Blood Physiology Quiz

Blood Physiology

• Blood is a circulatory fluid, transporting molecules and cells.
• Blood is composed of plasma and cellular elements.
• Cellular elements include erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets).

Hematocrit

• Hematocrit (PCV) indicates oxygen delivery capacity.
• Human hematocrit: 45% (male), 42% (female).
• Other animals have varying hematocrit values (e.g., Weddell seal, Pekin ducks, icefish).

Plasma

• Plasma is mostly water (90% or more).
• Plasma proteins are the most abundant component.
• Electrolytes in plasma include Na+ and Cl-.
• Plasma contains various nutrients (glucose, amino acids, lipids, and vitamins).

Plasma Proteins

• Plasma proteins (6-8% of plasma) have various functions.
• Examples include:
  • Fibrinogen (blood clotting)
  • Albumins (abundant, bind substances)
  • Globulins (α, β, λ; transporters, clotting agents, immune effectors)

Lipoproteins

• Lipoproteins are composed of apolipoproteins and lipids (energy and structural lipids).
• Major lipoproteins include chylomicrons, HDL, LDL, and VLDL.
  • Chylomicrons transport lipids after a meal.
  • HDL contains mostly proteins and little cholesterol.
  • LDL contains less protein and more cholesterol.
  • VLDL contains the least protein and mostly triglycerides (energy source).

Respiratory Pigments

• Respiratory pigments carry oxygen.
• Hemoglobin is the pigment in vertebrates.
• Hemocyanin is the pigment in non-vertebrates.

Erythrocytes

• Erythrocytes (red blood cells) transport oxygen.
• Erythrocytes contain hemoglobin.
• Erythrocytes also transport carbon dioxide (via bicarbonate production and hemoglobin).
• Mammals' erythrocytes are flat, disc-shaped, and biconcave, lacking a nucleus.
• Animals vary in erythrocyte count per mL (e.g., chicken, cows, pigs, horses).

Erythrocyte Replacement

• Erythrocytes have a short lifespan (e.g., ~100-110 days in mammals, ~30 days in chickens).
• The spleen removes and stores worn-out erythrocytes.
• Erythropoiesis (red blood cell production) replaces worn-out cells.
• Kidneys detect low oxygen levels and release erythropoietin to stimulate erythropoiesis.

Leukocytes

• Leukocytes (white blood cells) are key components in the vertebrate immune system.
• Leukocytes develop from pluripotent stem cells in bone marrow.

Thrombocytes/Platelets

• Platelets (thrombocytes) are involved in clotting.
• Megakaryocytes produce platelets.
• Thrombopoietin stimulates megakaryocyte production.

Hemostasis

• Hemostasis involves three processes:
  • Vascular spasm (constriction of injured blood vessels)
  • Platelet plug formation (platelets adhere to injured site)
  • Blood coagulation (transformation of blood from liquid to gel)

Clot Dissolution

• Fibrinolytic plasmin dissolves clots.
• Plasminogen is converted to plasmin.
• Tissue plasminogen activator (tPA) prevents inappropriate clot formation.

Quiz on Vascular Physiology

• The quiz asks for morphology and function of different blood vessels (arteries, arterioles, capillaries, veins).