Gas transport and pH regulation dr.Syazili Mustofa
pH regulationdr.Syazili MustofaBiochemistry departement of
medical faculty lampung university ASAM BASA..pH[H+]
AcidBaseNotasi pH diciptakan oleh seorang ahli kimia dari
Denmark yaitu Soren Peter Sorensen pada thn 1909, yang berarti log
negatif dari konsentrasi ion hidrogen. Dalam bahasa Jerman
disebutWasserstoffionenexponent (eksponen ion hidrogen) dan diberi
simbol pH yang berarti: potenz (power) of Hydrogen. pHpH
Regulation4Maintenance of relatively constant blood pH value is
essential for health, since changes in blood pH will affect
intracell pH alter : - metabolism - protein conformation - enzyme
activity - equilibria of reaction that consume / generate
H+(oxidation - reduction reaction)Maintenance of a constant blood
pH is, in part, achieved by - buffer system in the blood control
short - term changes in acid - base metab. - in long term :
balancing proton loss & proton gainSyazili Mustofa5pH value of
plasma may be affected by :- malfunctioning of buffer system or-
disturbance of acid base balance e.g. due to - kidney disease or -
altered breathing frequency ( hypo / hyperventilation)Normal
alterial plasma pH : 7.40 0.05- pH < 7.35 acidosis- pH > 7.45
alkalosisSyazili MustofaBuffer System63 major body water components
: - plasma : within circulating system - interstitial fluid : fluid
that bathes cells - intracellular fluidComposition : - plasma : -
major kation : Na+ - small amounts : K+, Ca2+, Mg2+- dominant
anions : HCO3-, Cl-- small amount anion : protein, HPO42-, SO42--
mixture organic anions - interstitial fluid : - similar - contain
less protein plasma & interst. fluid extracell. Fluid
- intracell fluid : - major kation : K+- major anions : -
organic P (ATP, BPG, glycolitic intrmd) - protein
Syazili Mustofa7Each fluid makes a different contribution to
buffering* Major buffer of extracell fluid : HCO3- / CO2 system-
not very effective in resisting pH changes from changes in pCO2-
effective in controlling pH changes caused by other than pCO2
changes* Intracell fluid : responsible for buffering pCO2 changes (
Hb buffering within RBC)* Extracell fluid & intracell fluid :
equal in buffering strong organic / inorganic acids Plasma :
excellent indicator to handle additional loads of acids
Syazili Mustofa8Every buffer consist of : - a weak acid : H A -
conjugate base : A- e.g. acetate-/acetic acid, NH3 / NH4+, HPO42- /
H2PO4- weak acid : neutral, (+) charged, (-) charged conjugate base
: 1 less (+) charge / 1 more (-) charge than weak acid Henderson -
Hesselbalch equation :pH = pK + log
direct relationship between pH & ratio .[conj. base ]
[acid]Syazili Mustofa9[HCO3-] / [CO2] buffer system :Blood pH : 7,4
p.k. : 6,1
[HCO3-] / [CO2] ratio = 20/1 at normal blood pH = 7,4Every
changes in [HCO3-] or [CO2] changes the ratio changes pH
compensation to normalize blood pH.7,4 = 6,1 + log 20/1Syazili
Mustofa10Blood plasma is a mixed buffer system :HCO3- / CO2 ,
HPO42- / H2PO4-, protein / H proteinMajor buffer of plasma :
bicarbonate buffer system an open system : pCO2 is adjusted to meet
the bodys needsIf respiration can not accomplish this adjustment
pCO2 changes strikingly bicarbonate syst. would be
ineffective.Syazili MustofaAcid - base balance & its
maintenance11Acidosis : excess acid or def. of alkali in the
bodyAlkalosis : excess alkali or def. of acid in the bodyThere
exist mechanisms where the body normally rids itself of excess acid
or alkali
Individuals produce large amounts of acids* Major acid : CO2
volatile : normally excreted by the lungs Inability of the lungs
respiratory acidosis or alkalosisSyazili Mustofa12* Respiratory
acidosis : result of hypoventilation of alveoli CO2 accumulates
Alv. hypoventilation : occur when depth or rate of respiration -
airway obstruction - neuromuscular disorders- diseases of CNS
- chronic resp. acidosis : chronic obstructive lung disease
(emphyema)- inhalation of gas mixture with high pCO2 resp.
acidosisIncrease the PCO2 ------> the pH goes down.
Hypoventilation.
Acute resp. acidosisSyazili Mustofa13* Respiratory alkalosis :
arises from decreased alv. pCO2 Hyperventilation : - anxiety : most
common cause - CNS injury involving resp. center - salicylate
poisoning - fever - artificial ventilation High altitude alv. pCO2
chronic resp. alkalosis
Decrease the PCO2 ------> the pH goes up.
Hyperventilation.
