Keseimbangan Air dan
Natrium
Figure 27-1a The Composition of the Human Body
SOLID COMPONENTS
(31.5 kg; 69.3 lbs)
Kg
Proteins
Lipids
Minerals
Carbohydrates Miscellaneous
The body composition (by weight, averaged for both
sexes) and major body fluid compartments of a 70-kg
individual.
Figure 27-1a The Composition of the Human Body
WATER (38.5 kg; 84.7 lbs)
Other
Plasma
Liters
Interstitial
fluid
Intracellular fluid
Extracellular fluid
The body composition (by weight, averaged
for both sexes) and major body fluid
compartments of a 70-kg individual.
Figure 27-1b The Composition of the Human Body
WATER 60%
ICF
ECF
Intracellular
fluid 33%
Interstitial
fluid 21.5%
Plasma 4.5%
Solids 40%
(organic and inorganic materials)
Other
body
fluids
(1%)
SOLIDS 40%
Adult males
A comparison of the body compositions of adult
males and females, ages 18–40 years.
Figure 27-1b The Composition of the Human Body
WATER 50%
ECF
ICF
Intracellular
fluid 27%
Interstitial
fluid 18%
Plasma 4.5%
Solids 50%
(organic and inorganic materials)
Other
body
fluids
(1%)
SOLIDS 50%
Adult females
A comparison of the body compositions of adult
males and females, ages 18–40 years.
Figure 27-2 Cations and Anions in Body Fluids
CATIONS
ICF
ECF
KEY
Na
Cations
Na
Milliequivalents per liter (mEq/L)
K
Ca2

Mg2
K
Na
K
Ca2
Plasma
Na
K
Interstitial
fluid
Mg2
Intracellular
fluid
Figure 27-2 Cations and Anions in Body Fluids
ANIONS
ECF
ICF
KEY
Anions
HCO3
Cl
HCO3
Cl
HPO42
HCO3
SO42
HCO3
Organic
acid
HPO42
Proteins
Cl
Cl
HPO42
Org. acid
Proteins
Plasma
SO42
Proteins
HPO42
SO42
Interstitial
fluid
Intracellular
fluid
Figure 27-3 Fluid Gains and Losses
Water absorbed across
digestive epithelium
(2000 mL)
Water vapor lost
in respiration and
evaporation from
moist surfaces
(1150 mL)
ICF
Metabolic
water
(300 mL)
ECF
Water lost in
feces (150 mL)
Water secreted
by sweat glands
(variable)
Plasma membranes
Water lost in urine
(1000 mL)
Table 27-1 Water Balance
Figure 27-4 Fluid Shifts between the ICF and ECF
Intracellular
fluid (ICF)
Extracellular
fluid (ECF)
The ECF and
ICF are in
balance, with
the two
solutions
isotonic.
Decreased ECF volume Water loss from
ECF reduces
volume and
makes this
solution
hypertonic with
respect to the ICF.
Decreased ICF volume
Increased
ECF volume
An osmotic water
shift from the ICF
into the ECF
restores osmotic
equilibrium but
reduces the ICF
volume.
Figure 27-5 The Homeostatic Regulation of Normal Sodium Ion Concentrations in Body Fluids
ADH Secretion Increases
Recall of Fluids
The secretion of ADH
restricts water loss and
stimulates thirst, promoting
additional water
consumption.
Because the ECF
osmolarity increases,
water shifts out of
the ICF, increasing
ECF volume and
lowering Na
concentrations.
Osmoreceptors
in hypothalamus
stimulated
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Decreased Na
levels in ECF
Na
Increased
levels in ECF
HOMEOSTASIS
Normal Na
concentration
in ECF
Start
Figure 27-5 The Homeostatic Regulation of Normal Sodium Ion Concentrations in Body Fluids
HOMEOSTASIS
HOMEOSTASIS
DISTURBED
Normal Na
concentration
in ECF
Start
HOMEOSTASIS
RESTORED
Decreased Na
levels in ECF
Osmoreceptors
in hypothalamus
inhibited
Increased Na
levels in ECF
Water loss reduces
ECF volume,
concentrates ions
ADH Secretion Decreases
As soon as the osmotic
concentration of the ECF
drops by 2 percent or more,
ADH secretion decreases, so
thirst is suppressed and
water losses at the kidneys
increase.
