Body Fluid Compartments/Homeostasis DSA

Question 1

Define molarity and its units

Answer 1

Amount of an uncharged substance dissolved in a solution (mmol/L)

Question 2

Define equivalence and give its units

Answer 2

Amount of a solute dissolved in a solution mEq/L

Question 3

Practice problem 1

What is the molarity of a 1L sol. Of 9g of NaCl

MW = 58.4 g/mol

Answer 3

154 mmol/L or mEq/L

See page for explanation

Question 4

Practice problem 2

What is the molarity of a 1L sol. Of 0.1g of Ca (+2)

MW = 40.1 g/mol

Answer 4

5 mEq

See paper for explanation

Question 5

What is osmotic pressure solely determined by

Answer 5

The number of solute particles in the solution

NOT dependent on the size, mass, or chemical make-up of particles

Question 6

What is the equation for osmotic pressure

Answer 6

(Pi) = nCRT

N - number of dissociable particles per molecule
C = total solute concentration
R = gas constant (0.082 atm L/mol)
T = temp in K (c + 273)

Question 7

What is the equation for osmolarity and osmolality in the human body

Answer 7

Concentration x number of dissociable particles

Question 8

Practice problem # 3

What is the osmolality of a 150 mmol/L sol. Of NaCl

Answer 8

300 mOsm/L

See paper for explanation

Question 9

Define the difference between osmolality and osmolarity

Answer 9

Osmolarity - # of solute particles per 1L of solvent (temp. Dependent)

Osmolality - # of solute particles per Kg of solvent (temp. Independent)

Question 10

Define isotonic, hypotonic, and hypertonic solution sin terms of what they contain and also what will happen to the cell and the ECF

Answer 10

Isotonic - does not change vol. of cell

Hypotonic - solution that causes the cell to swell. Has less solute that solvent. Causes a decrease of ECF and increase of IF

Hypertonic - solution that causes the cell to shrink. Has more solute that solvent. Causes an increase in ECF and a decrease in IF

Question 11

To exert an osmotic pressure across a membrane, a solute must not be what

Answer 11

Permeable to the membrane

Question 12

Define an effective and an ineffective osmole

Answer 12

Effective - can not cross membrane

Ineffective - can cross membrane

Question 13

Define the equation to calculate a solute’s permeability

Answer 13

(Pi) = (theta) (nCRT)

Theta = the osmotic coefficient

Question 14

An ineffective osmole will have what coefficient? What about an effective one

Answer 14

Ineffective - 0 - very permeable

Effective - 1 - not permeable

Question 15

Define oncotic pressure

Answer 15

Osmotic pressure generated by large molecules especially proteins

Question 16

What is the normal oncotic pressure in humans

Answer 16

26 - 28 mmHg

Question 17

The ICF contains how much of the total body water

What about the ECF

Answer 17

ICF = 2/3
ECF = 1/3

Question 18

How to calculate ECF and ICF

Answer 18

ECF - 0.2 x BW

ICF - 0.4 x BW

Question 19

The ECF is broken down into what two things

Answer 19

IF (3/4 x ECF)

Plasma (1/4 x ECF)

Question 20

What is the major cation and anions of the ECF

Answer 20

Cation - Na

Anion - Cl and HCO3

Question 21

Plasma and IF have the same ion concentration why

Answer 21

Cap. Is semipermeable

Question 22

How to calculate a rough estimate of ECF? What about a clinic ECF?

Answer 22

Rough - 2 x Na concentration

Clinic - 2(Na of plasma) + glu/18 + urea/2.8

Question 23

What is the major cation of ICF

Answer 23

K

Question 24

Only what can move fluid across the ICF/ECF

Answer 24

Osmotic pressure

Question 25

Define the starling equation

Answer 25

FR = Kf[(Pc - Pi0 - (Theta)(PiC - PiI)] Kf = filtration coefficient

Question 26

Typical sterling forces push fluids where

Answer 26

Out of capillary, taken up by lymphatics

Question 27

Hyperosmotic patients need what type of fluid

Answer 27

Hypotonic which increases the ECF and ICF

Question 28

Hypotonic patients need what

Answer 28

Hypertonic fluid which increases the ECF and decreases the ICF