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PHYL2062 > Cell Membrane and Osmosis Practical > Flashcards

Cell Membrane and Osmosis Practical Flashcards

1
Q

What is diffusion?

A

When particles of a substance (solute) are introduced into a solvent, continuous random movement of the particles tends to spread them from regions where their concentration is high to regions where it is low until the concentration is uniform through-out the solution.

High concentration –> disperse –> low concentration

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2
Q

What is osmosis?

A

If the particles are prevented from diffusing to all regions by a membrane which is impermeable to the solute particles but permeable to the solvent solvent molecules move across the membrane into the region where the concentration of solute is higher i.e. the solvent is diffusing down its concentration gradient. The solvent (usually water) moves until it is opposed by an equal and opposite force.

High water concentration –> low water concentration

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3
Q

The osmotic pressure of an aqueous solution is _____ (equal/different) to the hydrostatic pressure (P) which develops when water moves across a semi-permeable membrane and prevents further ____ movements.

A

equal; water

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4
Q

Normally the total concentration of solute particles inside cells is approximately the ____ (same/different) as that in the extracellular fluid but if cells are suspended in a solution with a lower concentration of particles, water moves _____ (into/out of) the cell; conversely when cells are suspended in a solution of greater concentration, water moves ____ (into/out of) the cells.

A

same; into; out of

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5
Q

What is haemolysis?

A

Erythrocytes in dilute solutions swell and the cell membrane is disrupted, allowing haemoglobin to escape;

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6
Q

What is crenation?

A

Erythrocytes placed in more concentrated solutions lose water, their volume decreases and the cell membrane becomes folded

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7
Q

The osmotic pressure of a solution depends on the ___________, consequently solutes which dissociate into ions (electrolytes) have a _______ (larger/smaller) osmotic pressure at the same concentration than solutes which do not.

A

number of particles in solution; larger

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8
Q

Theoretically, a 0.5 M solution of an electrolyte which dissociates into two ions will have the same osmotic pressure as a 1 M solution of a non-electrolyte. True or false?

A

True

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9
Q

What is an isotonic cell?

A

A solution in which red cells retain their normal volume, neither shrinking nor swelling

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10
Q

What does tonicity mean?

A

describe the osmotic pressure relative to plasma and depends on the concentration of those particles which cannot cross the cell membrane

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11
Q

Solutions which are iso-osmotic with plasma will not also be ____ if some of the solutes in the solution can pass through the cell membrane because, as particles move into the cell, the osmotic pressure of the solution is _____ (increased/decreased) and it becomes _______.

A

isotonic; decreased; hypotonic

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12
Q

What is a hypotonic cell?

A

Water moves into the cells and they swell and may lyse

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13
Q

What is a hypertonic cell?

A

Cells lose water and shrink

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14
Q

Haemoglobin free in plasma after haemolysis of erythrocytes is _______ (quickly/slowly) destroyed and is not available to carry ______.

A

quickly; oxygen

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15
Q

What is a mole?

A

the molecular weight of a substance in grams

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16
Q

What does a molar solution contain?

A

contains one mole of solute per litre of solution.

  • All molar solutions contain the same number of molecules.
17
Q

What does osmolarity of solution equal to?

A

molarity x the number of freely moving particles each molecule liberates in solution

  • e.g. an ideal 1 M solution of an electrolyte which dissociates into two ions is 2 osmoles/l. A 1 M solution of any undissociated solute has an osmolarity of 1 osmol/l.
18
Q

Two solutions which have the same osmotic pressure are said to be ________.

A

isoosmotic

19
Q

If solution A has a greater osmotic pressure than solution B, solution A is _______ with respect to B.

A

hyperosmotic

20
Q

If solution A has a lower osmotic pressure than solution B, A is _____ to B.

A

hypoosmotic

21
Q

A solution is _______ if cells placed in it retain their normal volume.

A

isotonic

22
Q

In a _____ solution cells lose water and shrink.

A

hypertonic

23
Q

In a _______ solution, cells swell and may lyse.

A

hypotonic

24
Q

What are the 2 equations for molarity?

A

Molarity = volume (L) x concentration (mol/L)

Molarity = mass (g) / molecular mass

25
Q

What is the equation for osmolarity?

A

Osmolarity = molarity x no. of dissociated particles

26
Q

What might be the consequences of cells swelling in vivo?

A

Explode –> organ destruction; lyses of RBC; disruption of K+ and Na+2 channels due to created tension

27
Q

On the basis of your results and observations, what concentration of NaCl would you use to store red blood cells such that they would neither shrink nor swell (isotonic)?

A

9g/L of Na (concentration) = 9/58.5 = 0.153.85mol/L = 153.85 mmol/L

28
Q

On the basis of your results, what general conclusions can you draw about the permeability of cell membranes to different types of solutes?

A

Non-polar (ethanol and urea) can diffuse through membrane easily

Distilled water- purified- no solutes

Glycerol- bulky

Glucose, sucrose- very big and very slow permeability because need carrier molecules (facilitative transport- active- secondary transport)

29
Q

How much total water does ICF make up?

A

2/3 of total body water

30
Q

How much total water does ECF make up?

A

1/3 of total body water

31
Q

What are 2 components that make up the ECF?

A
  1. plasma which has a high plasma protein content and the proteins cannot diffuse out of the capillaries
  2. interstitial fluid which has the same Na and K content as plasma but almost no protein
32
Q

The intracellular fluid (equivalent to the red cells you placed in your test tubes) has a ___ and _____ content very different from that of the extracellular.

A

Na; K

33
Q

Water can diffuse freely across most cell membranes. The osmotic pressure is _____ (same/different) in the ECF and the ICF even though the particles that make up the solute concentration ____ (same/differ).

A

same; differ

34
Q

How will water be distributed in the extracellular fluid and intracellular fluid if a person drinks 600 ml of tap water:

  1. molarity and osmolarity of tap water
  2. tonicity (hypo, iso, hyper) of tap water
  3. what solute present/will it cross membranes
  4. how much water will be distributed in the extracellular fluid
  5. how much water will be distributed in the intracellular fluid
A
  1. Nil
  2. Hypotonic
  3. Nil
  4. 200mL
  5. 400mL
35
Q

How will water be distributed in the extracellular fluid and intracellular fluid if a person receives an intravenous infusion of 600 ml of isotonic saline solution:

  1. molarity and osmolarity of isotonic saline solution
  2. tonicity (hypo, iso, hyper) of isotonic saline solution
  3. what solute present/will it cross membranes
  4. how much water will be distributed in the extracellular fluid
  5. how much water will be distributed in the intracellular fluid
A
  1. 300mL
  2. Isotonic
  3. Nil
  4. 600mL
  5. 0mL
36
Q

How will water be distributed in the extracellular fluid and intracellular fluid if a person receives an intravenous infusion of 600 ml of isotonic glucose solution:

  1. molarity and osmolarity of isotonic glucose solution
  2. tonicity (hypo, iso, hyper) of isotonic glucose solution
  3. what solute present/will it cross membranes
  4. how much water will be distributed in the extracellular fluid immediately after the glucose solution was infused
  5. how much water will be distributed in the intracellular fluid immediately after the glucose solution was infused
  6. how much water will be distributed in the extracellular fluid 1-2 hours after the glucose solution was infused
  7. how much water will be distributed in the intracellular fluid 1-2 hours after the glucose solution was infused
A
  1. 300mL
  2. isotonic
  3. Nil
  4. 600mL
  5. 0mL
  6. 200mL
  7. 400mL

PHYL2062 (17 decks)

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