WATER
Water is vital for human existence.
We can live with out food for extended periods of time, but without water will
result in death.
Water is colourless, calorie less compound of hydrogen and
oxygen that virtually every cell in the body needs to survive. Water is closer
being a universal solvent than any other compound.
Water is the largest single compound
of the body and it is distributed as follows.
Distribution of water in the body
1. Intracellular water
(Present inside the cell)
2.Extracellular water
(present outside the cell)
2.a.Intravascular
(Present as plasma of blood)
2.b.Extravascular
(Present outside the blood vessels)
2.b.Extravascular
(i)
Interstitial fluid
(
between the cells)
(ii)
Lymph
(iii)
Water present in brain,aqueous humor of the eye, pericardium, pleural cavities.
Total body water content is mainly determined by total
amount of salt in the body. Salt and water concentration in the body is
controlled by the kidneys.
FUNCTIONS
OF WATER
1.
It is an essential constituent of all
the cells of the body and the internal environment.
2.
Serves as a transport medium by
which most of the nutrients pass into the cells and removes excretory products.
3. Water is a medium for most biochemical reactions within the
body and sometimes a reactant.
4.
It is a valuable solvent in which
various substances such as electrolytes, non - electrolytes, hormones, enzymes,
vitamins are carried from one place to another.
5.
Plays a vital role in the
maintenance of body temperature. Heat is produced when food is burnt for
energy. Body temperature must be kept at 80º - 108º Fahrenheit for higher or
lower body temperature will cause death. Body heat is lost through the skin,
lungs, urine and faeces.
6. It forms a part of fluids in body tissues; (eg) the amniotic
fluid surrounds and protects the foetus during pregnancy.
7. Saliva is about 99.5 percent water. In healthy individuals
it makes swallowing easier by moistening the food.
8. Water helps in maintaining the form and texture of the
tissues.
9.
Water is essential for the maintenance
of acid base and electrolyte balance. It should be noted that pure water
consists of hydrogen ion (H+) and hydroxyl ion (OH-).
Substances dissolve in water as ions with positive and
negative charge. They are called electrolytes. The common electrolytes in our
body are sodium, potassium and chloride.
Changes
in electrolyte balance causes accumulation or depletion of water in
intracellular and extra cellular fluid.
The balance between the positively
and negatively charged ions is essential for water flow and maintain osmolarity
between the cells. This is called electrolyte balance.
Acid base balance is the dynamic state of equilibrium of
hydrogen ion concentration. When pH falls below 7 it is termed acidity and when
it increases above 7 it is termed alkalinity.
Extremes of both cases results in death. The pH of the body
should be maintained near neutrality. Enzymatic action depends on the pH. The
digestion, absorption and utilization of nutrients are dependent on pH. Most
body fluids are near neutral with the exception of gastric juice.
The
pH value of some solutions are given below:
---Acid---
0 - Hydrochloric acid
1
2 - Gastric juice
3 - Vinegar, orange juice
4 - Grapes
5 - Bread, coffee
--Neutral
------
6 - Urine
7 - Pure water, eggs, blood
8 - Sea water
14 - Sodium
---hydroxide
Alkali---
Water forms good source of macro minerals like Calcium,
Magnesium, Fluoride, Iron and Iodine.
REQUIREMENTS
Requirements of water varies with climate, dietary
constituents, activities and surface area of the body. As a rule a person
should take enough water to excrete about 1200 -1500 ml of urine per day. In
tropics because of greater water loss through perspiration increased water
intake is required to maintain urine volume. Normal intake of water ranges
between 8 - 10 glasses per day.
Daily Water Input
In
tropical countries like India the daily water input amounts to 2400 - 3000 ml
of water through food, as fluid drinks and as metabolic water.
1. As
fluid drinks - water, tea, coffee,
milk
soups 1500 - 1750 ml
2. Water
intake through solid food 600 - 900
ml
3. Oxidation
of carbohydrate, fat, 300 - 350
ml
proteins
(metabolic water)
Total 2400 - 3000 ml
Daily
output of water
1. Urine 1200 - 1500 ml (kidney)
2. Perspiration 700 - 900 ml (Skin)
3. Respiration 400 ml (lung)
4. Faeces 100 - 200 ml (intestine)
Total 2400
- 3000 ml
Therefore the water intake and output is fairly kept
constant. This is called water balance. The average adult metabolises 2.5 -
3.00 litres of water and a constant balance is maintained between intake and
output. Inadequate water intake disturbs water equilibrium resulting in
decreased urinary output, thereby causing changes in Extra Cellular Fluid (ECF)
and Intra Cellular Fluid (ICF). The water equilibrium is maintained by kidneys,
lungs, intestine and pituitary gland. The water balance coordinates with both
electrolyte and acid base balance.
CAUSES, EFFECTS
And PREVENTION OF DEHYDRATION
Causes :
When water is constantly lost from
the body as in severe vomiting, diarrhoea, excessive sweating or excessive
urine formation due to treatment with diuretics, the total water content of the
body is reduced. Extra cellular and intra cellular fluid decreases leading to dehydration.
Effects of dehydration
1.
Tongue is dry.
2. Pinch test is done by raising and releasing the skin. Slow
return of skin to original position indicates decreased ECF.
3. Decrease in plasma volume reduces cardiac output and may
lead to cardiac failure.
PREVENTION
OF DEHYDRATION
Dehydration can be prevented by
taking sufficient amounts of water as fluids. The correction of dehydration is
called rehydration.
Oral rehydration therapy
It is the administration of fluid to
prevent or correct dehydration.
Oral rehydration salt
WHO, UNICEF formula consist of the
NaCl - 3.5 g, NaHCO3 - 2.5 g, KCl - 1.5g and glucose - 20 g to be dissolved in
one litre of potable drinking water.
The Glucose present aids in the absorption of sodium
chloride and potassium chloride apart from giving energy. This mixture is
administered through the oral route at frequent intervals until the normal
state is attained.
Potable water is that water which is
safe and wholesome. It should be:
1.
free from pathogenic agents
2.
free from harmful chemical substance
3.
pleasant to taste; free from colour
and odour
4.
usable for domestic purpose.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.