principles of fluid balance 1

Question 1

what % of an adult animal’s body is made up of water

Answer 1

60-70%

Question 2

where in the body is water found

Answer 2

• intracellular fluid
• interstitium
• intravascular

Question 3

what solutes exist in the extracellular fluid

Answer 3

• proteins
• Na
• Cl
• HCO3

Question 4

what solutes exist in the intracellular fluid

Answer 4

• K+

Question 5

discus the permeability of the capillary membrane

Answer 5

freely permeable to water and electrolytes

Question 6

discuss the permeability of the cell membrane

Answer 6

freely permeable to water only

Question 7

define osmotic pull/force

Answer 7

Water diffuses from an area of highest concentration of water to area of lower concentration of water

Question 8

define hydrostatic pressure

Answer 8

The force that results from the pressure of a liquid (in this case water) within a container (or compartment)

Question 9

define oncotic pressure

Answer 9

Also known as colloid pressure, induced by proteins which look to pull water back into plasma - opposite to hydrostatic pressure

Question 10

define permeability

Answer 10

The ease with which things can pass through the membrane

Question 11

describe the process of exchange of water between the plasma and interstitial spaces

Answer 11

• The hydrostatic pressure of the capillaries is significantly greater than the hydrostatic pressure in the tissue, thus water would move out of the capillary due to hydrostatic pressure.
• However compared to tissue the capillary has a higher concentration of plasma proteins than the surrounding interstitial fluid therefore fluid would be drawn into the capillary by the osmotic pull that results from the oncotic pressure driven by a higher concentration of plasma proteins in the capillary
• These 2 opposing forces are known as starling’
• fluid drawn into capillary by osmotic pull which is driven by oncotic pressure

Question 12

define tonicity

Answer 12

The osmotic pressure of a solution relative to the plasma e.g. isotonic = same osmotic pressure as plasma

Question 13

define concentration

Answer 13

The amount of a substance that is present in the fluid compartment e.g. the amount of Na+ present in the ECF

Question 14

define osmolarity

Answer 14

The concentration of particles dissolved in a fluid (number of solute particles per L of solvent)

Question 15

define osmolality

Answer 15

The concentration of particles dissolved in a fluid (number of solute particles per kg of solvent)

Question 16

define oncocity/oncotic pressure

Answer 16

The pressure exerted by plasma proteins on the capillary wall (pulls water back into the plasma)

Question 17

in an isotonic solution water move ….. of the cell

Answer 17

in between

Question 18

if a solution is hypotonic will water move in or out of the cell

Answer 18

in

Question 19

is a cell is in a hypertonic solutio will water move in or out of the cell

Answer 19

out

Question 20

if osmotic pressure or osmolarity is too high in the capillary (concentration of Na ions too high in the plasma) where will fluid flow

Answer 20

into the plasma

Question 21

if a solution is described as hypertonic, what is its concentration in relation to plasma

Answer 21

more concentrated than plasma

Question 22

7.2% saline is an example of a …….. solution

Answer 22

hypertonic => draws fluid into the intravascular space

Question 23

what is an effective osmole

Answer 23

a solute that doesn not freely cross the membrane (Na, K)

Question 24

what is an ineffective osmole

Answer 24

a solute that freely crosses the membrane (glucose and urea)