FORM & FUNCTION (Diffusion, Osmosis, Tonicity)

Question 1

diffusion

Answer 1

-critical process
-facilitates passive movement of molecules across various biological barriers
-higher to lower concentrations
-results in uniform distribution of substances within a medium
-no energy required
-can occur in gases, liquids and solids

Question 2

Factors influncing rate of diffusion

Answer 2

1. Directly proportional
   -concentration gradient (most important)
   -surface area where it occurs
2. Inversely proportional
   -solvent visocosity (thickness)
   -radius of diffusing particles (larger=slower)

Question 3

oxygen transport

Answer 3

-moves through tissues by simple diffusion (high to low concentration (pO2))
-does not need a transporter

Question 4

partial pressure (pO2)

Answer 4

-relates to the concentration of gases

Question 5

hydrated ions

Answer 5

-ions are surrounded by water molecules in solution and are diffused as a hydrated particle
*need to consider the size of the hydrated ion and not just the size of the ion

Question 6

electrochemical gradient

Answer 6

-determines the direction of movement of ions
-major driving force=ions move down their concentraion gradient
-as like-charges build up they start to repel in the opposite direction
*combination of the electrical and the concentration gradient

Question 7

PM charges

Answer 7

-positive outside the cell
-negative inside the cell

Question 8

osmosis

Answer 8

-specific type of diffusion
-net movement of water caused by concentration difference for water developing across a semi-permeable membrane

Question 9

osmotic pressure

Answer 9

-a quantitative measure of the tendency for water to diffuse (how many particles are in the solution?)
-water will osmose to a compartment that has a higher osmotic pressure
Ex. more particles=higher osmotic pressure

Question 10

effective osmolality or tonicity

Answer 10

-ability of a solution to initiate water movement (‘osmoles restricted to the one side’)
-depends on impermeant or effective osmoles (impermeable solute that do NOT cross the membrane)

Question 11

Examples of effective osmoles

Answer 11

1. Sodium
2. Glucose in diabetic patients

Question 12

sodium

Answer 12

-common salt used in IV fluid
-most cells are impermeable to sodium (keep fluid in vasculature)

Question 13

glucose in diabetic patients

Answer 13

-normally it is permeable and your cells take it up
-diabetic patients, their cells don’t take up glucose

Question 14

example of ineffective osmoles

Answer 14

Urea
-if cells are metabolically active
-won’t change water concentration as it can move freely across all membranes

Question 15

tonicity

Answer 15

-describes the concentration of impermeant solutes compared to normal plasma
-RBC can respond to changes in osmolality and can be used as an osmoter (erythrocytes agility)

Question 16

isotonic

Answer 16

-contain an equal amount of impermeable solutes compared to plasma
Ex. RBC stays the same

Question 17

hypotonic

Answer 17

-contains less impermeable solutes compared to plasma
-RBC expands

Question 18

hypertonic

Answer 18

-contain more impermeable solutes compared to plasma
Ex. RBC shrinks

Question 19

clinical relevance of osmosis in blood vessels

Answer 19

-osmotically active particles in blood draw water in from the interstitial space
-hydrostatic pressure pushes water out of the interstitual space

Question 20

plasma osmolarity/osmolality

Answer 20

-measures the number of osmotically active particles
-important clinical parameter
-measured using an osmometer that measue other colligative properties

Question 21

osmolal gap

Answer 21

=measured - calculated osmolality
-normal osmolal gap <10mOsm/kg
-high osmolal gap >10mOsm/kg
*can help detect toxins

Question 22

osmoreceptors

Answer 22

-how the body senses changes in tonicity
-when change, the receptors will be activated to bring the osmotic pressure back to the base line

Question 23

colligative properties

Answer 23

-boiling point elevation
-freezing point depression