Blood Physiology Quiz

Blood Functions

• Blood supplies tissues with oxygen and nutrients (e.g., glucose, amino acids, fatty acids).
• It removes waste products from tissues, such as carbon dioxide, urea, and lactic acid.
• Blood has immunological functions, including circulating white blood cells and detecting foreign material using antibodies.
• It plays a role in self-repair by clotting to stop bleeding.
• It acts as a messenger by transporting hormones and signaling tissue damage.
• Blood controls acid-base balance, water balance, and electrolyte balance.
• It regulates body temperature.

Blood pH

• Normal blood pH is maintained within a narrow range of 7.35 to 7.45.
• A pH below 7.35 indicates acidosis (acidemia).
• A pH above 7.45 indicates alkalosis (alkalemia).

Blood Composition

• Plasma comprises 55% of blood volume.
• Cellular elements account for 45% of blood volume.
  • Red blood cells (RBCs)/Erythrocytes
  • White blood cells (WBCs)/Leukocytes
  • Platelets/Thrombocytes

Blood Plasma vs. Serum

• Plasma is the whole blood without cellular components.
• Serum is plasma without clotting factors.

Plasma Proteins

• Albumin is a major contributor to osmotic pressure and transports lipids and hormones.
• Globulins transport ions, hormones, lipids, and certain immune components.
• Fibrinogen is essential for blood clotting.
• Regulatory proteins include enzymes and hormones.

Other Plasma Solutes

• Electrolytes are essential for vital cellular activities and osmotic pressure (e.g., Na+, K+, Cl−, HCO3−).
• Organic nutrients (e.g., glucose, fatty acids, amino acids) are used for ATP production, growth, and maintenance.
• Organic wastes (e.g., urea, uric acid, bilirubin, creatinine, ammonium ions) are removed from the body.

Plasma Proteins - Distribution in Animal Species

• Albumin predominates over globulin in humans, sheep, goats, and dogs.
• In horses, pigs, cows, and cats, the relative proportions of albumin and globulin are relatively equal.

Albumin Functions

• Maintains colloid osmotic pressure (oncotic pressure) between blood and tissue fluids.
• Transports thyroid hormones and other fat-soluble hormones.
• Transports fatty acids to the liver.
• Transports unconjugated bilirubin.
• Transports many drugs (e.g., penicillin).
• Binds calcium ions (Ca2+).
• Acts as a buffer to regulate pH.

Oncotic Pressure and Hydrostatic Pressure

• Oncotic pressure is a form of osmotic pressure exerted by blood plasma proteins (albumin), usually pulling water into the circulatory system.
• Hydrostatic pressure in blood vessels is the pressure of the blood against the vessel walls, opposing oncotic pressure.

Hypoalbuminemia and Hyperalbuminemia

• Hypoalbuminemia is a decrease in blood albumin below normal levels, resulting from conditions such as liver disease, kidney disease, and excessive burns.
• Hyperalbuminemia is an increase in blood albumin above normal levels, often a sign of dehydration or high-protein diets.

Edema

• Edema is abnormal fluid accumulation in the interstitial tissues.
• Causes include increased hydrostatic pressure (e.g., heart failure) and decreased oncotic pressure (e.g., nephrotic syndrome, liver failure).

Globulins (Alpha, Beta, and Gamma)

• Alpha and beta globulins function as substrates for new substances (e.g., angiotensinogen) and transport various substances (ions, hormones, lipids) in the blood.
• Gamma globulins have immune functions.

Fibrinogen and Clotting Proteins

• Fibrinogen is one of several clotting factors involved in the blood clotting process.
• It plays a role in red blood cell (RBC) Rouleaux formation and blood viscosity.

Rouleaux Formation

• Rouleaux formation is a process where RBCs stack together like coins.
• It frequently occurs when certain serum proteins (especially fibrinogen) are elevated, such as during inflammation.

Hematopoiesis

• Hematopoiesis is the formation of various blood cells in the bone marrow.
• Erythropoiesis is the production of RBCs, while Myelopoiesis is the production of WBCs and platelets.

