Body Fluids by Habeeb.

BODY FLUIDS:

Body is formed by solids & fluids. Fluid part is more than two third of the whole body, water forms most of the fluid part of the body. In human being, the total body water varies from 45% to 75%.

Composition of body fluids:

Body fluid contains water and solids , solids are organic and inorganic substances.

Organic Substances:

Glucose, amino_ acid & other proteins , fatty acids and other lipids , hormones and enzymes.

Inorganic Substances:

Inorganic Substances present in body fluids are Na+ , K+ , Ca++ Mg++ , Cl- , HCO3- , PO4-, SO4-.

ECF contains large quantity of Na+ , Cl- , HCO3- , glucose, fatty acids and oxygen.

ICF contains large quantity/ies of K+ , Mg++ , PO4- , SO4- , and  proteins.

The PH of ECF is  7.4

The PH of ICF is 7.0

Compartments And Distribution Of Body Fluids:

Total water in the body is about 40L distributed into two major compartments.

Intracellular Fluid:

Its volume is 22L and its forms 53% of the total body water.

Extracellular Fluid:

Its volume is 18L and it forms 45% of the total body water.

ECF is divided into 5 subunits:

1) Interstitial fluid and Lymph (20%) .

2) plasma 7.5% .

3) Fluid in bone (7.5%) .

4) Fluid in dense connective tissue like cartilage 7.5% .

5) Transcellular fluid 2.5% that include:

a . Cereberospinal fluid.

b . Intracellular Fluid.

c . Digestive juices.

d . Serous fluid , interpleural fluid , pericardial fluid , and peritoneal fluid.

e . Synovial fluid in joints.

f . Fluid in urinary tract.

Chart of distribution:

Water :

Water is the most abundantcomponent in living cell . Its amount varies app:  from 70 to 90% life activities occur in the cell due to the presence of water.

The ability of water to play its importance in biological systems is due to the basic chemistry of the molecule. The chemical formula of water is H2O which tell us that two atoms of hydrogen are joined to one atom of oxygen to make up each water molecule.

Water is a polar molecule. It means that it has a very slightly _ve end , _ the oxygen atom and a very slightly +ve end , _ the hydrogen atoms. The separation of electrical charge is called dipole. Which gives the water molecule its very important properties. One of the most important results of their charge separation is the tendency of H2O molecule to form hydrogen bonds.

Structure of water molecule:

Biologically important properties of water:

1) Behave as best solvent.

2) Slow to absorb and release heat ( high heat capacity)

3) High heat of vaporization.

4) An amphoteric molecule.

5) Cohesive forces in water molecule.

Function of Iron:

It play a vital role in cellular respiration.It forms the part of:

Hemoglobin=70%

Myoglobin=3-5%

Ferratin=2-5%

Body cells=3%

Heme-enzymes=0.1%

As xanthine oxidase, cytochromes catalase. Increase or decrease quantity of the iron.........

Macromineral (Sodium ):

Serum Level:      136 - 145 mEq/L .

Dietary Sources :  

Table salt orally or added to prepared food, bread , cheese, milk , whole grains..

Functions:

1 . Principal cation of extra cellular fluid.
2 . Regulates plasma volume.
3 .Regulates acid - base balance.
4 .Regulates osmotic pressure.
5 . Controls nerve and muscle functions as entry of sodium in a nerve or muscle fiber results in its depolarization.
6 . Help in glucose and amino acids absorption (Secondary active transport ).
7 .Regulates Na+  _ K+ ATPase activity.

Modes of Excretion:

 Mainly in :    1 ) sweat.

  POTASSIUM:-

 Serum level 3.5 - 5.5mEq/l.

Diatery sources:

       Citrus fruits , vegetables, meat, legumes, milk.

    FUNCTIONS:

          Principal cation of intracellular fluid.

          Causes repolarization.

          Act as vasodilator.

          Enhances the processes of 

           gluconeogenesis.

          Regulates Na+/k+ ATPase activity.

MODES OF EXCRETION:

       Feces:(10%).
     Urine:(90%).

CALCIUM:-

    Serum level: 4.2-5.2mEq/l

  Diatery sources: Milk and its production, beans, egg yolk, leafy vegetables, supplements like CaCO3.

DISTRIBUTION OF CALCIUM:
       Adult human body contains abut 1100gm of calcium and 99% of its is in skeleton.
The distribution of plasma calcium is as follows :

        DIFFUSIBLE:
 Occur as
        a)-Ionized calcium(50%).
        b)-Complexed to HCO3, Citrate etc.(10%).

     NON-DIFFUSIBLE:
       40% Calcium bound to:
        a)-Albumin.
        b)-Globulin.

CALCIUM IN THE BONES:
      Bone calcium is of two types:
1)- A ready exchangeable reservior (regulates plasma calcium level).
2)-A stable, larger and slowly exchangeable reservoir (concern with bone absorption and remodeling account for 95%of bone formation).

 CALCIUM ABSORPTION:-
    30% -80% of ingested calcium is absorbed ,primarily in the  upper small intestine by the active transport .Some calcium is also absorbed by passive diffusion.

ROLE OF KIDNEY:
    98%-99% of thr filtered calcium in kidney is absorbed,60% reabsorption is occur in proximal  tubules and remainder in the ascending loop of henle and distal tubules.
      FUNCTIONS OF CALCIUM:

     Important consitutents of bone and teeth.
     Regulates blood clotting.
     Regulates nerve and muscles function.
     Maintains the integrity of the capillary wall.
     Act as co-factors and activator for certain  enzymes like phospholipase A2.
     Act as vital second messenger.
     Involved in release of catecholamines in adrenal medulla in response to  cholergenic stimulation.
    Effect of adrenaline on liver cells (to increase guluconeolysis) is partly due to  an increase in calcium ion  within these cells (independent of cyclic AMP).

      MODE OF EXCRETION:
   1)-Feces(400 -800mEq/ day).
   2)- Urine(120- 200mEq/day).

    PHOSPHORUS:-
   Serum level:     In children:4-7 mg/dl.
                               In adults: 3-4.5mg/dl.

 DIATERY SOURCES:   Milk, beans, cereals,egg yolk, meat.

     DISTRIBUTION:
    Total body phosphorus is 500-800 gms of this 85-90% is  in skeleton.Total plasma phosphorus is  12ml/dl comprises of:
 
1. Inorganic phosphorus ( 4 mg / dl ) as PO4-3 , HPO4 - 2 , H2PO4 -1 .

2. Organic phosphorus ( 8 mg / dl ).

Absorption of phosphorus :

Phosphorus is absorbed in its inorganic form in the duodenum & small intestine by active transport and passive diffusion.

Role of kidney :

Inorganic phosphorus is filtered through the glomeruli & 80_ 90% is absorbed.

Modes of Excretion : 
1- feces ( 20 % ) .
2- Urine ( 80 % ) .

FUNCTIONS: 
1- Form  a part of the high energy compounds like ATP , UTP.
2- An important intracellular anion.
3- Bone and tooth development.
4- An important constituent of :

   a) Nucleic acids ( DNA & RNA ) .
   b) phospholipid .
   c) Cell membrane .


Magnesium : 

Serum level :
1.25 _ 2.5 mEq/ L .

Dietary sources :
Nuts, legumes, whole grains.

DISTRIBUTION :

About 21g of magnesium occurs in the body fluids , soft tissue, inorganic matter  of bones . Chiefly it exists as  in intracellular electrolytes.

FUNCTIONS :
1- constituent of bone and teeth.
2- Act as enzyme cofactor.
3- Decrease neuromuscular activity.