heart and cardiovascular function review

Define cardiac regurgitation

Cardiac regurgitation is the abnormal backflow of blood into the atria when the ventricles contract, and it is prevented by the chordae tendineae and papillary muscles.

Name the four cardiac chambers

Right Atrium, Left Atrium, Right Ventricle, Left ventricle

What do semilunar valves prevent?

Semilunar valves prevent the backflow of blood in to the ventricles.

Define tissue perusion

Tissue perfusion is blood flow to tissues that is sufficient to deliver adequate oxygen and nutrients.

List the phases of the cardiac cycle

Atrial systole, atrial diastole, ventricular systole, and ventricular diastole.

Define automaticity

Automaticity is the ability of cardiac muscle to contract without neural or hormonal stimulation

Explain the function of baroreceptor reflexes

Baroreceptor reflexes respond to change in blood pressure. The baroreceptors- located in the walls of the carotid sinuses, aortic sinuses, and right atrium- monitor the degree of stretch at those sites.

Identify the hormones responsible for short-term regulation of decreasing blood pressure and blood volume.

Epinephrine and norepinephrine from the adrenal medullae provide short-term regulation of decreasing blood pressure and blood volume.

Describe the roles of natriuretic peptides

Excessive stretching of the right atrium during diastole causes the release of atrial natriuretic peptide (ANP). Excessive stretching of the ventricles during diastole causes the release of brain natriuretic peptide (BNP). The roles of these peptides are to trigger responses whose combined effects act to decrease blood volume and blood pressure. As blood volume and blood pressure decrease, natriuretic peptide production stops.

Why is it beneficial for capillary pressure to be very low?

It is beneficial for capillary pressure to be very low so blood can flow slowly and allow time for diffusion between the blood and the surrounding interstitial fluid.

Caffeine has effects on conducting cells and contractile cells that are similar to those of NE. What effect would drinking large amounts of caffeinated beverages have on the heart rate?

Like NE, caffeine acts directly on the conducting system and contractile cells of the heart, increasing the rate at which they depolarize. Drinking large amounts of caffeinated beverages would therefore increase the heart rate.

Neutral and hormonal regulation influence which factors?

Neutral and hormonal regulation influence heart rate, stroke volume, peripheral resistance, and venous pressure.

The great veins and arteries are attached to which aspect of the heart

The base of the heart

Define the cardiac cycle

The cardiac cycle is the period between the start of one heartbeat and the beginning of the next

What effect would an increase in venous return have on the stroke volume?

An increase in venous return would stretch the heart muscle. The more the heart muscle is stretched, the more forcefully it will contract (to a point). The more forceful the contraction, the more blood the heart will eject with each beat (stroke volume). Therefore, increased venous return would increase the stroke volume (if all other factors are constant).

What would reduce peripheral resistance: an increase in vessel length or an increase in vessel diameter?

An increase in vessel diameter would reduce peripheral resistance.

Identify the conditions that would shift the balance between hydrostatic and osmotic forces

Any condition that affects either blood pressure or osmotic pressures in the blood or interstitial fluid will shift the balance between hydrostatic and osmotic forces.

Which is greater: Arterial pressure or venous pressure?

Arterial pressure is much higher than venous pressure because it must push blood a greater distance and through progressively smaller vessels.

List the arteries and veins of the heart

Arteries: left coronary artery, anterior interventricular artery, right coronary artery, marginal arteries, circumflex artery, and posterior interventricular artery. Veins: great cardiac vein, anterior cardiac veins, posterior cardiac vein, middle cardiac vein, and small cardiac vein.

Why does tetany not occur in cardiac muscle?

Cardiac muscle has a long refractory period that continues until relaxation is well under way. As a result, another action potential cannot arrive quickly enough for summation to occur, and thus tetany cannot occur.

Why can cardiac tamponade be a life-threatening condition?

Cardiac tamponade can be a life-threatening condition because the accumulating fluid within the pericardial cavity restricts heart movement.

Why is it important that cardiac tissue contain many mitochondria and capillaries?

Cardiac tissue is metabolically active and dependent on mitochondrial activity for ATP and local capillaries for obtaining oxygen and nutrients.

Describe autoregulation as it pertains to cardiovascular funcftion

Cardiovascular autoregulation involves local factors changing the pattern of blood flow within capillary beds in response to chemical changes in interstitial fluids.

Which structures collect blood from the myocardium, and into which heart chamber does this blood flow?

Coronary veins collect blood from the myocardium and carry it into the right atrium.

Damage to the semilunar valve on the right side of the heart would affect blood flow to which vessel?

Damage to the semilunar valve on the right side of the heart would affect blood flow to the pulmonary trunk.

Under what general conditions would fluid move into a capillary

Fluid moves into a capillary whenever blood colloid osmotic pressure (BCOP) is greater than capillary hydrostatic pressure (CHP).

