the

• As the blood goes from the artery to the glomerulus, it creates extremely high pressure. This is because it is a different arteriole wider than the efferent arteriole. 


  All of the small molecules in the blood are forced out and enter the first part of the nephron; the Bowmans capsule. This includes, the urea, glucose, amino acids, water, salts, and some hormones.

  Proteins and blood cells are too big to stay i the blood, (a healthy kidney)
• Proximal convoluted tubule 


  The fluid containing the filtered molecules (renal fluid) trickles down from the Bowmans Capsule into the proximal convulted tubule. This is a long coiled tube.

  The renal fluid contains water, salts, urea, glucose, amino acids, any hormones and also drugs.

  However. the body needs to reabsorbed the useful products back into the blood. This is called selective re absorption.

  This mainly happens in the proximal convoluted tubule, where glucose, amino acids, sodium ions, chloride ions, and water are reabsorbed into the capillaries surrounding the nephron.
• The next section of the nephron is the loop of henle. It is a long hoop, that goes into the medulla of the kidney. It is here that the water balance is maintained.
• The loop of Henle is involved in the reabsorption of water. 


  It allows us to produce a urine that is hypertonic to the blood (more concentrated)

  It does this by concentrating salt in the tissue surronding the loop of the Henle, (in the medulla of the kidney) which helps draw water out of the tubule by osomosis.
• This is the next section of the nephron. It is another coiled tubule. Anything else that needs reabsorbing will be reabsorbed here, (water and salt if neccessary)

  The walls of the convulted tubule can be made more permeable or less permeable by a hormone called ADH.
• The collecting duct

  All of the leftover substances end up in the collecting duct.

  This includes urea, excess water, and salts, any drugs and other waste products from the body's chemical reactions.

  If the body gets dehydrated, water can be absorbed from the collecting duct since this is also affected by ADH.

  The leftover waste liquid is known as urine.
• There are two main functions of the kidney

  • Removal of urea
  • Regulation of water levels
• When we digest proteins, they become amino acids, (these are what we use to bulid up proteins)

  They usually have more amino acids than we can use.

  We can not store this excess, so they are taken into the liver where they are stripped of nitrogen containing proportion of the acid. 


  This forms ammonia, which is toxic. This is then converted into (less toxic but still posionous) urea by the liver.
• This urea passes into the blood and reaches the kidneys.

  Kidneys remove the urea from the blood and the other parts of the body.

  Parts of each kidney nephron called the glomerulus and the Bowmans capsule act like a filter to do this.
• Blood vessel draining from the glomerulus is narrower than one entering it, which means that the blood under pressure within the glomerulus to do this.
• Blood vessel draining from the glomerulus is narrower than one entering it, which means the blood is under high pressure within the glomerulus.
• The high pressure means that the plasma is forced out through the capillary walls and into the Bowmans capsule.

  This rapid exit of the plasma is called ultra filtration and removes wastes, nutrients and also water from the plasma. This leaves blood proteins and also cells behind. 7