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Flashcards in SM01 Mini1 Deck (46):
1

TBW

Total Body Water

75%v/w for infants, 60% v/w adult male, 50% v/w adult female, drops approx. 10% in elderly of each

differences in sex are due to fact content, fat (10% water) & muscle (75% water)

ICF=55%, ECF=45%

2

ECF

Extracellular Fluid

in descending order of volume of ECF= interstitial & lymph, blood plasma, & transcellular (sinovial & vitreous fluids)

3

Measuring Volume

use an indicator of know quantity (mass or radioacitity), allow to equilibriate, measure concentration

V=Mass/Concentration

reality: V= (M - Mexcreted)/C

4

Criteria for an Idicator

  1. nontoxic
  2. rapidly distribute through relevant compartment
  3. restricted to comparment of interest
  4. not metabolized
  5. conveniently measured
  6. not change bocy fluid distribution

5

TBW indicator

3H2O, D2O, antipyrine

6

ECF indicator

SO42-, insulin, mannitol, thiosulfate

7

Plasma

125I-albumin, Evan's blue (dye that binds plasma proteins, but turns things blue, so not used in humans)

8

ICF

Intracellular fluid

calculated volume=TBW - ECF

9

Interstitial Volume

= ECF-plasma

trancellular is ignored bc it is negligable

10

Osmosis

passive movement of water from an area of low osmostic pressure (low solute/high water) to one of high osmotic pressure (high solute/low water)

goal: equalize osmotic pressure between the two

11

Osmotic Pressure

π = nCRT

π= osmotic pressure

n= # of particles

C= concentration of solute in M (mol/L)

R= universal gas constant

T= absolute temperature

R & T are ignored 

12

Osmolarity

osm/L

13

Osmolality

osm/kg

clinically measured by freezing point depression technique

14

Normal ICF Osmolality

275-290 mosmol/kg H2O

same as ECF

15

Normal ECF Osmolality

275-290 mosmol/kg H2​O

same as ICF

16

Isosmotic

two solutions are of the same osmolality

17

hypoosmotic

a solution that has a lower osmolality than another

water moves into cell

18

hyperosmotic

solution that has a higher osmolality than another

water moves out

19

reflection coefficient

σ

how effectively a membrane reflects a solute, inverse to the solutes permeability

ranges from 0 to 1

 

20

effective osmolyte

σ = 1

does NOT permeate membrane

21

ineffective osmolyte

σ = 0

readily permeates membrane

22

Effective Osmotic Pressure

π = σnC

to account for solute permeability

23

Isotonic

solutions that cause no change in cell volume

same molarity

24

Hypotonic

causes cells to swell

25

Hypertonic

solution that causes cells to shrink

26

RVD

Regulatory Volume Decrease

activation of solute export transporters

solute dumping

H2O exit

return to normal

27

RVI

Regulatory Volume Increase

activation of solute import transporters (usually Na+)

solute accumulation

H2O entry

return to normal

28

Osmotic Fluid shifts

SLIDE 21 pictures (cell volume lecture)

diarrhea: V contraction ECF only, isotonic

dehydration: V contraction ECF & ICF, hypertonic

adrenal insufficiency: V contraction ECF only, V expansion ICF, hypotonic

isotonic NaCl infusion: V expansion ECF, isotonic

excessive NaCl intake: V expansion ECF, V contraction ICF, hypertonic

SIADH: Volume expansion ICF & ECF, hypotonic

29

Fick's Law

flux: diffusion of solute across barrier of given surface area (usually 1cm2)= Js

Js is inversely proportionaly to (A/T)S(C1-C2)

A= surface area, T= thickness of barrier, S=lipid solubility, C1&2= concentrations of nonelectrolytes acorss barrier/concentration + electrical potential for electrolytes

 

30

Flux

diffusion of (S)olute across barrier of given surface area (usually 1cm2)

determined by Fick's Law

31

Fick's Working Formula

Jx= -(Dxx/w) * ([X]out-[X]in)

Dx= diffusion coefficient (cm2/sec) accounts for molecular radius

A= membrane surface area

ßx= partition coefficient (unitless) ability of solute to dissolve into membrane

w= membrane thickness

non-electrolyte will be linear, passive diffusion

32

Simple Diffusion

nonpolar uncharge molecules go through lipid bilayer down their concentration gradient

NO energy requirement

33

Facilitated Diffusion

diffusion aided by carrier protein down gradient, change in conformation of protein after binding

NO energy required

34

Primary Active Transport

direct coupling of transport protein hydrolysis of ATP & solute movement

uses energy; ALL ATPases

  1. 3Na+/2K+: preserves low Na+ & high K+ in cells
  2. Ca2+/H+: maintains low Ca2+ in cell
  3. H+/K+: acid secretion in stomach
  4. H+: organelle membranes & plasma membrane of kidneys "proton pump"

35

Secondary Active Transport

indirect coupling of ATP hydrolysis between two solute movements

eneregy generated by one transport drives another

uses energy

36

Uniporters

facilitated diffusion

selective for single solute

bind on one side of membrane, conformational change, release on other side of membrane, return to unbound conformation

ex. GLUT 1-4

37

Pores

simple diffusion through water filled protein tunnel

non-selective

unregulated

DANGEROUS b/c always open

38

Ion Channels

facilitated diffusion

selective filter

gating mechanism

inactivation particle, gate stays open but particle blocks thruway

39

Types of Gates

  1. voltage
  2. ligand
  3. mechanical (stretch activated)

40

Na+ Channels

influx

voltage gated: action potential generation

non-voltage dependent: Na+ transport (in epithelia)

41

K+ Channels

efflux

  1. generation of resting membrane potential
  2. termination of action potential (excitable cells)
  3. secretion of K+ in transporting epithelia (GI & kidney)

42

Ca2+ Channels

influx

transmembrane signaling

generation of action potential in some excitable cells

43

Cl- Channels

efflux

  1. transport across epithelia
  2. control of cell volume
  3. acidification of endosomes
  4. resting membrane action potential in skeletal muscle

44

Cotransporters

type of secondary active transport

symporters: driving & driven solute in the same direction

can be eletrogenic or electroneutral

45

Exchangers

type of secondary active transport

antiporters: driving & driven solute in the opposite direction

can be eletrogenic or electroneutral

46

Pump-leak Coupling

occurs in all cells to maintain high [K+] & low [Na+] & membrane potential

K+ leaks out of channels & pumped in through Na/K pump

Na+ in thru Na/Ca antiporter & out by Na/K pump

30% of ATP used up this way