Physiology of Muscle Contraction

In order for an active site on actin to be exposed for the cross-bridging binding, the presence of _______ is required

• Potassium

• Sodium

• Calcium

• Water

Which of the following muscle types are voluntary?

• Skeletal

• Cardiac

• Smooth muscle

Found in the walls of hollow organs; also called visceral

• smooth

• cardiac

• skeletal

• all

What is the name of the neurotransmitter that is released from the neuron to the sarcolemma?

• Acetylcholine

• Acetone

• ATP

• Calcium

Which of these occurs first during a muscle contraction?

• The nerve signal reaches the neuromuscular junction

• Ach is released and opens Na ion channels

• The sarcomere shortens

• The myosin binds to the actin

Which of these occurs last during a muscle contraction?

• The nerve signal reaches the neuromuscular junction

• Ach is released and opens Na ion channels

• The sarcomere shortens

• The myosin binds to the actin

During a muscle contraction, cross-bridges from between what two structures?

• Actin and myosin fibers

• neuron and muscle

• mitochondria and actin

What state is the sarcomere in B.

• Relaxed

• Contracting

• Both

• None of the above

Which of the following best describes the power stoke?

• actin's troponin pulls on the myosin filament

• myosin filament heads pull on binding sites of the actin filament

• myosin filaments pull on the Z lines of the actin filament

• The A bands shrink

Contractile unit of a muscle which is also the functional unit of a muscle is ...

• sarcomere

• motor unit

• fascicle

• myofibril