Upload
pravinkumarr
View
213
Download
0
Embed Size (px)
Citation preview
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 1/27
1
ACID BASE BALANCE
pH (Potential of Hydrogen) =Log H+
The concept was introduced byS.P.L.S. Rensen in 1909
Acid - Release H + ions
Base - Accept H+
ions
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 2/27
2
Buffer system
Provide or remove H+ and stabilize the pH
Include weak acids that can donate H+
andweak bases that can absorb H+
Does NOT prevent a pH change
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 3/27
3
pH different in different fluids
Blood pH 7.4
Urine 4.5 8.0 Gastric HCl 0.8
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 4/27
4
What happens if body is too acidic
q Energy Production
q Ability to repair damaged cells
q ability to detoxify heavy metals
Enable tumor cell to thrive
Susceptible to illnessTherefore Acidosis is more dangerous
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 5/27
5
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 6/27
6
Body produces more acids
than bases Acids taken in the foods
Acids produced by metabolism of lipids& Proteins
Cellular metabolism produces CO2
CO2+H2O H2CO3 H
+
+ HCO3
-
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 7/27
7
First line of Defence
Second line of Defence
Chemical
Buffer
Physiological
Buffer
Bicarbonate
Buffer system
Phosphate
Buffer system
ProteinBuffer system
Respiratory
Mechanism
(CO2 Excretion)
Renal
Mechanism
(H+ Excretion)
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 8/27
8
Defense against H+ concentration
Chemical buffer system
Within fraction of a second Bicarbonate Buffer system
Phosphate Buffer system
Protein Buffer system
Haemoglobin Respiratory system - Within few minutes
Renal system - Slowly but very powerful
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 9/27
9
Bicarbonate Buffer system Present in large quantities
Respiratory and renal systems act onthis buffer system
Most important ECF buffer
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 10/27
10
Bicarbonate BufferNaHCO3 and H2CO3
20:1 ratio , HCO3- : CO
2
HCl + NaHCO3 H2CO3+NaCl
NaOH + H2CO3 NaHCO3 + H2O
Henderson Hesslebach EquationpH=pk +log Base
acid
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 11/27
11
Phosphate Buffer system Low activity in ECF
Better buffer in the ICF, Kidneys andbone
pK = 6.8
HPO4
2-
& H2PO4
-
H+ + HPO42- H2PO4
-
OH- + H2PO4- H2O + HPO4
2-
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 12/27
12
Proteins Buffer system Abundant in Blood and ISF pK close to 7.4 Carboxyl group gives up H+
Amino group Accepts H+
RCOOH RCOO- + H+
RNH3 + H+ RNH4+
Haemoglobin Buffer Inside RBCs, Less efficient pK = 7.7
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 13/27
13
Respiratory system 2nd line of defence
Acts within min (maximum 12-24hrs)
H2CO3 produced converted to CO2, andexcreted by the lungs
Alveolar ventilation also increases as pHdecreases (Rate & Depth)
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 14/27
14
Kidney buffer system
2nd line of defence
Can eliminate large amounts of acid
Can also excrete base
Can conserve and produce HCO3- ions Most effective regulator of pH If kidneys fail, pH balance fails
Why this is important? Because no other way to excrete these
acids (plasma conc 40nmols/day)
Reabsorption of filtered HCO3-
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 15/27
15
Renal Acid Base Regulation Kidneys help regulate blood pH by
excreting H+ & reabsorbing HCO3-
Most of the H+ secretion occurs across thewalls of the PCT in exchange for Na+
Urine is slightly acidic because kidney
absorbs almost all the HCO3- & excrete H+
Returns blood pH back to normal range
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 16/27
16
SECRETION OF H+ IN PCT & DCT
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 17/27
17
7.4
Acidosis Alkalosis
Increase in H+ conc
Decrease in H+ conc
AccumulationOf Acid
Loss of base
Accumulation
Of Base
Loss of
Acid
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 18/27
18
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 19/27
19
Acid Base Imbalance pH<7.35 Acidosis
pH>7.45 Alkalosis
Bodys response to Acid base imbalanceCOMPENSATION
If Cause is Metabolic Change in ventilation
can help RESPIRATORY COMPENSATION If cause is Respiratory change in renal
excretion can help RENAL COMPENSATION
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 20/27
20
ACIDOSIS Principal effect CNS depression
Generalized weakness Severe acidosis causes
Disorientation
Coma
Death
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 21/27
21
ALKALOSIS Over excitability of Central and
Peripheral Nervous system
It can cause Nervousness
Muscle spasms or Tetany
Convulsions Loss of consciousness
Death
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 22/27
22
Respiratory Acidosis FALL IN pH
pH=pK + log HCO3
CO2
pCO2 > 45 mmHg
Cause
Depression of Resp. Centre Respiratory disorders
RenalCompensation
Renal loss of H+
Retain HCO3-
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 23/27
23
RESPIRATORY ALKALOSIS RAISE IN pH
pH=pK + log HCO3
CO2
pCO2 < 35mmHg
Cause
Hyperventilation High altitude
Congestive heart failure
Renalcompensation
Conserve H+ ions
Excrete Bicarbonateions
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 24/27
24
METABOLIC ACIDOSISHCO3
- deficit (<22mEq/L)
Cause
Loss of HCO3-
Diarrhea/Renal dysfunction
Accumulation of acids
Lactic acid
Ketone Bodies Failure of kidneys to
excrete H+
Respiratorycompensation
Ventilation If possible Renal
Excretion of H+ ions
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 25/27
25
METABOLIC ALKALOSIS HCO3
- (>26mEq/L)
Cause
Excess vomiting
Use of diuretics
Severe dehydration
Respiratorycompensation
Hypoventilation
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 26/27
26
SUMMARY pH, Acid, Base, Buffer
Importance of Body pH maintenance
Buffer systems of our body
Role of Respiratory system in pH balance
Role of Kidneys in pH maintenance
Acidosis, alkalosis Cause, symptoms, Compensation mechanisms
& therapy
8/3/2019 Acid Base Bal Rsl
http://slidepdf.com/reader/full/acid-base-bal-rsl 27/27
27