Blood biology and physiology (Hole's Human Anatomy & Physiology - Chapter 14)

A comprehensive set of practice flashcards covering key concepts from the blood chapter (hematopoiesis, RBCs, WBCs, platelets, plasma, coagulation, transfusion medicine, anemia, and RBC life cycle).

What is hematocrit and what are the normal values for men and women?

Hematocrit (packed cell volume) is the percentage of blood volume occupied by red blood cells; normal values are about 47% in men and 42% in women (with ~1% white blood cells as a minor component).

Where are hematopoietic stem cells located and what is their role?

They reside in the bone marrow and give rise to all cellular components of blood through hematopoiesis.

What is haematopoiesis and erythropoiesis?

Haematopoiesis is the formation of all blood cellular components; erythropoiesis is the production of red blood cells.

What hormone stimulates RBC production and which organs produce it?

Erythropoietin stimulates RBC production; it is produced by the kidneys and liver in response to low blood oxygen.

Which nutrients are essential for red blood cell production?

Iron, vitamin B12, and folic acid are essential for RBC production (DNA synthesis and hemoglobin synthesis).

Why do mature red blood cells lack nuclei and mitochondria?

To maximize space for hemoglobin and optimize oxygen transport.

What is the typical size and shape of a red blood cell?

Biconcave disc about 7.5 micrometers in diameter.

What are the normal RBC counts for adult males and females?

Males: 4.6–6.2 million cells/µL; females: 4.2–5.4 million cells/µL.

How long do red blood cells circulate and what happens at the end of their life cycle?

RBCs circulate for about 120 days; worn-out cells are destroyed by macrophages in the spleen and liver. Heme is broken down into iron and biliverdin, iron is reused or stored, bilirubin is excreted in bile, and globin is converted to amino acids.

What happens to heme during RBC destruction?

Heme is decomposed into iron and biliverdin; biliverdin is eventually converted to bilirubin and excreted in bile.

What genetic mutation causes sickle cell anemia and what is the consequence for hemoglobin?

A mutation in the beta-globin gene produces HbS, which polymerizes into fibers that deform RBCs into a sickle shape.

What treatments are available for sickle cell disease?

Stem cell/bone marrow transplant and hydroxyurea to increase HbF (fetal hemoglobin).

What are the major categories of white blood cells?

Granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (monocytes, lymphocytes).

What is diapedesis?

The process by which white blood cells squeeze through capillary walls to reach tissues.

What is chemotaxis in the context of WBCs?

Movement of leukocytes toward damaged tissue in response to chemical signals.

What is the normal range for white blood cell counts?

About 5,000–10,000 cells per cubic millimeter.

What are platelets and what is their normal count?

Platelets (thrombocytes) are cell fragments from megakaryocytes; they help control blood loss and release serotonin to constrict vessels. Normal count is about 130,000–360,000 per mm³.

What are plasma proteins and their major classes?

Albumin (60%), globulins (36% including alpha, beta, gamma), and fibrinogen (4%).

What is the function of albumin?

Maintains colloid osmotic (oncotic) pressure in the blood.

What is agglutination in blood typing?

Clumping of red blood cells due to antibody–antigen interactions.

Who discovered the ABO blood groups and why is this discovery important?

Karl Landsteiner; incompatible blood types cause agglutination and transfusion reactions, leading to safer transfusions.

What distinguishes Rh positive from Rh negative blood?

Rh-positive means the D antigen is present on RBCs; Rh-negative means it is absent.

What is RhoGAM and when is it used?

RhoGAM prevents Rh sensitization in Rh-negative mothers, given during pregnancy and around delivery or other events that cause fetal-metal bleeding.

What are the extrinsic and intrinsic coagulation pathways?

Extrinsic pathway is triggered by tissue thromboplastin outside the blood; intrinsic pathway is triggered by factors inside the blood (e.g., factor XII) when blood contacts a non-endothelial surface.

What is fibrin and its role in coagulation?

Fibrin is an insoluble protein formed from fibrinogen that forms the mesh of a blood clot.

What is the difference between a thrombus and an embolus?

A thrombus is a stationary clot; an embolus is a clot moving through the bloodstream.

What are the three stages of hemostasis?

Vessel spasm, platelet plug formation, and coagulation (clot formation).

What are the major components of plasma and their functions?

Albumin maintains osmotic pressure; globulins include antibodies and transport proteins; fibrinogen is essential for coagulation.

What is agglutination’s relevance to transfusion compatibility?

Agglutination indicates incompatibility between donor and recipient blood types.

What are the two main categories of leukocytes in terms of staining and function?

Granulocytes (neutrophils, eosinophils, basophils) with cytoplasmic granules; agranulocytes (monocytes, lymphocytes) lacking granules and with varied functions.

What is the typical percentage of neutrophils among leukocytes and their primary function?

About 54–62% of leukocytes; they are first responders and are phagocytic.

What is the role of eosinophils and their typical abundance?

Defend against parasitic worms and participate in allergic reactions; constitute about 1–3% of leukocytes.

What is the role of basophils?

Release histamine and heparin, involved in inflammatory and allergic responses; less than 1% of leukocytes.

What is the role of monocytes?

Largest WBCs; become macrophages to phagocytize bacteria and debris; 3–9% of leukocytes.

What is the role of lymphocytes?

Include T cells, B cells (antibody production), and natural killer cells; 25–33% of leukocytes.

What is meant by the term reticulocyte?

An immature red blood cell released from the bone marrow during erythropoiesis.

What is bilirubin and how is it produced?

Bilirubin is produced from biliverdin during heme breakdown and is excreted in bile.

What are heme and globin composed of in hemoglobin?

Heme contains an iron ion within a porphyrin ring; globin is the protein chains (alpha and beta).