Blood & Cardiovascular System - Practice Flashcards

Key concepts from lecture notes on blood composition, RBCs/WBCs/platelets, anemia, hemostasis, coagulation pathways (intrinsic and extrinsic), clot formation and stabilization, and related disorders.

What are the main formed elements of blood?

RBCs (erythrocytes), WBCs (leukocytes), and platelets, suspended in plasma.

What is the primary oxygen-carrying protein inside RBCs and its approximate intracellular prevalence?

Hemoglobin (Hb); it constitutes about 97% of the RBC intracellular content and carries oxygen and carbon dioxide.

Which cytoskeletal protein gives RBCs their flexibility and allows shape changes?

Spectrin.

Describe the basic structure of hemoglobin.

Hb is composed of globin protein bound to a heme group; each heme contains Fe2+ that binds one O2; one Hb can transport up to four O2 molecules.

How many O2 molecules can a single hemoglobin molecule transport?

Four.

Approximately how many Hb molecules are contained in a typical RBC?

About 250 million Hb molecules per RBC.

What is oxyhemoglobin and deoxyhemoglobin?

Oxyhemoglobin is Hb bound to oxygen (in the lungs); deoxyhemoglobin is Hb after delivering O2 to tissues.

What are the three phases of erythrocyte (RBC) development described in erythropoiesis?

Phase 1: ribosome synthesis; Phase 2: hemoglobin production; Phase 3: nucleus ejection.

What is the typical lifespan of an erythrocyte (RBC)?

About 100–120 days.

What is the normal total white blood cell (WBC) count per microliter?

Approximately 4,800 to 10,800 WBCs per μL.

What is the primary function of neutrophils?

Phagocytize bacteria; they account for about 50–70% of circulating WBCs; lifespan roughly 6 hours to a few days.

What is the primary function of lymphocytes?

Mount immune responses; include B cells and T cells; can live from days to years.

What is the primary function of monocytes?

Phagocytosis; differentiate into macrophages in tissues; lifespan days to weeks.

What is the primary function of eosinophils?

Kill parasitic worms; modulate inflammatory responses; comprise about 2–4% of WBCs.

What is the primary function of basophils?

Release histamine and other mediators of inflammation; contain heparin; involved in allergic responses; about 0.5–1% of WBCs.

What are platelets and what is their role in blood?

Disk-shaped cytoplasmic fragments essential for clotting; normal count about 150,000–400,000 per μL; lifespan ~5–10 days.

What are the three phases of hemostasis?

Vascular spasm (vasoconstriction), platelet plug formation, and coagulation (blood clotting).

What prevents platelets from adhering in intact vessels?

Endothelial cells release nitric oxide (NO) and prostacyclin (prevent platelet adhesion).

What protein connects exposed collagen to platelets during platelet plug formation?

von Willebrand factor.

What initiates the intrinsic coagulation pathway?

Damage to blood vessels exposing collagen and platelets; Factor XII activation with PF3 involvement.

What initiates the extrinsic coagulation pathway?

Tissue trauma releases tissue factor (TF) and phospholipid–enzyme complexes to start the pathway.

What forms the Prothrombin activator in coagulation?

A complex of Factor Xa, Ca2+, PF3, and Va.

What converts prothrombin to thrombin?

Thrombin.

What is the role of thrombin in coagulation?

Converts soluble fibrinogen into insoluble fibrin.

What stabilizes the fibrin clot?

Factor XIII (fibrin-stabilizing factor) cross-links fibrin in the presence of Ca2+.

What is clot retraction and its purpose?

Platelets contract to squeeze serum from the clot, stabilizing it; PDGF and VEGF promote vascular repair.

Name two mechanisms that limit clot growth.

Rapid removal of clotting factors by blood flow; inhibition of activated clotting factors (e.g., heparin, aspirin effects on thromboxane A2).

What is a thrombus versus an embolus?

A thrombus is a clot that forms in a vessel; an embolus is a clot freely floating in the bloodstream.

What is thrombocytopenia and its typical sign?

Deficiency of circulating platelets; petechiae are common signs; can result from bone marrow suppression; treated with transfusion.

How can liver disease or vitamin K deficiency affect coagulation?

Impaired synthesis of coagulation factors; vitamin K deficiency from fat malabsorption; liver disease can impair bile production essential for fat and vitamin K absorption.

What are the three general types of anemia described?

1) Low RBC count (hemorrhagic, hemolytic, aplastic); 2) Low Hb (iron-deficiency, pernicious); 3) Abnormal Hb (thalassemias, sickle-cell).

What causes hemorrhagic, hemolytic, and aplastic anemias?

Hemorrhagic: loss of blood; Hemolytic: premature RBC rupture; Aplastic: destruction or suppression of red bone marrow.

What causes iron-deficiency anemia and its typical treatment approach?

Low iron intake or impaired absorption or blood loss; treated with iron supplementation and addressing underlying cause.

What is pernicious anemia and its treatment?

Autoimmune B12 deficiency due to loss of intrinsic factor; treated with intramuscular B12 injections.

What are thalassemias?

Genetic disorders with absent or faulty globin chains; RBCs are thin and Hb-deficient; more common in the Mediterranean region.

What causes sickle-cell anemia and what happens to RBCs in low oxygen?

Genetic mutation in beta-globin; Hb polymerizes and RBCs become sickle-shaped in low oxygen conditions.

What is polycythemia and its major forms?

Excess RBCs increasing blood viscosity; Polycythemia vera (bone marrow overreacts to low EPO), secondary polycythemia (e.g., high altitude), and blood doping.

Why is blood doping dangerous?

It increases blood viscosity and raises the risk of thrombosis, stroke, and heart complications.

What is the function of platelets in relation to clotting factors and the vascular endothelium?

Platelets adhere to exposed collagen via von Willebrand factor, aggregate with ADP, and release serotonin/thromboxane A2 to promote spasm and plug formation; NO and prostacyclin from endothelium keep platelets in check.

What is diapedesis and positive chemotaxis in WBC function?

Diapedesis: WBCs leave capillaries to reach tissues; chemotaxis: they migrate toward chemical signals of infection or injury.

What are the standard WBC differential components and their approximate ranges?

Neutrophils (50–70%), Lymphocytes (25–45%), Monocytes (3–8%), Eosinophils (2–4%), Basophils (0.5–1%).

What is the typical fibrin clot stabilization process involving calcium?

Calcium ions are required for the activity of several clotting factors, including XIII; they help cross-link fibrin to stabilize the clot.

What is PDGF and VEGF’s role after clot formation?

PDGF stimulates rebuilding of the vessel wall by smooth muscle and fibroblasts; VEGF promotes endothelial cell proliferation and restoration of the lining.

What is the role of red blood cell membrane integrity and shape in gas transport?

RBCs have biconcave shape and spectrin-based membrane flexibility to maximize surface area for gas exchange and allow deformation as they traverse capillaries.

What is the consequence of anucleate RBCs for their lifespan and function?

Lack of nuclei and most organelles allows more space for Hb and gas transport, but they cannot synthesize new proteins, contributing to their limited lifespan.

What is the significance of hemoglobin’s four O2 binding sites per molecule?

It allows loading of four O2 molecules in the lungs and unloading them in tissues, optimizing oxygen transport.