Cairan tubuh dan elektrolit Dr.H.Hasrul Han Bag: Patologi klinik FK Unsri
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Cairan tubuh danelektrolit
Dr.H.Hasrul Han
Bag: Patologi klinik FK Unsri
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Body Fluids - distribution
Body fluids constitute 55-
60% of body mass
• Higher in males due to
greater muscle mass and
lower fat
Total body water declines
throughout life with
changes in muscle mass
and fat
Water occupies 2 main
fluid compartments:
• Intracellular (~2/3 of
total water)
•
Extracellular (~1/3 totalwater)
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Water balance
Normally body fluid volumeremains constant
• water loss = water gain
Water gain:
• ~60% ingested liquids
• ~30% ingested in foods
• ~10% metabolic water(from oxidation)
Water loss:
•
~4% faeces• ~28% insensible water loss
(skin & lungs)
• ~8% perspiration
• ~60% urine
Additional fluid loss inmenstrual flow in females ofre roductive a e
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Regulation of body water gain and
loss
Regulation of body water gaindepends mainly on regulatingvolume of water intake• Thirst centre in hypothalamus
governs urge to drink
Thirst centre stimulated by :
• Nerve impulses fromosmoreceptors in hypothalamus in PV or in plasma osmolality
• Hypothalamic osmoreceptors lose waterto plasma
Increased transmission of nerveimpulses to thirst centre
• dry mouth and pharynx - lesssaliva from blood plasma
• in PV = BP increased angiotensin II (via JGA)
• stimulates thirst centre
Regulation of body water (andsolute) loss depends mainly on
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Fluid Balance
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Water loss
Ambient air temperature
Solar and thermal radiation
Water vapor pressure (humidity)
Solutes and wastes to be excreted Amount and timing of activity
Amount of water intake
Physiological, behavioral, andanatomical adaptations to reducewater loss
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Insensible water loss
(unaware of)
Not precisely regulated
Evaporation (respiration and skin)
Independent of sweating(anhydrosis)
Minimized by cholesterol-filledcornified layer of skin (barrier)
Increase loss in burn patients (10x)
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Sweating
Highly variable
Dependent on physical activity andenvironment temperature
↑ water intake via thirst mechanism
Loss via feces Normally small amount
Severe during diarrhea
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Water loss via kidney
The most important regulator of water and
electrolyte balance Several mechanisms controlling the rate of
excretion
↓ water excretion (dehydration), ↑ excretion
with ↑ increased intake (same for electrolyte) Kidneys adjust the excretion rate to match
intake and disease state
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Body Fluid Compartments
Extracellular• Interstitial fluid and plasma (non-
cellular part of blood)
Transcellular (specialized type ofextracellular fluid)
• Cerebrospinal fluid, intraocular fluid,GI tract, potential fluid (peritoneal, joint space)
Intracellular
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Fluid andelectrolytescome into theplasma thenredistribute to
the other fluidcompartmentsover time.Note also the
lymphatics asa recirculatorof plasmaproteins
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Body Fluid Compartments
Total body water - 50-60 % of body weight
• decrease with age, gender and obesity
Intracellular water - 40% of body weight
• 75 trillion cells
• Similar composition in different species
Extracellular water - 20% of body weight
• % is important in fluid therapy• Transcellular accounts for ~ 1-2 liters
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Plasma
Plasma is the liquid portion of the blood that is
separated from the blood cells by centrifugation. One of the characteristics of plasma is that it clots
easily.
Serum plus clotting factors is plasma, and clottedplasma yields serum (as an interesting aside,
"serum" is Latin for whey, the liquid portion ofclotted milk removed in making cheese).
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Plasma
Exchanges substances withinterstitial fluid via pores of thecapillary membrane
Pores permeable to all solutes inextracellular fluid, except proteins
Plasma have higher proteinconcentration
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Composition of extracellular and
intracellular fluids
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Theserepresent thenon-electrolytes in
the plasma.They alsocontributeosmolarity to
the plasma orextracellularfluid.
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Intracellular volume• Can not be measured directly
• Calculated as Total body water -Extracellular volume
Plasma volume•
Indicator can not permeate capillarymembrane
• Most common 125I-albumin, alsoEvans blue dye (T-1824)
Interstitial volume • Can not be measured directly
• Calculated as Extracellular volume -Plasma volume
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Forces impacting fluid distribution
Plasma vs Interstitial Space
• Balance between Hydrostatic and
Colloid Osmotic forces across thecapillary membranes
Intracellular vs Extracellular• Osmotic effect (e.g. electrolytes)
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Osmosis
Osmosis is the net movement of
water molecules over a partiallypermeable membrane from an areaof less osmotic potential to an areaof more negative osmotic potential.
