The SA Is the Heart's Normal Pacemaker Because

question 116

Multiple Choice

The SA is the heart's normal pacemaker because

• A) It has the fastest rate of autorhythmicity.
• B) It has both sympathetic and parasympathetic innervation.
• C) It lies in the right atrium.
• D) Activation of K⁺ channels occurs more rapidly in this region than elsewhere in the heart.
• E) None of these.

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Definitions:

DNA

Deoxyribonucleic acid, a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms.

Ribose

A five-carbon sugar that is a crucial component of RNA (ribonucleic acid) molecules.

Helix

A three-dimensional, spiral shape, common in structural biology, particularly in the structure of proteins and nucleic acids like DNA.

Adenine

A purine nucleobase vital for the structure of DNA and RNA, where it pairs with thymine in DNA and uracil in RNA.