Midterm 2: 4B

What are the three main steps of hemostasis?

Vascular spasm → platelet plug formation → coagulation.

What is the immediate response to blood-vessel injury?

Vascular spasm reduces blood loss.

What exposes a surface for platelet adhesion after endothelial injury?

Subendothelial collagen.

What bridges platelets to exposed collagen?

von Willebrand factor (vWF).

Which platelet signals recruit additional platelets?

ADP and thromboxane A₂.

What does thromboxane A₂ promote?

Platelet aggregation and vasoconstriction.

What is coagulation?

Formation of a fibrin mesh that stabilizes the platelet plug.

What initiates the extrinsic coagulation pathway?

Tissue factor (factor III) exposed by damaged tissue.

What initiates the intrinsic coagulation pathway?

Contact activation involving exposed collagen or negatively charged surfaces.

Where do intrinsic and extrinsic pathways converge?

Activation of factor X.

What is the common coagulation sequence?

Factor X activation → prothrombin activator → thrombin → fibrin → stabilized clot.

What is factor I?

Fibrinogen.

What is factor II?

Prothrombin.

What is factor III?

Tissue factor.

What is factor IV?

Calcium ions.

What is factor X?

A factor activated by both intrinsic and extrinsic pathways.

What is factor XIII?

Fibrin-stabilizing factor that cross-links fibrin strands.

Which enzyme converts fibrinogen to fibrin?

Thrombin.

Which clotting factors require vitamin K for synthesis?

Factors II, VII, IX and X.

Where are most clotting factors synthesized?

The liver.

What is clot retraction?

Platelet-driven contraction that pulls clot edges together.

Which platelet proteins cause clot retraction?

Actin and myosin.

What is serum?

Plasma after clotting factors have been consumed or removed.

What does platelet-derived growth factor (PDGF) do?

Stimulates fibroblast and smooth-muscle growth during repair.

What does vascular endothelial growth factor (VEGF) do?

Promotes endothelial growth and vessel repair.

What is fibrinolysis?

Enzymatic breakdown of fibrin in a clot.

Which enzyme breaks down fibrin?

Plasmin.

What is plasminogen?

Inactive precursor of plasmin.

Which endothelial product activates plasminogen?

Tissue plasminogen activator (tPA).

What is the fibrinolysis sequence?

tPA activates plasminogen → plasmin digests fibrin.

How does antithrombin III prevent excessive clotting?

Inactivates thrombin and other activated coagulation factors.

How does heparin limit coagulation?

Enhances antithrombin III activity.

What inhibits platelet adhesion on healthy endothelium?

Nitric oxide and prostacyclin.

What is thrombocytopenia?

Abnormally low platelet count.

Below what platelet count is significant bleeding risk highlighted?

About 50,000 platelets/µL.

What is hemophilia A?

Factor VIII deficiency affecting the intrinsic pathway.

What is hemophilia B?

Factor IX deficiency affecting the intrinsic pathway.

How is classic hemophilia inherited?

X-linked recessive inheritance.

What is the chance of an affected son from a carrier mother and unaffected father?

50% of sons.

What happens to daughters of an affected father and a noncarrier mother?

All daughters are carriers.

What is a thrombus?

A clot formed and remaining within a blood vessel.

What is an embolus?

Material traveling through the bloodstream that may obstruct a vessel.

What is a pulmonary embolism?

An embolus obstructing pulmonary circulation.

Why can liver disease cause bleeding?

Reduced production of clotting factors and impaired vitamin K handling.

What determines ABO blood type?

Presence or absence of A and B antigens on RBCs.

What antigens and antibodies are found in type A blood?

A antigen; anti-B antibodies.

What antigens and antibodies are found in type B blood?

B antigen; anti-A antibodies.

What antigens and antibodies are found in type AB blood?

A and B antigens; neither anti-A nor anti-B antibodies.

What antigens and antibodies are found in type O blood?

Neither A nor B antigens; both anti-A and anti-B antibodies.

