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.
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.
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.
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.
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.
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.
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 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.
Interstitial Fluid vs. Plasma:
Interstitial fluid bathes cells and is formed from blood plasma.
Major Differences:
Dissolved Gases: O2 higher in plasma; CO2 higher in interstitial fluid favoring diffusion.
Proteins: Plasma has proteins; interstitial fluid typically does not, due to size preventing passage through capillaries.
Liver synthesizes >90% of plasma proteins; liver disorders can cause bleeding issues due to insufficient protein synthesis, especially fibrinogen, essential for clotting.