• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Excretion and the functioning of the kidneys

Extracts from this document...

Introduction

´╗┐Excretion Excretion is the removal of metabolic waste from the cells. Metabolic waste is the unwanted material that is formed as a result of the bodies metabolism. That is the large number of chemical reactions that occur in the cells, tissues and organs. The waste products of metabolism are frequently toxic and so must be removed from the body. Deamination and Urea Synthesis In the liver deamination is the process which breaks down excess amino acids in to ammonia and keto acids. Ammonia is still very toxic so it is converted to urea by the process called urea synthesis. Urea is less toxic than ammonia and so can travel in the blood, but it must be got rid of quickly because it can still have ill effects. ...read more.

Middle

The most important part of the Kidneys is the nephron. The Nephron The Nephron is a the kidney tubule and there are thousands of nephrons in each kidney. Within the nephron there are: Renal Capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule and the collecting duct. Each part of the nephron has a different role to play in filtering the blood to rid it of toxins and in the overall kidney waste and water control. The stages are ultrafiltration, selective reabsorption, production of an iron gradient in the medulla and adjustment of the water and ion gradients. Ultrafiltration Ultrafiltration occurs in the renal or bowman's capsule. The renal artery which brings blood to the kidney is split up into numerous arterioles, each feeding a nephron. ...read more.

Conclusion

Small proteins are reabsorbed. 80% of water is absorbed back into the blood by osmosis. The proximal convulated tubule cells have many mitochondria to provide ATP for active transport and mirovilli to increase surface area for absorption. Loop of Henle The loop of henle creates the conditions for the final reabsorption of water in the collecting duct by creating an ion gradient. In the loop of henle salt is added to the filtrate in the descending limb. The cells surrounding are impermeable to ions. Due to water moving from a less negative to a more negative water potential, water comes into the filtrate. In the ascending limb the walls are impermeable to water so the water remains and the ions leave creating an ion gradient in the medulla. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. the role of the microbiology department

    such as incubators, refrigerators, microscopes and water baths located in the laboratories where the main work is done rather than in separate instrument rooms.

  2. AN ACCOUNT OF NITROGENOUS EXCRETION IN MAMMALS Excretion is the disposal of the waste ...

    Consequently, less water is needed for the safe elimination of urea from the body than for that of ammonia. Urea excretion (ureotelic excretion) is seen in organisms of aquatic and terrestrial habitats. Urea is synthesised from ammonia and carbon dioxide by reaction with the amino acid ornithine.

  1. Homeostasis and excretion.

    Glucose is needed for cell respiration. Excretion: the removal of waste products produced my metabolism. (Skin-salt, kidney-urea, lungs- O2&CO2, liver-bile). Surplus amino acids must be degraded to harmless levels. Fresh water fish can get rid of ammonia because the water dilutes it straight away.

  2. Photosynthesis - Absorption spectrum.

    The canines are there to grip and kill the prey, these are adapted very well, and since they are sharp so it can pierce the prey's skin very easily. The molars and premolars are there to crush bones and chew the flesh even further; these are very well adapted since

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work