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OPERATION OF HOMEOSTASIS
The purpose of this essay is to explain the meaning and mode of the operation of
homeostasis, with regard to the nervous and endocrine system, in relation to
osmoregulation
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This is done by a process called negative feedback control, where various receptors
and effectors bring about a reaction to ensure that such conditions remain
favourable
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It will also be stated the relation of osmoregulation
to homeostasis
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However, the activities of the two
systems are coordinated by the pituitary gland, the master gland of the endocrine
system working in tandem with the hypothalamus, the control center of the
autonomic nervous system of the brain
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The hypothalamus also monitors the level of
hormones in the blood and regulates secretion by negative feedback control
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One of its major functions if to relay impulses and stimuli between the brain and
organs such as the kidneys
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ADH, and oxytocin, are released from the pituitary
under the direct control of nerve impulses generated in the hypothalamus (Weston,
2002: p21)
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The characteristics of this extra cellular fluid must
remain nearly constant to enable the cells to live and work properly
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Conditions in
the blood are maintained at an optimum – the best values for the cells to function
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Homeostasis involves several organs, such as the cell the heart the skin the kidneys

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the lungs, liver and intestines
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Information about the conditions in the body is continuously
fed to the brain from sensory receptors around the body (Pickering, 2000: p110)
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The

homeostatic control of water is a change in water concentration, which leads to
active via negative feedback control
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To remain healthy our bodies must be regulated in a constant state of internal
balance, under ever-changing conditions
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It involves control by negative feedback
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When the
water content of the blood is low, the hypothalamus registers a change in water
levels
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When the hormone reaches its target tissues, it alerts the tubules of the
kidney to become more/less permeable to water
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This allows water to be withdrawn from the
filtrate of the tubule into the medulla, owing to the high concentration of sodium and
chloride ions present
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Meanwhile, the ADH circulating in the blood is removed at the
kidneys, so small amounts of concentrated urine are formed
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Water, drunk to quench thirst felt by a
dry mouth and throat, replenishes the water levels in the body
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When no ADH is secreted
the walls of the collecting duct become less permeable
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Without the complex structures and organs of the human body such as the kidneys
and the pituitary gland in the brain which bring about homeostasis and
osmoregulation, and the control by negative feedback the body would not be able to
survive
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However, it can only work within tolerable limits, where

extreme conditions can disable the negative feedback mechanism
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biologyonline
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REFERENCES:
Clegg C J, (2000), Introduction to advanced biology, London, John Murray
Publishers Limited
Pickering W R, (2000), Complete Biology, Oxford, Oxford University Press
Weston T, (2002), Atlas of Anatomy, Singapore, Times Media Private Limited
www
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org (Homeostasis of water)

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