Physiology of Body Fluid
3
parts of body fluids,
the intracellular (ICF) and extracellular (blood plasma), intertisial. The
intracellular fluid is inside of
the cells and extracellular is
outside of cell. Extracellular fluid
(ECF) divided into two intravascular fluid (located in the blood vessels) and
liquids intertisial is outside the cell and
outside the blood vessels.
Distribution of Body Fluids
Water is the largest component of the body, about 45-75% of total
body weight, the bigger of it is intracellular (about 60%) and remaining of it is extracellular fluid with 25% in the
intravascular and the 75% in intertisial. Bodyfat is free
water, so that
thin has more
water than the amount of fat.
Distribution of body fluids is relatively
dependent on the size of the body itself.
- adult 60%
- child 60 – 77%
- infant 77%
- embrio 97%
- elderly 40 – 50 %
the elderly, the percentage of total body fluid is reduced because
it is already experiencing loss
of tissue.
- intracellular volume = total body water – extracellular volume
- interstitial fluid volume = extracellular fluid volume – plasma volume
- total bloods volume = plasma volume / (1 - hematocrite)
Function of Body Fluids
·
give shape to the body
·
regulation of body temperature
·
role in various functions of lubrication
·
as a cushion
·
as a solvent and tranfortation of various
nutrients and electrolytes
·
media for the various chemical reactions in the body
·
for physical
work performance
Regulation of Body Fluid
The body has
regulatory mechanisms to maintain
the composition of the liquid so that the equilibrium
conditions or fixed.
Many organs are
involved in the mechanism.
Normal
fluid requirement is 35 cc /bodyweight/day. However, when averaged, needs
intake (input) water in adults is 1500 cc of liquid ingestion, food 700 cc, 200 cc water oxidation is a total of
2400 cc / day. As for the regulation of body fluid balance are body fluid
disposal mechanism involving various organs. Organ is through the skin in the
form of 300-400 cc and evaporation of sweat, but depending on the activity and
temperature. Of lung 300-400 cc of water vapor in the form of expiration. From
GIT about 200 cc / day and will increase in cases of diarrhea. Spending most of
water occurs in the kidney, about 1200-1500 cc /day.
When the extracellular fluid volume
deficit, there will be some mechanism :
·
produced
ADH (anti-diuretic hormone) which serves to reabsorption of water
·
Aldosterone
is produced by the adrenal corteks, serves to reabsorption of Na. effect on the
increase in extracellular water
·
jukstaglomerural
cells released renin kidney function to vasoconstriction and aldosterone
secretion.
Body Fluids Tranfortation Process
a.
Diffusion
Displacement
of particles passing through the membrane permeable and thus the two
compartments of solution or gas to equilibrium. Electric particles can diffuse
as ions of different charge can attract. Speed of
diffusion (a continuous movement of molecules in a solution or gas) is
influenced by:
·
the
size of molecules (small molecules diffuse faster than large molecules)
·
concentration
of molecules (molecules move from high concentration to low concentration)
·
solution
temperature (higher temperatures increase the rate of diffusion)
b.
Osmosis
The solvent
moves across the membrane into a higher concentrated
solution. Osmotic pressure is formed when two different
solutions that are restricted a selectively permeable
membrane. The process of osmosis (movement of a
solvent from low
concentration to high concentration),
influenced by:
·
movement of water
·
semipermeabilitas membrane.
c.
Active transfort
It is the
process of moving molecules or ions that have
electrochemical gradient from areas
of lower concentration toward higher concentrations. In this process requires ATP
molecules to cross the cell
membrane.
d.
Hidrostatic Pressure
The power of
liquid pressure for
resistance against blood vessel walls. Hydrostatic pressure
is between arteries and veins (capillaries) that the solution moves from the capillaries into
intertisial beautiful. Hydrostatic pressure is determined by:
·
strength of the heart pump
·
velocity of blood flow
·
arterial blood pressure
·
venous blood pressure
e.
filtrastion
Filtration
is influenced by the presence of arterial and capillary
hydrostatic pressure higher than intertisial
space. Movement of liquid through the permeable membrane from a high pressure hidrostatic
to a lower pressure hidrostatic.
Composition of Body
electrolyte
electrolyte
|
Intracell
(mEq/L)
|
Extracell
(mEq/L)
|
Na
K
Ca
Mg
Cl
HCO3
phosphat
(HPO4)
sulfat
(SO4)
|
15-20
150-155
1-2
27-29
1-4
10-12
100-104
2
|
135-154
3,5-5
4,5-5,5
4,5-5,5
98-106
25-27
1,7-1,4
1
|
f.
Colloid Osmotic Pressure
Formed
by the colloidal solution (protein or substance that can not diffuse) in
plasma. Colloid osmotic pressure causes fluid shifts between the intravascular
and intertisial through a semi-permeable layer. This is because the protein in
intravascular 16x larger than intertisial liquids, liquids into capiler or
compartment of the blood vessels when the heart pumping effectively.
