guyton & hall fisio : capitulo 25 los compartmentos liquidos del cuerpo

U N I T V

Textbook of Medical Physiology, 11th Edition

GUYTON & HALL

Capitulo 25:Los Compartimientos Líquidos del Cuerpo:

Liquido Extracelular y Liquido Intracelular; Liquido Intersticial y Edema

Diapositivas por John E. Hall, Ph.D.Traducción por Rene R. García – Szabó, M.D., Ph.D.

Figure 25-1;Guyton and Hall

Regulación del Líquido CorporalRegulación del Líquido Corporal

Balance Líquido (ml/dia) – Adulto de 70 kg

EntradasLíquidos ingeridos 2100A partir del metabolismo 200

Normal

Salidas Insensibles - piel 350Insensibles - pulmones 350Sudor 100Heces 100Urina 1400

Dieta Alta en Sal

4100 2004300

350 350 100 10034004300

El Concepto de Balance

El balance es necesario, en el mantenimiento a largo plazo de la vida.

Perdidas liquidas = Ingesta liquidaPerdidas electrolíticas = Ingesta electrolítica

La ingesta liquida: es regulada por el mecanismo de la sed, hábitos La ingesta electrolítica: es regida por habitos dieteticos.Las salidas liquidas: son reguladas principalmente por los riñones.Las salidas electrolíticas: re son reguladas principalmente por los riñones.

Effect of increasing sodium intake 10-fold on urinary sodium excretion and extracellular fluid volume

Fluid Balance (ml/day) – 70 kg Adult

IntakeFluids ingested 2100 ?From metabolism 200 200

2300 ?Output

Insensible - skin 350 350 Insensible - lungs 350 650Sweat 100 5000 Feces 100 100Urine 1400 500

2300 6600

Normal Heavy Exercise

Body Fluid DistributionBody Fluid Distribution

70 kg adult

Total Body Water in Relation to Body Weight:Effects of Gender, Body Build and Age

Body Build TBW (%) TBW (%) TBW (%) Adult Male Adult Female Infant

Normal 60 50 70

Lean 70 60 80

Obese 50 42 60

Increasing age decreases TBW %

Increasing obesity decreases TBW %

Total Body Water in Relation to Body Weight:Effects of Gender, Body Build and Age****aqui grupo #3****

Body Build TBW (%) TBW (%) TBW (%) Adult Male Adult Female Infant

Normal 60 50 70

Lean 70 60 80

Obese 50 42 60

Increasing age decreases TBW %

Increasing obesity decreases TBW %

Indicator Dilution Principle

Volume (B) = Indicator Mass (B) Concentration (B)

Valid if:• Indicator disperses only in compartment measured

• Indicator disperses evenly in compartment

• Indicator not metabolized or excreted

Measuring Body Fluid Compartments

Total Body water:• D2O, 3H2O, antipyrine (C11H12N2O)

Intracellular fluid = total body water - extracellular fluid

Extracellular fluid volume:• 22Na, inulin, thiosulfate

Plasma volume:

• 125I-albumin, 51Cr-red blood cells

blood volume = plasma volume /(1 -HCT)plasma volume = blood volume x (1 -HCT)

Interstitial fluid vol. = Extracell fluid vol. - plasma vol.

Control of Body Fluid Distribution

Distribution across capillaries: determined by hydrostatic and

colloid osmotic forces

Distribution across cell membranes:determined by osmotic forces (mainly from electrolytes)

Osmotic Pressure ()

= CRTC = concentration (osm/L)R = gas constant (62.3 if = mmHg)T = Kelvino = 273o + Co

= 310o (normal body temp.) = 19,300 mmHg / Osm

If C = mOsm/L,= C x 19.3 mmHg

Principles of Osmotic Equilibria

• H2O moves across cell membranes easilyi.e. ECFosm = ICFosm

0 10 20 30

OsmolaritymOsm/

Normal State

VOLUME (L)

ICF ECF

28 L 14 L

7980 mOsm 3920 mOsm

• Many solutes (e.g. NaCl) are relatively impermeant to cell membranes

• Hydrostatic pressure differences have onlya small effect on fluid movement across cell membrane

Figure 25-5; Guyton and Hall

Isotonic(no change)

Hypertonic(cell

shrinks)

Hypotonic(cell

swells)

Effects of solutions on Cell Volume

Isosmotic - has same osmolarity as body fluids

Hyperosmotic - higher osmolarity than body fluids

Hyposmotic- lower osmolarity than body fluids

• What is the osmolarity of a

5 % glucose solution?

