Muscle Structure & Function

What is the name of the thick myofilaments of a muscle fiber?

• Actin

• Myosin

• Myoglobin

• Troponin

What is the name of the thin myofilaments of a muscle fiber?

• Actin

• Myosin

• Myoglobin

• Tropomyosin

Number 3 represents which of the following events

• action potential reaching the axon terminal

• sodium rushing into the muscle fiber

• potassium leaving the muscle fiber

• a neurotransmitter crossing the synaptic cleft

The shortening of a muscle is caused by

• shortening of thick myofilaments

• shortening of thin myofilaments

• sliding of thin myofilaments past thick myofilaments

• "accordian-like" folding of thick and thin myofilaments

The actin is represented by the letter

• A

• B

• C

Skeletal muscle contraction is initiated when the ________ sends a message to the muscle cell.

• muscle cell

• neuron (nerve cell)

• gland

• none of the above

The region where a motor neuron comes in close contact with a muscle cell.

• neurotransmitter

• muscular dystrophy

• muscle tension

• neuromuscular junction

The axon terminal is represented by

• 7
• 8
• 9
• 10

The muscle cell surface is represented by

• 9

• 10

• 11

• 12

Which of the following statements concerning the role of Ca²⁺ in the normal contraction of skeletal muscle is correct?

• The mitochondria act as a store of Ca²⁺ for the contractile process

• Ca²⁺ entry across the plasma membrane is important in sustaining the contraction of skeletal muscle

• An increase in Ca²⁺ in the muscle cell allows actin to interact with myosin

• The tension of a skeletal muscle fiber is partly regulated by G proteins.