostic for muscular dystrophies and rhambdomyolysis?

Answer 26

Skeletal isoform. CK MM elevated Cardiac muscle CPK form CK MB Test would be for total CK

Question 27

What is an indicator rhambdomyolysis and MI?

Answer 27

Myoglobin

Question 28

Another diagnostic for rhabdomyolysis?

Answer 28

Muscle cells lyse, release K, increase in serum

Question 29

Rigor mortis?

Answer 29

ATP depleted after death, muscle cannot resequester Ca in SR, Ca allows cross ridge cycle contraction Without ATO, myosin will stop after power stroke, myosin still bound to actin Rigor mortis ends when tissue degrades, about 3 days

Question 30

Myasthenia gravis is?

Answer 30

Progressive muscle weakness and fatigability often start with eye muscles,

Question 31

Cause of myasthenia gravis?

Answer 31

Depletion of nAchR because autoantibodies attack them Which cause less depolarisation of muscle fibres and repeated stimulation will lead to neuromuscular fatigue

Question 32

Symptoms of myasthenia gravis?

Answer 32

Ptosis - one eyelid droopy Diplopia- double vision Proximal muscle weakness

Question 33

Treatments for myasthenia gravis?

Answer 33

AchE inhibitors Pyridostigmine- increases ACh activity Edrophonium- short lived AchE inhibitor Thymectomy- for immune system- reduces symptoms in 70% of patients Immunosuppressive Drugs- corticosteroids Plasmapheresis- remove antibodies

Question 34

Spinal muscular atrophy cause?

Answer 34

Death of lower motor neurons in anterior horn of spine, causing muscular atrophy, hypotonia and muscle weakness causes fibre type grouping Autosomal recessive

Question 35

Malignant hyperthermia?

Answer 35

Genetic susceptibility to gas anaesthetics Mutation in RyR, causes release of calcium, Autosomal dominant, SERCA works too hard ca back into SR Increase O2 and CO2, acidosis tachypnea, body overheats, rhabdomyolysis

Question 36

What happens in malignant hyperthermia?

Answer 36

Muscle cells open and leak contents | Increase in CK MM

Question 37

How to treat malignant hyperthermia?

Answer 37

Dantrolene sodium can stop calcium release, inhibits ryanodine receptor

Question 38

Muscular dystrophies present with?

Answer 38

Muscles weakness, waddling gate, contracture and cardio respiratory muscle involvement

Question 39

Duchenne muscular dystrophy?

Answer 39

X linked, 1 in 3500 males Loss of muscle tissue replaced by fibre fatty connective tissue Dystrophin protein mutation

Question 40

What is gowers sign?

Answer 40

To weak to pick themselves up | Sign of muscular duchenne dystrophy?

Question 41

Testosterone effects?

Answer 41

Increase protein synthesis Decrease catabolism, by opposing cortisol and glucocorticoids Reduces fat, increases BMR, differentiation to muscle

Question 42

Myosatellite cells are what kind of cells?

Answer 42

Progenitor cells

Question 43

Fibre type grouping?

Answer 43

Surviving axons innervate surrounding fibres, determine which type of muscle fibre it will be

Question 44

How to test for myasthenia gravis?

Answer 44

Give short acting inhibitor endophonium, see if ptosis stops

Question 45

Drug for myasthenia gravis?

Answer 45

Pyridostigmine

Question 46

How can you treat malignant hyperthermia?

Answer 46

Inhibit the Ry receptor, with dantrolene sodium