Types of Muscle fibers

Question 1

Type I:

Answer 1

Slow-twitch muscle fibers
High mitochondria
Slow rate of fatigue
Slow speed of contraction
Relies on aerobic metabolism

Question 2

Type IIa

Answer 2

Fast-twitch muscle fibers
Higher mitochondria when compared to Type IIb
Intermediate rate of fatigue
Fast speed of contraction
Relies on both aerobic and anaerobic metabolism

Question 3

Type IIb:

Answer 3

Fast-twitch muscle fibers
Low mitochondria
Rapid rate of fatigue
Fast speed of contraction
Relies on anaerobic metabolism

Question 4

Skeletal Muscle

Answer 4

• Striated
• Peripheral nuclei
• Elongated
• Voluntary
• T-tubules: triads, center at A-I junction
• Quick, forceful contraction
• **Satellite cells- limited capacity for re-generation

Question 5

Cardiac Muscle

Answer 5

• Striated
• Central nucleus
• Branched
• Involuntary
• T-tubules: diads at the Z disc
• Rapid, forceful contraction
• **Intercalated discs- keep muscle cells from pulling apart during
• Adult heart cannot regenerate

Question 6

Smooth Muscle

Answer 6

• No striations
• Central nucleus
• Short elongate, spindle-shaped
• Involuntary
• No T-tubules
• Slow contraction
• **Pericytes- source of new smooth m. cells and repair damage; good capacity for re-generation