Kompartemen Cairan Tubuh (for PSPDG)

7/30/2019 Kompartemen Cairan Tubuh (for PSPDG)

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BODY FLUID

COMPARTEMENTS(KOMPARTEMEN CAIRAN TUBUH)

Oleh:

dr. HUSNIL KADRI, M.Kes

PSPDG Departement

Medical Faculty Of Andalas University

Padang


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Water Intake and Output

Intake = Output


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Fluid Compartments

Water occupies 2 main fluid compartments Intracellular fluid (ICF) about two thirds

by volume, contained in cells

Extracellular fluid (ECF) : Plasma the fluid portion of the blood

Interstitial fluid (IF) fluid in spaces betweencells

Other ECF lymph, cerebrospinal fluid,eye humors, synovial fluid, serous fluid,and gastrointestinal secretions


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Fluid Compartments

Total Body Water: varies with fat

ICF high in K and Mg; ECF high in Na, Cl

Plasma high in protein, but

interstitial fluid low in protein

Smallest compartment (plasma) most important

(intravascular volume thats controlled by kidney)


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Composition of Body Fluids

Water is the universal solvent Solutes are broadly classified into:

Electrolytes inorganic salts, all acids and

bases, and some proteins Nonelectrolytes glucose, lipids, creatinine,

and urea

Electrolytes have greater osmotic power

than nonelectrolytes

Water moves according to osmotic

gradients


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Functions of Body Water

Give structure to the body

Medium / Participates in biological rxns

Medium for transportation

Lubricant

Temp control (600 kcal / L perspiration)


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The Volume and Distribution of

Total Body Water (TBW)

Extracellular Fluid (ECF)~1/3 TBW or 20% body mass

Intracellular Fluid (ICF)~2/3 TBW or 40% body mass

Intravascular

Fluid (~1/4 ECF)

InterstitialFluid (~3/4 ECF)

cell membrane

capillary endothelium28 L H20

10.5 L H20

Plasma = ~3.5 L H20

TBW = ~60% total body mass

Adapted from C.A. Burtis, ed., et. al. Tietz Textbook of Clinical Chemistry. 3rd

ed. Philadelphia: WB SaundersCompany, 1999, pg 1096.


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Extracellular and Intracellular

Extracellular fluids are similar (except for

the high protein content of plasma)

Sodium is the chief cation

Chloride is the major anion

Intracellular fluids have low sodium and

chloride

Potassium is the chief cation

Phosphate is the chief anion


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Extracellular and Intracellular

Sodium and potassium concentrations in

extra- and intracellular fluids are nearly

opposites This reflects the activity of cellular ATP-

dependent sodium-potassium pumps

Electrolytes determine the chemical andphysical reactions of fluids


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Mechanisms Controlling Fluid and

Electrolyte Movement

Diffusion molecules move from high to low concentration

Facilitated diffusion involves carrier molecules

Active transport movement against concentration gradient

requires energy

E.g.: keeping Na out and K in the cells (requires

ATP)


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Fluid Movement Among

Compartments

Compartmental exchange is regulated byosmotic and hydrostatic pressures

Net leakage of fluid from the blood is

picked up by lymphatic vessels andreturned to the bloodstream

Exchanges between interstitial and

intracellular fluids are complex due to theselective permeability of the cellular

membranes


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Water Balance and ECF

Osmolality

To remain properly hydrated, water intake

must equal water output Water intake sources

Ingested fluid (60%) and solid food (30%)

Metabolic water or water of oxidation (10%)


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Water Balance and ECF

Osmolality

Water output

Urine (60%) and feces (4%)

Insensible losses (28%), sweat (8%) Increases in plasma osmolality trigger

thirst and release of antidiuretic hormone

(ADH)


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Regulation of Water Intake

The hypothalamic thirst center is

stimulated:

By a decline in plasma volume of 10%15%

By increases in plasma osmolality of 12%

Via baroreceptor input, angiotensin II, and

other stimuli


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Regulation of Water Intake

Thirst is quenched as soon as we begin to

drink water

Feedback signals that inhibit the thirst

centers include:

Moistening of the mucosa of the mouth and

throat

Activation of stomach and intestinal stretchreceptors


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Regulation of Water Output

Obligatory water losses include:

Insensible water losses from lungs and skin

Water that accompanies undigested food

residues in feces

Obligatory water loss reflects the fact that:

Kidneys excrete 900-1200 mOsm of solutes

to maintain blood homeostasis

Urine solutes must be flushed out of the body

in water


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Influence and Regulation of ADH

Low ADH levels produce dilute urine and

reduced volume of body fluids

High ADH levels produce concentrated

urine

Hypothalamic osmoreceptors trigger or

inhibit ADH release

Factors that specifically trigger ADH

release include prolonged fever; excessivesweating, vomiting, or diarrhea; severe

blood loss; and traumatic burns


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Electrolyte Balance

Electrolytes are salts, acids, and bases,but electrolyte balance usually refers onlyto salt balance

Salts are important for: Neuromuscular excitability Secretory activity

Membrane permeability

Controlling fluid movements Salts enter the body by ingestion and are

lost via perspiration, feces, and urine


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Electrolytes The Ion Components Inside and

Outside the Cells Are Not the Same.

Electrolyte Symbol Reference range

(serum)

Potassium K+ 3.7-5.2 mEq/L

Magnesium Mg2+ 1.8-2.4 mg/dL

Phosphate PO4- 4.5-6.0 mg/dL ( 11 yrs)3.0-4.5 mg/dL ( 12 yrs)

Sodium Na+ 136-145 mEq/L

Chloride Cl- 98-108 mEq/L

Bicarbonate HCO3- 22-32 mEq/L

Calcium Ca2+ 8.9-10.2 mg/L

ICF

ECF

Adapted from Sara Duesterhoefts lecture, 2002.


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Sodium in Fluid and Electrolyte

Balance

Sodium holds a central position in fluid andelectrolyte balance

Sodium salts:Account for 90-95% of all solutes in the ECF Contribute 280 mOsm of the total 300 mOsm

ECF solute concentration

Sodium is the single most abundant cation inthe ECF

Sodium is the only cation exerting significantosmotic pressure


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Disorders of Water Balance:

Dehydration

Water loss exceeds water intake and thebody is in negative fluid balance

Causes include: hemorrhage, severe

burns, prolonged vomiting or diarrhea,profuse sweating, and diuretic abuse

Signs and symptoms:thirst, dry flushed

skin, and oliguria Other consequences include hypovolemic

shock and loss of electrolytes


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Dehydration

Excessive loss of H2O from

ECF12 3ECF osmotic

pressure rises Cells lose H2Oto ECF byosmosis; cells

shrink

(a) Mechanism of dehydration


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Amount of water ingested quickly can leadto cellular overhydration or water

intoxication ECF is diluted sodium content is normal

but excess water is present

The resulting hyponatremia promotes netosmosis into tissue cells, causing swelling


Hypotonic Hydration


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Hypotonic Hydration

Excessive H2O enters

the ECF12 ECF osmotic

pressure falls3 H2O moves into

cells by osmosis;

cells swell

(b) Mechanism of hypotonic hydration


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Sources

1. Beaudoin, D. Electrolytes and ion sensitive

electrodes. PPT. 2003.

2. Ivkovic, A ., Dave, R. Renal review. PPT

3. Kersten. Fluid and electrolytes. PPT.

4. Marieb, EN. Fluid, electrolyte, and acid-base

balance. PPT. Pearson Education, Inc. 2004

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