Muscle Physiology and Adaptation

Flashcards covering key concepts from the lecture on muscle physiology and adaptation.

What are the three types of skeletal muscle fibers based on ATP hydrolysis and synthesis?

Slow-oxidative (type I), Fast-oxidative (type IIa), Fast-glycolytic (type IIx)

What characterizes slow-twitch oxidative muscle fibers?

They have a large amount of red myoglobin, numerous mitochondria, and an extensive capillary blood supply, making them fatigue-resistant.

What is the primary difference between fast-twitch glycolytic muscle fibers and slow-twitch oxidative muscle fibers?

Fast-twitch glycolytic muscle fibers have a larger diameter, pale color, and are easily fatigued, while slow-twitch fibers are smaller and darker due to myoglobin.

Which type of muscle fiber has high myosin-ATPase activity and is fast to contract?

Fast-twitch glycolytic muscle fibers (Type IIx) have high myosin-ATPase activity and contract quickly.

What happens to muscle fibers in response to exercise demands?

Muscle fibers adapt by improving oxidative capacity, undergoing muscle hypertrophy, and can interconvert between fast muscle types.

What is the difference between central fatigue and muscle fatigue?

Muscle fatigue occurs when an exercising muscle can't respond to stimulation adequately, while central fatigue involves the CNS no longer adequately activating motor neurons.

Describe the characteristics of smooth muscle.

Smooth muscle is unstriated, involuntary, can contract over a range of lengths, and responds to neurotransmitters and hormones.

What unique feature does cardiac muscle have compared to skeletal and smooth muscles?

Cardiac muscle has intercalated discs that connect cells and is controlled by the autonomic nervous system.

What is the latch phenomenon in smooth muscle?

The latch phenomenon allows smooth muscle to maintain force with minimal energy expenditure.

How do slow-twitch and fast-twitch muscle fibers differ in their oxygen consumption capacity during exercise?

Slow-twitch fibers have a high oxidative phosphorylation capacity, while fast-twitch fibers have a low capacity.