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”