internal environment of the body.
Internal environment ? milieu interieur
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extracellular fluid which includesinterstitial fluid.
Simple diffusion -
Movement of molecules from higher
concentration to lower concentration till
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equilibrium is reachedDiffusion can takes place through:
a) Lipid bilayer
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i) Lipid soluble substances-
O2,Co2,alcohol, steriods etc
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ii) Lipid insoluble ? water (throughspaces bet lipid mol) urea, sugar
(less or no permeability)
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iii) Electrolytes ? impermeable
? charge on fatty acid chain
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- Hydrated forms are largerFactors affecting rate of diffusion
? Lipid solubility
? Molecular size & wt.
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Molecular? Temperature
? Thickness of membrane
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Membrane related? Surface area
? Concentration gradient
? Pressure gradient
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Gradients
? Electrical gradient
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p. Fick's law of diffusion ?Im
Q
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CPA
MW X
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Q = net rate of diffusionC = conc. gradient of a substance
P = permeability of membrane to the sub.
A = surface area of a membrane
MW = molecular wt. of sub.
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X = thickness or distanceTwo big jump in the tree of LIFE
? Movement
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? MulticellularityVolume and composition of this fluid
should be maintained constant (within
narrow limits) in spite of changes in
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external environment for the normalfunction of cell.
Failure of homeostasis leads to disease
Some regulating systems and their
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functions ?
Resp. system - CO2 content
Liver and pancreas ? glucose
Kidney ? conc. of ions
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CVS ? blood flow and temp regulationNervous and endocrine systems
regulate the function of other systems
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Composition of ECF is same all overthe body because of constant mixing
of interstitial fluid and blood and
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circulation of blood
Foundation steps for the movement
? Mass and Newton law of motion
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? Self generated movement (Intention and will )
? Role of dual nature of Charge
The role of permeability and RMP
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? Cell membrane
? Lipid bilayer
? Lipid soluble substance can freely pass though the cell
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membraneThought question?
? Does lipid soluble substance pass through the gap between
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two lipid molecule or it pass through the lipid itself?
Transport of charge ions across cell membrane
? Need for special carrier or channel or transporter
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? Sodium channelThought question
? Size of sodium channel
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? Approximate number of sodium channel in typical cell? Carrying capacity of sodium channel
? Number of transported molecule in unit time
? Duty cycle duration
Body fluid compartments-
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60% of body wt.(70kg.) ? 42 lits.
ICF-2/3 -28lits
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ECF ? 1/3 ? 14 lits2 lits in RBC
Transcellular -
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Plasma -3lits -
Interstitial fluid 1-2 lits
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5% 1/5-11 lits. 3/4
7% of fluid in intravascular compartment
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Body fluids
?62% of body wt in males and 52 % in
females
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?72% of lean body mass (adipose free)body wt is 70kg in man
body water is 42 lits.
28 lits ( 2/3) ICF ? 2 lits - intravascular
14 lits. (1/3) ECF ? 3 lits - intravascular
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Body fluidsMeasurement of body fluid compartments-
?indicator dilution technique ?
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?Criteria for ideal dye ?
?Dye should get uniformly diluted only in
the compartment whose whose volume
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is to be measuredBody fluids
?Dye should be nontoxic,
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?should not change fluid volume,
? should not be metabolized, altered
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?or excreted in significant amount? should be able to estimate easily
Body fluids
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Two spaces are calculated indirectly ?- Intracellular fluid compartment
( TBW ? ECF)
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- Extravascular fluid compartment
(ECF - plasma vol.)
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Body fluidsExample
Inulin for ECF ? 100 mg inulin injected
After 30 min. inulin conc in blood ?
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0.75 mg /dl
25 mg excreted in urine during 30
mins.
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ECF vol = 100 ? 25 / 0.75 = 10000 ml
= 10 lits.
Body fluids
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Substances used ?TBW ? D2O, tritiated H2O, aminopyrine
ECF ? Na thiosulphate, sucrose, mannitol,
Intravascular fluid ?
Plasma vol. - Evan's blue, T
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131
1824 ,
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I2Hematocrit
Osmolarity of ECF = 290 mOsm / lit
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? Control system
? OR
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? Regulating systemLimitations ?
- age
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Undamped oscillations due to long deadtime and more gain of system ?
overcorrection
e.g. Chyene Stoke's breathing, clonus
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during deep reflexesBody fluid compartments-
60% of body wt.(70kg.) ? 42 lits.
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ICF-2/3 -28lits
ECF ? 1/3 ? 14 lits
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2 lits in RBCTranscellular -
Plasma -3lits -
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Interstitial fluid 1-2 lits
5% 1/5
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-11 lits. 3/47% of fluid in intravascular compartment