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BODY FLUID COMPARTMENT AND FLUID BALANCE. Body fluid compartment . ECF also includes lymph, CSF, synovial fluid, aqueous & vitreous humor, endolymph & perilymph and fuild present in pleural, pericardial and peritoneal cavities . - PowerPoint PPT Presentation
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BODY FLUID COMPARTMENT
AND FLUID BALANCE
1
Body fluid compartment ECF also includes
lymph, CSF, synovial fluid, aqueous & vitreous humor,
endolymph & perilymph and fuild present in
pleural, pericardial and peritoneal cavities
2
The osmosis, diffusion, filtration and reabsoption provide for continual exchange of
water and solutes (electrolytes) among different body compartments
Yet, the volume of the fluid in different body compartments remains remarkably stable 3
Dynamics of capillary exchange (Starling’s Law of capillaries)
4
Concentration of
important solutes in ICF, ECF
5
Sources of body water gain and loss
Body fluid volume remains constant because water loss is equal to water gain 6
Sourse of metabolic water
Rate of formation of metabolic water is not regulated7
Regulation of body water gain
Rate of formation of
metabolicwater is not regulated to
maintain homeostasis
Water gain is regulated
mainly by drinking
through thirst
mechanism
2% decrease in body mass due
to fluid loss causes mild dehydration
Baroreceptor
8
Regulation of water and solute
loss This is
mainly done by the
kidneys 9
27_table_01
10
One osmole is 1 gram molecular weight of undissociated solute.
Thus, 180 grams of glucose, which is 1 gram molecular weight of glucose, is equal to 1 osmole of glucose because
glucose does not dissociate.Therefore, 1 gram molecular weight of NaCl (58.5 gm) is
equal to 2 osmole because NaCl dissociates into Na+ and Cl- (and both are osmotically active).
A solution that has 1 osmole of solute dissolved in 1 Kilogram of water is said to have an Osmolality of 1
osmole per kilogram. A solution that has 1 osmole of solute dissolved in 1 liter (1000 ml) of water is said to have an Osmolarity of 1
osmole per liter.
Osmolality vs Osmolarity
11
Principle of OsmosisOsmosis is the net movement of water molecules
through a selectively permeable membrane
During osmosis water molecules pass through a selectively permeable membrane in two ways (1) through the lipid bilayer and (2) through
aquaporins (aqua = water) channels. 12
1. Is a measure of the total number of dissolved particles in a solution 2. Ionic composition of the ICF fluid is different from that of ECF
3. But Osmolarity of ICF is equal to that of ECF.
Osmolarity
13
ECF IS ISOTONICOsmotic equilibrium is maintained rapidly between ICF and ECF
Isotonic fluid gain: e.g Intravenous infusion of isotonic saline (0.9 % NaCl, 5% glcose solution) Isotonic fluid loss: Hemorrhage
No net fluid shift occur 14
ECF IS HYPERTONICWhat happens?
Water moves out of the cells to ECF until osmotic equilibrium is achieved Cells shrink as water leaves them
Neurons dehydration causes disturbances in brain function manifested as mental confusion to coma.
What Causes this?Dehydration due to: Insufficient
water intake Excessive
water loss (vomiting or
diarrhea) Diabetes
Insipidus (deficiency of
ADH)
Accumulation of high levels of osmotically active solutes (urea in kidney
failure) 15
ECF IS HYPOTONICWhat happens?
Water moves into the cells from ECF until osmotic equilibrium is achieved. Pronounced swelling of neurons leads to brain dysfunction
Swelling of muscle leads to muscle weakness.Hypertension and edema caused by expansion of plasma volume.
What Causes this?Over hydration:
Renal failure with inability
to excrete diluted urine
Excessive drinking (transient)
Increase in ADH secretion
Water intoxication:
condition of over hydration,
hypotonicity and cellular swelling
from excess water. 16
Movement of water between body fluid compartments
17
Measurement of fluid volumes in the different body
compartmentsDye-dilution metod
(Indicator-dilution)
18
27_table_02
19
20
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