Physiology · MU Sofia

14. Blood: functions and properties

Covers the functions of blood in transport, regulation and protection, then the composition of plasma with its water, proteins and dissolved solutes. Goes on to the roles of plasma proteins, the lifespans of erythrocytes, neutrophils and platelets, and how haematopoiesis shifts from yolk sac to liver to bone marrow before birth. Ends with the role of colony-stimulating factors in haematopoiesis and where red bone marrow is found with age.

Inside: 2 sections · 5 labelled pictures · 18 flashcards · 5 min

Topic 14 of 104 in the MU Sofia syllabus for Physiology (Medicine, Year 2). The free AceMed note covers it in 2 sections, about 755 words (5 min of reading), with 18 flashcards.

In this note

  1. Introduction
  2. Blood: functions and properties :

Blood: functions and properties :

  • 1. 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.
  • 2. 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.
  • 3. 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:

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