ultrafiltration

• • In the kidney, blood is filtered before the key substances are reabsorbed back into the blood again
  • The process occurs in the following order:

  1. Ultrafiltration
  2. Selective reabsorption of glucose
  3. Reabsorption of water and salts
• ULTRAFILTRATION

  • Arterioles branch off renal artery, lead to each nephron -> form a knot of capillaries (glomerulus) in cup shaped Bowman’s capsule
  • capillaries narrow further into glomerulus = increase pressure on blood moving thru them (already high pressure bc coming directly frm renal artery which is connected to aorta)
  • So smaller molecules in blood forced out of capillaries into Bowman’s capsule -> filtrate = ultrafiltration
  • substances forced out of capillaries: glucose, water, urea, salts
  • Some r useful -> reabsorbed back into blood further down the nephron
• label

  A) ultrafiltration

  B) glomerulus

  C) renal artery

  D) bowmans capsule

  E) high pressure

  F) forces

  G) out

  H) bowmans capsule

  I) urea

  J) glucose

  K) salts

  L) water

  M) filtrate

  N) nephron

  O) reabsorption

  
• label

  A) loop of henle

  B) collecting duct

  C) loop of henle

  D) proximal convoluted tube

  E) not reabsorbed

  
• • Renal Artery transports Oxygenated blood to the Glomerulus within the Bowman's Capsule under high pressure
  • High hydrostatic pressure is due to the wider afferent arteriole transporting blood to the Bowman's Capsule, and narrow efferent arteriole transporting blood out of Capsule
  • Blood is therefore filtered at high pressure to produce Glomerular Filtrate composed of Water, Glucose, Salts and Urea
  • However, as Proteins and Red blood cells are too large to be filtered through base membrane - material between Glomerulus and Bowman's Capsule, they will remain in blood