RBC Lecture Flashcards

1
Q

What is a Permeable Membrane?

A
  • Everything can cross
  • At equilibrium:
    1. [solute] of A= [solute] of B
    2. Volume of A= Volume of B
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2
Q

What is a Semi-Permeable Membrane?

A
  • Only the solvent (H2O) can cross
  • At equilibrium: osmotic pressure generated by the solute in A EQUALS the hydrostatic pressure generated by the extra solvent in A from B
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3
Q

What is a Permselective Membrane?

A
  • Solvent can cross

- Solutes have DIFFERENT permeabilities

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4
Q

What is the osmotic pressure equation?

A

pi= pgh

  • pi= osmotic pressure
  • p= density of the solution
  • g= gravitation constant
  • h= height difference of fluid in the tubes
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5
Q

What is a non-electrolyte?

A

Molecules that don’t dissociate into multiple parts when put into solution
- Sucrose, urea, proteins, etc

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6
Q

What is the osmolarity for non-electrolytes?

A

Molarity=osmolarity

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7
Q

What is an electrolyte?

A

Molecules that dissociate into multiple parts when put into solution

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8
Q

What is the osmolarity for electrolytes?

A

Molarity x dissociation #= osmolarity

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9
Q

What is the Permeability Coefficient?

A

P= how fast things can cross the membrane

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10
Q

Osmolarity terms compare what?

A

solutions

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11
Q

What is Isoosmotic?

A
  • generate the same pi; two solutions with the same osmolarity and generating equal osmotic pressure (pi)
    ex:
    A= 2mM sucrose= 2mOsm
    B= 1mM NaCl= 2 mOsm
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12
Q

What is Hypoosmotic?

A
  • generates a lower pi
  • a solution having a lower osmolarity and osmotic pressure (pi) than another solution
    ex:
    A= 1mM sucrose= 1 mOsm is hypoosomotic to
    B= 1mM NaCl= 2mOsm
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13
Q

What is Hyperosmotic?

A
  • generates higher pi
  • a solution having a greater osmolarity and osmotic pressure(pi) than another solution
    Ex:
    A= 2mM sucrose is hyperosmotic to
    B= 0.5 mM NaCl
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14
Q

What does Isotonic mean?

A

no net H2O flow

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15
Q

What is an Isotonic solution? (compared to inside of cell)

A

no volume change

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16
Q

What does Hypotonic mean?

A
  • if A is hypotonic to B then:

A -H2O-> B

17
Q

What is a Hypotonic solution? (compared to inside of cell)

A
  • cell swells; volume increases

- if too much then lysis of cells

18
Q

What does Hypertonic mean?

A
  • if A is hypertonic to B then:

B -H2O-> A

19
Q

What is a Hypertonic solution? (compared to the inside of cell)

A

cell shrinks; volume decreases

20
Q

What are the features of Red Blood Cells (RBCs)?

A

1) no nucleus
2) few internal structures
3) little lipid bilayer “bags” of hemoglobin (Hb)

21
Q

What are the features and assumptions of the membrane of RBCs?

A
  • selective permeable membrane
  • H2O and urea cross the membrane quickly
  • Assume K+, Na+, sucrose, and Hb don’t cross
22
Q

What are the contents of plasma?

A

H2O and solutes

23
Q

What are the contents of the Buffy Coat?

A

White blood cells (WBCs) and platelets

24
Q

How is the Hematocrit (Hct) measured?

A

Hct= vol of RBCs / total volume

25
What is a Wintrobe tube used for?
used to measure the Hct; the % of total volume taken up by RBCs Ex: 0.37 or 37%
26
What are the normal Hct values for men and women?
Women: 36%-46% (0.36-0.46) Men: 41%-53% (0.41-0.53)
27
Why do men have a higher Hct than women?
- males have a higher Hct bc male androgens trigger RBC production - females lose RBC bc of menstruation
28
What is the Hct level in anemia and was causes it?
Low Hct - bleeding (lose RBC) - low iron (need iron to make Hb and for maturation of RBCs) - pregnancy (expansion of plasma vol) - RBC breakage (hemolytic anemias, immune attack on RBCs) - some types of kidney disease (decreased erythropoietin (EPO) production) *EPO= hormones that makes RBCs
29
What is the level of Hct in polycythemia and what are the causes?
High Hct - dehydration (decreased plasma vol) - hereditary overproduction of RBCs (polycythemia vera) - low blood oxygen (live at high altitude, heart/lung disease, smokers) - blood packing (transfuse extra RBCs) - EPO injections (make extra RBCs)
30
What is the equation of the total volume of RBCs?
V= W+b - V= total volume of an RBC - W= volume of H2O in an RBC (can cross) - b="osmotically inactive volume" (can't cross- Hb, other solutes)
31
What is the equation of the solute concentration inside of an RBC? What is the assumption of S?
C= S/W - C= [solute] inside of an RBC - S= # of particles - W= volume of H2O in an RBC - Assume that solutes don't cross the RBC membrane therefore S is constant
32
What is the Osmometer equation?
V/Vo= ((Co - (bCo/Vo)) (1/C) + (b/Vo) | - Describes the changes in RBC volume when RBCs are put into different tonicity solutions
33
What is the b/Vo value?
- where the line crosses the y-axis - in humans: 0.4-0.45 - Hypertonic solutions plot closer to the origin, lower values - Hypotonic solutions plot further from the origin, higher values
34
What is V/Vo?
V/Vo= H/Ho - H= measured Hct - Ho= Hct in an isotonic solution - on the y axis; isotonic = 1
35
What are the axis on the plot for V/Vo and 1/C?
y-axis: V/Vo | x-axis: 1/C (mOsm^-1)