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Physiology Kerry > 1. Fluid & Electrolytes > Flashcards

1. Fluid & Electrolytes Flashcards

1
Q

What is the total body water in an adult male

A

42L in 70kg

60% Total body weight

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2
Q

Body Compartments

A

Exist in collections as compartments

ICF / ECF
- membrane side ->

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3
Q

ECF divided into

A

ISF
Itranvascular
CT / bone
transcellular

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4
Q

Transceullar

what

whats included

A

Virtual compartment - diverse group small fluid clollection

Transport activity / epithelail spaces
2.5% TBW

CSF
Joint fluid aqeous
Bile
Bowel
Body cavity
urine
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5
Q

What controls distrubiton water

A
  1. Water can cross most - ease - solutes cant

Water moves until osmolality equal

ECF - easier sample

ECF osmality - controlls distrub TBW ECF/ICF

Osmoal ECF increased - net water movement out
Continue until ICF equals

  1. Na is major cation in ECF
    Must asoc anion opposite equal total charge

Na & oblig anion - 86% osmality & 92% tonicty
Innefctive osmoles not counted

Distib EC & ICF - determ by Na in ECF - indirectly by controls of ECF na

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6
Q

Additional mechanisms @ local level

A

Cells can regulate intracellular solute

  • allows adjust volume against tonicity

Local control - esp important in brain
eg neurones can produces extra osomole when bol decrease d/t extra hypertonicty - draw water back in

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7
Q

Conrol of TBW

A

Miantained fairly constant from day to day
Thirst ADH mechaninsm

Thirst afffect input & adh regulates output

Sesnsor - intergrator & effector

Closed loop changes - have effects monitored by sesnosr

Sensors:
Osmoreceptors
Volume receptor
High pressure barorectoprs

Central Controller
Hypothalamus

Effectors
Thirst ADH

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8
Q

Osmoreceptors

A

Special cell in hypothalamus - repson tonicity chagne

exact detail - ?
Neurone firing response volume
‘osmo=sodium’ - change balance - change tonicity

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9
Q

Volume receptors

A

Low pressure barorecptor - stretch wall large veins & RA

Mon volume - easses CVP

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10
Q

High pressure barorectpor

A

Cartoid sinus & arch - abp - affect if IV change - large affect systemic bp

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11
Q

No single antamoically discrete water balance - hypothalamus

A

Overall coordinates water balance
SOsmorectpor
other receptor - input pathway
Effector - controlled parts hypotahlamus

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12
Q

Thirst

A

Physiological urge drink

Hypertonictiy
hypovolame
hypotension
ang II

THirst centre hypothal - baclup - stimulate water when inadeq

Non regulatory - habit beahicour social

regulatory - backup

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13
Q

ADH
What is
Where prod
secreted

A

Nonapetide -
Prod - hypotahlamus &
secreted - posterior pituitary

acts kidney - increase h2o reabsoprtion

Increase reabsoprtion = decr plasma Na
Increase IV volume

Compeltes loop in negative feedback - control
fall tonicty rise vol sense

ADH Approp reg renal exretion reponse ecf tonicty / IV volume

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14
Q

How does ADH Act kidney

A

Si[rptoc & pv nucelie hypothal

Secret granules adh axons - [ppsteroor pituitary

Stimuli:
Increased tonicty
hyypovol
hypotension
AGII
Stress
Drugs - chlorproamide, barbituate, nicotine, morphine

Short t/12 15min
inact liver & kidney

Acts cortical & medullary CD
Two major cell types
Princial cell - Na.K
Intercalated cells - h ion

ADH combinces w/ V2 receports on BL membrane of principal cells - CD
Act AC & cAMP
- second messnegre

Cytoplsms fuse w/ luincal membrane - h2o channel - incor - water reabs down osmotic drag

when no adh - luminal membrane imprerable

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15
Q

Nature of water channels in vesicles

A

Aquaporin 2 - water cannel -

Present in membrane of vesicles - chennls inserted apical membra ne camp - removed when camp falls

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16
Q

What cell memebrane in the body are not permeable to water

A

Water crosses most easily - some low - functional require

  1. BLadder epithelium
  2. AscLOH - Na & cl transport out can produce hypotoinic
  3. Cortical & medullary CD in absence ADH - hypotinic urine
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17
Q

Principle in measure of body fluid compartments

A

Volme of ditrubtion of tracer - distrub only compartment measure - dilution principle’
Vol = amt/conc

