Human Body Functions: Metabolism, Respiration, and Excretion

Posted on Nov 27, 2024 in Biology

Metabolism

  1. Formation of complex substances from simpler ones, e.g., protein synthesis from amino acids.
  2. Glucose and other organic compounds.
  3. Burning nutrients to release energy.
  4. Note: The term “consumption” is not accurate for energy, as it transforms (e.g., chemical energy in organic substances to heat).
  5. In winter, it’s colder.
  6. Chewing expends energy.
  7. Calculation example: (7.4 x 42 + 428 x 1.65 + 572 = 1589)
  8. Consuming a varied diet is important.
  9. Diseases: Beriberi, malaria, and rickets.
  10. Global distribution of diseases: Africa, Europe, America.

Respiratory System

  1. Blood Vessels: Capillaries have very small diameters, forming dense networks within organs, connecting arteries and veins.
  2. Air Pathway: Pharynx, trachea, larynx, lungs, alveoli, bronchi, bronchioles.
  3. CO2 collection from body cells for respiration.
  4. Gas exchange between alveoli and capillaries by diffusion. Gases move from high to low concentration areas. CO2 concentration is higher in capillaries reaching the alveoli.
  5. Lung, trachea, and bronchi function is due to volume changes in the thoracic cavity.
  6. Cellular Respiration: Oxygen burns organic substances, releasing energy and transforming them into CO2 and water. Lungs retain oxygen, and CO2 is expelled.

Excretory System

  1. Blood Composition: Plasma is the fluid part of blood with dissolved substances, excluding blood cells (red, white, and platelets).
  2. Excretion of substances.
  3. Feces are undigested food remnants.
  4. Large molecules (e.g., proteins) do not filter into the nephron capsule. Glucose is reabsorbed into the plasma by the tubule.
  5. Approximately 99% of water is reabsorbed.
  6. Fluid Balance: Higher water loss through sweat leads to lower urine volume.
  7. Kidney Function: Regulates body water content. Water passes from the intestine to the blood, is filtered by the kidneys, and urine volume/composition varies with plasma.
  8. Artificial Kidney: Patient’s blood contacts a plasma-like solution through a semipermeable membrane, removing urea and waste but not proteins or blood cells.
  9. Excretion aids in dissolving and eliminating waste.