What region of the heart acts as the heart's pacemaker?

A) sinoatrial (SA) node
B) atrioventricular (AV) node
C) semilunar valve
D) ventricle


A

Biology & Microbiology

You might also like to view...

Early in mitosis chromatin condenses into the compact, rodlike structures known as chromosomes

Which of the following processes takes place more easily as a result?

a. disappearance of the nuclear envelope b. replication of DNA c. orderly distribution of DNA into the two new nuclei d. formation of the mitotic spindle e. disintegration of nucleoli

Biology & Microbiology

When scientists use a radioactive or fluorescent probe to label target DNA fragments and then transfer the hybridized fragments to a nylon membrane, what is this process called?

a. Southern blotting b. Northern blotting c. gel electrophoresis d. molecular cloning

Biology & Microbiology

The type of viral infection in which a virus enters a host cell, immediately replicates, and causes the host cell to burst is a infection.

A. systematic B. transgenic C. lytic D. lysogenic E. rare form of viral

Biology & Microbiology

. A severely injured animal is still able to defend itself due to the action of ____

a. dopamine b. endorphins c. endorphins d. acetylcholine e. GABA

Biology & Microbiology