Blood Corpuscles/Cells

•  Red blood cells (RBCs): Erythrocytes
• White blood cells (WBCs): Leukocytes
• Platelets: Thrombocytes

Red Blood Cells (RBCs) Characteristics

• Human RBCs are biconcave discs.
• Dog RBCs are biconcave discs.
• Goat RBCs are more spherical.
• Camel RBCs are elliptical.
• Deer RBCs are sickle-shaped.

Hemoglobin (Hb) Components

• Hb molecules are composed of four heme groups combined with one globin molecule.
• Each heme group contains an iron atom that reversibly combines with oxygen forming oxyhemoglobin.
• Each Hb molecule can carry four molecules of oxygen.
• Ferrous iron (Fe2+) is critical for oxygen transport.

Myoglobin

• Myoglobin, the Hb of muscles, has one polypeptide chain and one heme group, binding one oxygen molecule.

Abnormal Forms of Hb

• Methemoglobin is formed by oxidation of ferrous iron to ferric iron, impairing oxygen transport.
• Carboxyhemoglobin forms in carbon monoxide poisoning, significantly reducing oxygen transport due to carbon monoxide's high affinity for hemoglobin.

RBC Functions

• Hemoglobin transports oxygen from the lungs to the tissues (as oxyhemoglobin) and carbon dioxide from the tissues to the lungs (as carbaminohemoglobin).

Erythropoiesis Stages

• Early stages: yolk sac, spleen, and liver
• Later stages: bone marrow (postnatal)

Erythropoietin

• Erythropoietin is a protein hormone produced in the liver (20%) and kidneys (80%) to control RBC production.
• Production is stimulated by low oxygen levels.

Conditions Affecting O2 Levels

• High altitude, increased demand in athletes, anemia, and cardiopulmonary diseases decrease oxygen levels, stimulating erythropoietin production.

Liver and Bone Marrow in Erythropoiesis

• Healthy liver stores vital nutrients (B12, folic acid, iron, copper) for erythropoiesis.
• It's essential in globin synthesis.
• Healthy bone marrow is crucial to erythropoiesis; aplastic anemia is caused by bone marrow destruction due to irradiation or drug impact.

Hormones and Erythropoiesis

• Hepcidin regulates hemoglobin production and iron absorption in the gastrointestinal tract and its release from reticuloendothelial tissue.
• Thyroid hormones stimulate erythropoiesis.
• Androgens enhance erythropoietin output and RBC production.
• Estrogens inhibit erythropoietin effects on stem cells and RBC maturation.
• Hematopoietic growth factors regulate the proliferation and differentiation of progenitor stem cells to produce RBCs.

Nutrition for Erythropoiesis

• Vitamins B12 and folic acid are essential for DNA synthesis in RBC maturation, avoiding anemia.
• Vitamin B12 also known as "extrinsic factor", requires intrinsic factor from the gastric juice for small intestine absorption.

Proteins, Iron, Cobalt, and Copper

• Sufficient essential amino acids are required for hemoglobin (globin) formation.
• Iron is essential for heme synthesis.
• Cobalt is a component of vitamin B12, and deficiency causes pernicious anemia.
• Adequate copper is necessary for oxidation-reduction reactions and various physiological pathways.

RBC Lifespan

• RBC lifespan varies among species.

Fate of RBCs in Phagocytic Cells

• Hemoglobin is broken down into globin and heme in phagocytic cells.
• Globin is degraded into amino acids for reuse.
• Heme breaks down into biliverdin and iron.
• Iron is reused or stored.
• Biliverdin converts to bilirubin (water-insoluble).

Bilirubin Metabolism

• Bilirubin is transported by albumin.
• Liver conjugates bilirubin with glucuronic acid (creating conjugated bilirubin- more water soluble).
• Conjugated bilirubin is excreted in bile and further metabolized into urobilinogen.
• Urobilinogen converts to urobilin (urine) or stercobilin (feces) for excretion.

Hemolysis

• In vivo hemolysis involves conditions like bacterial infections, parasites, immune disorders, genetic defects, or toxins.
• In vitro hemolysis is caused by improper sample collection, mechanical processing, improper storage, or exposure to water, chemicals, or extremes in temperature.

Consequences of Hemolysis

• Hemolytic anemia, jaundice, intravascular hemolysis (hemoglobinemia/hemoglobinuria), and renal issues are all possible results.

