the kidney

• what are the three sections of the kidney, what are they called?

  The outer region is called the cortex

  The inner region is called the medulla

  The centre is called the pelvis, it leads into the ureter
• describe the fine structure of the kidney?

  The bulk of each kidney consists of tiny tubules called nephrons. Each kidney contains about one million nephrons. Each nephron starts in the correct at the Bowman's capsule. The remainder of the nephron is a coiled tubule that passes through the cortex, forming a loop down into the medulla and back to the cortex before joining a collecting duct that passes back into the
• describe the blood supply of the kidneys?

  The renal artery splits to form many afferent arterioles, which each lead to a knot of capilliaries called the glomerulus. Blood from the glomerulus continues into an efferent arteriole which carries the blood to more capilliaries surrounding the rest of the tubule. These capilliaries eventually flow together into the renal vein.
• how is fuid from the blood pushed int other bowmans capsule from the glomerulus?

  Ultra filtration
• the filter is the barrier between the blood in the glomulerus and the lumen of the bowmans capsule, what are the 3 layers of this filter?

  Endothelium of the capillary

  Basement membrane

  Epithelial cells of the bowman's capsule
• how is the endothelium of the capillary adapted to it's function for filtering blood?

  There are narrow gaps between the cells of the endothelium of the capillary wall. The cells of tye endothelium also contain pores called fenestrations. The gaps allow blood plasma and substances dissolved in it to pass out of the capillary
• how is the basement membrane of the barrier adapted for it's function?

  The membrane consists of a fine mesh of collagen fibres and glycoproteins. This mesh acts as a filter to prevent the passage of molecules with a relative molecular mass of 69000. This means that most proteins, and all red blood cells, are held in the capillaries of the glomerulus.
• how are epithelial cells of the bowman's capsule adapted for their function?

  These cells, called podcytes, have a specialised shape. They have many finger like projections, called major processes. On each major process, there ar eminor processes that hold the cells away from the endothelium of the capillary. These projections ensure that there are gaps between the cells. Fluid from the blood in the glomerulus can pass between these cells into the lumen of the bowman's capsule
• The bowman's capsule leads into the rest of the tubule, which has 3 parts called?

  Proximal convoluted tubule

  Loop of Henle

  Distal Convoluted tubule
• What is ultrafiltration?

  the filtering of blood at the molecular level. Blood flows into the glomerulus via the afferent arteriole which is larger than the efferent arteriole. The difference in diameter ensures that the blood in the capillaries of the glomerulus maintains a higher pressure than in the bowman's capsule. the pressure difference tends to push fluid from the blood into the capsule that surrounds the glomerulus
• What is left in the capillaries after fluid is pushed out into the bowman's capsule?

  Blood cells and proteins. The presence of proteins means that the blood has a low water potential. this ensures that some fluid is retained in the blood which contains water and dissolved ions, glucose, urea, and amino acids. this low water potential of the blood is important to reabsorb water later on.