3. Body Fluid Compartments

Question 1

What is the main function of the kidney?

Answer 1

To regulate the volume and composition of the body fluids

Question 2

Body fluid composition

Answer 2

60% water (40% ICF, 20% ECF)

Question 3

What can have the volume and composition altered?

Answer 3

Plasma - will affect ECF

Question 4

Third spacing

Answer 4

Too much fluid will shift from blood vessels to non-functional areas of the cells. is problematic

Question 5

Which way does water move in osmosis?

Answer 5

From higher water concentration to lower water concentration (so from lower solute to higher solute)

Question 6

What is the most abundant cation in ECF? Anion?

Answer 6

Cation: Na+. Anion: Cl-

Question 7

What is the most abundant cation in ICF? Anion?

Answer 7

Cation: K+. Anion: PO4^2-

Question 8

Nonelectrolytes

Answer 8

Contain covalent bonds that won’t dissociate in solution, so will produce no charge

Question 9

Electrolytes

Answer 9

Dissociate to form ions in water

Question 10

When would you use D5W (dextrose in water)

Answer 10

Fluid loss, dehydration, hypernatraemia

Question 11

When would you use 0.9% sodium chloride?

Answer 11

Shock, hyponataemia, resuscitation, fluid challenges, DKA

Question 12

When would you use Lactated Ringers (Hartmann’s) solution

Answer 12

Dehydration, burns, lower GI fluid loss, acute blood loss, hypovolaemia due to third spacing

Question 13

Plasma osmality equation

Answer 13

2(plasma[Na])

Question 14

How is ECF regulated?

Answer 14

By changes in Na+ balance

Question 15

How is serum Osmolality and [Na+] determined?

Answer 15

By H2O balance

Question 16

Hypotonic Dehydration

Answer 16

Have greater SODIUM loss than water loss. Water flows into ICF, cells swell

Question 17

Hypertonic Dehydration

Answer 17

Loss of water is greater than the loss of sodium

Water shifts from ICF to ECF!

Question 18

What can hyponatremia cause?

Answer 18

Increase ICF causes edema, brain cell swelling, irritability, depression, confusion, weakness, muscle cramps, anorexia, nausea, and diarrhea

Decrease sodium causes hypotension, tachycardia, and decrease urine output
Hypotonic dehydration

Question 19

What can hypernatremia cause?

Answer 19

Muscular weakness and hyperactive reflexes from high Na

Low ICF causes thirst, decreased urine output, confusion, and coma

Question 20

ISO-osmotic volume contraction

Answer 20

Caused by an acute fluid loss

Won’t change Osmolality or ICF but will decrease ECF

Question 21

Hyper-osmotic volume contraction

Answer 21

Increases Osmolality and will decrease ICF and ECF

Question 22

Isoosmotic volume expansion

Answer 22

Comes from exposure to isotonic saline. Will increase ECF but nothing else

Question 23

Hypo-somatic volume expansion

Answer 23

Caused by a gain of hypotonic fluid (like drinking too much water) and will increase ECF and ICF but decrease Osmolality

Question 24

Osmolality

Answer 24

Measure of number of osmotically active particles per Kg of H2O

Question 25

Osmolarity

Answer 25

Number of osmotically active particles per liter of total solution

Question 26

Na serum

Answer 26

135-147 mEq/L

Question 27

Cl- serum

Answer 27

95-105 mEq/L

Question 28

Albumin serum

Answer 28

3.5-5.5 g/dL

Question 29

Creatinine serum

Answer 29

0.6-1.2 mg/dL

Question 30

Serum osmolality

Answer 30

285-295 mOsm/Kg H2O

Question 31

Gibbs-Donnan

Answer 31

Shows that because proteins can’t move across the membrane, they create a negative charge gradient to move charge into the cells and they create an osmotic gradient so that water favors inward movement

Question 32

Na+/K+ pump and Gibbs-Donnan

Answer 32

Gibbs-Donnan would rupture cells if left unchecked, so Na+/K+ keeps more Na+ outside the cell to maintain a high sodium concentration and prevent swelling and rupture of the cells

Question 33

What are the two factors making free movement of fluid possible?

Answer 33

Water molecules diffuse through capillary walls faster than blood

there’s pressure difference between the inside and outside of the vessels

Question 34

Hydrostatic pressure

Answer 34

Movement of fluids across the capillaries as a result of blood pushing against the walls of the capillaries