Tracer - non tox rapid distrib & confined comparment

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18
Q

How colume ecf mesure

A

Ionics - br so4
Crystalloids inulin mannitol

Ionic tracers small - distrubite throught ecf - tracers also enter
ECF over est using ionic

Crystalloids - larger - not diffused thru ecf
Do not enter cells - lack full equal distrib = higher plsama conc - ecf under estimated w/ tracer

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19
Q

How is blood volume measure

plasma

Probs using Venous blood - est HCT

A

Indirectly - separate measure of
Hct
+
Plasma vol

PLASMA VOL - calc VD thru intvasc -

  1. dye Evans blue
  2. RadioIodine

BLOOD VOLUME

= Plasma vol x 100 / (100 - Hct)
or

Radiochromium labelled red cell as tracer

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20
Q

Effect of pregnancy on blood volume RC mass & plasma volume

A 
All increase - differ amohts
Blood volume 40-45% by term
Plasma 50%
Result in haemodiln
Hb falls - phys anaemia preg = increase in RCM 250mls - 18% without supplemts
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21
Q

intracellular volume what is

A

23L - 55% of 42l TBW

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22
Q

Outline factors controlled ICF

A
  1. Tonicity
    Water free movement - ecf tonicity change -
  2. Concentration of colloid - non diffusible
    set up Gibbs-Donnan effect -
  3. Na main extra-cell cation - excluded cell -
    a low permeability
    b active extrusion sodium pump

Non diffusible - set up Gibbs-Donnan equil - tend extra-cell excess anion v intracell - cause water out

Second gibbs donnan equil - oppose action of first - intracell colloid

= balance - double donnnan - stable volume

Pump blcok - cell swell and rutpure

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23
Q

How do cells repsond to change in extracell tonicty

A

If acute change - cell vol change padily - equil
hypetnonicty - dehydration
hypo - cell swell

Mannitol - infused - increase ec tonicty & decrease celrebral cell volume

Cells - mechanisms minimse disurtion

alter intracellular solute
gain/ lose solute - change vol minimised
hypetonictiy - gain solute ecf or increase intra cell solute

Brain – meatnbolic alter o intracell particles - idogenic osmoles increase tonicty - draw water
chronic hyuptonicty - tolerated betetr acute

General - cells posses capacity lose gain solute - vary tonicty olume min change

Source ex cell or intra`1

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24
Q

What are colliigative properties

A

Colligative properties of a solution

Depend only on particle concetration - osmalility

Number particle per unit volume - iompratant and not type

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25
Q

Colligative properties are

A

Vapour pressure depression
frezing point depression
BP elavation
Osmotic pressure

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26
Q

What is osmositc presure

A

Meausre osmotic tendency for water to cross membrane

Hydrosatitc pressure - measure of osmolality of solution - ‘osmotic pressure’

Depened partilce concentration

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27
Q

What is total osmotic pressure of plsams

A

For osmalitly of 287mosm/lf - plasma osmotic pressure 5545mmHg -7.3atm

How is it calculated - vant hoff eqn

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28
Q

Molality

A

Molaity - no moles of solute per kg solvent - mole si amt sub

Number particles of sub pressent - 1 mole 10x23 particles avaogradors no

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29
Q

osmolality

A

Number of osmoles of solute per kg of solvent - 1 osm cont avogadros no no distinct about particles - amny types

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30
Q

Normal osmalitly of ECF

A

285-290 mosm /kg

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31
Q

Is Osmolaity same in ICF

A

Weater cross easily - osmotic gradient no continue - water will move

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32
Q

Osmolarity

A

Number of osmoles per litre of of soltion - alter by temp cahnge - expansion

cause 1l water = 1kg - numerical value almost same -

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33
Q

Tonicity

A

effective osmolaity of solitoon

Importance -

Water crosses nearly all cell membranes easily

Most solutes do not cross cell membranes easily

some do - urea
if added - water leak back - - no change across membrane ultimately

Osmolality needs to be corrected for type of solute - most do not cross - and edffective at exerting osmotic force -
some do n ot cross and ineffective at exerting force

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34
Q

Tonicity

A

Measusre only particles exerting osmotic force - effective osmolatiy - part of total osmolaity due to effective osmoles

Improtant detgermin fluid distrb accross membrane - allow solute cross membrea
osmorec - hupoyahl - respon to tonicty not osmolaltiy - omsol easy ,easure

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35
Q

Glucose & osm oles

A

Glucose can cross easily -
fat/muslce - facil insulin

not effective osmole

tONICTY ESTIMATEDD - OSMO - CONC UREA +_ GLUC

daibetics - insulin absent - effective osmole - exert osmotic effect accross membrane
hyperglycameia - can cause hypetonictiy