Body Electrolyte
Body electrolyte
, can dissolve in water or in other
solvents. Electrolyte has a
specific physiological functions in the body such
as in the work process neuromuscular
junction. Electrolytes are positively
charged (cationic), usually a
metal element, and negatively charged (anionic), a non-metallic element.
Some of the major cations in the body are
sodium (Na +), potassium (K +),
calcium (Ca ²
+), magnesium (Mg
² +). While
the min anion of body is chloride (Cl ˉ),
bicarbonate (HCO3 ˉ), phosphate (HPO4 ˉ).
a. Sodium
The basic function of
sodium is to regulate the ECF volume , increased membrane permeability,
regulate vascular osmotic pressure, control the distribution of intracellular
and extracellular fluid, plays a role in delivery nerves inpuls, maintain
neuromuscular irritability.
b. Potasium
Basic
function of potassium is to regulate ICF, support the
transmission nerves inpuls, play
/ support contraction
of skeletal muscle and smooth muscle, help
enzymatic reactions in the metabolism of
carbohydrates and amino acids into protein restructuring, acid-base balance (switching places with hydrogen ions).
c. Calcium
The basic function of
calcium is to support the strength and constituent of bones and teeth, forming
the thickness and strength of cell membranes, helps the transmission of nerves
impulses , decrease neuromuscular excitability, blood clotting material, helps the absorption and use of
vitamin B12, activate the enzyme reactions and hormone secretion.
d. Magnecium
The basic function of magnesium is to activate the enzyme system, mostly in
conjunction with vitamin B
metabolism and the use of K, Ca and protein. Helps regulation
of levels of serum calcium, phosphorus and calcium. Helping
neuromuscular activity.
Acid-Base Balance
Acid-base
balance with respect to homeostasis
of hydrogen ion concentration in the
extracellular fluid. Little
change in the hydrogen ion
concentration will lead to changes in the intracellular
chemical reactions. The pH Marks are used to indicate of hydrogen ion concentration in body fluids, normally about 7.35 to
7.45. hydrogen ions (H +), is positively
charged protons. The presence of
a certain concentration of hydrogen
ions causes a
solution to be in the acid,
neutral or alkaline
(base). Elevated levels of H + causes a sour(acid) condition. When H + is reduced, the solution becomes alkaline and
the pH increases, the solution under alkaline
conditions. Acid pH <7, neutral pH
= 7, alkaline pH>
7.
Body fluids
have a pH of 7.34 to 7.45. said acidosis if
pH <7.35 (increased
hydrogen ion concentration)
and said alkalosis
when the pH> 7.45 (hydrogen ion concentration decreases).
Regulation of Acid-Base Balance
The body has
three systems of control in the regulation of acid base balance to
overcome or avoid acidic or alkaline
conditions. The system is a buffer system,
respiratory and kidney.
a. Buffer System
All of
body fluid are equipped with acid-base buffer system (ie several chemical compounds that can change when the concentration of hydrogen ions in a solution of acid or base). Buffer system reacts
when there is a change in the concentration of hydrogen ions.
There are
several chemical buffer systems in body fluids, bicarbonate-carbonic acid
system (carbonate system) is the main buffer system. Carbonate
system consists of carbonic acid (H2CO3 → HCO3
ˉ + H +) and sodium bicarbonate (NaHCO3 → HCO3
ˉ + Na +). In ektraseluler
fluid, the pH can
be restored to normal by this buffer system
because carbonic acid
is a weak acid and bicarbonate is a weak base.
In a chemical
reaction can be described as follows
CO2 + H2O ↔ H2CO3 ↔ HCO3ˉ
+ H+
If there is an increase of hydrogen ions in the extracellular concentration, the reaction will lead to the left, but when a decline in the concentration of hydrogen ions, the reaction will lead to the right.
b. Respiration System
Regulation
of acid-base balance on respiration by controlling the levels of carbon dioxide
(CO2) emissions. In ektraseluler fluid, metabolism rate will affect the amount
of carbon dioxide. CO2 is continuously formed in different intracellular
metabolic processes. Mechanism of regulation of respiration will respond shortly
after a change level of CO2. As CO2 increases in extracellular fluid, the
breathing will be fast and deep, so CO2 can be removed be the expiration.
c. Regulation of Hydrogen Ions concentration by Kidney
The
kidneys regulate the pH of the extracellular fluid by releasing hydrogen ions
or bicarbonate ions (HCO3 ˉ) of body fluids. When the concentration of
bicarbonate over normal then the kidneys will dischard of it so that the urine
becomes alkaline, when the hydrogen discherged the urine becomes acidic. Regulation
of pH by the kidneys can not be fast but it will take several hours or days to
restore the acid-base balance.
