In the myogenic response, ________.a. muscle contraction promotes venous return to theheartb. ventricular contraction strength is decreasedc. vascular smooth muscle responds to stretchd. endothelins dilate muscular arteries

The sinoatrial node sets the pace for the heart as a whole because sinoatrial node cells _____.   A are the only heart cells with an unstable resting membrane potential.   B are the only heart cells capable of initiating an action potential without the influx of positive ions through gap junction   C are located at the top of the heart in the interatrial septum   D have a faster rate of spontaneous depolarization than other pacemaker cells

The function of the right and left bundle branches is to _____.   A rapidly transmit action potentials along the interventricular septum   B contract forcefully to eject blood from the ventricle   C spontaneously depolarize to start a second action potential in the ventricles   D delay action potentials so that the atria have time to contact before the ventricles

Fill in the blank:  In the presence of damaged blood vessels, platelets release a substance called _______________________ thatcauses smooth muscle contraction.

An ectopic pacemaker refers to the condition in which _____.   A the rate at which the SA node cells undergo spontaneous depolarization is abnormal   B "all of the heart cells function independently of one another such that the heart vibrates, but fails to pump blood"   C action potentials in the heart are initiated by a region other than the sinoatrial node   D the endothelial cells

Cells of the sinoatrial node __________ during the pacemaker potential. a. depolarize fast b. repolarize slow c. depolarize slow d.repolarize fast

Blood leaves the right ventricle through the ______.   A pulmonary trunk   B right atrium   C superior vena cava   D aorta

Blood pressure sounds heard when listening to the brachial artery are caused by _______.   A turbulent blood flow   B heart valves closing   C heart valves opening

Heart muscle cells ______.   A will not contract unless acetylcholine is released at a neuromuscular junction   B use glucose as their primary energy source and are easily damaged by hypoglycemia   C have gap junctions that allow action potentials to be transmitted from one cell to the next   D "are very long, with individual cells running the entire length of the heart"

In a normal heartbeat the atria contract ______.   A at exactly the same time as the ventricles   B immediately before the ventricles   C immediately after the ventricles   D at the very beginning of ventricular diastole