Osmotic & Oncotic Pressure and Body Fluid Compartments

Question 1

Osmolarity for the body

Answer 1

300 mOSM/L

Question 2

Osmolarity

Answer 2

The concentration of osmotically active particles. It is a measure of the concentration of particles in a solution, calculated by mM/L x g

g=# of particles associated with a molecule of solute in solution

Question 3

Osmoles=

Answer 3

= # of particles

Question 4

Importance of osmolarity in body fluids

Answer 4

Intracellular osmolarity must be carefully maintained, thus fluid fluxes are kept at a minimum

Question 5

Define Osmotic Pressure

Answer 5

The external pressure that would be required to prevent solvent flow across a membrane

Question 6

Do higher solute or lower solute concentrations have a higher osmotic pressures?

Answer 6

HIGHER- because it draws in the water

Question 7

Tonicity

Answer 7

The effective osmolarity of a solution, a measure of a solutions ability to create an osmotic pressure gradient relative to another solutions

Question 8

Is sucrose permable?

Answer 8

no, its impermeable

Question 9

Is Urea permeable?

Answer 9

Yes. it moves throuugh membrane quickly

Question 10

Relative Osmolarity

Answer 10

Isosmotic, Hyperosmotic, Hypoosmotic-Refers to the concentration of osmotically active particles in a solution relative to a reference solution

Question 11

Relative tonicity

Answer 11

Isotonic, Hypertonic, Hypotonic-considers only the particles that are impermeant to the biological membrane seperating two solutions

Question 12

Homeostasis depends on…

Answer 12

Fluid balance

Question 13

How much of our body weight is water?

Answer 13

60%

Question 14

What ions make up the intrascellular and extracellular fluid, and how are concentrations controlled?

Answer 14

The major cations are distributed by active Na+/K+ pumps

Question 15

Body fluid compartments are…

Answer 15

Intracellular fluid and Extracellular fluid (interstitial fluid and plasma)

Question 16

TBW stands for…

Answer 16

Total body water

Question 17

TBW is __% of body weight or __ L in 70 kg person

Answer 17

60%, 42 L

Question 18

Intracellular Fluid (ICF)

Answer 18

ICF=2/3 TBW (28L)

Question 19

Extracellular fluid (ECF)

Answer 19

ECF=1/3 TBW (14L)

Question 20

Interstitial Fluid (ISF)

Answer 20

ISF=~3/4 ECF (11L)

Question 21

Plasma Vol (PV)

Answer 21

PW=~1/4 ECF (3L)

Question 22

What can be used to measure fluid compartments

Answer 22

• Inulin
• Tritrated water
• Evans blue

Question 23

Intracellular Fluid=

Answer 23

TBW-ECF

Question 24

Interstitial Fluid=

Answer 24

ECF-Plasma

Question 25

Volume (L)=

Answer 25

Amount of indicator injected (mg)/FInal concentration of indicator (mg/L)

Question 26

The volume of a compartment is determined by…

Answer 26

the osmoles present

Question 27

What forces govern movement of fluid across a capillary wall?

Answer 27

Starling Forces

Question 28

Define Starling Forces

Answer 28

Oncotic+ HP= Starling Forces

Question 29

Net Filtration is…

Answer 29

the sum of the forces moving fluid out of the capillary and forces pulling fluid into the capillary

Question 30

Extracellular fluid (ECF) is the __ for cells and needs to be maintained

Answer 30

bathing medium or internal milieu

Question 31

Small increases in plasma osmolarity (>2%) will elicit…

Answer 31

a thirst response as well as a systemic response to retain fluid (decrease urine.sweat/ increasesaliva production)

Question 32

Importance of ECF osmolality to homeostasis

Answer 32

Dehydration- hypotonic loss of primary water and some electrolytes- ECF osmolality increases 2% above normal, fluid is absorbed from the intestines into the plasma and osmolality is restored

Hemorrhage-blood loss of 12%- longer recovery