Recording-2025-02-06T16:30:13.097Z

Classification of Blood

• Blood is classified as fluid connective tissue.

• It distributes nutrients, oxygen, and hormones to the body's cells (~75 trillion cells).

• Blood carries metabolic waste to kidneys for excretion.

• It also transports specialized cells for defense against infection and disease.

• Vital for cell circulation; without blood flow, cells can die within minutes.

Functions of Blood

Transport Functions

• Dissolved Gases: Carries oxygen from lungs to tissues and carbon dioxide from tissues to lungs for exhalation.

• Nutrient Distribution: Transports nutrients absorbed from the digestive tract, such as glycogen (stored form) which breaks down to glucose for energy.

• Metabolic Waste Removal: Moves metabolic waste to the kidneys for excretion.

Immune Functions

• Defense Against Toxins and Pathogens: Transports white blood cells to fight infections.

• Antibody Transport: Carries antibodies, the proteins that attack invading organisms or foreign compounds.

• Removing Toxins: Collects toxins produced by infection and delivers them to the liver and kidneys for inactivation or excretion.

Homeostasis Functions

• Temperature Regulation: Stabilizes body temperature by absorbing and redistributing heat.

  • Increased blood flow to the skin when body temperature is high helps cool down.

  • In cold conditions, blood flow is redirected to vital organs, protecting extremities.

• Fluid Loss Prevention: Clotting reactions seal breaks in blood vessels to prevent blood volume changes, essential for maintaining blood pressure.

• pH Stability: Stabilizes the pH and electrolyte composition of interstitial fluids by absorbing, transporting, and releasing ions.

Composition of Blood

• Two Major Components:

  • Plasma: Liquid component constituting 55% of blood volume; contains dissolved proteins, nutrients, electrolytes, and waste.

    • Plasma has a density slightly greater than water, where water accounts for 92%.

  • Formed Elements: Blood cells (red and white blood cells) and platelets suspended in plasma.

• Whole Blood: A mixture of plasma and formed elements.

Viscosity of Blood

• Whole blood is sticky, cohesive, and resistant to flow (viscosity).

• Comparative Viscosity:

  • Plasma: 1.5 higher than water.

  • Whole Blood: Five times as viscous as water.

Blood Volume and Characteristics

• Average adult blood volume: ~5 liters.

• Blood is slightly alkaline with a pH range of 7.35 to 7.45.

• Normal body temperature: 37°C (98.6°F); Blood is slightly warmer at 38°C (100.4°F).

Plasma Makeup

• Plasma Composition:

  • 55% of blood volume.

  • 92% water, 7% proteins (including albumin and globulins), 1% other solutes.

• Function: Plasma transports organic/inorganic molecules, formed elements, and heat.

• Key Proteins:

  • Albumins (60%): Transport fatty acids and steroid hormones.

  • Globulins (35%): Includes antibodies and transport proteins for ions, hormones, and lipids.

  • Fibrinogen (4%): Essential for blood clotting, forms fibrin strands in clotting process.

Important Differences in Fluid

• Interstitial Fluid vs. Plasma:

  • Interstitial fluid bathes cells and is formed from blood plasma.

  • Major Differences:

    1. Dissolved Gases: O2 higher in plasma; CO2 higher in interstitial fluid favoring diffusion.

    2. Proteins: Plasma has proteins; interstitial fluid typically does not, due to size preventing passage through capillaries.

Clinical Relevance

• Liver synthesizes >90% of plasma proteins; liver disorders can cause bleeding issues due to insufficient protein synthesis, especially fibrinogen, essential for clotting.