Osmosis

Question 1

What is the movement of the SOLUTE across a membrane when there is a concentration gradient
(High —> low)

Answer 1

Diffusion

Question 2

What is the movement of SOLVENT as a result of pressure gradient

Answer 2

Osmosis

Question 3

What is the bodies natural solvent

Answer 3

Water

Question 4

The difference between the intracellular and extracellular fluid compositions are produced and maintained by what two major things?

Answer 4

1. Semi-permeable membrane (hydrophilic wont cross easily, hydrophobic will)
2. Presence of a variety of active transporters (Na/K ATPase) moves ions across membrane and can go against gradient

Question 5

Despite the difference ion concentrations in the intracellular and extracellular fluid, the osmolarity of the two is the ______.

Answer 5

Same

*important bc then under normal circumstances, we have no gradient that would make osmosis occur

Question 6

Osmosis doesn’t depend on the concentration of solutes (and whether solutes are different). Osmosis only occurs if what?

Answer 6

If there is a gradient for the water

Question 7

T/F
The potassium channel that allows the entry and exit of potassium in/out the cell is open most of the time to allow potassium exchange

Answer 7

True

*high permeability

Question 8

T/F

Chloride has a channel that is open at rest

Answer 8

True

*high permeability

Question 9

Why does bicarbonate have a high permeability to cross in/out of the cell membrane

Answer 9

Because bicarbonate is made from CO2 and converts between the two rather quickly. CO2 can cross easily, therefore so can bicarbonate

Question 10

When are sodium and calcium channels open to allow entry and exit from the cell

Answer 10

Only under specific circumstances therefore they have low permeability

Question 11

The measure of the number of osmotically active particles (solute) in the solution

Answer 11

Osmolarity

Question 12

What are the two things osmolarity depends on?

Answer 12

1. Molar concentration of solute [C]
2. Number of participles the solute dissociates into when placed into solution

Osmolarity = g x [C]

*under normal circumstance g = 1

Question 13

What is a “fancy” measure of the solutes permeability across the membrane

Answer 13

Reflection coefficient (sigma symbol)

Question 14

What are the ranges of the reflection coefficient? And what do they mean?

Answer 14

Range: 0-1

0 = solute is fully permeable

1 = solute is fully impermeable

*IMPORTANT BC WILL TELL YOU IF OSMOSIS OCCURS

Question 15

Characteristics if the reflection coefficient is 0

Answer 15

• completely permeable
• osmotic pressure = 0
• solute will diffuse across membrane
• NO VOLUME CHANGE THERE NO OSMOSIS OCCURS

Question 16

What are the characteristics if the reflection coefficient = 1 ?

Answer 16

• impermeable membrane
• solute cannot cross
• osmotic pressure is high
• OSMOSIS WILL OCCUR
• volume will increase proportionate to water motion

Question 17

What is the average osmolarity of the ICF and ECF of the human body ?

Answer 17

290 mOsm

270 - 300 is normal range

Question 18

.9% NaCl is _____ to our RBC’s and is known as normal saline

Answer 18

Isotonic

Question 19

What is created by the difference in solute concentration one other side of the semi-permeable membrane

Answer 19

Osmotic pressure

*visualized by U tube

Question 20

When osmosis occurs, the height of the columns of the U-tube is changed. The difference in heigh is known as

Answer 20

Osmotic pressure

Question 21

What is the equation for estimated osmolality

Answer 21

Estimated osmolality =

2 x Na) + (Glucose/18) + (BUN/2.8

Question 22

Isoosmotic solutions can cause what change in a cell’s volume because of there is no gradient present for water to move

Answer 22

NO VOLUME CHANGE

Question 23

What does a hypoosmotic solution cause ?

Answer 23

• osmolarity is less outside cell
• higher water “concentration” outside of cell
• causes water movement inside cell
• CELL SWELLING/ RUPTURE

[remember osmolarity is measure of solutes. The more solutes the less water. A hypoosmotic solution has less solutes therefore more water]

Question 24

What does a hyperosmotic solution cause ?

Answer 24

• osmolarity of the solution is greater outside cell
• less water outside of the cell
• water moves out of cell
• cell will SHRINK/ CRENATE

[hyperosmotic solution has more solutes and therefore less water]

Question 25

If the reflection coefficient is close to 1, the osmolarity and toxicity will _____

Answer 25

Match (a hypoosmotic solution = a hypotonic solution)

Question 26

If the reflection coefficient is close to 0, the solute is permeable. The osmolarity and toxicity willl ______

Answer 26

Not match.

Question 27

T/F
A solution can be isosmotic or hyperosmotic but still cause cell to swell and rupture because the solute in the solution is permeable to the cell membrane (reflection coefficient = 0)

Answer 27

TRUE

*tonicity and osmolarity will not match because reflection coefficient is 0

Question 28

____ is determined by the cell’s response to being put into the solution (not just the number like osmolarity)

Answer 28

Tonicity

Question 29

What happens to a cell in an isotonic solution

Answer 29

The cell does not change volume

No osmosis

Question 30

What happens to a cell in a hypotonic solution ?

Answer 30

-the cell will swell, rupture, or lose due to movement of water into the cell

Question 31

What happens to a cell in a hypertonic solution ?

Answer 31

-cell will shrink/crenate because of the water movement out of the cell

Question 32

T/F
The osmolarity and tonicity of a solution may not “match” if the solute in the solution is permeable to the cell membrane (reflection coefficient = 0)

Answer 32

True

• NO OSMOSIS
• the solute in the solution will simply come to equilibrium via diffusion

Question 33

If the cell contains a number of solutes with a reflection coefficient of 1, then those solutes will create what and have what effect?

Answer 33

The solutes will create a pressure gradient that draws water in/out of cell