excretory system/ kidneys

• What is excretion?


  It is the process of removing waste material from the body
• Why is excretion necessary for cells?


  To prevent toxic by-products from accumulating
• What would happen if waste products were not removed from the body?

  Cells would be poisoned and metabolism would slow down
• Name the main excretory organs in mammals.

  Kidney, Ureter, Bladder, Urethra, renal artery, renal vein
• What are the waste products excreted by the body?


  Urea, Uric acid, Water, Salt, Poisons, Bilirubin
• What is the purpose of the urinary system?


  To eliminate waste from the body and regulate blood volume and pressure
• What is the structure of the kidney?


  Dark red, bean-shaped organ with an inner medulla and outer cortex
• How does blood flow through the kidney?

  Blood enters through the renal artery and exits through the renal vein
• What are the functions of the ureters, bladder, and urethra?


  Ureters carry urine from kidneys to bladder, bladder stores urine, urethra expels urine
• function of sphincters?

  control the release of urine from the bladder
• What is a nephron?


  The individual and basic unit of the kidney
• How many nephrons are approximately in each kidney?


  About a million
• What are the main steps of urine formation?

  Ultrafiltration, Selective reabsorption, Excretion
• What is ultrafiltration?


  It is the process where blood is filtered in the Bowman’s capsule the water,

  glucose, salts and wastes

  flow through. Blood cells

  stay in capillaries.
• What happens during selective reabsorption?


  Useful substances are reabsorbed back into the blood
• What is the role of ADH in the kidneys?


  It controls the amount of water excreted by the kidneys
• What is the composition of normal urine?

  Water, urea, and salts such as sodium chloride
• How does urine travel from the bladder to the outside of the body?

  Through the urethra
• What are the adaptations of the excretory systems in different animals?


  • Birds: Produce uric acid to conserve water
  • Desert animals: Minimize water loss through concentrated urine
  • Fish: Vary excretion based on freshwater or marine environments
• What is the role of the collecting duct in the nephron?


  It collects urine from multiple nephrons and drains into the renal pelvis
• What is the function of the renal pelvis?


  It collects urine from the collecting ducts and directs it to the ureter
• What color does bilirubin give urine?


  Yellow
• What signals the brain that the bladder needs to be emptied?


  Stretch receptors send signals when the bladder is full
• How are the urinary and reproductive systems connected in animals?


  They both use the same outlet to the exterior, known as the urinogenital tract
• What is the function of the renal artery?


  It carries oxygenated blood to the kidneys
• What is the function of the renal vein?


  It carries filtered blood away from the kidneys back to the heart
• function of the bladder ?

  It collects and stores urine before it is expelled from the body
• What is the structure of the urethra?


  It is a tube through which urine flows from the bladder to the outside
• What is the function of the proximal convoluted tubule (PCT)?


  It reabsorbs useful substances from the filtrate back into the blood
• What is the function of the Loop of Henle?


  It helps concentrate urine and reabsorb water
• What is the function of the distal convoluted tubule (DCT)?


  It further adjusts the composition of urine by reabsorbing additional substances
• What is the role of the collecting duct in urine formation?


  It collects urine from nephrons and transports it to the renal pelvis
• What happens to the waste products after they are filtered in the nephron?


  They travel to the collecting duct and then to the ureter
• What is the significance of the high pressure in the glomerulus during ultrafiltration?


  It forces most of the blood into the Bowman’s capsule for filtration
• What is the filtrate in the context of the nephron?


  It is the liquid that filters through the Bowman’s capsule containing water, glucose, salts, and waste
• What substances are actively secreted back into the distal convoluted tubule?


  Potassium, ammonium, hydrogen ions, and certain drugs
• What is the role of pigments in urine?


  They give urine its yellow color
• How do stretch receptors function in the urinary system?


  They signal the brain when the bladder is full and needs to be emptied
• What is the connection between the urinary system and the reproductive system in animals?


  They share the same outlet to the exterior, known as the urinogenital tract
• What is the significance of the renal capsule surrounding the kidney?


  It protects the kidney and maintains its shape