Question 1

Jaundice is caused by an excess of iron in the blood.

Accepted Answer

Jaundice is caused by a buildup of bilirubin in the blood, not an excess of iron.

Question 2

Protein C inhibits both the intrinsic and extrinsic clotting pathways.

Accepted Answer

Protein C, once activated, inhibits factors V and VIII, which are key components of both the intrinsic and extrinsic clotting pathways, thereby reducing the formation of thrombin and slowing down clot formation.

Question 3

Iron can be stored in the liver and spleen bound to ferritin.

Accepted Answer

Iron is stored in the liver, spleen, and bone marrow bound to ferritin, a protein that allows the body to store iron safely and release it when needed.

Question 4

Coagulation factors continuously circulate in the blood in their inactive form.

Accepted Answer

Coagulation factors circulate in the blood in their inactive forms and are activated as part of the coagulation cascade when needed to respond to injury and stop bleeding.

Question 5

Thrombin not only promotes clotting at injury sites, but also indirectly inhibits clotting in healthy tissue.

Accepted Answer

Thrombin has a dual role in the coagulation process: while it promotes clot formation at injury sites by converting fibrinogen to fibrin, it also activates protein C, which in turn inactivates factors Va and VIIIa, thus providing a negative feedback mechanism that prevents clotting in areas where it is not needed.

Question 6

Carbonic anhydrase is an enzyme in erythrocytes essential for the transport of carbon dioxide as bicarbonate ions.

Accepted Answer

Carbonic anhydrase catalyzes the conversion of carbon dioxide and water into carbonic acid, which then dissociates into bicarbonate ions and protons, facilitating CO2 transport in the blood.

Question 7

Thrombin is activated by factor X.

Accepted Answer

Thrombin is generated from its precursor, prothrombin, through the action of activated factor X (factor Xa) in a complex with factor V, phospholipids, and calcium ions.

Question 8

The ability to prevent blood loss from vessels that have been damaged is an important hemostatic function. Describe in detail the three steps in the process of hemostasis including the compounds involved in those processes.

Accepted Answer

The answer of The ability to prevent blood loss from...

Question 9

Collagen activates factor X.

Accepted Answer

Collagen primarily plays a role in platelet adhesion and aggregation during the initial stages of blood clot formation, but it does not directly activate factor X. Factor X activation is part of the coagulation cascade, typically initiated by tissue factor (Factor III) or contact with negatively charged surfaces in the intrinsic pathway.

Question 10

Anemia is caused by a low hematocrit.

Accepted Answer

Anemia is caused by a low hemoglobin level or a low red blood cell count, not specifically by a low hematocrit, although hematocrit can be low in anemia.

Question 11

Erythrocytes have no nucleus or organelles. Therefore, the lifespan is short. Describe the lifecycle of erythrocytes.

Accepted Answer

The answer of Erythrocytes have no nucleus or organelles. Therefore,...

Question 12

The breakdown of bilirubin imparts the color in both feces and urine.

Accepted Answer

Bilirubin, a byproduct of the breakdown of red blood cells, is processed by the liver and excreted into the bile. This bile helps to digest fats and imparts the characteristic brown color to feces. A portion of bilirubin is also converted into a form that is excreted by the kidneys, contributing to the yellow color of urine.

Question 13

Oxygen and carbon dioxide are poorly soluble in plasma so they require erythrocytes for their transport in blood. Describe how erythrocytes transport these gases.

Accepted Answer

The answer of Oxygen and carbon dioxide are poorly soluble...

Question 14

In healthy endothelial cells, arachidonic acid is converted to thromboxane A₂.

Accepted Answer

In healthy endothelial cells, arachidonic acid is primarily converted to prostacyclin (PGI2), not thromboxane A2, which is mainly produced by platelets.

Question 15

Release of ADP by platelets is part of a positive feedback loop for platelet aggregation.

Accepted Answer

ADP release from activated platelets enhances the aggregation process by attracting more platelets to the site of injury, amplifying the platelet aggregation response in a positive feedback loop.

Question 16

Leukocytes are necessary to protect the body against foreign substances, including bacteria and viruses. Describe the different classes of leukocytes and their major functions.

Accepted Answer

The answer of Leukocytes are necessary to protect the body...

Question 17

A fibrin clot can occur in the absence of platelet aggregation.

Accepted Answer

The answer of A fibrin clot can occur in the...

Question 18

Vitamin K is necessary for blood clot formation because it activates the extrinsic pathway.

Accepted Answer

Vitamin K is necessary for blood clot formation because it activates proteins in the intrinsic pathway (factors II, VII, IX, and X) and proteins C and S, which are part of the anticoagulation system, rather than specifically activating the extrinsic pathway.

Question 19

Blood is composed of fluid components and formed elements (cells). Describe the properties of the fluid and cellular components of blood.

Accepted Answer

The answer of Blood is composed of fluid components and...

Question 20

Calcium is required for formation of a blood clot.

Accepted Answer

Calcium ions (Ca2+) play a crucial role in the blood clotting process by acting as a cofactor for various enzymes in the coagulation cascade, ultimately leading to the formation of a blood clot.

Quiz 15: The Cardiovascular System: Blood