body fluids, diffusion and osmosis Flashcards

19.08.08

1
Q

Of the body how much of it is water? where is this water use in the measurment?

A

50-70%

  1. water comes from (60% of weight is water)
    1. ICF-40%-2/3 of TBW
    2. ECF-20%-1/3 of TBW
      1. intestitial fluid
      2. plasma-1/4 of TBW

60-40-20

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2
Q

what are some clinical aproaches for managing wate?

A
  1. burns
    1. 486000 in 2016
  2. bleeding
    1. 10.8 mil car accidents in 2009
  3. cholera- induced diareah
    1. 1.4 -4 mil in 2013
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3
Q

total body water for males vs females

A
  1. males
    1. 60
  2. females
    1. 50

this is due to the fat:water ratio

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4
Q

What % of body tissue is water

A
  1. 100% of body
    1. muscle
      1. 79-80% h2o
    2. fat
      1. males
        1. 10-15
      2. female
        1. 20-24
    3. bone
      1. rest

body fat measurment

  1. Dual energy X-ray absorptiometry
    1. uses
      1. conductivity difference allow body fat estimation through impedance
  2. general recommendations
    1. age and gender dependent, b/c of difference anatomically
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5
Q

what is plasma?

what is the hematocrit

A

blood devoid of cells.

Hematocrit = concentration of blood cells

  1. varies with age
    1.
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6
Q

what is the difference between osmolarity and tonicity?

define the three states of tonicity with osmolarity as a reference.

A

these are not interchangeable.

  1. osmolarity
    1. the total solute concentration in an aqueous solution
  2. tonicity
    1. the effects of carious osmotic solutions on cells

the nature of the solues is often as important os the total osmolarity

  1. hypotonic
    1. the solution is hyposmotic, more stuff intracellularly than extracellularly. cuasing the cell to swell with water
  2. isotonic
    1. isosmotic- ICF and ECF are equal in osmolarity
  3. hypertonic
    1. solution is hyperosmotic, containing more solutes than the intracellular compartment
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7
Q

what is the composition of body fluids

compare ICF to ECF

A
  1. non-electrolytes-uncharged moieties
    1. glucose
    2. lipids
    3. creatine
    4. urea
    5. uncharged proteins
  2. electrolytes-charged moiteies
    1. salts
    2. acids/bases
    3. charged proteins

ICF vs ECF

  1. ECF electrolytes
    1. cation
      1. Na
    2. anion
      1. chloride
    3. protein
      1. lower
  2. ICF electrolytes
    1. cation
      1. K
    2. anion
      1. phosphate
    3. protein
      1. higher
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8
Q

list the values of each

  1. TBW-total body water
    1. male vs female
  2. TBW caluculations
  3. ECF (X/Y)and BPV% TBW
A
  1. male TBW>female TBW
    1. 60 vs50
  2. TBW=ECF + ICF; ECF =BPF+ISF
    1. blood plasma fluid
    2. interstitial fluid
  3. ECF=1/3 TBW; BPV=12% TBW
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9
Q

how much is a 1mmol/L? how can you use the molecular weight?

explain an equivelent. use Na+, Cl- and Ca++ as examples

explain %solution. use 10%NaCl, vs 1Liter

A

this is a unit of measurement called molarity

  • 1mmol/L = 0.001mol/L
  • mmol/L x 1mol/1000mmol x grams(MW)/mole = g/L

equivelent

  • Eq/L = mol/L xcharge/atom
    • example
      • Na+ 135mmol/L=135mEq/L
      • Cl-
        • 108mmol/L=108mEq/L
      • Ca++
        • 2.1mmol/L=4.2 mEq/L

