The urinary system

• The three main roles of the kidneys are to remove waste products like uvea from the blood, regulate the levels of ions in the blood, and regulate the amount of water in the blood.
• Blood constantly cycles through the kidneys, passing in through the renal arteries and out through the renal veins.
• The kidneys produce urine which passes down the ureters and is stored in the bladder until urinated out through the urethra.
• A kidney can be sliced down the middle in a cross-section, revealing a structure known as a nephron.
• The yellow part of a nephron is the tubule which carries the filtered fluid that becomes urine.
• The red parts of a nephron are the blood vessels.
• Filtration is the process that starts up in the kidneys, where some of the liquid part of the blood is forced from the glomerulus into the bowman's capsule, the start of the tubule.
• Only very small substances can be filtered through to the boneless capsule, so only things like water, amino acids, urea, glucose, and ions can pass through.
• The fluid that passes through the tubules in the kidneys reabsorbs all the things it wants back into the blood vessels, for example, glucose and amino acids are reabsorbed almost entirely, while water and ions are reabsorbed selectively, and urea is not reabsorbed.
• The different parts of the nephron are named as follows: glomerulus, bowman's capsule, proximal convoluted tubule, loop of henle, distal convoluted tubule, and collecting duct.
• Any fluid that passes out of the collecting duct is classified as urine and will pass down the ureter to the bladder and can then be released as waste.
• what is the glomerelus?

  small knot of capillaries
• function of urinary system?

  maintains water balance, removes waste and excess substances
• renal veins?

  Veins that carry deoxygenated blood from the kidneys back to the heart.
• ureters?

  carry urine from the kidneys to bladder
• urethra?

  A tube that carries urine from the bladder to the outside of the body.
• muscle?

  keeps exit from bladder closed until urination
• kidney?

  removes waste substances i.e urea from blood and makes urine
• renal arteries?

  supply blood to kidneys
• the kidney is made up of millions of nephrons which filter blood to remove waste products.
• nephron = tubule + glomerulus
• tubule - carries filtered fluid away from the glomerulus, reabsorbs useful substances back into the body and forms urine
• tubule - where filtered substances are reabsorbed back into the body or excreted as urine
• filtration occurs at the glomerular membrane, which has small pores allowing only water and small molecules through
• glomerulus - network of capillaries where filtration occurs
• movement of blood through nephron?

  glomerulus, bowmans capsule, proximal convoluted tube, loop of henrie, distal convoluted tube, collecting duct
• what do ureters do?

  carry urine from kidneys to bladder
• what does urethra do?

  Excretes urine.
• what does bladder do?

  store urine
• what does renal arteries do?

  carry blood from body to kidneys
• what does renal veins do?

  carry cleaned blood back to body#