Tuesday, December 4, 2007

Kidney's yey!!

Well as it always seems i useally get the longest powerpoints to do but thats ok challenges are good.

Mammalian System
Its key functions are...
Filtration- Collects blood and filters out water and soluble material.
Reabsorption- reabsorbs needed substances (water NaCl) back into the blood
Secreation- pumps out unwanted substances to urine.
Excretion- removes excess fluids and harmful toxis from teh body

One of the main parts of the kedney is the Nehron. Each KIdney has 1 million, yes million (thats alot) nephrons. Its function is to filter out urea & other solutes (sugar salts). The process is the Nephron filters blood plasma (the liquid part of the blood) through it. Valuable solutes and water are reabsorbed.
Filtered out- Water (good) glucose (good) salts/ions (good) urea (bad very bad)
Not filtered out_ cells and proteins (toob ig to fit through the membrane).

THe kidneys are an interaction between the Circulatory sustem and exretory system.
The Circulatory cystem includes the glomerulus (a ball of capillaries).
The ecretory system includes- nephrons, the bowmans capsule, the loop of henle, and the collecting duct.

nephron re-absorption
Proximal tubule- the 1st series of loops in the nephron. Most of the "good stuff" is re abosrbed bak into the blood here.
NaCl- Na+ is re-absorbed by useing atp and Cl- follows by diffuseion. This process only takes half teh engery needed to absorb NaCl regullary.
ALso Absorbed- water glucose and HCO3.
Loop of henel
-Decending limb
high permiablility to water. This is becasue it contains many awuaporins in cell membranes. Low permiability to salt, this is because its missing salt channels.
-Ascending limb
Low permeablity to water, lack of aquaporens. It contains a CL- pump Na+ follows it by diffusion. Different membrane proteins. This means salts are reabsorbed.
Distal tubule Salts water and HCO3 are reabsorbed.
Collection Duct- Water is reabsorbed
. Urea is passed through the bladder and exreted.

TO do all this diffusion Osmotic Control is uised int he nephron. This reduces the cost of energy. This is because diffusion is used instead of active transport.

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