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.

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