Date post: | 15-Apr-2016 |
Category: |
Documents |
Upload: | awie-safitri |
View: | 3 times |
Download: | 1 times |
DYNAMIC EQUILIBRIUM OF BODY FLUID
DENNY AGUSTININGSIH
In average young adult male:
% of body weightBody composition
18%Protein, & related substances
15%Fat
7%Mineral
60%Water
Body composition
Factors affecting body fluids Water intake & output Age:
- infant: 73%- elderly: 45%
Sex:- adult male: 60%- adult female: 40-50%
Body temperature healthy adult can sweat 1
liter/hr for 2 hrs (5% of body wt without problem)
perspire (1000cc wet sheet)
Every degree F = 75 ml increase/day in fluid needs
Obesity Climate Habits Level of physical activity
• solvent
• transportMain functions
• Give shape and form to the cells
• Regulate body temp.
• Joint lubricant
• Cushion body organs
• Maintain peak performance
Other functions
Body Fluid Compartments
Figure 5-13: Body fluid compartments
Total body water (TBW)
0.6 X body weight (men), 0.5xbody weight (women ?)
35L - 42L
Interstitial fluid
(ISF)
3/4 ECF
10.5L
Plasma
1/4
ECF
3.5 L
capillary wall
Extracellular fluid
(ECF)
0.2 X body weight
14L
Intracellular fluid
(ICF)
0.4 X body weight
28L
cell membrane
TranscellularwaterGI, kidney, sweattears, synovial, CSF
variable volume~ 1L
epithelial
layer
input
output
epithelial
Distribution of body water in an average 70 kg person
COMPOSITION OF BODY FLUIDS
Normal Ions and electrolytes Composition of the Body Fluids.
capillary wall plasma membrane
NaK
sodium pump ~ Na,K-ATPase:
Differences between ECF & ICF
ECFAnions:Cl- (108)
HCO3- (24)
Cations:
Na+ (142mmol/L)
K+ (4.2)
Mg2+ (0.8)
Nutrients:
O2, glucose, fatty acids, &
amino acids.
Wastes:
CO2, Urea, uric acid,
excess water, & ions.
ICFAnions:Cl- (4)
HCO3- (10)
Phosphate ions
Cations:
Na+ (14)
K+ (140)
Mg2+ (20)
Nutrients:
High concentrations of proteins.
Daily Water Gain and Loss
Copyright 2009, John Wiley & Sons, Inc.
HOMEOSTASIS
Claude Bernard (1878):
animals have 2 environtments- milieu exteriur : physically surrounds the whole
organism
- milieu interieur : surrounds the tissue and cells of the organism•organic liquid
•homeostasis
HOMEOSTASISParameters of the milieu interieur that must be
tightly controlled
– - core temperatures
– - levels of oxygen
– - glucose
– - potassium ions
– - calcium ions
– - hydrogen ions
Volume Contraction
Isotonic Hypertonic HypotonicE
CF
EC
F
ICF
EC
F
ICF
Osm
ola
lity
Volume Expansion
Isotonic Hypertonic Hypotonic
EC
F
ICF
EC
F
ICF
EC
F
ICF
Osm
ola
lity
From H. Valtin
ICF
PATHOPHYSIOLOGICAL CHANGES IN EXTRACELLULAR FLUID VOLUME
Changes in the osmolality of plasma lead to AVP secretionat a much lower threshold than they lead to thirst
Very small increases in AVP lead to very large changes in urine volume
Thus – the kidney is the first line of defense against cellular dehydration
Ongoing behavior is not disrupted by thirst unless the buffering effects of osmosis and antidiureses are insufficient
Osmotic homeostasis
• Dehydration produces a need for water
• Osmolality (expression of concentration) is the ratio of the amount of solute dissolved in a given weight of water: solute (osmoles)/water (kilograms)
• Body water can decrease as a result of deprivation or sweating, whereas solute can increase as a consequence of salt ingestion
• Either water decrease or solute increase leads to an increase in osmolality
Osmotic homeostasis
Excessive loss of H2O from ECF
1 2 3ECF osmotic pressure rises
Cells lose H2O to ECF by osmosis; cells shrink
Volume homeostasis
Hypovolemia triggers not only thirst, but also salt appetite
Blood volume is corrected only by replacing both water and salt
Drinking water alleviates thirst(by reducing plasma osmolality), but triggers salt appetite, whereas consuming salt triggers subsequent thirst (by increasing plasma osmolality)
Series of Events in Water Intoxication
Copyright 2009, John Wiley & Sons, Inc.