Define heart failure

Heart failure is a condition in which the heart can no longer meet the oxygen and nutrient demands of peripheral tissues.

If the cells of the SA node failed to function, how would the heart rate be affected?

If the cells of the SA node failed to function, the heart would continue to beat, but at a slower rate; the AV node would act as the pacemaker.

Why is it important for impulses from the atria to be delayed at the AV node before they pass into the ventricles?

If the impulses from the atria were not delayed at the AV node, they would be conducted through the ventricles so quickly by the bundle branches and Purkinje cells that the ventricles would begin contracting before the atria had finished contracting as a result, the ventricles would not be as full of blood as they could be, and the pumping actin of the heart would be less efficient.

In a healthy person, where is the blood pressure greater: in the aorta or in the inferior vena cava? explain.

In a healthy person, blood pressure is greater in the aorta than in the inferior vena cava. If the pressure were higher in the inferior vena cava than in the aorta, blood would flow in the reverse direction.

Describe the purpose of a stent

Stents are wire-mesh tubes that prop open the natural blood vessel, creating a conduit to restore blood flow. Without adequate blood flow to the cardiac muscle, the tissue would die.

Explain the formula R=1/r⁴

That resistance is inversely proportional to the fourth power of the vessel radius. This means that a small change in vessel diameter results in a large change in resistance.

Give the alternate terms for heart contraction and heart relaxation

The alternate term for heart contraction is systole, and the term for heart relaxation is diastole.

Why is it a potential problem if the heart beats too rapidly?

The amount of blood that the heart pumps is proportional to the amount of blood that enters it. A heart that is beating too rapidly does not have adequate filling time, and it pumps less blood; peripheral tissues can be damaged by inadequate blood flow.

Compare the anterior cardiac veins to the posterior cardiac vein

The anterior cardiac veins drain the anterior surface of the right ventricle and empty into the right atrium. The posterior cardiac vein drains the area (posterior surface of the left ventricle) supplied by the circumflex artery.

Describe the respiratory pump

The respiratory pump is a mechanism by which a reduction of pressure in the thoracic cavity during inhalation assists venous return to the heart.

compare arteriosclerosis with atherosclerosis

Arteriosclerosis is any thickening and toughening of arterial walls; atherosclerosis is a type of arteriosclerosis characterized by changes in the endothelial lining and the formation of fatty deposits in the tunica media

Define electrocardiogram

An electrocardiogram (ECG or EKG) is a recording of the electrical activities of the heart over time.

What effect would an increase in sympathetic stimulation of the heart have on the end-systolic volume (ESV)?

An increase in sympathetic stimulation of the heart would increase heart rate and force of contraction. The end-systolic volume (ESV) is the amount of blood that remains in a ventricle after a contraction (systole). The more forcefully the heart contracts, the more blood it ejects. Therefore, increased sympathetic stimulation results in a lower ESV.

Define the blood flow, and describe its relationship to blood pressure and peripheral resistance

Blood flow is the volume of blood flowering per unit of time through a vessel or group of vessels; it is directly proportional to blood pressure and inversely proportional to peripheral resistance.

Compare bradycardia with tachycardia

Bradycardia would be an abnormally low heart rate below 60 bpm. Tachycardia is an abnormally high heart rate above 100 bpm.

Describe circulatory shock, progressive shock, and irreversible shock.

Circulatory shock occurs when blood loss exceeds about 35 percent of the total blood volume. Circulatory shock involves a series of positive feedback loops that are initiated after homeostasis has been disrupted. Progressive shock is the next stage after circulatory shock. It, too, is a series of positive feedback loops that accelerate tissue damage. Irreversible shock is the fatal stage that occurs if the positive feedback loops initiated during progressive shock are not broken.

Identify the compensatory mechanisms that respond to blood loss

Compensatory mechanisms that respond to blood loss include an increase in cardiac output, a mobilization of venous reserves, peripheral vasoconstriction, and the release of hormones that promote retention of fluid and the maturation of erythrocytes.

What prevents the AV valves from swinging into the atria?

Contraction of the papillary muscles pulls on the chordae tendineae, which prevent the AV valves from swinging into the atria.

What is coronary ischemia?

Coronary ischemia is a condition in which the blood supply of the coronary arteries is reduced.

Describe what happens to blood flow during elastic rebound

During elastic rebound, some blood in the aorta is driven forward into the systemic circuit, and some is forced back toward the left ventricle and into the coronary arteries.

Describe the changes in cardiac output and blood flow during exercise

During exercise, cardiac output increases, and blood flow to skeletal muscles increases at the expense of blood flow to less essential organs.

Define edema

Edema in an abnormal accumulation of interstitial fluid in peripheral tissues.

