Sunday, December 2, 2007

Regulating The Internal enviorment

Homeostasis is the tendency of the body to seek and maintain a condition of balance within its internal environment, even when faced with external changes. this includes cell growth ion balance temperature blood sugar levels energy production cell growth water balance and nutrients.

There are conformers and Regulators. Conformors change their internal conditions to what ever the external enviorment is. An example of a conformors are snakes.
Regulators maintain their interal conditions constant. Such as as body temperature, in humans the normal body temperatur is 98.6

Osmoregulation is the balance of fluids in order to maintain homeostasis.
Their are three conditions that are involved. For each of these conditions the kidney works in different ways.

Hypertonic is a solution with higher solute concentration (higher osmotic pressure) than another so water wants to move in.
Hypotonic is a solution with lower solute concentration (lower osmotic pressure) than another so water wants to move out of
Isotonic is solution with the same solute concentration (same osmotic pressure) as another no net movement of water.
fish that live in fresh water take up salt from the enviorment. Water will flow into the fish and the fish will excrete a low concentration urine to get rid of all of the extra water.
As for fish that live in salt water they tend to lose water and gain salt. They excrete salt from their gills. Water organisms excreteamonia they do not transform it.
Land animals need to conserve water and may need to conserve salt since they live in a dry enviormnent. When we digest foods we create waste products . when we consume nucleic acids we create amonia. Amonia is toxic an carcinogenic it is easily put into cells(soluble). Land animals change amonia into urea to make it less toxic and terrestrial. Uric acid is Eliminated in a pastelike form through the cloaca (mixed with feces) in birds and reptiles. Land animals must excrete it quickly, the longer that amonia is in our body the more problems we can encounter

Egg animals conserve as much water as possible. They create uric acid which is less soluble. it is not a liquid waste. To make something less soluble you make it bigger.
The kidney maintains homeostasis in the body by

removing waste products from the body
removing drugs form the body
balance the body's fluids
releases hormones that regulate blood pressure
produce an active form of vitamin D that promotes strong, healthy bones
control the production of red blood cells.

The kidney works in 4 steps

Filtration- body fluids are collected (blood).

Water and soluble material are removed.

Reabsorption- reabsorb needed substances back in the blood

Secretion- pump out unwanted substances to urine.

Excretion-remove excess substances and toxins from body.

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