• Is the solution hyperosmotic, hypo-osmotic, or isosmotic?

Question

Osmolarity of a 5 % Glucose Solution

MW glucose = 180 gm/mol5 % = 5 gm/100 ml = 50 gm/L

Isosmotic

50 gm x 1 mol = .278 mol =L 180 gm L

278 mOsmL

• What is the osmolarity of a 3.0% NaCl solution?

• Is the solution hypertonic, hypotonic, or isotonic?

Question

Osmolarity of a 3% NaCl Solution

MW NaCl = 58.53 % = 3 gm/100ml = 30 gm/L30 gm x 1 mol = .513 mol = 513 mmol

L L LFor NaCl, 1 mmol = 2 mOsm513 mmol x 2 mOsm = 1026 mOsm

LL mmol

Hypertonic

58.5 gm

What are the changes in the following variables after giving 2.0 liters of 0.9% NaCl (Isotonic) i.v.****aqui grupo No. 1***

Extracellular Fluid Volume?Extracellular Fluid Osmolarity?Intracellular Fluid Volume?Intracellular Fluid Osmolarity?

0 10 20 30

Normal State

VOLUME (L)

ECFICF A.

Effect of adding 2 L of 0.9 % NaCl ?

What are the Changes in the following variables after giving 2.0 liters of

water i.v.?

0 10 20 30

/LNormal State

VOLUME (L)

ECFICF A.

Effect of adding 2 L of water ?

What are the Changes in the following variables after giving 2.0 liters of

3.0% NaCl i.v.?

0 10 20 30

/LNormal State

VOLUME (L)

ECFICF A.

Effect of adding 2 L of 3 % NaCl ?

What are the Changes in the following variables after giving 2.0

liters of 3.0% NaCl i.v.?

> 2.0 Liters

Normal State A. Add Isotonic NaCl

B. Add Hypertonic NaCl

C.Add Water (or hypotonicFluids)

0 10 20 30 40

Volume (L)

Which of the diagrams below representssimple dehydration caused by water loss?

0 10 20 30 40Volume (L)

• Calculation of intracellular and extracellular fluid volumes and osmolarities after fluid

administration.

Osmotic Equilibrium Problems

Effect of Infusing 2.0 liters of 3% NaCl to a 70 kg Person

Assume: 1) no excretion of water or solutes, 2) osmotic equilibrium, 3) ECF =20% body wt, ICF =40 % body wt.

• What is the extracellular osmolarity?

• What are the intra- and extracellular fluid volumes?

Step 1. Initial conditions

Volume Conc. Total(L) mOsm/L mOsm

Extracell. Fluid (.2 x 70) = 280

Intracell. Fluid (.4 x 70) = 280

Total Fluid = 280

Assume: extracell vol. = 20 % BW; intracell. vol. = 40 % BW

11,760

Osmolarity of a 3% NaCl Solution

MW NaCl = 58.53% = 3 gm/100ml = 30 gm/L

513 mmol x 2 mOsm = 1026 mOsmLL mmol

30 gm x 1 mol = .513 mol = 513 mmolL L L58.5 gm

For NaCl, 1 mmol = 2 mOsm

2.0 L x 1026 mOsm/L = 2052 mOsm

Extracell. fluid 14+2= ? 3920+2052=

Intracell. fluid 28 +0= 28 280 7840 + 0 = 7840

Total Fluid 42+2= ? 11,760+2052= no equilibrium

Step 2. Instantaneous Effect Volume Conc. Total (L) mOsm/L mOsm

13,812

Extracell. fluid 3920+2052=

Intracell. fluid 7840 + 0 = 7840

Total Fluid 42+2= 44 11,760+2052=

Step 2. After osmotic equilibrium Volume Conc. Total (L) mOsm/L mOsm

13,812

Net effect: Extracell. Volume by 5.0 L Intracell volume by 3.0 L

Abnormalities of ExtracellularFluid Na+ Concentration

(Osmolarity)

Hyponatremia : Na+ conc.

