Download Unit One: Introduction to Physiology: The Cell and General Physiology

Chapter 25: The Body Compartments:
Extracellular and Intracellular Fluids;
Edema
Guyton and Hall, Textbook of Medical Physiology, 12th edition
Balance of Fluid Intake and Output
•
Steady-State Balance
a.
b.
c.
d.
e.
Daily intake of water
Daily loss of water-insensible water loss
Fluid loss in sweat
Water loss in feces
Water loss by the kidneys
Table 25.1 Daily Intake and Output of Water (ml/day)
Normal
Prolonged Heavy
Exercise
Fluids ingested
2100
?
From metabolism
200
200
Total Intake
2300
?
Insensible-skin
350
350
Insensible-lungs
350
650
Sweat
100
5000
Feces
100
100
Urine
1400
500
Total Output
2300
6600
Intake
Output
Body Fluid Compartments
Fig. 25.1 Summary of body fluid regulation, including the major body fluid compartments
Compartments (cont.)
• Body Fluid Compartments
a. Intracellular
b. Extracellular-interstitial fluid and blood plasma
c. Transcellular-fluids in the synovial, peritoneal,
pericardial, intraocular spaces, and the CSF
d. Total body water for men is about 60% and 50%
for women
e. Varies with age, gender, and degree of obesity
Compartments (cont.)
• Intracellular Fluid Compartment
a. Constitutes about 40% of the fluid in the average
person
b. Concentration of substances is similar from cell
to cell
Compartments (cont.)
• Extracellular Fluid Compartment
a. Interstitial fluid-makes up about 75% of the fluid
b. Blood plasma-makes up 25% of the fluid
c. Only real difference between the two types is the
protein composition of the plasma
Blood Volume
• Blood Volume
a. Makes up about 7% of the body weight (5 L)
b. 60% plasma and 40% cells
c. Percentages vary according to gender, weight, etc.
•
Hematocrit
a. Red blood cell fraction of the blood
b. 96% accurate because you cannot pack the cells
completely
c. Males (o.40) and females (o.30)
Constituents of Extra- and Intracellular Fluids
Fig. 25.2 Major cations and anions of intracellular and
extracellular fluids.
Fig. 25.2 Nonelectrolytes of the plasma
Constituents of Extra- and Intracellular Fluids
Table 25.2 Osmolar substances in extracellular and intracellular fluids
Plasma (mOsm/L
of Water
Interstitial
(mOsm/L of Water
Intracellular
(mOsm/L of Water
Sodium
142
139
14
Potassium
4.2
4.0
140
Calcium
1.3
1.2
0
Magnesium
0.8
0.7
20
Chlorine
108
108
4
Bicarbonate
24
28.3
10
Phosphate
2
2
11
0.5
0.5
1
Sulfate
Phosphocreatine
45
Carnosine
14
Amino acids
2
2
8
Constituents of Extra- and Intracellular Fluids
Table 25.2 Osmolar substances in extracellular and intracellular fluids
Plasma (mOsm/L
of 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
Hexose
monophosphate
3.7
Glucose
5.6
5.6
Protein
1.2
0.2
4
Urea
4
4
4
4.8
3.9
10
301.8
300.8
301.2
Corrected osmolar
activity
282
281
281
Total Osmotic
Pressure (37 C)
5443
5423
5423
Others
Total mOsm/L
Basic Principles of Osmosis and Osmotic Pressure
• Osmosis is the net diffusion of water across a
selectively permeable membrane from a
region of high water concentration to one
that has a lower water concentration.
• Rate of diffusion of water is called the rate of
osmosis.
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 active
particles in a solution rather than to the molar
concentration
Osmolality vs. Osmolarity
• Osmolality = osmoles/kg of water
• Osmolarity = osmoles/L of solution
Osmotic Equilibrium
• Isotonic-occurs if the water concentration of both intracellular and extracellular fluid is the same; cells do
shrink or swell
• Hypotonic-occurs if the water concentration is lower
inside the cell (solutes are higher inside) and
the cell will swell and possibly lyse
• Hypertonic-occurs if the water concentration is
higher inside the cell (solutes are lower inside)
and the cell shrivels (crenates); water flows out
of the cell
Fig. 25.5 Effects of isotonic, hypotonic, and hypertonic solutions on cell volume
Equilibrium (cont.)
• Isosmotic-solutions with an osmolarity the same as the cell
• Hyperosmotic-solutions with a higher osmolarity
• Hyposmotic-solutions with a lower osmolarity
Volume and Osmolality in Abnormal States
• Effect of adding saline to extracellular fluid
• Hyponatremia
• Hyperantremia
Edema
• Intracellular Edema
a. Hyponatremia
b. Depression of metabolic systems of tissues
c. Lack of adequate nutrition to the cells
•
Extracellular Edema
a. Abnormal leakage of fluid from plasma
b. Failure of the lymphatics to return the fluid
(lymphedema)