Select the Correct Statement About the Function of Myocardial Cells

question 71

Multiple Choice

Select the correct statement about the function of myocardial cells.

• A) The refractory period in skeletal muscle is much longer than that in cardiac muscle.
• B) Cardiac muscle cells are innervated by sympathetic, parasympathetic, and somatic nerve fibers so that the nervous system can increase heart rate.
• C) The entire heart contracts as a unit or it does not contract at all.
• D) The influx of potassium ions from extracellular sources is the initiating event in cardiac muscle contraction.

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Definitions:

Levator Labii Superioris

The Levator Labii Superioris is a facial muscle that elevates the upper lip, aiding in expressions of disgust or snarling.

Platysma

A broad, thin muscle located in the chest and neck that is involved in facial expression and movement of the jaw.

Quadriceps Femoris

A large muscle group that covers the front and sides of the thigh, responsible for extension of the knee.

Third-class Lever

A type of lever where the effort is applied between the fulcrum and the load, used in scenarios where speed and range of movement are more important than force amplification.