Hypernatremia : Na+ conc.

Abnormalities of ExtracellularFluid Na+ Concentration

Normal plasma [Na+] = 140-145 mmol / L

• water loss • Na+ excess

• water excess• Na+ loss

Consequences of Hyponatremia and Hypernatremia

• Water moves in and out of cells cells swell or shrink

• This has profound effects on the brain. - Neurologic function is altered

- Rapid shrinking can tear vessels and cause hemorrhage

- Rapid swelling can cause herniation Because the skull is rigid, the brain cannot increase its volume by more than 10% without being forced down the neck (herniation).

Defense of Cell Volume

• Extracellular hypertonicity increases expression of genes encoding proteins that increase intracellular osmoles.- Membrane transporters (Na+-H+- exchanger)- Enzymes (e.g. aldose reductase that synthesize

intracellular solutes (e.g. sorbital)

• Clinical significance: Rapid changes in extracellular fluid tonicity alter cell volume and cause neurologic complications, while slow changes have much less effect on cell volume and much less clinical effect.

Hypernatremia

With Decreased Extracellular Fluid Volume(water loss: hyperosmotic dehydration)

What lab measurements would help in diagnosis?

With Increased Extracellular Fluid Volume( NaCl excess: hyperosmotic overhydration)

• Hematocrit, plasma proteins• Urine volume

Hypernatremia

With Decreased Extracellular Fluid Volume(water loss: hyperosmotic dehydration)

• Large volume of dilute urine - diabetes insipidus

• Increased hematocrit, plasma proteins

• Small volume of concentrated urine - dehydration, excess sweating

- lack of ADH (“central” diabetes insipidus)- “nephrogenic” diabetes insipidus

Hypernatremia

With Increased Extracellular Fluid Volume( NaCl excess: hyperosmotic overhydration)

• Primary aldosteronism• Cushing’s syndrome

Usually the Hypernatremia is mild in these examples,but the person may have very low plasma K +

(hypokalemia).

• Decreased hematocrit, plasma proteins

A 52 year old male comes to you office complaining of frequent headaches and large volumes of urine. His medical history indicates that he is being treated with lithium for manic-depressive disorder. your laboratory tests give the following results:

Body weight = 70 kgPlasma Na+ = 162 mmol/LPlasma K+ = 4.7 mmol/LBlood pressure = 102/65 mmHgHeart rate = 92 beats/minHematocrit = 0.50 Plasma protein = 8.40

• What are some potential causes of his hypernatremia?

• What additional tests would help in making a differential diagnosis?

Hypernatremia – Clinical Case

Hypernatremia****aqui preguntas del examen parcial****

A. With Increased Extracellular Fluid Volume( NaCl excess: hyperosmotic overhydration)

• Primary aldosteronism• Cushing’s syndrome

B. With Decreased Extracellular Fluid Volume(water loss: hyperosmotic dehydration)

• Large volume of dilute urine - diabetes insipidus- lack of ADH (“central” diabetes insipidus)- “nephrogenic” diabetes insipidus

• Small volume of concentrated urine - dehydration, excess sweating

Hyponatremia

With Decreased Extracellular Fluid Volume ( NaCl Loss: hypo-osmotic dehydration)

• diarrhea, vomiting• Addison’s disease (decreased aldosterone)• overuse of diuretics• sodium wasting renal diseases

Increased hematocrit, plasma proteins

Hyponatremia

With Increased Extracellular Fluid Volume(water excess: hypo-osmotic overhydration)

• Inappropriate ADH syndrome• Bronchogenic tumors• Fibrosing tuberculosis lung lesions• Circulatory failure (e.g., congestive heart

failure)

