Blood: functions and properties:
- Transport:
- Oxygen and Carbon Dioxide: Blood carries oxygen from the lungs to the tissues and transports carbon dioxide, a waste product of metabolism, from the tissues back to the lungs for exhalation.
- Nutrients and Wastes: It transports nutrients absorbed from the digestive tract to cells throughout the body and carries waste products from cellular metabolism to the kidneys and liver for excretion.
- Regulation:
- pH Balance: Blood helps regulate the body's acid-base balance using buffer systems that maintain the pH within a narrow range, essential for proper cellular function.
- Fluid Volume and Composition: It regulates both the volume and composition of body fluids. This function is critical in maintaining blood pressure and overall fluid balance within the body.
- Body Temperature: Blood plays a role in thermoregulation by distributing heat throughout the body and to the skin where heat can be lost to the environment.
- Protection:
- Immune Function: Blood contains leukocytes (white blood cells) and immunoglobulins (antibodies) that detect and destroy invading pathogens, providing a critical defense mechanism against infections.
- Hemocoagulation: Blood has the ability to coagulate, or clot, a vital process that occurs when blood vessels are injured to prevent excessive blood loss. This coagulation process involves platelets, a type of blood cell, and plasma proteins, which form a clot that seals leaks in blood vessels.
Composition of Blood Plasma:
- Water (Approximately 91%): Serves as the solvent for carrying various substances. The high water content also helps in the regulation of body temperature.
- Proteins (7%): Includes various proteins like:
- Albumins: Contribute to plasma's osmotic pressure, helping to regulate the exchange of water between blood and tissues.
- Globulins: Include immunoglobulins (antibodies) which play a key role in immune responses, and other globulins involved in transport, clotting, and other functions.
- Fibrinogen: A key clotting factor that is converted to fibrin during the blood clotting process.
- Other Solutes (1-2%):
- Electrolytes (e.g., Na+, K+, Ca2+, Mg2+, Cl-, HCO3-): Important for maintaining pH balance, osmotic pressure, and proper nerve and muscle function.
- Nutrients: Such as glucose, fatty acids, and amino acids that are essential for cellular function.
- Gases: Including oxygen and carbon dioxide, critical for cellular respiration and metabolic processes.
- Vitamins and Waste Products: Essential for various biochemical processes and the elimination of metabolic waste.
Functions of Blood Plasma: