Osmosis

Question 1

What is the description for the permeability of the plasma membrane?

Answer 1

selectively permeable

Question 2

How does water flow between the ICF and the ECF?

Answer 2

by osmosis

Question 3

What does the volume of a compartment in the body depend on?

Answer 3

the total number of osmotically active solute particles trapped inside the compartment

Question 4

How do the volumes of ICF and ECF compare?

Answer 4

ICF is approximately double the volume of ECF

Question 5

What does the difference in volume of the ICF and ECF mean for amount of solute particles in both?

Answer 5

ICF contains approximately double the amount of osmotically active solute particles

Question 6

What is a mole a unit of?

Answer 6

quantity

Question 7

What is one mole contain?

Answer 7

the same number of particles as there are atoms in 12g of carbon-12 isotope

Question 8

what is avogadros number?

Answer 8

6x10 to the 23 (one mole)

Question 9

what is molarity a unit of?

Answer 9

concentration

Question 10

What does molarity measure?

Answer 10

the number of moles of solute per litre of solution

Question 11

What is the property called that refers to solvents that can be changed by adding solute?

Answer 11

colligative properties

Question 12

What is a semi permeable membrane?

Answer 12

permeable to water but not to solutes

Question 13

What is the plasma membrane permeable to?

Answer 13

water

Question 14

What is the plasma membrane selectively permeable to?

Answer 14

some solutes

Question 15

What conditions are required for maximum osmotic effect?

Answer 15

ions must be trapped on one side of the membrane

Question 16

What is permeability to a particular solute indicated by?

Answer 16

reflection coefficient

Question 17

What does the reflection coefficient range from?

Answer 17

0 to 1

Question 18

What does a reflection coefficent of 0 mean?

Answer 18

membrane is totally permeable to solute

Question 19

What does a reflection coefficent of 1 mean?

Answer 19

membrane is impermeable to solute

Question 20

Which solutes exert greatest osmotic effect?

Answer 20

those with a reflection coefficent of 1 that are trapped on one side of a membrane

Question 21

What is the value of one osmole?

Answer 21

6x10 to the 23 osmolyte particles

Question 22

What effect does an osmole have on the activity of water?

Answer 22

decreases the activity of water

Question 23

What is osmolarity a measure of?

Answer 23

the activity of water

Question 24

What does osmolarity show?

Answer 24

the number of osmoles per unit volume of solution

Question 25

what does an increase in osmolarity lead to?

Answer 25

a decrease in water activity

Question 26

What is the osmotic coefficient?

Answer 26

degree of disassociation when a solute is placed in water

Question 27

How can you calculate osmolarity?

Answer 27

osmotic coefficient x molar concentration of all osmolyte particles

Question 28

Define osmosis

Answer 28

flow of water molecules from an area of high water activity (lower osmolarity) to an area of lower water activity (higher osmolarity) across a semi-permeable membrane

Question 29

What does higher osmolarity mean in terms of solute particles?

Answer 29

there are increased solute particles

Question 30

What can the difference in osmolarity also be called?

Answer 30

osmotic pressure gradient

Question 31

Give 5 ways that osmosis could be stopped

Answer 31

place an impermeable membrane to both solute and water place a membrane that is selectively permeable to the solute (has a reflection coefficient of 0) add water to the compartment with higher osmolarity add solute to the compartment with lower osmolarity Increase the hydrostatic pressure

Question 32

What is the effect of placing a membrane that is selectively permeable to the solute that is creating the osmotic pressure gradient?

Answer 32

solute can flow through the membrane and will then remove the osmotic pressure gradient

Question 33

what effect will adding water have on the compartment with high osmolarity?

Answer 33

increase the activity of water and reduce the osmotic pressure gradient

Question 34

what effect will adding solute have on the compartment with lower osmolarity

Answer 34

decrease the activity of water and reduce the osmotic pressure gradient

Question 35

What effect does increasing hydrostatic pressure have?

Answer 35

increases activity of water

Question 36

What is the effective osmotic pressure?

Answer 36

actual osmotic pressure in a system

Question 37

What is the concerntration of normal saline?

Answer 37

0.9% NaCl

Question 38

What effect does bathing cells in 0.9% NaCl have?

Answer 38

no change in shape or size of cells

Question 39

What sort of solution is 0.9% NaCl?

Answer 39

isotonic

Question 40

What happens to cells bathed in an isotonic solution?

Answer 40

no net movement of water into or out of the cells by osmosis

Question 41

How does the activity of water in ICF compare to the activity of water in 0.9% NaCl solution?

Answer 41

they are equal to each other

Question 42

How does the EOP of ICF compare to the EOP of 0.9% NaCl solution?

Answer 42

they are equal

Question 43

What is 0.9% NaCl solution used for?

Answer 43

medical treatment of fluid loss

Question 44

What is the difference in osmolarity between 0.9% NaCl solution and 2.7% NaCl solution?

Answer 44

2.7% NaCl solution has higher osmolarity

Question 45

What happens to cells bathed in 2.7% NaCl solution?

Answer 45

shrink and become crenated, water flows out of cells by osmosis

Question 46

How does the activity of water in ICF compare to the activity of water in 2.7% NaCl solution?

Answer 46

Activity of water in ICF is higher

Question 47

How does the EOP of ICF compare to the EOP of 2.7% NaCl solution?

Answer 47

EOP of ICF is less than EOP of 2.7% NaCl solution

Question 48

What sort of solution is 2.7% NaCl?

Answer 48

hypertonic

Question 49

What happens to red blood cells bathed in distilled water?

Answer 49

they grow larger and then burst releasing haemoglobin

Question 50

What is the bursting of red blood cells and release of haemoglobin known as?

Answer 50

haemolysis

Question 51

What sort of solution is distilled water?

Answer 51

hypotonic

Question 52

What is the difference in water activity in ICF and distilled water?

Answer 52

activity is greater in distilled water than in ICF

Question 53

What does the difference in water activity between RBC and distilled water cause?

Answer 53

water flows into the RBC by osmosis

Question 54

How does the EOP of ICF compare to the EOP of distilled water?

Answer 54

EOP of ICF is greater than the EOP of distilled water

Question 55

Why would distilled water never be given through an IV?

Answer 55

would cause mass haemolysis of the RBC

Question 56

Define isosmotic

Answer 56

equal concentrations of impermeable solutes on each side of the semi permeable membrane

Question 57

What are two major osmolytes in the mammalian body?

Answer 57

sodium and chloride ions

Question 58

Define solute, solvent and solution

Answer 58

substance, liquid and mixed solute and solvent

Question 59

What happens to NaCl in solution?

Answer 59

dissociates into constituate ions

Question 60

Why doesnt double osmolarity occur in practice when a solute dissolves?

Answer 60

not all of the solute will dissolve into its constituent ions, some of them remain whole

Question 61

What is dissociation coefficient?

Answer 61

the degree to which a solute dissociates in a solution

Question 62

What is osmotic equilibrium?

Answer 62

no net movement of water across the semi permeable membrane

Question 63

What is the volume of a cell determined by?

Answer 63

movement of water

Question 64

What does the volume of a cell depend on?

Answer 64

relative EOP of ICF and ECF

Question 65

What is haematocrit?

Answer 65

In treated (non clotted) blood the ratio of volume of RBC to total volume (RBC and plasma)

Question 66

What does reduced ICF volume mean in terms of haematocrit?

Answer 66

reduced haematocrit

Question 67

What does increased ICF volume mean in terms of haematocrit?

Answer 67

increased haematocrit unless cells lyse