HOMEOSTASIS (BIOLOGY)

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can any one pls help me.......to ans this this question

describe how the kidneys help to maitain a constant internal environment? (3 marks)
5090/02/O/N/03
 
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Kidneys regulate the amount of water in the body and hence the osmotic balance. They reabsorb more water from the collection duct by adding water channels to the membrane which are available in their cytoplasm. If the amount of water gets high then the kidneys absorb less water by removing these channels. Hence, a more diluted urine is produced. So, whatever the situation the kidneys ensure that the amount of water is at a constant level. Therefore, maintaining the constant internal environment.
 
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CAN YOU PLS HELP ME OUT ONCE MORE............
PLS EXPLAIN ME BOTH CARBON CYCLE AND NITROGEN CYCLE IN FULL DETAIL WITHOUT EVEN MISSING OUT A SINGLE POINT.....
PLS PLS ....
 
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Carbon Cycle:

Co2 is found in the atmosphere------> Plants absorb Co2 to synthesize carbohydrates. Plants respire at night/absence of light to release Co2 back into the air------->Animals eat plants------>Carbon compounds are transferred to Animals----->Humans eat plants and animals------->Carbon Compounds are transferred to them------>Bacteria digest faeces to release Co2 as well as feed on the remains of dead plants, animals to release Co2.

Nitrogen Cycle:

------>Proteins are formed in the body of plants and animals by DNA and Ribosomes and by nitrogen fixing bacteria in leguminous plants that form nitrates using atmospheric nitrogen------>Excess proteins are deaminated in Animals and Humans as Urea. Urea is converted to ammonium ions by soil bacteria----->Nitrosomonas bacteria convert ammonium ions to nitrite ions------->nitrobacter bacteria converts nitrite to nitrate. A similar process acts when animals, plants die----->Denitrifying bacteria convert nitrate ions back to nitrogen gas in air.
 
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Basically the kidney has two major function is relation to homeostasis:
1. Osmoregulation
2. Salt concentration balance.

As you might already know osmo regulation is the balance of water concentration in the body. this is extremely important as if there is too little water in the blood the blood will be concentrated and enzymes will fail to function. When blood flows through the brain the concentration of water is detected by the hypothalamus which secretes the hormone ADH ( anti dieuretic hormone) this is secreted when the water concentration is less and this prevents the water from being lost with urine. The effect is actually the stimulation of the renal tubules to absorb more water by increasing the permeablity of the cell membrane thus reducing the loss of water. In turn the urine passed out is highly concentrated. The balance of salt concentration can be incorporated into this answer.

hope this helps, good luck with the exams :D
 
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