What is the universal RBC donor type considering ABO and Rh?

O negative.

What is the universal RBC recipient type considering ABO and Rh?

AB positive.

What determines Rh-positive status?

Presence of the D antigen on RBCs.

What determines Rh-negative status?

Absence of the D antigen.

When do anti-D antibodies usually arise?

After exposure to Rh-positive RBCs.

What does RhoGAM prevent?

Maternal sensitization to the Rh(D) antigen.

What is erythroblastosis fetalis?

Hemolytic disease caused by maternal antibodies attacking fetal RBCs.

What is agglutination?

Antibody-mediated clumping of red blood cells.

What is hemolysis?

Destruction or rupture of red blood cells.

What is a major danger of an incompatible transfusion?

Agglutination and hemolysis that may injure the kidneys.

What does crossmatching test?

Compatibility of a particular donor and recipient.

What is an autologous transfusion?

Receiving one's own previously collected blood.

Anti-A positive, anti-B negative, anti-D positive identifies which blood type?

A positive.

Anti-A negative, anti-B negative, anti-D positive identifies which blood type?

O positive.

Anti-A positive, anti-B positive, anti-D negative identifies which blood type?

AB negative.

Anti-A negative, anti-B positive, anti-D negative identifies which blood type?

B negative.

Where is the heart located?

In the mediastinum of the thoracic cavity.

What is the heart's main pumping muscle layer?

Myocardium.

What is the innermost heart-wall layer?

Endocardium.

What is the outer heart-wall layer?

Epicardium, also the visceral serous pericardium.

What reduces friction between serous pericardial layers?

Pericardial fluid.

Which ventricle has the thickest wall?

Left ventricle.

Why is the left ventricle thicker?

It pumps against greater systemic vascular resistance.

What is the approximate systemic-to-pulmonary resistance ratio in the practice questions?

About 5:1.

Which vessels return systemic blood to the right atrium?

Superior and inferior venae cavae.

Which vessel carries blood out of the right ventricle?

Pulmonary trunk.

Which vessels return oxygenated blood to the left atrium?

Pulmonary veins.

Which vessel carries blood out of the left ventricle?

Aorta.

What is the complete route of blood through the heart?

Venae cavae → RA → tricuspid → RV → pulmonary valve → lungs → pulmonary veins → LA → mitral → LV → aortic valve → aorta.

Which valve lies between the right atrium and right ventricle?

Tricuspid valve.

Which valve lies between the left atrium and left ventricle?

Mitral or bicuspid valve.

Which valve lies between the right ventricle and pulmonary trunk?

Pulmonary semilunar valve.

Which valve lies between the left ventricle and aorta?

Aortic semilunar valve.

Which valves have chordae tendineae?

Atrioventricular valves.

What prevents AV valves from prolapsing into the atria?

Papillary muscles and chordae tendineae.

Which valves do not have chordae tendineae?

Semilunar valves.

What determines blood-flow direction across heart valves?

Pressure differences.

What are trabeculae carneae?

Muscular ridges lining ventricular walls.

What are pectinate muscles?

Muscular ridges found mainly in the atria.

What are auricles?

Ear-like extensions that increase atrial capacity.

What is the coronary sulcus?

External groove separating atria from ventricles.

What is the fossa ovalis?

Adult remnant of the fetal foramen ovale.

Where do coronary arteries originate?

Ascending aorta just above the aortic valve.

What are the two main coronary arteries?

Right coronary artery and left coronary artery.

Which left coronary branch is also called the LAD?

Anterior interventricular artery.

Which left coronary branch curves around the left side?

Circumflex artery.

Which branches arise from the right coronary artery in the review diagram?

Marginal and posterior interventricular arteries.

Which major veins drain cardiac muscle into the coronary sinus?

Great, middle and small cardiac veins.

Where does the coronary sinus empty?

Right atrium.

Which cardiac veins drain directly into the right atrium?

Anterior cardiac veins.

When is left ventricular coronary perfusion greatest?

During ventricular diastole.