Muscle Physiology

Question 1

What are the types of skeletal muscle

Answer 1

Extrafusal fiber - type I,IIa, IIb muscle

Intrafusal fiver - muscle spindle

Question 2

What are the types of smooth muscle?

Answer 2

1. Visceral (single unit) smooth muscle - found in GIT,ureter, vessel
2. Multi unit smooth muscle - found in eye, airway, hair follicles

Question 3

What are the types of cardiac muscle?

Answer 3

Contractile - atria and ventricle

Autorhythmic - pacemaker

Question 4

Which muscles are striated?

Answer 4

Skeletal and cardiac

Smooth muscle is not striated

Question 5

Which muscle types have only a single nucleus?

Answer 5

Smooth and cardiac

Skeletal muscle are multi nucleated

Question 6

How are skeletal, smooth, cardiac muscle cells connected intercellularly

Answer 6

Skeletal muscle - no gap junctions present
Smooth muscle - gap junctions present
Cardiac muscle - intercalated discs (gap junctions and desmosomes)

Question 7

Energy source for skeletal, smooth, cardiac muscle

Answer 7

Skeletal - rich in mitochondria, creatine phosphate energy stores
Smooth - very few mitochondria, increased glycolysis, no CP energy stores
Cardiac - rich in mitochondria, CP phosphate stores

Question 8

Which muscle cell types are autorhythmic?

Answer 8

Smooth (visceral)
Cardiac (pacemaker)

Skeletal muscle is not

Question 9

What are the resting membrane potentials for each muscle group

Answer 9

Skeletal muscle -70 to -90 mV
Smooth muscle - no set RMP, but wanders around -50mV
Cardiac - pacemaker no RMO but wanders, contractile cell stable -90mV

Question 10

Muscle AP duration

Answer 10

Cardiac - long 150-250msec
Skeletal - 1-3msec
Smooth - short