Jaundice

• Jaundice is caused by a yellow discoloration of skin and mucous membranes from increased bilirubin levels in the blood.
• Pre-hepatic, hepatic, and post-hepatic jaundice are types based on bilirubin processing issues.

Anemia

• Anemia is a condition characterized by reduced oxygen-carrying capacity of blood due to decreased RBCs count, or abnormal RBCs, abnormal Hb content, or impaired oxygen binding.
• Causes include inadequate RBC production, rapid RBC destruction, or genetic abnormalities.

Specific Anemia Types

• Iron deficiency anemia is the most common anemia, caused by insufficient iron intake or absorption, characterized by small RBCs.
• Pernicious anemia is an autoimmune disorder characterized by a lack of intrinsic factor for B12 absorption, creating abnormally large RBCs.
• Ruminant animals are less likely to suffer from pernicious anemia due to rumen-microorganism synthesis of vitamin B12.
• Lead poisoning anemia involves lead's interference with hemoglobin production.
• Anemia due to chronic diseases often results from compromised production or accelerated destruction of RBCs during illnesses.
• Anemia due to kidney disease is linked to impeded erythropoietin production (regulating RBCs production).
• Aplastic anemia is caused by bone marrow damage, leading to decreased RBC production.
• Anemia from rapid RBC destruction can happen due to G6PD deficiency, hereditary spherocytosis, autoimmune hemolytic anemia, or sickle cell anemia.

Platelets (Thrombocytes)

• Platelets are produced at a rate of approximately 200 billion per day, regulated by thrombopoietin.
• Their lifespan is 8-10 days.

Platelet Functions

• Platelets aggregate to form plugs at vessel ruptures, releasing factors to promote vasoconstriction and blood coagulation (e.g., thromboxane A, serotonin, thromboplastin).

Hemostasis

• Hemostasis is a series of reactions stopping bleeding, including vascular spasm, platelet plug formation, coagulation, clot retraction, and fibrinolysis.

Blood Coagulation (Clotting)

• Clotting factors (e.g., fibrinogen, prothrombin) are involved in clotting processes, following either the intrinsic or extrinsic pathway.

Clot Retraction

• Clot retraction involves platelets contracting the clot to reduce its size for wound healing, requiring platelets.

Fibrinolytic System

• The fibrinolytic system is a process reversing the clotting system, involving plasminogen conversion to plasmin.
• Products of fibrin breakdown are generated.
• Plasminogen activation inhibitors and α2-antiplasmin control fibrinolysis.

Leukocytes (WBCs)

• Leukocytes are classified into granulocytes (e.g., neutrophils, eosinophils, basophils) and agranulocytes (e.g., monocytes, lymphocytes).

Neutrophils

• Neutrophils are the most common WBCs, part of first-line bacterial defense, characterized by amoeboid movement, chemotaxis, and phagocytosis (engulfing foreign particles).

Eosinophils

• Eosinophils play a role in combating multicellular parasites and certain infections, along with allergy and asthma-related mechanisms.

Basophils

• Basophils help in inflammatory and allergic responses; they contain heparin and histamine (promotes blood flow).

Monocytes and Macrophages

• Monocytes circulate briefly before turning into macrophages in tissues.
• Macrophages phagocytize pathogens and waste materials, also presenting antigens to initiate immune responses.

Lymphocytes

• Lymphocytes are a type of WBC important for antibody-mediated and cell-mediated immunity.
• Natural killer (NK) cells are involved in innate immunity, controlling tumors and virally infected cells.
• B cells produce antibodies (humoral immunity), reacting specifically to antigens.
• Plasma cells result from activated B cells and secrete antibodies.
• Memory cells are long-lasting cells.
• Helper T cells (TH) help other lymphocytes.
• Cytotoxic T cells (Tc) directly destroy infected cells.
• Suppressor T cells (Ts) regulate immune responses to prevent overreactions.
• Memory T cells (TM ) react rapidly to re-exposure of a specific antigen.

Test your knowledge on the essential functions and components of blood. This quiz covers various aspects of blood physiology including waste removal, pH balance, and the roles of different proteins and electrolytes. Perfect for students studying biology or health sciences.