inside the kidney

• what are the 3 observable sections of the kidney?

  cortex, capsule and medulla
• what does the capsule of a kidney do?

  It is the outer membrane of the kidney and helps to maintain the kidneys shape and protect it from damage
• what is the cortex?

  Outer part of the kidney
• what is the medulla?


  Inner part of the kidney
• what colour is the renal artery normally shown as?

  Red
• what colour is the renal vein normally shown as?

  Blue
• what is urine produced by?

  Microscopic tubules called nephrons inside each kidney
• how many nephrons does each kidney contain​?

  1 million
• where is the top and bottom of the nephron found?

  Top part: cortex

  lower part: (loop of henlé) medulla
• which blood vessels allow blood to enter and leave the kidney?

  Renal arteries and renal veins.
• how does blood enter the kidney?

  Under high pressure from the renal artery, it contains many branches each leading to a glomerulus, and each glomerulus contains a knot of capillaries
• what does increased blood pressure in narrow blood vessels near the exit to the glomerulus mean?

  It forces small molecules (water, glucose, salt, urea) out through the capillary wall and into the Bowman's capsule. large molecules (proteins) are too large to fit through the capillary wall so remain in the bloodstream
• what is selective reabsorption?

  As the filtrate moves through the nephron tubule, all of the glucose is reabsorbed as well as some of the water and any salts needed by the body
• what is the last step before excretion?

  The filtrate passes through the loop of henlé and the collecting ducts and these structures regulate the amount of salt and water in the body by reabsorbing extra water and salt if needed
• what happens during excretion?

  The waste solution (urine)collects in the collecting duct and travels to the bladder to be removed from the body
• how is volume of urine produced controlled?

  Through a negative feedback loop , your hypothalamus detects the water potential of your blood as it passes through your brain and responds by secreting the hormone ADH from the pituitary gland. it then travels in the bloodstream to the kidney where it makes the walls of the collecting ducts more permeable to water which means more water is reabsorbed into the blood.
• what does ADH stand for?

  Anti diuretic hormone
• what happens if the blood water potential is too low?

  More ADH is produced, resulting in more water being absorbed from the nephron and into the bloodstream, less water is lost from the body so only a small volume of concentrated urine is produced
• what happens if the blood water concentration is too high?

  Less ADH is produced, resulting in less water being absorbed from the nephron and into the blood stream. more water is lost from the body so a large volume of dilute urine is produced