UNIT/CHAPTER 1

Basic Biochemistry

WATER

Water

Water molecule (H2O), is the most abundant

inorganic compound in the body.

O

WATER • Most abundant

inorganic

compound

• Forms 60-70% of

body weight

• Closely associated

with electrolytes

• Present both inside

and outside of the

cells

• Two water compartments

–Intracellular water

–Extracellular water

• Extracellular water is

further subdivided into:

–Plasma

–Interstitial fluid

–Dense connective tissue

(bones, cartilages)

–Transcellular fluids

WATER

In lean adults, body fluids

constitute 55% of female and 60% of male total body

mass

Intracellularfluid (ICF) inside cells

• About 2/3 of body fluid

Extracellular fluid (ECF) outside cells

• Interstitial fluid between cell is 80% of ECF

• Plasma in blood is 20% of ECF

FUNCTIONS OF WATER

• Acts as a carrier of nutritive elements to tissues and remove waste materials from tissues.

• It provides the media in which chemical reactions of the body take place.

• The fluidity of blood is because of water

• It is a solvent for electrolytes and regulates the electrolytic balance of the body.

• Maintains the equilibrium of osmotic pressure extended by the solutes dissolved in water.

water

• Is a

• Polar molecule

Water

• Neutral charge

water

• Essential in maintaining acid base balance

WATER BALANCE

• Maintain by a body when

water gained by the body is

equal to the water lost from

the body.

Maintaining Water

Balance

• Is necessary for normal reactions within the cells

• Is maintained by adaptation to changes in water intake and water loss

Fluid homoestasis

• Amount consumed = Amount excretedWater balance

- The only physiological control is through variations in urine

volume. - urine volume regulated by

hormones

DEHYDRATION

• Occurs when fluid loss from the body is abnormally high.

• Electrolyte changes

• Corrected by electrolytes and water

• Excessive perspiration in hot weather, severe diarrhea, fever, vomiting, severe burns, and in uncontrolled diabetes with frequent urination.

ELECTROLYTES

• Substances that conduct an electrical

current in solution.

• Acids, base and salts are soluble in water

are called ELECTROLYTES.

COMMON ELECTROLYTES

• SODIUM CHLORIDE NaCl Na+ + Cl-

• POTASSIUM CHLORIDE KCl K+ + Cl-

• CALCIUM CHLORIDE CaCl2 Ca+2 + 2Cl-

• MAGNESIUM CHLORIDE MgCl2 Mg+2 + 2Cl-

• CALCIUM CARBONATE CaCO3 Ca+2 + CO3-2

• CALCIUM PHOSPHATE Ca3(PO4)2 3Ca+2 + 2PO4-3

• SODIUM SULPHATE Na2SO4 2Na+ + SO4-2

PROPERTIES OF WATER

• HIGH HEAT CAPACITY

–Absorbs and releases large amounts of

heat

–Prevents the sudden changes in body

temperature

• Intense sun exposure

• Chilling winter winds

• Internal events such as vigorous

muscle activity

PROPERTIES OF WATER• POLARITY / SOLVENT PROPERTIES

–Nutrients, respiratory gases (O2 & CO2) and

waste are dissolved in water – act as transport

and exchange medium in the body.

–Substances ---- Blood plasma exchanged

between blood and tissue cells------} Interstitial

fluid

PROPERTIES OF WATER• CHEMICAL REACTIVITY

–Important reactant in a chemical reactions

–Examples

• To digest foods

• Breakdown biological molecules

When bones meet at a joint, they need a fluid between the bones to prevent scraping against each other.That fluid is called a synovial fluid, which is made mainly of water.Many internal organs have fluid around them to keep them protected. Examples:

Brain: Cerebro-spinal fluidLungs: Pleural FluidEyes: Mix of fluids.

During pregnancy the fetus is surrounded by watery amniotic fluid

Water As A Lubricant

Synovial

Fluid

PROPERTIES OF WATER• CUSHIONING

–Serves a protective function

–Forms:

• Cerebrospinal fluid (CSF ) – cushion around

the brain

• Amniotic fluid – surrounds a developing

fetus and protecting as well

–Water as lubricant – prevents friction

–Synovial fluid – within joint cavities prevents

friction as bones move