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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
Colligative properties are
Vapour pressure depression frezing point depression BP elavation Osmotic pressure
26
What is osmositc presure
Meausre osmotic tendency for water to cross membrane Hydrosatitc pressure - measure of osmolality of solution - 'osmotic pressure' Depened partilce concentration
27
What is total osmotic pressure of plsams
For osmalitly of 287mosm/lf - plasma osmotic pressure 5545mmHg -7.3atm How is it calculated - vant hoff eqn
28
Molality
Molaity - no moles of solute per kg solvent - mole si amt sub Number particles of sub pressent - 1 mole 10x23 particles avaogradors no
29
osmolality
Number of osmoles of solute per kg of solvent - 1 osm cont avogadros no no distinct about particles - amny types
30
Normal osmalitly of ECF
285-290 mosm /kg
31
Is Osmolaity same in ICF
Weater cross easily - osmotic gradient no continue - water will move
32
Osmolarity
Number of osmoles per litre of of soltion - alter by temp cahnge - expansion cause 1l water = 1kg - numerical value almost same -
33
Tonicity
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
34
Tonicity
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
35
Glucose & osm oles
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
36
If urea crosses why is it effect at cerebral dehydrating
Urea crosses BBB solwer than water - increase d/t hypetonic w/draw water brain - decrease icp
37
Oncotic pressure What is it What size are they Why is it improtant
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
Vant Hoff Why is the actual pressure higher
- 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
Excluded boume effect
Large size of protein - van hoff ideal soluton - col ovvupy large mol wt protein signif adittiioanl factor discrep
40
How is oncoptic pressure measured
Oncometer - Two chambers - semi perm membrane - permeable to water - all solutes except mol wt >30000 Pressure measured trasnducer
41
Which protein calc most to osmotic
Albumin ~75% Pl protein considered albumin glob fibro Alb 45g/l Net neg charge - major [prt responsible
42
Sudden decrease in plsama oncotic
Increased loss h20
43
Factors protect agianst oedema when albumin low
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
Est Plasma Osm
2 Na + Glu + Ur
45
Sodium - typical value plasma
140 (135-145)
46
Intra cellular
12 - muscle | red cell 20
47
Why low
Na pump 3 Na out cell 2 K in Sodium permeability Low - prevents re renty
48
ISF Na | Should this be by the gibbs donnan?
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
Why does the plasma Na only cotriubte to 0.4 of oncotic
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
What is NaCl conc in plasma
0 - dissoc in ions No undoss Strong electoyle
51
How much sodium in the body
Tot body 60mmls/kg 4000-42000 adult male ECF 50 Bone 45 ICF Exchangeable Na 70%
52
If drop in ECF vol
``` Drop in Bp Drop in glo cap pressure Drop GFR Drop Na filter Increased tubular absoption Na - aldo ```
53
Pottasium - total body pottasium
40-45mmols/kg ICF 90% ECF 2% Bone 8% Bone - stable not read mobil can say 98% Intracell 2% excell
54
How total body K measure
Radioactive pottasium isotope
55
Functions of Pottasium | x5
Major component itracell tonicty Na pump - all membr Membrane potential Regulation intracell processess NM excitability
56
What are ECG change a/w hyperK
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
How Rx
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
How much insulin
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
What is reference range for Mg
0.7-4 mmol 1% - ECF - total amount 10mmols 40% protein bound
60
Functions of Mg
Cofactor in metabolism action nerves muscle Major intracell cation
61
Catalyst or cofactor
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
Effects on nerves & muscles
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
Hypermag at plsam level
<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
Hypomg
Myocolonus adbo pain htn angina tdp reentry arryhtmia
65
Use mg
``` Crease normal impulse propagation conditons Anaglesic asthma eclamspia Hypotens relax vessel - ```
66
Gibbs Donnan equilibrum
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
Euil stable state
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
Divalent ion Ca & Mg
Colpiacted - protein bind - only conc - free ion used divalted 0.9 cation divalent anion 1.1
69
Gibbs Donnan effect improtant?
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
Lymph - How does ISF enter term lypahtic
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
What makes lymph flow
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
Functions
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
Protein concentration of lymph
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
Diff between ISF & Lymph
Lymph is ISF - entered lymph channel Thoracic duct hogher protein - protein rich hpeatic lymph Thoracic duct drains into curlation @ junction L SC & IJ
75
How much lymph day
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
What perecent retuns circulation via thoracic duct
83% 120mls/hr - include 100mls thoraic duct
77
Why is lymph milky?
High fat content - drain bowel after meal
78
What is the role lympahtic in fat aborsption
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
Normal skin blood flow _ factors control skin blood flow - skin requires for 2 reasons
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
'insensible water loss'
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
How is insens loss differe sweating
Solute free- only water sweat solute - electolytes Insne loss skin - water diffused thru skin Sweat - glands
82
What is sweating - role
``` Secretion sweat gland skin - major role - increased heat loss situation stress Losses occur - water electolytes heat ```
83
Fluid loss occur with sweating
Eccrine sweat gland impraont sympthtic cholinergic (musc) innerv hypotahlmus control = thermosense neuor hypothl - sense core Fluid loss - extreme 2000mls / hour - max Po replace
84
Solute loss
Na swat 30-65 depend allimitasion na decrease aldo
85
Acclimitasion of sweting
adapting change - sweat mech cold to hot - max rate increase na decrease benef loss heat
86
effective heat loss
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
signifcant of wsweating ill patient
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
What are the effects of insuing of 1L 3N saline
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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