5% dex isosm - first infused - glucsoe taken and metabolised - infusion 5% - pure water

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36
Q

If urea crosses why is it effect at cerebral dehydrating

A

Urea crosses BBB solwer than water - increase d/t hypetonic w/draw water brain - decrease icp

37
Q

Oncotic pressure

What is it

What size are they

Why is it improtant

A

Colloid osmotic pressure = component total osmolality d/t colloids
L

Large MW >3000 daltons
plasma - protein major colloids

typiocal value for plasma oncotic 25-28mmHg
0.5% total plasma pressur osmotic pressure

Why is it improtant - role capillary fluid dynamics - starlings
Capil membrane - imperm protein - ermeable most others
proteins only effective solutes - retain water & circ volume - plasma oncotic pressure only force retain intravascular volume

38
Q

Vant Hoff

Why is the actual pressure higher

A
  • Calculated ~15mmHg
  • propt conc 0.9mOsm

Actual value - 25mmHg -
1 Gibbs donnan
2 Excluded volume

Net neg charge on protien - large - non readily diffusable

Retneon increase Na in plasma - gibbs donnan - net inc 0.4
Donnan excess pressure
Ret Na not bound Albumin - excess particles

39
Q

Excluded boume effect

A

Large size of protein - van hoff ideal soluton - col ovvupy large mol wt protein signif adittiioanl factor discrep

40
Q

How is oncoptic pressure measured

A

Oncometer - Two chambers - semi perm membrane - permeable to water - all solutes except mol wt >30000

Pressure measured trasnducer

41
Q

Which protein calc most to osmotic

A

Albumin ~75%

Pl protein considered albumin glob fibro

Alb 45g/l
Net neg charge - major [prt responsible

42
Q

Sudden decrease in plsama oncotic

A

Increased loss h20

43
Q

Factors protect agianst oedema when albumin low

A

Increase lymph flow - remove ecvess ISF & return circulation

Inc ISF = Inc tissue hydrostaitc 0 further oppose excess filtration

Decrease insttestil protein - decrease albumin - decrease interstitial oncotic

44
Q

Est Plasma Osm

A

2 Na + Glu + Ur

45
Q

Sodium - typical value plasma

A

140 (135-145)

46
Q

Intra cellular

A

12 - muscle

red cell 20

47
Q

Why low

A

Na pump
3 Na out cell 2 K in

Sodium permeability
Low - prevents re renty

48
Q

ISF Na

Should this be by the gibbs donnan?

A

140

Plasma consistant water 93% solids 7%
Solids - protein
Gibbs donnan causes Na plsam water than Na isf by 6 or 7
Gibbs donnnan causes Na in plsama water high than ISF by 6 or 7
Na is presesnt only in water component - measured whole. - decrease samll amt
‘Plasma solids effect’

Decreased measuredd Na same magnitude in Na - plasma Na d/t gibbs donnan
Result is measure Na as sameq

49
Q

Why does the plasma Na only cotriubte to 0.4 of oncotic

A

Actual na in plsams water is only 7 mmols increase

Not only change electro conc
Cl lower plsama water & higher ISF - Gibbs donn

Na & cl - highest con plsama & isf -

Net change in ion not jkust na
diff increase 0.4 plsama - net increase osmolaity d/t gibbs donan 0.4 mOsm - overall protein 1.3mOsm

Net increase is only 0.5 0 fall in total anion cocnc offest rise Na

50
Q

What is NaCl conc in plasma

A

0 - dissoc in ions
No undoss
Strong electoyle

51
Q

How much sodium in the body

A

Tot body 60mmls/kg
4000-42000 adult male

ECF 50
Bone 45
ICF

Exchangeable Na 70%

52
Q

If drop in ECF vol

A 
Drop in Bp
Drop in glo cap pressure
Drop GFR
Drop Na filter
Increased tubular absoption Na - aldo
53
Q

Pottasium - total body pottasium

A

40-45mmols/kg

ICF 90%
ECF 2%
Bone 8%

Bone - stable not read mobil can say 98% Intracell 2% excell

54
Q

How total body K measure

A

Radioactive pottasium isotope

55
Q

Functions of Pottasium

x5

A

Major component itracell tonicty

Na pump - all membr

Membrane potential

Regulation intracell processess

NM excitability

56
Q

What are ECG change a/w hyperK

A

Decrease in RMP - hyperexcitability & reduced conduction velocity

typical progress 
Increase t wave
Short Q-T
Prolong P-R
P wave flatter
Progressive wide QRS
Sine wave - VF / ASystole
57
Q

