11 - Fluid Compartments

Question 1

What are extracellular and intracellular fluids?

Answer 1

Extracellular

• trancellular
• plasma water
• fat
• interstitial fluid

Intracellular
- fluid inside the cell

Question 2

Types of transceullar fluids?

Answer 2

Fluid found in epithelial lined spaces

• peritoneal space in abdomen
• Cerebrospinal fluid CSF [blood brain barrier]
• pleural cavity [lungs]
• sinovial fluid [between joints]

Question 3

Blood plasma proportions?

Answer 3

50% plasma
40% of it is haemotocritic:
- has erthyrocytes/leukocytes/platelets

Question 4

2 methods that are destructive to measure fluid compartments?

Answer 4

Centrifugation and Exsanguination [draining blood]

Question 5

Non-destructive method of measuring?

Answer 5

Inject a liquid that can distribute
Then calculate Volume of Distribution

(For water: use H2 (deuterium))

Eq: vd = q/cp

Q - drug
Cp - plasma conc

Question 6

Define osmole?

Answer 6

Number of moles a compound dissociates into when dissolved.

Question 7

Difference between osmolality and osmolarity?

Answer 7

Osmolality - no. of solute particles per MASS of solvent

Osmolarity - no. of solute particles per VOLUME of solvent

Question 8

What is osmotic pressure and relationship with osmolality?

Answer 8

• force that opposes osmosis
• osmotic pressure prop to osmolality

Equation: OP = ncRT

nc = osmolality 
R = ideal gas const
T = temp

Question 9

Describe is-osmotic and isotonic solutions?

Answer 9

2 isosmotic solutions - same osmolality

Isotonic sol - no net fluid movement

Urea is isosmotic (if applied to cells it will pass freely through the membrane