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Regulation

the bloodstream. This hormone stimulates hydroxide ions. There are three types of
reabsorption of sodium and chloride ions buffer systems:
from the kidney tubules and loop of Henle. Bicarbonate Buffer System: This is the
The overall effects of these mechanism primary buffer in extracellular fluid. It
helps the animal to conserve water and involves the reversible reaction:
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mineral salts.
(a) Chemical buffers
For example, a camel is a mammal with the Buffers are substances that minimise
longest loop of Henle. The loop of Henle changes in pH by binding or releasing H +
plays a vital role in water conservation, by ions.
enhancing their ability to concentrate urine
and conserve water. The descending limb
of the loop is permeable to water, allowing If pH drops (acidosis), binds with
it to be reabsorbed into the bloodstream, H ions to form H CO , which dissociates
+
3
2
whereas the ascending limb actively into water and CO , expelled via respiration.
2
transports sodium and chloride ions out of When pH increases (alkalosis), carbonic
the filtrate, creating a high osmotic gradient. acid dissociates to release hydrogen ions
This mechanism allows camels to excrete to restore the balance.
highly concentrated urine, minimizing
water loss and enabling survival in arid Protein buffer system: Proteins, such as
environments. hemoglobin and plasma proteins, act as pH

buffers by accepting or donating hydrogen
Regulation of the pH of the body fluid ions.
The pH is the negative logarithm of
hydrogen ion concentration. In simpler Phosphate Buffer System: This system is
terms, pH is the measure of how basic or particularly important for intracellular pH
alkaline the solution is. In mammals the regulation. Phosphate ions help neutralize
pH of the body fluid is maintained within excess hydrogen ions in the cytoplasm.
a narrow range between 7.2 and 7.4. This
is the optimum range for the activity of Respiratory Regulation: The lungs
intracellular enzymes. Deviations of pH regulate pH by controlling CO levels.
2
outside this range leads to denaturation When CO accumulates in the blood,
2
of enzymes and disruption of biological it forms carbonic acid, lowering pH.
processes. Hyperventilation (increased breathing
rate) expels CO rapidly, reducing
2
Mechanisms of pH regulation acidity and raising pH. Hypoventilation
Buffer systems: The body uses buffer (slow breathing) retains CO , increasing
2
systems to resist drastic pH changes acidity and lowering pH. This respiratory
by neutralizing excess hydrogen or compensation is a quick response to pH
imbalances.

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