Describe the slow calcium channels and the significance of their activity

Slow calcium channels are voltage-gated calcium channels that open slowly and remain open for a relatively long period about 175 msec. When they are open, the entry of calcium ins into the cell roughly balances the loss of sodium ions through the active transport of sodium ions. As a result, the membrane potential remains near 0 mV for an extended period.

The anterior view of the heart is dominated by which structures?

The Right Ventricle, and Right Atrium

Describe the site and actions of the cardioinhibitory and cardioaccelatory centers.

The cardioacceleratory center in the medulla oblongata activates the sympathetic neurons to increase heart rate; the cardioinhibitory center (also in the medulla oblongata) controls the parasympathetic neurons that slow heart rate.

Define end-diastolic volume (EDV) and end-systolic volume (ESV).

The end-diastolic volume (EDV) is the amount of blood a ventricle contains at the end of diastole, just before a contraction begins; the end-systolic volume (ESV) is the amount of blood that remains the ventricle at the end of ventricular systole.

Describe the tissue layers of the epicardium

The epicardium consists of an outer mesothelium and an underlying layer of areolar tissue that attaches directly to the myocardium.

From superficial to deep, name the layers of the heart wall

The epicardium, myocardium, and endocardium

Describe the heart's location in the body

The heart is surrounded by the pericardial sac in the anterior mediastinum, deep to the sternum and superior to the diaphragm.

Name the immediate and long-term problems related to profuse blood loss

The immediate, short-term, problem during hemorrhaging is maintaining adequate blood pressure and peripheral blood flow; the long-term problem is restoring normal blood volume.

List the important features of the ECG, and indicate what each represents

The important features of an ECG are the P wave (atrial depolarization), the QRS complex (ventricular depolarization), and the T wave (ventricular repolarization).

Is the apex located on the superior or inferior aspect of the heart

The inferior aspect of the heart

mediastinum

The mediastinum is the region between the two pleural cavities that contain the heart along with the great vessels, thymus, esophagus, and trachea

Why is the left Ventricle more muscular than the right ventricle?

The more muscular left ventricle must generate enough force to propel blood throughout the body (except the lungs), whereas the right ventricle must generate only enough force to propel blood to the short distance to the lungs.

List the three stages of an action potential in a cardiac muscle cell

The three stages of an actin potential in a cardiac muscle cell are rapid depolarization, plateau, and repolarization.

Compare the structure of the tricuspid valve with that of the pulmonary valve

The tricuspid valve is composed of three relatively large cusps; the pulmonary valve is made up of three smaller half-moon-shaped cusps.

What are the two phases of ventricular systole?

The two phases of ventricular systole or isovolumetric contraction ventricular contraction

List the factors that contribute to total peripheral resistance

Total peripheral resistance reflects a combination of vascular resistance, vessel length, vessel diameter, blood viscosity, and turbulence.

Why must blood flow to visceral organs be reduced during exercise?

Unless compensatory vasoconstriction occurs in "nonessential" organs, such as those of the digestive system, vasodilation in skeletal muscles would cause a potentially dangerous decrease in blood pressure and blood flow throughout the body during exercise.

Calculate the mean arterial pressure for a person whose blood pressure 125/70

Using the formula MAP= diastolic pressure + (pulse pressure)/3, MAP equals 70+(125-70)/3, which equals 70+18.3, or 88.3 mm Hg.

How does the kidney respond to vasoconstriction of the renal artery?

Vasoconstriction of the renal artery would decrease both blood flow and blood pressure at the kidney. in response, the kidney would increase the amount of renin it releases, which in turn would increase the level of angiotensin II. The angiotensin II would bring about increased blood pressure and increased blood volume.

Why is ventricular fibrillation fatal?

Ventricular fibrillation, which causes the condition known as cardiac arrest, is fatal because the ventricles merely quiver and do not pump blood into the systemic circulation.

When a chamber is relaxed, which phase is it in?

When a chamber is relaxed, it is in the diastole phase of the cardiac cycle.

Is the heart always pumping blood when pressure in the left ventricle is rising? Explain.

No. When pressure in the left ventricle first rises, the heart is contracting but blood is not leaving the heart. During this initial phase of contraction, called the period of isovolumetric contraction, both the AV valves and the semilunar valves are closed. The increase in pressure is the result of the cardiac muscle contracting. When the pressure in the ventricle exceeds that in the aorta, the aortic semilunar valves are forced open, and blood is rapidly ejected from the ventricle.

Compute Joe's stroke volume if his end-systolic volume (ESV) is 40 mL and his end-diastolic volume (EDV) is 125 mL.

SV = EDV - ESV, so SV= 125 mL - 40 mL = 85 mL.

Name and describe the shallow depressions and grooves on the heart's external surface

The anterior interventricular sulcus marks the boundary between the left and right ventricles on the heart's anterior surface; the shallower posterior interventricular sulcus marks the boundary between the left and right ventricles on the posterior surface; and the coronary sulcus is a deep groove that marks the border between the atria and the ventricles.