Heart Lecture A&P II

Norepinephrine is considered a positive chronotropic agent because it causes

Less calcium to enter the heart cells, which leads to lower risk of heart attack

Sympathetic innervation of the heart a: increases the heart rate b: decreases the heart rate c: increases the force of contractions d: decreases the force of contractions e: has no effect on contraction force

a,c

Once an SA nodal cell reaches threshold, the depolarization phase occurs during which

calcium comes in through fast voltage-gated channels

Which of the following is not one of the three main factors influencing stroke volume?

chronotropic agents

Cardiac output equals the

heart rate times stroke volume

What are the cell-to-cell contacts of the cardiac muscle fibers called?

intercalated discs

Pectinate muscles are found on the

internal walls of the right and left atria

Cardiac output is usually expressed in

liters per minute

In an ECG, what doesthe T wave represent?

repolarization of ventricles

Each of the receiving chambers of the heart has awrinkled flaplike extension; the one that is more visible from an anterior view is the

right auricle