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Balance of Fluid Intake and Output
Steady-State Balance
a. Daily intake of waterb. Daily loss of water-insensible water loss
c. Fluid loss in sweatd. Water loss in fecese. Water loss by the kidneys
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Body Fluid Compartments
Fig. 25.1 Summary of body fluid regulation, including the major body fluid compartments
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Compartments (cont.)
Body Fluid Compartments
a. Intracellularb. Extracellular-interstitial fluid and blood plasmac. Transcellular-fluids in the synovial, peritoneal,
pericardial, intraocular spaces, and the CSFd. Total body water for men is about 60% and 50%
for womene. Varies with age, gender, and degree of obesity
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Compartments (cont.)
Intracellular Fluid Compartment
a. Constitutes about 40% of the fluid in the averageperson
b. Concentration of substances is similar from cellto cell
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Compartments (cont.)
Extracellular Fluid Compartment
a. Interstitial fluid-makes up about 75% of the fluidb. Blood plasma-makes up 25% of the fluidc. Only real difference between the two types is the
protein composition of the plasma
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Blood Volume
Blood Volume
a. Makes up about 7% of the body weight (5 L)b. 60% plasma and 40% cellsc. Percentages vary according to gender, weight, etc.
Hematocrit
a. Red blood cell fraction of the bloodb. 96% accurate because you cannot pack the cells
completelyc. Males (o.40) and females (o.30)
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Constituents of Extra- and Intracellular Fluids
Fig. 25.2 Major cations and anions of intracellular andextracellular fluids.
Fig. 25.2 Nonelectrolytes of the plasma
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Constituents of Extra- and Intracellular Fluids
Plasma (mOsm/L of Water
Interstitial (mOsm/Lof Water
Intracellular(mOsm/L of Water
Sodium 142 139 14
Potassium 4.2 4.0 140
Calcium 1.3 1.2 0Magnesium 0.8 0.7 20
Chlorine 108 108 4
Bicarbonate 24 28.3 10
Phosphate 2 2 11
Sulfate 0.5 0.5 1
Phosphocreatine 45
Carnosine 14
Amino acids 2 2 8
Table 25.2 Osmolar substances in extracellular and intracellular fluids
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Constituents of Extra- and Intracellular Fluids
Plasma (mOsm/Lof Water
Interstitial(mOsm/L of Water
Intracellular(mOsm/L of Water
Creatine 0.2 0.2 9
Lactate 1.2 1.2 1.5
ATP 5
Hexosemonophosphate
3.7
Glucose 5.6 5.6
Protein 1.2 0.2 4
Urea 4 4 4Others 4.8 3.9 10
Total mOsm/L 301.8 300.8 301.2
Corrected osmolaractivity
282 281 281
Total OsmoticPressure (37 C) 5443 5423 5423
Table 25.2 Osmolar substances in extracellular and intracellular fluids
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Basic Principles of Osmosis and Osmotic Pressure
Osmosis is the net diffusion of water across aselectively permeable membrane from aregion of high water concentration to one
that has a lower water concentration. Rate of diffusion of water is called the rate of
osmosis.
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Moles vs. Osmoles
Osmoles-the total number of particles in a solution
One osmole is equal to 1 mole of solute particles
Osmole refers to the number of osmotically activeparticles in a solution rather than to the molarconcentration
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Osmotic Equilibrium
Isotonic- occurs if the water concentration of both intra-cellular and extracellular fluid is the same; cells doshrink or swell
Hypotonic- occurs if the water concentration is lowerinside the cell (solutes are higher inside) andthe cell will swell and possibly lyse
Hypertonic- occurs if the water concentration ishigher inside the cell (solutes are lower inside)and the cell shrivels (crenates); water flows outof the cell
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Fig. 25.5 Effects of isotonic, hypotonic, and hypertonic solutions on cell volume
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Equilibrium (cont.)
Isosmotic- solutions with an osmolarity the same as the cell
Hyperosmotic- solutions with a higher osmolarity
Hyposmotic- solutions with a lower osmolarity
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Volume and Osmolality in Abnormal States
Effect of adding saline to extracellular fluid
Hyponatremia
Hyperantremia
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Edema
Intracellular Edema
a. Hyponatremiab. Depression of metabolic systems of tissuesc. Lack of adequate nutrition to the cells
Extracellular Edema
a. Abnormal leakage of fluid from plasmab. Failure of the lymphatics to return the fluid
(lymphedema)