Chapter 19

Q: What are the parts of blood?

A: Plasma (liquid, 55%), Buffy coat (WBCs + platelets, 1%), RBCs (hematocrit, ~44%).

Q: What’s in plasma?

A: Mostly water, plus proteins:

• Albumin = keeps water in blood (osmotic pressure).

• Globulins = transport + antibodies.

• Fibrinogen = clotting.

Q: What is hematocrit?

A: The % of blood that is red blood cells. Men: ~45–52%. Women: ~37–47%. Used to check for anemia or dehydration.

Q: Shape and job of RBCs?

A: Biconcave discs (like donuts without a hole). They carry oxygen to tissues and carbon dioxide back to lungs.

Q: How long do RBCs live?

A: About 120 days. Old ones are broken down in spleen/liver. Iron is recycled, heme becomes bilirubin → bile, urine, feces.

Q: What protein is inside RBCs?

A: Hemoglobin. Each has 4 chains with iron. Iron binds oxygen in lungs and lets it go in tissues.

Q: What triggers new RBCs to be made?

A: Low oxygen → kidneys release erythropoietin (EPO) → bone marrow makes more RBCs.

Q: What is anemia?

A: Low oxygen-carrying ability of blood. Causes: blood loss, not enough production (iron/B12 deficiency), or too much destruction (hemolysis, sickle cell).

Q: What do WBCs do overall?

A: Defend against infection.

Q: What are the 5 types of WBCs and their jobs?

• Neutrophils → most common, eat bacteria.

• Eosinophils → fight parasites, allergy reactions.

• Basophils → release histamine (allergy, inflammation).

• Lymphocytes → T cells (kill infected cells), B cells (make antibodies).

• Monocytes → become macrophages, big eaters that clean up

Q: What are some WBC disorders?

A: Leukocytosis (too many, usually infection), Leukopenia (too few, chemo/autoimmune), Leukemia (cancer of WBCs).

Q: What are platelets?

A: Tiny cell fragments from megakaryocytes. Live 7–10 days. Help stop bleeding.

Q: How do platelets work?

A: Stick to damaged vessel walls, clump together, release clotting factors, and help form a clot.

Q: Platelet problems?

• Too few = bleeding/bruising.

• Too many = clots, strokes.

• Poor function = bleeding disorders (like Von Willebrand disease).

Q: What are the 5 steps of clotting?

• Vessel spasm (constricts).

• Platelets stick and form a plug.

• Coagulation cascade makes fibrin → stable clot.

• Clot retraction (edges pull together).

• Clot dissolves (plasmin breaks fibrin).

Q: What’s the difference between intrinsic and extrinsic clotting?

A: Intrinsic = triggered by damage inside vessel (collagen). Extrinsic = triggered by tissue factor outside vessel. Both lead to Factor X → thrombin → fibrin clot.

What is fibrin?

Fibrin = sticky net that traps blood cells and seals the cut

Q: What does it mean if blood agglutinates (clumps) when tested?

A: That antigen is present. Example: clumping with anti-A means type A blood.

Q: Which blood type is universal donor, and why?

A: O negative → no A, B, or Rh antigens to trigger a reaction.

Q: What are the 3 main plasma proteins and their functions?

• Albumin → maintains osmotic pressure, carries substances.

• Globulins → transport (alpha, beta) & antibodies (gamma).

• Fibrinogen → clotting (turns into fibrin).

Q: At the venule end of a capillary, why does fluid move in?

A: Osmotic pressure (from plasma proteins like albumin) pulls fluid back into capillaries (reabsorption).

Q: At the arteriole end of a capillary, why does fluid move out?

A: Hydrostatic pressure is higher than osmotic pressure → pushes fluid into tissues (filtration).

Q: What does Von Willebrand factor (vWF) do in clotting?

A: Makes platelets sticky by binding collagen → platelet plug formation.

Q: What happens during a transfusion reaction?

A: Recipient antibodies attack donor RBC antigens → agglutination (clumping) → hemolysis (RBC destruction) → blocked vessels, organ damage.