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Excessive loss of H2O from
ECF
1 2 3
ECF osmotic
pressure rises Cells lose H2O
to ECF by
osmosis; cells
shrink
(a) Mechanism of dehydration
Osmosis
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Osmosis
Excessive H2O enters
the ECF
1 2
ECF osmotic
pressure falls
3 H2O moves into
cells by osmosis;
cells swell
(b) Mechanism of hypotonic hydration
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Osmotic Pressure
Determined by number of particles perunit volume, not by mass! (Molar
Concentration)
1 molecule of Albumin (mw 70000) and 1molecule of Glucose (mw 180) has sameosmotic effect
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What is the osmotic pressure of a 0.9%
NaCl solution?
0.9 % NaCl solution= 0.9g in 100 ml ofsolution or 9g/1L
MW of NaCl =58.5
X mM=X mg/mw x 1000ml/ X ml
X mM=900mg/58.5 x 1000/100
154 mM = 154 mOsm
But wait, NaCl dissociates. So 154 x 2=308mOsm/L
Potential osmotic pressure would be 308 x19.3 mm Hg/mOsm/L or 5944 mm Hg
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What is the osmotic pressure of a 5%
glucose solution?
Glucose mw=180
5g of glucose in 100mL of solution
X mM=5000 mg/180 x1000ml/100mL
278 mM = 278 mOsm Potential osmotic pressure would be
278 x 19.3 mm Hg/mOsm/L or 5366mm Hg
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Osmolarity of body fluids
Interstitial fluid and plasma (80% Na+
and Cl- ions)
Intracellular fluid (50% K+ ions)
Total osmolarity of each around 300mOsm/L
Plasma 1 mOsm/L greater because ofosmotic affect of plasma proteins (20mmHg greater pressure in the
capillaries)
F h i i ll l d
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Factors that impact intracellular and
extracellular volume
Ingestion of water
Dehydration
IV infusion of differentsolutions
Loss of fluid via GI tract
Loss via sweat
Loss via kidneys
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Important principles for fluid therapy
Water moves rapidly across cellmembranes
• Osmolarity between compartments
will be almost exactly except for afew minutes after one changes
Cell membranes are almost
completely impermeable to manysolutes
• Osmoles remains constant, unlesssolutes are added or lost from the
extracellular compartment
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Edema Formation
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Edema Formation
“Excess fluid in body tissue” Most cases in the extracellular fluid
compartment
Can also occur in the intracellular fluidcompartment as well
Extracellular - pitting edema Decreased kidney excretion of salt andwater
Disease state (acute glomerulonephritis) with failure to filtrate
adequate amounts of fluid
Decreased plasma proteinsFailure of body to produce normal amounts of proteinsLeakage of proteins from plasma
Decreased plasma proteins (con’t)
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Decreased plasma proteins (con t)
1. Nephrotic syndrome (damage to themembranes of the renal glomeruli). Seriousedema when plasma protein falls below
2.5g/100ml.2. Cirrhosis of the liver (hepatic tissue fibrosis). ↓ protein synthesis leading to ↓ colloid osmoticpressure.
Elektrolition in the body fluid
1. Kation (Na,K,Ca,Mg)
2. Anion (Cl)
3. Penting pada perawatan penyakitakut
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Tujuan:
D/ dan Th/ gangguan elektrolit
Monitor hasil Th/
Mencegah komplikasi
C a r a :
Flame emission spectrophotometry
Ion selective electrode (ISE) Spectrofotometer kinetik
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Fungsi Kation
Na :tek. Osmotik CES, aktifitas neuromuskuler,mempengaruhi asam basa, Cldan K serta membantu pengeluar-an air.
K: tek.Osmotik CIS, aktifitas enzym danneuromuskuler, mempengaruhi asam basadan fungsi ginjal
Ca: aktifitas neuromuskuler,perkem-
bangan rangka, pembekuan darah, Mg: aktifitas intraseluler dan
mempengaruhi level Na,K,Ca dan fosfor
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Fungsi Anion
Cl: mempengaruhi asam basa, menjaga tek.Osmotik darah.
HCO3: sistem bufer yg mengatur pHHPO4: mengatur level Ca, metabolisme
energi dan asam basa