Blood Composition and Function

Blood Overview

• The heart pumps 75 mL of blood with each contraction, averaging 70 contractions per minute.
• The entire blood supply is circulated 5250 mL per minute.
• Blood functions include transport, defense, and regulation.

Blood Composition

• Formed elements (red blood cells, white blood cells, platelets) are produced in the red bone marrow.
• Plasma, consisting primarily of water (91%), with salts, nutrients, waste, hormones, and organic molecules (9%) maintaining osmotic pressure.
• Plasma proteins (albumins, globulins) are the most abundant organic molecules, mostly created by the liver and responsible for osmotic pressure within the blood.

Red Blood Cells and Gas Transport

• Biconcave shape increases surface area, specialized for oxygen transport.
• Contain hemoglobin, a pigment binding up to 4 oxygen molecules.
• Oxyhemoglobin, when bound to oxygen, is carried in the blood. Deoxyhemoglobin releases oxygen in tissues.
• Carbon dioxide transport occurs: 7% dissolved in plasma, 23% bound to hemoglobin (carbaminohemoglobin), 70% in plasma as bicarbonate ion.
• Red blood cells (RBCs) are produced in the bone marrow.
• Erythropoietin, a hormone produced by kidneys, stimulates RBC production when blood oxygen levels are low.

White Blood Cells and Disease Defense

• White blood cells (leukocytes) are translucent, less numerous than RBCs, produced in red bone marrow, and regulated by colony-stimulating factor.
• Some live for days, others months or years.
• Granular leukocytes (neutrophils, eosinophils, basophils) have distinctive granules
• Neutrophils (50-70% of WBCs), multi-lobed nucleus, are first responders to infection and use phagocytosis.
• Eosinophils have bilobed nuclei, many large granules, primarily involved in defense against parasites and allergies.
• Basophils are the rarest WBC type, have U-shaped nuclei, transform into mast cells, and release histamine during allergic reactions (dilates blood vessels, constricts airways).

Agranular Leukocytes: Lymphocytes and Monocytes

• Lymphocytes (25-35% of WBCs) include B cells (produce antibodies), some cytotoxic T cells (directly destroy pathogens), are part of the immune system.
• Monocytes are the largest WBCs; in tissues they become macrophages, engulfing pathogens, dead cells and cellular debris.
• Diseases like Severe Combined Immunodeficiency Disease (SCID), Leukemia, and infectious mononucleosis affect WBCs.

Platelets and Blood Clotting

• Platelets (thrombocytes) result from fragmentation of megakaryocytes in red bone marrow.
• Essential for blood clotting (hemostasis).

Blood Clotting

• Blood clotting prevents plasma and formed elements from leaking out of broken blood vessels.
• 13 clotting factors, calcium ions, and enzymes are involved in clot formation.
• Platelets, damaged tissues release prothrombin activator, triggering a cascade of enzymatic reactions, forming a fibrin clot.

Blood Disorders

• Disorders related to blood clotting include thrombocytopenia, thromboembolism, and hemophilia.
• Anemia represents reduced RBCs or hemoglobin.
• Jaundice, accumulation of heme, occurs when the liver cannot excrete it properly.
• Deficiencies in clotting factors (like in hemophilia) lead to prolonged bleeding.

Blood Types and Transfusions

• Blood types are determined by antigens on RBC surfaces.
• ABO blood groups (A, B, AB, O) and Rh factor are crucial in blood transfusions.
• Blood compatibility between donor and recipient prevents agglutination or clumping.
• O blood type is a universal donor due to lack of antigens.
• Hemolytic disease of the newborn can arise from Rh incompatibility between mother and fetus.

Homeostasis

• Interactions between cardiovascular and lymphatic systems, cardiovascular and respiratory systems, cardiovascular and digestive systems, and cardiovascular and skeletal systems maintain homeostasis. (Interstitial fluid, lymph transport, oxygen delivery, nutrient and waste transport, cardiac and skeletal muscle contraction for blood movement).
• Cardiovascular and endocrine, urinary systems regulate blood composition (hormones, kidneys, regulating water-salt balance, acid-base balance).
• Examples include erythroprotein regulation for red blood cell production and coagulation for maintaining blood within vessels.

Overview of blood's function in transport, defense, and regulation. Includes composition of formed elements (red blood cells, white blood cells, platelets) produced in bone marrow and the properties of plasma and plasma proteins like globulins and albumins. Red blood cells and their role in gas transport with hemoglobin.