Chemistry_Witrh_Physics

Gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney Renal dialysis is commonly used to treat patients with kidneys that are not functioning properly. In essence, renal dialysis is using as an alternative for the patient’s kidney. The two main types of renal dialysis are hemodialysis and peritoneal dialysis. Depending on the patient, either of the two processes can be used. Hemodialysis involves the patient going to a facility with a dialysis machine. This dialysis machine removes blood from a vein and it passes through a bundle of hollow fibres which are produced from a partially permeable membrane. This dialyser membrane acts as an artificial kidney and is similar to the filtration that takes place in a normal kidney. Diffusion of waste products takes place from the blood to the dialysis solution and ion components move into the blood. The “clean” blood is now returned to the body. Peritoneal dialysis uses the peritoneium inside the body. It is similar to hemodialysis, but the dialysis solution is introduced through a cathether. The diffusion takes place across the membrane and then the used dialysis solution can be thrown away in a disposable collection bag. This bag is replaced approximately every 4 hours. Function Ÿ Renal dialysis (hemodialysis) Use to filter out metabolic wastes and foreign materials Artificial process Regulated by machine and computer feed-back systems Each session is approximately 3-6 hours. Patients must undergo 3 sessions a week until they get a transplant Diffusion and osmosis across the semi-permeable membrane fibers found in the artificial kidney Type Regulation Ÿ Ÿ Renal dialysis (Peritoneal dialysis) Ÿ Use to filter out metabolic wastes and foreign materials Ÿ Artificial process Ÿ Regulated by the patient Ÿ Filtering of metabolic wastes is continuous, the mixture must be drained after a prescribed length of time Diffusion and osmosis across the patient’s peritoneum which is a semi-permeable membrane Kidney Ÿ Use to filter out metabolic wastes and foreign materials Ÿ Ÿ Ÿ Ÿ Ÿ Natural process Regulated by the brain and the homeostatic control centre. Filtering of metabolic wastes is continuous, it only stops when the kidneys stop functioning properly Processes used Ÿ for processing of metabolic wastes Ÿ Ÿ Pressure forces liquids out of the glomerulus into the Bowman’s capsules. Re-absorption efficiency Ÿ Dialysis commonly does not re-absorb all of the necessary sugars, amino-acids and metal ions. These substances are commonly drained out along with the nitrogenous wastes. Approximately $500 per session Ÿ Cost Ÿ Ÿ Dialysis commonly Ÿ does not re-absorb all of the necessary sugars, amino-acids and metal ions. These substances are commonly drained out along with the nitrogenous wastes. One-off cost for Ÿ surgery; low maintenance costs Diffusion and osmosis are used in selective-reabsorption No cost involved Current research into dialysis includes: Ÿ Ÿ Ÿ New methods in peritoneal dialysis Hemodiafiltration development Polymers to remove uremic toxins The Renal Research Institute reports on a new technology known as the Dialock in the Dialysis Times, (Volume 5, No. 5), “To address these difficulties with current hemodialysis access devices; the Dialock was developed on the concept of the totally implanted subcutaneous vascular access port.” Continued research into renal dialysis will make it painless and cost effective. Gather, process, analyse and present information to outline the general use of hormone replacement therapy in people who cannot secrete aldosterone and use available evidence to discuss the importance of this therapy. Aldosterone is a hormone that has two effects: Ÿ Ÿ Increase reabsorption of sodium ions in the collecting ducts and distal tubule Decrease reabsorption of potassium ions This results in a increased water volume within the blood and also a increased blood pressure. When aldosterone cannot be secreted by the person, the efficiency of the excretory system will decrease and potentially the person cannot maintain homeostasis and become severely dehydrated. This is where hormone replacement therapy can prove useful. Aldosterone, as a steroid hormone, is produced by the adrenal cortex within the kidney. The most commonly used replacement hormone is known as fludrocortisone. Fludrocortisone is mostly used to treat people with Addison’s disease, and this is caused by the destruction or shrinking of the adrenal cortex within the adrenal gland. When aldosterone is normally used, it takes part in a negative feed-back system. When one or more elements of the feed-back system are damaged, the secretion of aldosterone may be reduced or entirely stopped. The stimulus in this negative feed-back system is a low water volume or blood pressure. This causes the rennin to be secreted which in turn causes the adrenal cortex inside the adrenal gland to secrete aldosterone. Fludrocortisone is taken as tablets and doctors will specify the dosage amounts, depending on the severity of the lack of aldosterone. Because this replacement hormone is a corticosteroid, patients must be careful to watch for possible side effects. The hormone replacement therapy is extremely important for people who cannot secrete aldosterone because potentially without the hormone replacement, the patient will become extremely ill. In taking fludrocortisone, the patient can essentially maintain homeostasis and continue “living”. In this way, homeostasis in terms of water volume and blood pressure is maintained. Bibliography: Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ fludrocortisone.com [Internet]. [Accessed 5 December, 2002]. Keokuk Health Systems - Henry County Health Center's Renal Dialysis Unit[Internet]. [Accessed 29 October, 2002]. Renal Dialysis[Internet]. [Accessed 27 October, 2002]. The Kidney [Internet]. [Accessed 27 October, 2002]. Kidney Dialysis: Microsoft Encarta Encyclopedia 2001 [CD ROM]. Microsoft Corporation. Alford, D. (2000). Excel HSC Biology. Australia: Pascal Press. Kennedy, E. (2000). Biology in Context. Australia: Oxford University Press Dialysis Times (Volume 5, No 5.) p4:Renal Research Institute