How Rx

A

seveirty - absolute level & rate rise

  1. IV calcium - severe
    plasma levele not alter bu inmcrease Ca - stabilise myocardial membrane - decrease excite
    decrease risk serious arryh
  2. Glucose & insulin
    K move intracellular
  3. Na bic
    Decrease K - moving intracell & restore transmembrane K grad
  4. Resonium
    Ion exchange resin po / rectal - resin exchange 1 mmol kfor 1 mmol Na
    Exchange occurs in Colon - PO slow
  5. Dialysis
    Preferred option severe CRF & ARF
  6. Rx & cause
58
Q

How much insulin

A

50mls 50% w/ 10u insulin aeffective
should decrease 1-*2 mmols 30 mins - persist for 2-3h
Dose can be prepeated
Redist K intracell - not cause excretion

59
Q

What is reference range for Mg

A

0.7-4 mmol
1% - ECF - total amount 10mmols
40% protein bound

60
Q

Functions of Mg

A

Cofactor in metabolism
action nerves muscle

Major intracell cation

61
Q

Catalyst or cofactor

A

activating over300 sep enzyme body
Mg depend enzymes - calying phosphate tfer
thaimaonn pyrophos cof actor

Req sodium pump oxidtaive phsoprylation & all recation involving ATP - impratnt all cells without exception

62
Q

Effects on nerves & muscles

A

Contrasted to those of calicum

Reduce nerve & muslce membrane excirtablity - sim calcium less powerfull

antagonitc - transmiiter release at cholin & adrenergic juncitopn
& exciate contract coupling
tmiter & excitrae cotract inhib mg

Clin effects - portetial NMB

Action SM - sim to skeletal & cardiac
effect - admin - vasodiln

Mg - def casposam & precp angina

Phsiolog bloc NDMA

63
Q

Hypermag at plsam level

A

<4 asympto

Early - n/vb/drowsy

High levels - nmj & CVs

NM transiion impair - decrease deep tendon - resp paralysi

Minor ecg - ffrom CHB-> asystole

Monitoring - deep tendon reflex

Rx calcium gluctonaite

64
Q

Hypomg

A

Myocolonus adbo pain htn angina tdp reentry arryhtmia

65
Q

Use mg

A 
Crease normal impulse propagation conditons
Anaglesic 
asthma
eclamspia Hypotens
relax vessel -
66
Q

Gibbs Donnan equilibrum

A

Semipermeable membrane - separates 2 soln - 1 soln non diffus anion / cation - dsitrb other diffusable cation & anion altered

Wquil products Na & Cl on each membrane - equal
Soln

Gibbs Donnan factor - univalent cations - 0.95
na In ISF 0.95 x Na plasma water - gibbs donnan factor anion is 1.05

67
Q

Euil stable state

A

No - based ions distributing accorss embrane until elec & chemical gradients balanced - not stable unless fixed - quil stable - uneqal conc on 2 side - osmotic gradient - eleads water removal - upset queil

68
Q

Divalent ion Ca & Mg

A

Colpiacted - protein bind - only conc - free ion used
divalted 0.9 cation
divalent anion 1.1

69
Q

Gibbs Donnan effect improtant?

A

Stability cell volume
- non diff protein & organic phospahte - balanced - non iddusable na in ISF
Dynamic balance reposnilb eof rstability cell veolume

Plsama onctoic pressure - alter distrb other on - net increase ion in plsama - signif increase effective vlue plsama oncotic pressure in blood

Small contriobuion RMP

70
Q

Lymph - How does ISF enter term lypahtic

A

Lmyph - ISF enter lympathic vessle

Lymph capul - present all tissue excepti cartil bm & CNS

Blind ending & flap valves - adjacent dentohelial - functional valve - entry of ISF - prevent eturn to tinsterstiom

Nearly all pass thru LNode - bvefore reutn to venous

Returns via thoraic duct drains in toc circ at junction L SC & LIJ & R lymph duct

71
Q

What makes lymph flow

A

Intrinsic - walls ^ valves
Extrinsice - external pressure

Larger - sm in walls vavles -unidirect

Flows external pressure - copress vessels - flap valves between endothelial - capillary - rpevent return lymph to intsetitum - major soruce external pressure musclular contract & pulsation in neighbouring vessl

72
Q

Functions

A

Rtuen of protein & excess frlud tio circ from ISF
Transport fat from sml intestin

Immunoligcal role
Remova bacteria - macrophage in glands (RES)

Role lympahtics lympthcyte cirtualtion throught blood & lymph
Role nodes - activated proliofarate contact antigent