% Solution

  • grams of soulution/100mL, expressed in g/dL(deciliter)
  • example
    • 10% NaCl
      • 10grams of NaCl in 100mL
        • 1 liter = 10x’s -> 100g/L
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10
Q

how are the measurments of Osmolarity used? explain

  • osmole
  • osmolarity
    • 15mmol/L NaCl-> solution
    • 15mmol/L Ca++-> solution
  • osmolality
A
  • Osmole is the number of moles of a solute tht contribute to osmotic pressure
  • osmolrity
    • Osm/L of solvent= [S] x D
      • D= number of particles
    • independent of charge
    • example
      • 15mmol/L NaCl-> 30mOsm/L solution
      • 15mmol/L Ca++-> 15mOsm/L solution
  • osmolality
    • difference from osmolarity: water volume function of temp while mass is not.
    • Osm/kg h2o
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11
Q

calculate the following osmolarity

  • Ca++
    • 2.1-2.8mmol/L
  • Na+
    • 135-145mmol/L
  • glucose
    • 5mmol/L
  • NaCl
    • 5mmol/L
A
  • Ca++
    • 2.1-2.8mmol/L=4.2-5.6mEq/L
    • 2.1-2.8mmol/L=2.1-2.8mOsm/L
      • calcium does not dissociate,
  • Na+
    • 135-145mmol/L=135-145mEq/L
    • 135-145mmol/L-135-145mOsm/L
      • Na+ on its own does not dissociate
  • glucose
    • 5mmol/L=5mOsm/L
      • glucose does not dissociate
  • NaCl
    • 5mmol/L=10mEq/L
    • 5mmol/L=10mOsm/L
      • NaCl does dissociate in to sodium and chloride, so the solutions osmolarity is doubled
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12
Q

diffusion is an important concept in the body.

Explain the diffusion rate. what is the consequence on the vasculature?

calculate myoglobin if its MW is 68000

A

diffusion rate is proportional to 1/distance^2

  • O2 will diffuse 100microns in 2.38 seconds, 6.6 hours to diffuse 1cm
  • the vasculature will find itself densely through out the body and within 100microns of a cell

the higher the temperature= faster the diffusion

where it takes O2 2.38s to traverse 100microns, it will take myoglobin 1.2 minutes

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13
Q

why is it that measuring the plasma osmolarity tells us about the molarity through out the body?

A

at equilibrium osmolarity in the ECF = ICF

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14
Q

what is tonicity a function of?

A

tonicity is a function of permeability of the membrane.

is the solute can move accross into/out of the cell, the osmolarity of ICF and EFC changes. This leads to osmosis.

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15
Q

what is the length of time to achieve osmotic equilibrium through out the body. Why?

A
  1. ECF and ICF
    1. seconds to minutes
  2. whole body
    1. ~30min
    2. takes time to absorb the fluid into the gut
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16
Q

discuss the fluid infusion and changes in the ICF and ECF with respect to osmolarity and volume differences and changes.

A

fluid therapy is adding a solution of fluid to the body. In all these scenarios the ECF increases, bc you are adding fluid to the body

  1. isotonic NaCl
    1. just an increase in the ECF
    2. osmolarity of solution=body
  2. Hypotonic NaCl
    1. the osmolarity of solution
    2. there is a higher solute concentration in the cell than in the solution, causing the water to move into the cell. increasing the ICF and ECF. and decreasing the osmolarity of the ICF and ECF
      • hypertonic NaCl
  3. osmolarity of solution>body
    1. there is a higher solute concentration in the solution compared the ICF, causing water to leave the cell and into the ECF. Increasign the ECF, decreasing the ICF. and increasing the osmolarity of the ECF and ICF.
17
Q

discuss the varying terms, osmolarity and tonicity with the various IV therapies. Explain the affect each IVF will have on the body.

What is the glucoses osmolarity and how does the cell respond?

A

cell membranes are permeable to glucose, so the glucose gets absorbed quickly and is not osmotically active.

when all the glucose moves inracellular and is broken down/compartamentalized you are left with an isosmotic solution and isotonicity with respect to the cell (osmotic pressure in the cell).

18
Q

Tonicity applies to body compartments, including permeability. what affect do the follwing cellular conditions mean with reference to tonicity?

  1. isotonic
  2. hypotonic
  3. hypertonic
A
  1. isotonic
    1. no change in osmolarity or volume
    2. increase ECF
  2. hypotonic
    1. decrease osmolarity
    2. increase ICF volume
    3. increase ECF
  3. hypertonic
    1. increase osmolarity
    2. decrease ICF
    3. increase ECF