Question 1

In the clotting cascade, factor Xa helps convert prothrombin to thrombin.

Accepted Answer

This statement is true. Factor Xa is a critical component in the coagulation cascade as it helps convert prothrombin to thrombin, which is necessary for the formation of a blood clot.

Question 2

Hypertension is often treated with drugs that increase total peripheral resistance.

Accepted Answer

Hypertension is often treated with drugs that decrease total peripheral resistance, such as ACE inhibitors, beta blockers, calcium channel blockers, and diuretics. These drugs help to relax the blood vessels and decrease resistance, which in turn lowers blood pressure.

Question 3

In a failing heart, stroke volume does not increase as steeply when end-diastolic volume increases.

Accepted Answer

This is due to the impaired contractility of the failing heart, which cannot generate as much force to increase the stroke volume proportionally to the increase in end-diastolic volume.

Question 4

A blood clot is essentially an intricate network of interlacing strands of thrombin.

Accepted Answer

A blood clot is not made up of strands of thrombin. Thrombin is an enzyme that plays a role in the formation of a blood clot, but the clot itself is made up of mesh-like strands of fibrin, which are produced during the clotting process.

Question 5

Chemical mediators released from platelet granules and plasma membranes stimulate contraction of vascular smooth muscle.

Accepted Answer

Platelet granules and plasma membranes release chemical mediators such as thromboxane A2 and serotonin, which can stimulate contraction of vascular smooth muscle.

Question 6

The adaptive value of having a complex cascade system for blood clotting is that a defect of one participant in the cascade can be corrected by another enzyme later in the cascade.

Accepted Answer

The cascade system for blood clotting is highly specific, and each step is dependent on the previous one. A defect in one participant usually cannot be corrected by another enzyme later in the cascade, leading to potential clotting disorders.

Question 7

The Starling forces, which influence bulk flow of fluid between capillary plasma and interstitial fluid, are identical everywhere in the body.

Accepted Answer

The Starling forces are influenced by various factors such as hydrostatic pressure, osmotic pressure, and permeability, which can vary in different tissues and organs throughout the body. Therefore, the Starling forces are not identical everywhere in the body.

Question 8

Increased concentrations of plasma proteins, increased venous pressure, and lymphatic obstruction all tend to cause tissue edema.

Accepted Answer

The answer of Increased concentrations of plasma proteins, increased venous...

Question 9

The term AED (Automatic Electronic Defibrillator) refers to a recently developed device used to regulate blood pressure with the surprise benefit of being useful in contraception with some individuals within a narrowly defined age group.

Accepted Answer

The term AED (Automatic External Defibrillator) refers to a device used to treat sudden cardiac arrest and has no connection to contraception or blood pressure regulation.

Question 10

When arterioles constrict, it raises arterial blood pressure and increases the volume of forward flow into the veins, while constriction in veins reduces forward flow by decreasing pressure in the atria.

Accepted Answer

When arterioles constrict, it actually increases resistance to blood flow and decreases arterial blood pressure. Constriction in veins can also increase pressure, but it does not directly affect pressure in the atria.

Question 11

The function of the platelet plug is to block the blood vessel so that blood cannot flow through it.

Accepted Answer

The function of the platelet plug is to seal the damaged area of a blood vessel to prevent further bleeding, but not to completely block the vessel. The platelets form a temporary plug until the more stable fibrin clot forms.

Question 12

In the clotting cascade, thrombin feeds back and further stimulates its own activation, which is a positive feedback mechanism.

Accepted Answer

Thrombin activates factors V and VIII, which in turn stimulate the production of more thrombin. This creates a positive feedback loop that amplifies and sustains the clotting process.

Question 13

Hemostatic mechanisms can generally stop blood loss from a small vein that is cut.

Accepted Answer

Hemostatic mechanisms include vasoconstriction, platelet plug formation, and coagulation, which are activated to stop bleeding from a small vein that is cut.

Question 14

Left ventricular failure often results in increased net pulmonary capillary filtration into the interstitial fluid of the lungs and decreased diffusional exchange of O₂ and CO₂ between lung and blood.

Accepted Answer

Left ventricular failure leads to increased pressure in the pulmonary vasculature, resulting in increased net pulmonary capillary filtration into the interstitial fluid of the lungs. This can lead to pulmonary edema, which impairs diffusional exchange of gases, including oxygen (O2) and carbon dioxide (CO2), between the lungs and the blood. Therefore, both statements in the prompt are true.

Question 15

Thrombin is inactivated when it binds to heparin.

Accepted Answer

Thrombin is not directly inactivated by heparin; instead, heparin enhances the activity of antithrombin III, which inactivates thrombin and other proteases involved in blood clotting.

Quiz 12: Cardiovascular Physiology