Homeostasis

Question 1

total body water is what percent

Answer 1

60% of wt.

Question 2

The three major kidney functions

Answer 2

1. ) Regulation of water and inorganic ions
2. ) Removal of metabolic waste from the blood and their excretion in urine
3. ) Removal of foreign chemicals from the blood and their excretion in urine

Question 3

More fat = what effect on body water?

Answer 3

Less body water

Question 4

What percent of body wt is intracellular fluid?

Answer 4

40%

Question 5

Volume of unknown body fluid compartment = ?

Answer 5

quantity injected divided by final concentration

Question 6

What kind of probe do you use to measure plasma volume?

Answer 6

l-albumin or evans blue dye

Question 7

Plasma volume equals?

Answer 7

quantity of probe injected divided by plasma concentration of the probe. Blood volume can then be determined by dividing the plasma volume by 1- hematocrit

Question 8

Extracellular fluid is composed of what?

Answer 8

Plasma and interstitial fluid

Question 9

a good probe for ECF volume?

Answer 9

Inulin

Question 10

How do you calculate ISF from ECF volume?

Answer 10

ECF- Plasma Volume

Question 11

Probe for measuring total body water?

Answer 11

2H2O, 3H2O, Antipyrene

Question 12

How do you determine ECF from TBW volume?

Answer 12

ECF = TBW- ECF

Question 13

What factors determine fluid movement between plasma and ISF?

Answer 13

Starling forces: hydrostatic pressure and oncotic pressure

Question 14

Oncotic pressure?

Answer 14

caused by proteins that cannot penetrate the capillary wall. For example, if protein conc goes up in plasma, then fluid will come in from ISF to correct osmotic balance.

Question 15

Does plasma osmolarity play a role in fluid movement between ISF and plasma?

Answer 15

No…because the capillary wall is freely permeable to water and solute so these things are always in balance.

Question 16

So what is the difference between osmotic pressure and oncotic pressure.

Answer 16

Oncotic pressure is a form of osmotic pressure. My understanding is that oncotic pressure refers to the pressure created by large non-permeable proteins in the blood making sure that the blood retains a certain fluid volume.

Question 17

What regulates fluid movement between ICF and ECF?

Answer 17

OSMOSIS! Why?, because the plasma membrane is impermeable to most solutes. Therefore, a change in soulte concentration means a fluid shift must occur to keep things in homeostasis.

Question 18

Plasma membrane permeable to urea?

Answer 18

yes

Question 19

What is the difference between moles and osmoles?

Answer 19

Moles is a measure of molecules whereas osmoles is a measure of particles. You must differentiate because 1 mole can equal two osmoles and this has an effect on osmotic pressure created by that substnace.

Question 20

osmolarity

Answer 20

amt of substance dissolved in a solution

Question 21

What is osmotic pressure?

Answer 21

The pressure required to prevent osmosis. The amount of pressure that must be applied to prevent water from moving through the membrane

Question 22

Osmotic pressure is directly proportional to the number of osmotically active solute (particles) in that solution

Answer 22

true…so osmotic pressure is directly proportional to osmolarity

Question 23

Why is it important that the osmolarity be the same in different compartments

Answer 23

So that water is not moving into compartments rapidly

Question 24

What occurs during a state of dehydration>

Answer 24

You will lose water from the ECF. Kidney function cannot be stopped thus ECF will slowly deplete. This causes an increase in osmolarity due to a high conc of solutes in teh Extracellular compartments. This inc in osmolarity draws water out from the cells. All fluid compartments lose volume and osmolarity is increased everywhere.

Question 25

Normal osmolarity in all body compartments?

Answer 25

286mOsm

Question 26

Osmolarity gap?

Answer 26

when measured plasma osmolarity is higher than the estimated plasma osmolarity. There is a missing osmotic particle.