Decreased hematocrit, plasma proteins

Intracellular Edema

• Hyponatremia

• Depression of tissue metabolic systems(e.g. hypothyroidism)

• Inadequate tissue nutrition(e.g. ischemia)

• Inflammation of tissues (increased cell membrane permeability)

Determinants of Capillary Filtration

Causes of Extracellular Edema (increased interstitial fluid volume)

• Increased Capillary Filtration

• Failure of lymphatics to Return Interstitial Fluid to Circulation

Extracellular Edema

CapillaryPressure (Pc)

Plasma ColloidOsmotic Pressure ( c)

InterstitialFluid Pressure (Pisf)

Interstitial ColloidOsmotic Pressure (isf)

FILT = Kf (Pc - Pisf - c + isf)

Causes of Increased Capillary Filtration

FILT = Kf (Pc - Pisf - c + isf)

Increased Kf: toxins, ischemic damage, infections, etc.Increased Pc:• increased arterial pressure, excess fluid retention, • decreased arteriolar resistance• increased venous resistance, increased venous pressure

Decreased c:• nephrotic syndrome• cirrhosis• malnutrition

Normal Filtration

FILT = Kf x Net Filt Pressure= 6.6 x ( 17.3 - (-3) - 28 +8)= 6.6 x ( + 0.3)= 1.89 ml/min

FILT = 2722 ml/day

Where does all of this fluid (and protein in it) go?

Figure 25-1; Guyton and Hall

X Lymphatic Failure = Edema

Lymphatic Failure and Edema

Safety Factors Against Edema

• Low compliance of interstitium when = 3 mmHg interstitial fluid pressure is negative

• Increased lymph flow = 7 mmHg

• “ Washdown” of interstitial protein = 7 mmHg at high lymph flow rates

Total Safety factor = 17 mmHg

- 8 - 4 0 + 4

Interstitial Fluid Pressure (mmHg)

FreeFluid

GelFluid

Low compliance

HighCompliance

Low Tissue Compliance and Negative Intersititial Fluid Hydrostatic Pressure

InterstitialVolume

Interstitial FluidHydrostatic Pressure

Capillary Filtration

Increased Lymph Flow

InterstitialVolume

Lymph Flow

Lymph Flow( x normal)

- 6 - 4 - 2 0 2 4Interstitial Fluid Pressure ( mmHg)

Effect of Interstitial Fluid Pressure on Lymph Flow

0 20 40 60 80 100 120 140 160 180

Plasma Protein Concentration

Rate of Non-Visceral Lymph Flow (ml/hr)

Washdown of Interstitial Proteins

“Washdown” of Interstitial Fluid Proteins

InterstitialVolume

Interstitial FluidOncotic Pressure

Capillary Filtration

Lymph Flow

Protein Removal From Tissues

Saftey Factors Against Edema

• Low compliance of interstitium when = 3 mmHg interstitial fluid pressure is negative

• Increased lymph flow = 7 mmHg

• “ Washdown of interstitial protein = 7 mmHg at high lymph flow rates

Total Safety factor = 17 mmHg

Conditions Causing Edema

1. High capillary hydrostatic pressure• Excess fluid retention by kidneys- acute or chronic kidney failure- glomerulonephritis- mineralocorticoid excess

1. High capillary hydrostatic pressure• Decreased arteriolar resistance

- vasodilator drugs- autonomic insufficiency

• Increased venous pressure- congestive heart failure- high output heart failure (e.g. anemia)- venous obstruction- venous valve failure- cirrhosis

2. Decreased plasma proteins (low oncotic pressure)

• Loss of proteins- burns, wounds- nephrosis- gastroenteropathy

• Failure to produce proteins- malnutrition (“kwashiorkor”)- cirrhosis- analbuminemia

3. Increased capillary permeability• Immune reactions (histamine)• Toxins• Burns• Prolonged ischemia• Vitamin deficiency (e.g. vitamin C)• Pre-eclampsia and eclampsia in

pregnancy

4. Blockage of lymphatics• Cancer• Surgery• Infections (e.g. filaria nematodes)

guyton & hall fisio : capitulo 25 los compartmentos liquidos del cuerpo

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