Syazili Mustofa14 * Metabolic acidosis The body produced
nonvolatile acids H+ + SO42-- hydrolysis of phosphate- esters
phosphoric acid- metabolism - lactic acid - acetoacetic acid - -
hydr. butyric acid- administration of : NH4Cl / Arg hydrochloride /
Lys hydrochloride urea + HCl
Decrease the HCO3------> the pH goes downproduced in excess
accumulation acidosisSyazili Mustofa15- ingestion of salicylate,
methyl alcohol, ethylene glycol production of strong organic acid
accumulation of nonvolatile acids metabolic acidosis- abnormal loss
of base ;- renal tubular acidosis : abnormal amount of HCO3- escape
from blood into urine- severe diarrhea HCO3-
Syazili Mustofa16* Metabolic alkalosis - intake excess alkali :-
NaHCO3- salt of organic acid : Na - lactate NaHCO3- fruits &
vegetables : contain mixture of organic acids - metabolized to CO2
+ H2O no long term. effect on acid base balance - salt of organic
acids [HCO3-] - abnormal loss of acids : vomiting, gastric lavage
(Lose enough stomach acid to produce alkalosis) - rapid loss of
body water :diuresis temporary [HCO3-]Increase the HCO3------>
the pH goes upSyazili Mustofa17Causes of acid base
imbalanceAcidosis : Respiratory : alveolar hypoventilation
Metabolic : - H+ overproduction - HCO3- overexcretionAlkalosis :
Respiratory : alveolar hyperventilation Metabolic : - alkali
ingestion - H+ overexcretionSyazili Mustofa18Normal
Acidosis- Respiratory- Metabolic
Alkalosis- Respiratory- MetabolicBlood pH
7,4
Urine pH
6 7
[HCO3- ]/ [H2CO3
20/1
20 / > 1< 20 / 1
20 / < 1>20 / 1 Cause
HypoventilationH+ productionor HCO3- excretion
HyperventilationAlkali ingestionor H+ excretionSyazili
MustofaRespirasiHiperventilasiPenurunan kekuatan otot nafas dan
menyebabkan kelelahan ototSesakMetabolikPeningkatan kebutuhan
metabolismeResistensi insulinMenghambat glikolisis anaerobPenurunan
sintesis ATPHiperkalemiaPeningkatan degradasi
proteinOtakPenghambatan metabolisme dan regulasi volume sel
otakKomaKardiovaskularGangguan kontraksi otot jantung
Dilatasi Arteri,konstriksi vena, dan sentralisasi volume
darahPeningkatan tahanan vaskular paruPenurunan curah jantung,
tekanan darah arteri, dan aliran darah hati dan ginjalSensitif thd
reentrant arrhythmia dan penurunan ambang fibrilasi
ventrikelMenghambat respon kardiovaskular terhadap
katekolaminManagement of life-threatening Acid-Base Disorders,
Horacio J. Adrogue, And Nicolaos EM: Review Article;The New England
Journal of Medicine;1998AKIBAT DARI ASIDOSIS
BERATKardiovaskularKonstriksi arteriPenurunan aliran darah
koronerPenurunan ambang anginaPredisposisi terjadinya
supraventrikel dan ventrikel aritmia yg
refrakterRespirasiHipoventilasi yang akan menjadi hiperkarbi dan
hipoksemiaMetabolicStimulasi glikolisis anaerob dan produksi asam
organikHipokalemiaPenurunan konsentrasi Ca terionisasi
plasmaHipomagnesemia and hipophosphatemiaOtakPenurunan aliran darah
otakTetani, kejang, lemah delirium dan stuporAKIBAT DARI ALKALOSIS
BERATManagement of life-threatening Acid-Base Disorders, Horacio J.
Adrogue, And Nicolaos EM: Review Article;The New England Journal of
Medicine;1998ANION GAP:Essentially, the difference between the
concentrations of cations (Na+ primarily) and anions (Cl-, HCO3-)
in the blood.
Anion gap= ( Na + K ) ( Cl + HCO)
= 4-17 mmol l
High Anion Gap: It is high in any condition with reduced
clearance or excess production of any unmeasured anions. Metabolic
Acidosis. It indicates that you have added acids to the blood:
salicylic acid, formic acid, lactic acid, oxalic acid, sulfuric
acid.Normal Anion Gap: Respiratory Acidosis. It occurs when you
ultimately become acidotic because of losing HCO3
It is low in hyperalbuminaemia, liver disease and
paraproteinaemiasNormal value of arterial blood gasItem
valuepH7,4[HCO3-]22 - 28 mEq / LPaCO233 - 44 mEq / LPaO290 - 100
mEq / LInget brho.
Regulasi Ph dan mekanisme kompensasi
Chronic control (long-term)Rapid regulation (short-term)
Regulasi pH pasien PPOKPCO2PPOKpH
NH4Cl Hipoalbumin..?Sintesis Alb
