Fluid compartments

Question 1

What is oedema?

Answer 1

swelling due to an excess of fluid in the interstitial space, because it has leaked out of cells exceeding capacity of lymphatics

Question 2

What are the causes of oedema?

Answer 2

Obesity - high hydrostatic pressure - force fluid out (hydrostatic)
Breast cancer - remove lymph node - fluid cannot be returned - swell right arm
Elephantiasis - nematode worm - block lymph
inflammation - swelling
Bite - BV leaky - release plasma protein - reduce inflammation (inflammatory)

Question 3

List the different forms of exchange across a capillary

Answer 3

hydrostatic force fluid out
High conc of plasma protein, colloid osmotic pressure, force water in and bring with it solutes
plasma protein too big so stay in capillary, unless it has become leaky
lipid soluble pass through endothelial cells
water soluble pass through pores
vesicular transport

Question 4

Recall the main fluid compartments and their relative sizes

Answer 4

Interstitual 36% 15l
Intracellular 55% 23l
Plasma 7% 3l
Transcellular 2% 1l

Question 5

Recall the composition of intracellular fluid

Answer 5

High K+ ion
low calcium ion - cell signalling so concentration difference is important
Low proteins - high charge
high phosphate ions
Mg2+ present in significant amounts
low H+ conc but higher than extracellular

Question 6

Recall composition of extracellular fluid

Answer 6

high sodium
high chloride
plasma has more protein than interstitial
low H+ conc, lower than intracellular

Question 7

Compare osmolarity in intracellular and extracellular fluid

Answer 7

it is equal (except in kidney)

Question 8

define osmosis

Answer 8

Movement of water molecules from a low solute concentrate to a high solute concentration, down water’s concentration gradient, across a ppm
Toward area of higher osmolarity

Question 9

Define diffusion

Answer 9

Passive movement of particles down concentration gradient (spontaneous)

Question 10

define permeability

Answer 10

Ability of a membrane to allow substances to pass through it

Question 11

recall examples of transport across cells and whether it is passive or active

Answer 11

diffusion - passive - lipid soluble [simple or channels]
transporter mediated - down conc gradient is passive
active transport - through carrier protein - active - membrane impermeable
transcytosis - movement of vesicles containing large substances from one side of the cell to another

Question 12

Explain the difference between tonicity and osmolarity

Answer 12

Tonicity refers to permeability of the membrane and solute composition whereas osmolality only refers to conc gradients of all solute particles

Question 13

Explain how tonicity and osmolarity affect cell integrity

Answer 13

whether or not the cell bursts - osmosis cell will increase or decrease in size as water moves, tonicity - cells may burst as too much water has to move in if cells aren’t permeable to the solute.

Question 14

define hypotonic solution

Answer 14

osmolarity of solute higher in cell

Question 15

define hypertonic

Answer 15

osmolarity of solute higher out of cell

Question 16

define isotonic

Answer 16

osmolarity of solute equal in and out of cell

Question 17

define osmolarity

Answer 17

is a measure of the concentration of all solute particles in a solution.