Which statement(s) is(are) NOT true regarding cardiac muscle? Choose ALL that ap
ID: 3513189 • Letter: W
Question
Which statement(s) is(are) NOT true regarding cardiac muscle? Choose ALL that apply.
a) Autorhythmic cells do not contribute significantly to the force of heart contraction because they do not contain many myofibrils.
b) Cardiac muscle consists of autorhythmic fibers and contractile fibers.
c) Cardiac muscle is similar to skeletal muscle since it contains thick and thin filaments, sarcoplasmic reticulum, and T tubules.
d) Cardiac muscle is similar to skeletal muscle in that the muscle fibers function independently of one another.
e) Cardiac muscle is similar to skeletal muscle in that an external stimulus is required for muscle fibers to contract.
Explanation / Answer
Statement D and E are incorrect.
The correct statement are
A) autorythmic cells (in SA Node, AV Node and conduction pathway) are for conduction of electric signal to contractile fibers and thus doesn't contribute to force of contraction.
B) cardiac muscle = conduction system (autorythmic) + Contractile cardiac muscles.
D) cardiac muscle fiber CONTRACT TOGETHER (they are not independent contracting)
E) due to presence of Autoarythemic cells cardiac muscles DO NOT require external stimulus for contraction.
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