Topic 3: Cardiovascular System Physiology

As exercise progresses, muscular activity _________ venous return. This increases the _________ on the right ventricle.

increases; preload

Blood pressure is expressed in millimeters of mercury because mercury is so dense it enables pressure to be measured with shorter columns.

True

In the heart, an action potential originates in the _________

sinuatrial node

Which of the following is the correct sequential path of an action potential in the heart?

Sinuatrial node, atrioventricular node, atrioventricular bundle, bundle branches, subendocardial branches (Purkinje fibers)

Which of the following is true concerning the heart's conduction system?

Action potentials pass slowly through the atrioventricular node.

In the ventricles, the action potential travels along the interventricular septum to the apex of the heart, where it then spreads superiorly along the ventricle walls.

true

Action potentials are carried by the subendocardial branches (Purkinje fibers) from the bundle branches to the ventricular walls.

true

Which of the following statements is not true regarding ventricular systole?

The ventricles relax.

The semilunar valves close during _________

ventricular diastole

The atrioventricular valves open during _________

ventricular diastole

Atrial contraction accounts for most of the ventricular filling.

False

The ventricles begin to fill during ventricular diastole.

true

Which of the following is caused by ventricular contraction?

The atrioventricular valves close, and then the semilunar valves open.

When the pressure in the ventricles becomes lower than the pressure in the atria, _________

the atrioventricular valves open

Which of the following is the correct sequence of events regarding the cardiac cycle?

Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling

Where are baroreceptors found?

Carotid sinuses

Action potentials are conducted from the baroreceptors to the brain via which nerve?

Glossopharyngeal nerve

The action potential from the brain to the heart travels along which nerve(s)?

Vagus nerve

Heart rate and stroke volume decrease with a decrease in parasympathetic stimulation.

False

Increased sympathetic stimulation causes vasodilation, bringing elevated blood pressure back to normal.

False

Why do fluids leave the capillaries at the arterial end?

The net filtration pressure of the blood is higher at the arterial end than it is at the venous end.

Approximately what percent of fluid that exits the capillaries at the arterial end reenters the capillaries at the venous end?

90%

The lymphatic capillaries reabsorb as much as 20% of the fluid lost by the blood capillaries.

False

The net osmotic pressure is equal at both the arterial and the venous ends of the capillary.

true

Which of the following is not detected by chemoreceptors in the carotid and aortic bodies?

Blood pressure

Which of the following contains chemoreceptors?

Medulla oblongata

Which of the following will not increase the heart rate?

Increased blood pressure

Increased sympathetic stimulation causes increased heart rate and stroke volume.

True