BIO 365S Lecture Notes - Lecture 2: Body Water, Extracellular Fluid, Osmotic Concentration
Physiology man . . . 154lb
1lb = 0.454kg
154lb = 70kg
•Total body water?
•70 * 0.6 ~ 42kg.
•1L of water = 1kg à 42L
•
•Plasma osmolarity?
•290~300mOsM.
•Volumes of distribution?
•ICF = 2/3
•ECF 1/3 (plasma
60% of body weight is water.
Interstitial fluid (or tissue fluid) is a solution that bathes and surrounds
the cells of multicellular animals. It is the main component of the
extracellular fluid
Total blood volume has 5L, and most of it has RBC.
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Interstitial fluid: liquid b/w cells.
Physiological solutions
•Applied to the body to correct volume/osmolarity imbalances
•Usually described by two terms
•Osmolarity: number of particles in a solution
• ( mol x Dissociation Factor / L = Molarity x Dissociation Factor)
•Tonicity tells us the nature of the solute, how the cell behave. Takes into account the nature
of the particles in solution. Describes the behavior of a cell in a specific solution. Always
describe the solution, not the cell.
How is tonicity different from osmolarity?
What’s the total osmolarity of a 1L solution that contains 1M NaCl and
1M Glucose?
3OsM
Osmolarity is about the particles in the solution. How many molecules
per liter.
Tonicity: how water moves. Water moving in or out of cell can cause it
to swell or shrink. Biological situation of osmolarity.
-For NaCL: (mol/L) * 2 = molarity.
-Glucose: same molarity because doesn’t dissociate.
-CaCl2: (mol/L) *3
•What’s the osolarity of 0.9% Salie?
–Answer: 300mOsM
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