Muscle and myopathies

Question 1

How much body weight does muscle tissue amount to?

Answer 1

40-50%

Question 2

3 types of muscle:

Answer 2

skeletal
cardiac
smooth

Question 3

Cardiac muscle

Answer 3

• involuntary

- pacemaker for autorhythmicity

Question 4

Smooth muscle

Answer 4

• non-striated
• contains actin and myosin
• GI tract also has autorhythmicity

Question 5

Skeletal muscle

Answer 5

-muscle surrounded by connective tissue - fascia
-several layers of muscle
a) perimysium
b) endomysium
c)

Question 6

Skeletal muscle fibres

Answer 6

• many nuclei
• develop by fusion of myoblasts
• nuclei are in the periphery of the cell below the sarcolemma

Question 7

Skeletal muscle myofibrils

Answer 7

• sarcoplasm is filled with myofibrils
• cylindrical structures that carry out contractions
• these are where the striations can be seen

Question 8

Myofibrils

Answer 8

1-2um in diameter

• composed of functional units called sarcomeres
• I band
• H zone
• A band
• Z disc
• be able to identify on a diagram/photo

Question 9

Dystrophy

Answer 9

-muscle destroying disease –> progressive degeneration of muscle fibres

Question 10

Duchenne’s and Becker’s (prognosis better in Becker’s)

Answer 10

• mutation in dystrophin gene
• X-linked recessive
• necrotic fibres
• endomysial fibrosis
• muscle replaced by adipose and connective tissue

Question 11

Metabolic myopathies

Answer 11

-defects in any stage of muscle ATP metabolism can lead to myopathy

Question 12

Inflammatory myopathies

Answer 12

• chronic muscle inflammation and weakness
• often idiopathic
• autoimmune
• proximal –> distal

Question 13

Cardiomyopathies

Answer 13

• deterioration in the functioning of the heart muscle

- little or no regenration