Blood Composition and Functions

• Blood transports formed elements, dissolved molecules, and ions.
• It carries oxygen to and carbon dioxide from the lungs.
• Blood regulates body temperature by absorbing and releasing heat.
• Buffers in blood absorb acids and bases, maintaining body pH.
• Blood protects against pathogens with leukocytes and plasma proteins.
• Platelets and plasma proteins protect against blood loss.
• Hematocrit is the percentage of volume of all formed elements in blood
• Clinically, hematocrit refers to the percentage of erythrocytes in blood.

Blood Plasma

• Blood plasma accounts for approximately 55% of blood volume.
• It consists of about 90-92% water and 8-10% dissolved substances.
• Dissolved substances include electrolytes (Na+, K+, Ca2+, Cl-, HCO3-), nutrients, waste products, hormones, and gases (O2, CO2, N2).

Important Blood Proteins

• Albumins are the most abundant blood proteins (58%).
• Albumins exert colloid osmotic pressure and transport lipids, hormones, and ions.
• Fibrinogen is a key protein involved in blood clotting.

Red Blood Cells (Erythrocytes)

• Red blood cells are small, flexible, biconcave discs lacking a nucleus and organelles.
• They are packed with hemoglobin and transport oxygen and carbon dioxide.
• The absence of a nucleus allows for more hemoglobin capacity, enhances flexibility, promotes efficient gas exchange, and increases lifespan to 120 days.
• Hemoglobin is a red-pigmented protein that transports oxygen and carbon dioxide.
• It consists of four globin chains (two alpha, two beta) each containing a heme group with iron that binds to oxygen.

White Blood Cells (Leukocytes)

• White blood cells are part of the immune system and defend against infections and abnormal cells.
• Neutrophils fight bacterial/fungal infections.
• Lymphocytes consist of B cells (producing antibodies) and T cells (attacking infected/cancerous cells).
• Monocytes become macrophages, engulfing pathogens and dead cells.
• Eosinophils combat parasites and mediate allergic reactions.
• Basophils release histamine during allergic responses.

Blood Types and Compatibility

• Blood types are determined by A, B, and Rh antigens on red blood cells
• Blood types include A, B, AB, and O, with the Rh factor (+/-)
• Incompatible transfusions can cause hemolysis and agglutination, leading to serious reactions.
• Careful cross-matching is essential before transfusions.

The lesson covers blood composition. Blood transports elements, regulates temperature and pH, and protects against pathogens and blood loss. Plasma, consisting mainly of water, contains electrolytes, nutrients and gases.