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Excretory Products and Their Elimination One Shot Revision Biology | Class 11 Biology By Sonam Maam

Science and Fun Education・31 minutes read

The kidney's crucial role in removing metabolic waste like urea, uric acid, and ammonia is detailed, highlighting the different forms of waste excretion in various organisms based on habitat and physiology. The excretory system's structure, processes like glomerular filtration and reabsorption, and urine formation are covered, emphasizing the kidney's significance as a primary excretory organ in humans.

Insights

  • The excretory system in humans, primarily governed by the kidneys, eliminates metabolic waste such as urea, uric acid, and ammonia, with different organisms excreting waste in various forms based on their habitat and physiological needs.
  • The intricate structure and processes of the nephrons within the kidneys, including glomerular filtration, reabsorption in the proximal convoluted tubule, and concentration mechanisms in the loop of Henle, are vital for maintaining metabolic balance and forming urine, with the final urine concentration controlled by stretch receptors in the urinary bladder.

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Recent questions

  • What is the primary function of the kidneys?

    Filter blood and remove metabolic waste.

  • How do different organisms excrete waste?

    Through ammonia, urea, or uric acid based on habitat.

  • What are the components of the human excretory system?

    Kidneys, ureters, bladder, and urethra.

  • What is the structure of a kidney?

    Cortex, medulla, renal pelvis, calyces, pyramids.

  • What are the processes involved in urine formation?

    Filtration, reabsorption, and secretion.

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Summary

00:00

Excretory System: Elimination of Metabolic Waste

  • The chapter on excrete products and their elimination is part of human physiology, focusing on the excretory system.
  • The kidneys play a crucial role in removing metabolic waste like urea, uric acid, and ammonia from the body.
  • Different organisms excrete waste in various forms like ammonia, urea, or uric acid, based on their habitat and physiology.
  • Aquatic organisms excrete ammonia due to its high toxicity, requiring ample water for excretion.
  • Ureotelic organisms excrete urea, needing moderate water amounts, while uricotelic organisms excrete uric acid, conserving water.
  • Various excretory organs like flame cells, nephridia, Malpighian tubules, and tap glands are found in different organisms.
  • The human excretory system comprises kidneys, ureters, urinary bladder, and urethra, with kidneys being the primary excretory organs.
  • The kidney's structure includes the cortex, medulla, renal pelvis, calyces, and renal pyramids, divided into major and minor calyces.
  • Each kidney contains around 1 million tubular nephrons, the structural and functional units responsible for filtering blood and producing urine.
  • Nephrons consist of glomeruli and renal tubules, essential for maintaining the body's metabolic balance and eliminating waste products.

17:22

Renal anatomy and urine formation processes explained.

  • Glomerulus is a network of capillaries where ultrafiltration occurs, made from the afferent arteriole.
  • Bowman's capsule covers the glomerulus, collectively called Malpighian Body or Renal Corpus.
  • Renal tubule consists of Proximal Convoluted Tubule, Loop of Henle, and Distal Convoluted Tubule.
  • Loop of Henle has descending and ascending limbs, responsible for concentration and dilution of filtrate.
  • Peritubular capillaries emerge from the glomerulus, forming a network called Vas Rect.
  • Two types of nephrons exist: Cortical nephrons (85%) and Juxtamedullary nephrons (15%).
  • Glomerular filtration, reabsorption, and tubular secretion are the processes involved in urine formation.
  • Glomerular Filtration Rate (GFR) is approximately 125 ml per minute, with normal GFR being 180 liters per day.
  • Reabsorption occurs in the proximal convoluted tubule (PCT) where most nutrients are reabsorbed.
  • Loop of Henle maintains high osmolarity of medullary interstitial fluid, aiding in urine concentration.

34:27

"Human Urinary System: Filtration and Excretion"

  • Blood enters the upfront artery for filtration in the glomerulus, with a high glomerular filtration rate of about 180 liters per day, which is absorbed in the tubules at 99%.
  • Proximal convoluted tubule (PCT) and distal convoluted tubule (DCT) work to maintain ionic balance and concentrate urine, with secretions occurring in the collecting duct to form urine.
  • A counter current mechanism is performed in the loop of Henle and vas recta, leading to an increase in osmolarity from 300 to 1200 in the inner medulla.
  • The distal convoluted tubule (DCT) produces urine four times more concentrated than the initial filtration, increasing the concentration from 300 to 1200 ml.
  • The release of urine, known as micturition, is controlled by stretch receptors in the urinary bladder, sending impulses to the CNS to initiate the process.
  • An adult human excretes 1 to 1.5 liters of urine daily, containing approximately 25 to 30 grams of urea, with a light yellow color, slightly acidic pH around 6, and a characteristic odor.
  • Lungs eliminate CO2 and water, the liver secretes bile containing various substances, and the skin and saliva also play roles in excretion, with sweat containing water, salt, urea, and lactic acids.
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