Removal preotins keep ISF protein conc low
Maintains oncotic pressure gradient

Sinusioids - lined macropghages of RES = phagoctyose bacteria / cell debri

Nodes contain lymphocytes - prolif exposure antigent

73
Q

Protein concentration of lymph

A

Low compared plasma - same as ISF- derived
20g/l
Hepatic can be up to 60

Liver 50% total body lymph rest - hepeatic sinusiod - permeable - protein leave circulation

Liver lymph causes thjoraic duct pteo conc 50g l

74
Q

Diff between ISF & Lymph

A

Lymph is ISF - entered lymph channel
Thoracic duct hogher protein - protein rich hpeatic lymph

Thoracic duct drains into curlation @ junction L SC & IJ

75
Q

How much lymph day

A

2mls/,om 120 hr 3l day

Total increase w/ exercise - actual amt variable

net filtration at arterial end - 20mls/min - 18mls min returns venous circulation
10% of all fluid - returns to cirulation lymph

76
Q

What perecent retuns circulation via thoracic duct

A

83% 120mls/hr - include 100mls thoraic duct

77
Q

Why is lymph milky?

A

High fat content - drain bowel after meal

78
Q

What is the role lympahtic in fat aborsption

A

90% fat absorebed gut -extreuded ep cell isf - central lacteal vessels in villi
Fat form special globules - chlymicrons
respons milky appearance lymoh - cause milky appear plasma after fatty meal

Pass circulation via thoacic duct - not pass throuhg portal

79
Q

Normal skin blood flow

_ factors control skin blood flow - skin requires for 2 reasons

A

Normal skin blood flow 300mls /min

1 metabolism - nutrients /waste removal

2 temperature regulation

Nutritive skin blood flow low - main factor - need heat loss
10x normal under heat stress
Increased sweat & evaporative loss
Increase loss warm skin rad conduction convection

Evap = effective heat loss gram water loss 0.58 kclas

80
Q

‘insensible water loss’

A

Water passses thru skin - transepidraml diffusion - lost by evaporation skin suface

Evaportive water loss resp tract ventilation

insensible - unaware

Loss pure water
Loss not prevent
800mls day 400 + 400
Heat loss significant 464kcls - 25% basal heat

81
Q

How is insens loss differe sweating

A

Solute free- only water
sweat solute - electolytes

Insne loss skin - water diffused thru skin
Sweat - glands

82
Q

What is sweating - role

A 
Secretion sweat gland skin - major role - increased heat loss situation stress
Losses occur - 
water
electolytes
heat
83
Q

Fluid loss occur with sweating

A

Eccrine sweat gland impraont sympthtic cholinergic (musc) innerv
hypotahlmus control = thermosense neuor hypothl - sense core

Fluid loss - extreme 2000mls / hour - max
Po replace

84
Q

Solute loss

A

Na swat 30-65
depend allimitasion
na decrease aldo

85
Q

Acclimitasion of sweting

A

adapting change - sweat mech cold to hot - max rate increase na decrease
benef loss heat

86
Q

effective heat loss

A

very fective 1l evap skin = 580kclas

ecap skin heat low occur
if wiped or abosred towl - only water loss no heat loss

ambient temp & hmuidty imprat - det rate evap & thus loss

high humidity - marekdly decrease rate

87
Q

signifcant of wsweating ill patient

A

Ill - body temp reising increase hyptoahl set point 0 skin dry & patient shivery

Set point decreaes stop shiver - sweat
causes heat los and fall temp
temp fall - anti pyretics not necc - fever will subside

88
Q

What are the effects of insuing of 1L 3N saline

A

Very hypteoinc x3 paslam
fluid shifts

Na limit distrub ecf
water cross to osmolar grad

water drawn cell 0 until tonicty same both side

increase ecf vol 2.1 l - quater intravascular
Osmolatily increase above threholdblood bol increase

increased osmalt - sens osmrec hypothal - stim adh to retain water

thirst increase

increaevolume - lower livel snstiiivty - effect volurectpor inhib adh - allow water
volume stimuli less sesn more ptoent osmotic

Effect on Na- vol expan stim secr ANF
secretion aldo inhib cause of decrease renin & AgII
ANF also inhib renin

Final outcome - natriresis &e xcretion excess water - increased osmolaity - incraesed adh inhib rate exretion water

decrease ICF volume - effects brain - confsuion obrundation derebral dellular dehyradtion & hypetonicty - effects will probedom clin effects - function unlikely aeffect

Physiology Kerry (17 decks)

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