Human Physiology-Excretory Products And Their Elimination Topic

Excretory Products and Their Elimination

1. Formation and Composition of Urine:

  • Kidneys are the primary organs responsible for urine production.
  • Nephrons are structural and functional units of the kidneys involved in urine formation.
  • Filtration, reabsorption, and secretion processes occur in nephrons to regulate urine composition.
  • Urine includes various solutes, such as urea, creatinine, uric acid, ammonia, and electrolytes like sodium, potassium, chloride, and bicarbonate ions.

References:

  • NCERT Biology Class 11, Chapter 13 - “Transport in Plants”
  • NCERT Biology Class 11, Chapter 21 - “Excretory Products and Their Elimination”

2. Regulation of Urine Output and Homeostasis:

  • Antidiuretic hormone (ADH) promotes water reabsorption in the kidneys, influencing urine volume and concentration.
  • Aldosterone regulates sodium reabsorption and plays a role in maintaining electrolyte balance.
  • Renin-angiotensin-aldosterone system (RAAS) is involved in regulating blood pressure and fluid balance, affecting urine output.
  • Kidneys help maintain acid-base balance by excreting hydrogen ions (H+) and retaining bicarbonate ions (HCO3-).

References:

  • NCERT Biology Class 11, Chapter 21 - “Excretory Products and Their Elimination”
  • NCERT Biology Class 12, Chapter 7 - “Coordination and Control”

3. Micturition and Reflex Control:

  • Urinary bladder stores urine and communicates its fullness to the brain via nerve signals.
  • Micturition reflex involves involuntary and voluntary control of urine release through spinal cord and brain centers.
  • Stretch receptors in the bladder initiate nerve signals that trigger the reflex.
  • Voluntary control of micturition is achieved by the conscious relaxation of sphincter muscles.

References:

  • NCERT Biology Class 11, Chapter 21 - “Excretory Products and Their Elimination”
  • NCERT Biology Class 12, Chapter 7 - “Coordination and Control”

4. Disorders and Diseases:

  • Kidney diseases and disorders:
    • Acute kidney failure: sudden loss of kidney function requiring immediate medical attention.
    • Chronic kidney disease: gradual decline in kidney function over time, often leading to kidney failure.
    • Uremia: a condition characterized by high levels of nitrogenous waste products in the blood due to kidney failure.
    • Renal calculi (kidney stones): solid crystals formed from accumulated minerals and salts in the urinary tract.
    • Urinary tract infections (UTIs): bacterial infections affecting any part of the urinary system.
  • Endocrine disorders affecting urine output:
    • Diabetes mellitus: elevated blood glucose levels can lead to increased urine output and frequent urination.
    • Hyperthyroidism: overactivity of the thyroid gland can affect renal function and influence urine production.
  • Hypertension and kidney function:
    • Sustained high blood pressure can damage kidney blood vessels, impairing their filtration and regulatory functions.

References:

  • NCERT Biology Class 11, Chapter 21 - “Excretory Products and Their Elimination”
  • NCERT Biology Class 12, Chapter 6 - “Digestion and Absorption”
  • NCERT Biology Class 12, Chapter 7 - “Coordination and Control”

5. Excretion and Elimination:

  • Kidneys play a crucial role in excreting metabolic waste products through urine.
  • Lungs eliminate carbon dioxide (CO2) during respiration.
  • Liver contributes to waste removal by producing bile, which carries waste substances to the digestive system for excretion.
  • Skin, via sweat, excretes certain waste products, including urea, salts, and water.
  • Defecation, through the digestive system, allows for the elimination of solid waste and undigested materials.

References:

  • NCERT Biology Class 11, Chapter 13 - “Transport in Plants”
  • NCERT Biology Class 11, Chapter 21 - “Excretory Products and Their Elimination”
  • NCERT Biology Class 12, Chapter 6 - “Digestion and Absorption”