Figure 27-6 The Integration of Fluid Volume Regulation and Sodium Ion Concentrations in Body Fluids
Responses to Natriuretic Peptides
Increased Na loss in urine
Rising blood
pressure and
volume
Increased water loss in urine
Natriuretic peptides
released by cardiac
muscle cells
Reduced thirst
Inhibition of ADH, aldosterone,
epinephrine, and norepinephrine
release
Combined
Effects
Reduced
blood
volume
Reduced
blood
pressure
Increased blood
volume and
atrial distension
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Rising ECF volume by fluid
gain or fluid and Na gain
Falling ECF
volume
HOMEOSTASIS
Start
Normal ECF
volume
Figure 27-6 The Integration of Fluid Volume Regulation and Sodium Ion Concentrations in Body Fluids
HOMEOSTASIS
Start
Normal ECF
volume
HOMEOSTASIS
DISTURBED
Falling ECF volume by fluid
loss or fluid and Na loss
Decreased blood
volume and
blood pressure
Falling blood
pressure and
volume
HOMEOSTASIS
RESTORED
Rising ECF
volume
Endocrine Responses
Combined Effects
Increased renin secretion
and angiotensin II
activation
Increased urinary Na
retention
Decreased urinary water
loss
Increased thirst
Increased water intake
Increased aldosterone
release
Increased ADH release
Table 27-2 Electrolyte Balance for Average Adult
Scientific Knowledge Base : Location and Movement
of Water and Electrolytes
Intracellular Fluid
(ICF)
Extracellular Fluid (ECF)
= Fluid outside of cells
= Fluids within cells
 ~2/3 of total body water

~1/3 of total body water
 Three divisions:
– Interstitial
– Intravascular
– Transcellular
Distribution and Composition of Body Fluids
• Intracellular
• Solute
• Extracellular
• Vascular, interstitial fluid
Movement of Body Fluids
• Movement of body fluid across cell and capillary membranes
accomplished by:
•
•
•
•
Osmosis
Diffusion
Filtration
Active transport
Movement of Body Fluids, continued
• Osmosis
 Movement of water across cell membranes from less concentrated solution to
more concentrated solution
 Solutes: crystalloids, colloids
 Solvent: component of solution that can dissolve a solute
Check out this link to Khan academy on
 Osmosis/Diffusion
Movement of Body Fluids, continued
• Osmosis
• Osmolality: concentration of solutes
• Greatest determinants of osmolality in ECF: sodium, glucose, urea
• Greatest determinants of osmolality in ICF: potassium, glucose, urea
Movement of Body Fluids, continued
• Osmosis
• Tonicity: osmolality of solution
• Isotonic solution: same osmolality as body fluids
• Hypertonic solution: higher osmolality than body fluids
• Hypotonic solution: lower osmolality than body fluids
Isotonic, Hypotonic, and Hypertonic Solutions
Movement of Body Fluids, continued
• Osmosis
• Osmotic pressure: power of solution to draw water across membrane
• Colloid osmotic pressure (oncotic pressure): plasma proteins pull water from interstitial
space into vascular compartment
• Important in maintaining vascular volume
Movement of Body Fluids, continued
• Diffusion
• Intermingling of molecules
• Rate of diffusion varies by:
• Size of molecules
• Concentration of solution
• Temperature of solution
Movement of Body Fluids, continued
• Filtration
• Movement of fluid and
solutes together across a
membrane from one
compartment to another
• From area of higher
pressure to lower
• Hydrostatic pressure:
pressure a fluid exerts on
walls in closed system
Movement of Body Fluids, continued
• Active transport
• Substances move across membranes
• From less concentrated solution to more concentrated one
• Metabolic energy is expended
• Maintains higher sodium levels in ECF, higher potassium concentrations in ICF
• Sodium-potassium pump
PENGARUH OSMOLARITAS PADA SEL
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Komposisi Ion pd Cairan Tubuh
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Peranan ginjal
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Filtrasi, Reabsorpsi, Sekresi & Ekskresi di Nefron
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Peranan Renin-Angiotensin-Aldosteron
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Respons thd Asupan Garam
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