Question 1

Which statements are true concerning the method in which substances pass between capillaries and the interstitial fluid? (Select all that apply.)

Accepted Answer

Substances pass between the capillary lumen and the interstitial fluid in several ways: (1) through junctions between endothelial cells, (2) through fenestrations in endothelial cells, (3) in vesicles moved by active transport across the endothelial cell membrane, or (4) by diffusion through the endothelial cell membrane.

Question 2

A healthcare professional cares for older adults in a skilled nursing facility. What should the professional assess for in these individuals related to cardiovascular functioning?

Accepted Answer

The baroreceptor reflex is important in blood pressure control. Baroreceptor activity can decrease with age, slowing response to changes in blood pressure and posture. An older adult may not adjust rapidly to position changes, leading to falls and dizzy spells.

Question 3

What is the most important negative inotropic agent?

Accepted Answer

Chemicals affecting contractility are called inotropic agents. The most important negative inotropic agent is acetylcholine released from the vagus nerve. The most important positive inotropic agents produced by the body are norepinephrine released from the sympathetic nerves that supply the heart and epinephrine released by the adrenal cortex. Other positive inotropes include thyroid hormone and dopamine.

Question 4

The right lymphatic duct drains into which structure?

Accepted Answer

The right lymphatic duct drains lymph into the right subclavian vein only.

Question 5

A patient had a motor vehicle crash and suffered critical injuries to the brainstem. What physiological responses would the healthcare professional expect to see?

Accepted Answer

The major cardiovascular control center is in the brainstem in the medulla with secondary areas in the hypothalamus, the cerebral cortex, the thalamus, and the complex networks of exciting or inhibiting interneurons (connecting neurons) throughout the brain. The brainstem specifically controls blood pressure and pulse, so a severe injury to this area would manifest with changes in blood pressure and pulse. Changes on the ECG and fluid overload would not occur due to this injury.

Question 6

The healthcare professional explains to a student that the amount of volume of blood in the heart is directly related to the _____ of contraction.

Accepted Answer

As stated in the Frank-Starling law, the volume of blood in the heart at the end of diastole (the length of its muscle fibers) is directly related to the force (strength) of contraction during the next systole. This selection is the only option that accurately describes the relationship associated with the Frank-Starling law.

Question 7

What enables electrical impulses to travel in a continuous cell-to-cell fashion in myocardial cells?

Accepted Answer

The intercalated disks are thickened portions of the sarcolemma and enable electrical impulses to spread quickly in a continuous cell-to-cell (syncytial) fashion. A sarcolemma is a transparent sheath that surrounds nerve fibers. They are not subject to plaque buildup. The trabeculae carneae are beam-like projections of myocardial tissue. Bachmann bundles are part of the conduction system.

Question 8

What physical sign does the healthcare professional relate to the result of turbulent blood flow through a vessel?

Accepted Answer

Where flow is obstructed, the vessel turns or blood flows over rough surfaces. The flow becomes turbulent with whorls or eddy currents that produce noise, causing a murmur to be heard on auscultation. Increased blood pressure during stress is the result of sympathetic nervous system stimulation. A bounding pulse usually indicates fluid overload. Cyanosis would relate to a decrease in gas exchange and oxygenation.

Question 9

Reflex control of total cardiac output and total peripheral resistance is controlled by what mechanism?

Accepted Answer

Reflex control of total cardiac output and peripheral resistance includes (1) sympathetic stimulation of the heart, arterioles, and veins; and (2) parasympathetic stimulation of the heart only. Neither autonomic nor somatic controls are involved in this process.

Question 10

A healthcare professional is caring for a patient who has continuous increases in left ventricular filing pressures. What disorder would the professional assess the patient for?

Accepted Answer

Pressure changes are important because increased left ventricular filling pressures back up into the pulmonary circulation, where they force plasma out through vessel walls, causing fluid to accumulate in lung tissues (pulmonary edema). Problems such as mitral regurgitation and mitral stenosis are valve problems, not directly related to this patient's situation. Jugular vein distention can be a sign of fluid overload.

Question 11

An early diastole peak caused by filling of the atrium from peripheral veins is identified by which intracardiac pressure?

Accepted Answer

The V wave is an early diastolic peak caused by the filling of the atrium from the peripheral veins. The A wave is generated by atrial contraction. The C wave is a small pressure increase seen after the A wave in early systole. The X descent follows the A wave and is produced by the descent of the tricuspid valve ring and by the ejection of blood from both ventricles.

Question 12

Within a physiologic range, what does an increase in left ventricular end-diastolic volume (preload) result in?

Accepted Answer

This concept is expressed in the Frank-Starling law; the cardiac muscle, like other muscles, increases its strength of contraction when it is stretched. An inotropic substance would increase the force of contraction and consist of hormones, neurotransmitters, or medications, and do not include volume. Afterload is the force against which the heart must pump. A decrease in repolarization would affect electrical activity.

Question 13

The resting heart rate in a healthy person is primarily under the control of which nervous system?

Accepted Answer

The resting heart rate in healthy individuals is primarily under the control of parasympathetic stimulation.

Question 14

Where in the heart are the receptors for neurotransmitters located?

Accepted Answer

Sympathetic neural stimulation of the myocardium and coronary vessels depends on the presence of adrenergic receptors, which specifically bind with neurotransmitters of the sympathetic nervous system. The b₁ receptors are found mostly in the heart, specifically the conduction system (AV and SA nodes, Purkinje fibers) and the atrial and ventricular myocardium, whereas the b₂ receptors are found in the heart and also on vascular smooth muscle. b₃ receptors are also found in the myocardium and coronary vessels. This selection is the only option that accurately identifies the location of the receptors for neurotransmitters.

Question 15

The Bainbridge reflex is thought to be initiated by sensory neurons in which cardiac location?

Accepted Answer

The Bainbridge reflex causes changes in the heart rate after intravenous infusions of blood or other fluid. The changes in heart rate are thought to be caused by a reflex mediated by volume receptors found only in the atria that are innervated by the vagus nerve.

Question 16

What is the major effect of a calcium channel blocker such as verapamil on cardiac contractions?

Accepted Answer

The L-type, or long-lasting, channels are the predominant type of calcium channels and are the channels blocked by calcium channel-blocking drugs (verapamil, nifedipine, diltiazem). The major effect of these medications is to decrease the strength of cardiac contraction. These medications do not increase the rate of contractions or stabilize either rhythm of contractions or vessel response during contractions.

Question 17

What is an expected change in the cardiovascular system that occurs with aging?

Accepted Answer

Arterial stiffening occurs with aging even in the absence of clinical hypertension. Aging is not responsible for the other conditions.

Question 18

Pressure in the left ventricle must exceed pressure in which structure before the left ventricle can eject blood?

Accepted Answer

Pressure in the ventricle must exceed aortic pressure before blood can be pumped out during systole. The aorta is the only structure in which pressure must be less than the amount of blood in the left ventricle for ejection to occur.

Question 19

What is the major determinant of the resistance that blood encounters as it flows through the systemic circulation?

Accepted Answer

The muscle layer of the arterioles constricts or dilates depending on the stimulation it receives. The change in the diameter of the vessels determines the resistance to blood flow. Blood viscosity usually stays the same; however severe fluid loss can increase it, leading to an increase in resistance. This is not the major determinant however. The force of contraction does not determine resistance to flow.

Quiz 32: Structure and Function of the Cardiovascular and Lymphatic Systems