Download MBBS Biochemistry PPT 45 Final Acid Base Balane Lecture Notes

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Homeostasis of Blood pH

OR

Regulation of Blood pH

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Synopsis

? Introduction

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? Sources of Acids and Bases in body

? What is Acid Base Balance?

? Mechanisms Regulating Blood pH.

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? Significance of Maintaining Acid Base

Balance

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? Acid Base Imbalance and their

conditions.

? Diagnostic Tests

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Introduction

?Acid Base Balance is a

physiological and

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biochemical mechanism

associated to body/blood

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pH.

What Is pH?

? pH is a Hydrogen ion concentration.

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? pH = - log [H+]
? Different compartment of human

body has specific pH.

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? pH has role in Enzyme activity.
Why blood pH is Altered?

?Addition of various

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acids or alkalies by

metabolic activities

alters body/blood pH.

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Sources and Types

of

Acids and Alkalies

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Added During

Metabolic Life Processes

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?Acids are H+

donors.

?Bases are H+

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acceptors, or give

up OH- in solution.8
Acids and Bases can be strong or

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weak:

? A strong acid or base is one that dissociates

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completely in a solution

- HCl, NaOH, and H2SO4

? A weak acid or base is one that dissociates

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partial y in a solution
-H2CO3, C3H6O3, and CH2O, Lactate.
? Acidic Substances of body:

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?Carbonic acid(H2CO3)
?Phosphoric acid( H3PO4)
?Sulphuric acid (H2SO4)

? Organic Acids:

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?Lactate, Acetoactate, Pyruvate

? Alkaline Substances of body:

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?Citrate
?Bicarbonates.

What is Acid Base Balance?
Homeostatic Mechanisms

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That

Regulate Blood/Body pH

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? Acid Base balance is a

homeostatic mechanism

? Carried out to regulate the

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altered pH of blood and other

body compartments to its normal

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constant range.
?Maintenance of Acid

Base balance

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?Is a prime requisite to

maintain normal

healthy and active life.

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Acid-Base Balance

? It is the regulation of HYDROGEN ions.

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(The more Hydrogen ions, the more acidic the solution and the

LOWER the pH)

? The acidity or alkalinity of a solution is measured as

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pH
Acid Base Balance Regulates pH

Why it is Very Essential To Regulate

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pH?

? pH of blood and other body

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compartments are precisely

regulated.

? pH is always tried to be

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maintained to its normal constant

range.
? Acid Base Balance

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maintains the blood pH at

normal constant narrow

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range of 7.35-7.45.

? pH of the medium directly

affects the enzyme activities

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? Optimum pH is an essential

requisite for enzyme activities

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and normal metabolism.


? It is prerequisite for

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regulating blood/body pH:

?To maintain normal/optimal

Enzyme activities

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?Normal metabolism

?Normal Coordination

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?Normal Health

Factors Regulating

Acid Base Balance

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Acid Base Balance is Regulated By

? First Line of Defense

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vBlood Buffer System

? Second Line of Defense

?Respiratory Mechanism

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? Third Line of Defense

?Renal Mechanism

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1) Chemical Buffers

? React very rapidly (less than a second)

2) Respiratory Regulation

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? Reacts rapidly (seconds to minutes)

3) Renal Regulation

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? Reacts slowly (minutes to hours)

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Role of Blood Buffer System

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? First line of defense in

mechanism of Acid Base

Balance.

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? Acids (H+) added are

neutralized by the salt part of

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buffer.

Extracel ular Buffers

? Bicarbonate Buffer

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?NaHCO3/H2CO3 (20:1 at 7.4 pH)

? Phosphate Buffer

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?Na2HPO4/NaH2PO4 (4:1 at 7.4

pH)

? Protein Buffer

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?Na-Protein/H-Protein
Intracel ular Buffers

? Bicarbonate Buffer

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?KHCO3/H2CO3

? Phosphate Buffer

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?K2HPO4/KH2PO4

? Protein Buffer

?K-Hb/H-Protein

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Mechanism Action of Buffer Systems

? Buffers mixture of weak acids

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and its salts

? Resist change in pH of blood

when small amount of acids or

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alkalis added to the medium.

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?Buffers act quickly but not

permanently

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Bicarbonate Buffer System

Respiratory Buffer System

? Acid - Base balance is primarily concerned

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with Bicarbonate Buffer mechanism :

? H2CO3/ Hydrogen (H+)
? Bicarbonate (HCO - 3) (Alkali Reserve)

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H+

HCO -3

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Bicarbonate Buffer

? Bicarbonate Buffer- Chief Buffer

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system of Blood.

? NaHCO3 the salt part of buffer

neutralizes the strong and non

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volatile acids added to blood.

? It constitutes Alkali reserve(HCO3-)
Bicarbonate Buffer

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? Sodium Bicarbonate (NaHCO3) and carbonic

acid (H2CO3)

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? Maintain a 20:1 ratio : HCO -

3 : H2CO3

HCl + NaHCO3 H2CO3 + NaCl

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NaOH + H2CO3 NaHCO3 + H2O

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? Action of Bicarbonate

(NaHCO3) converts strong

dissociable acid into weak

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non dissociable acid

(H2CO3) and a neutral salt

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without altering the pH.
? Weak acid H2CO3 formed during

buffering action of Bicarbonate

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buffer is then expired out by Lungs.

? Thus Bicarbonate buffer is

connected to the respiratory system

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? Bicarbonate buffer is also termed as

Respiratory buffer.

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? Alkali reserve is represented by the

concentration of NaHCO3 in the blood.

? Alkali reserve concentration(HCO3-)

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determines the strength of buffering action

towards added H+ ions by acids.

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? More the concentration of Alkali reserve

,more is the buffering action and vice a versa.
? The blood buffers are effective

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as long as

?The acid load added is not very

high and

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?The alkali reserve (HCO3 -) is not

exhausted.

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Phosphate Buffer/Urine Buffer

Na2HPO4/NaH2PO4 (4:1 at 7.4

pH)

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? H+ + HPO 2-

4 H2PO4-

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? OH- + H

-

2-

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2PO4 H2O + H2PO4

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Phosphate Buffer Mechanism

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? When H+ ions added they are

neutralized/fixed by Na2HPO4

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(Alkaline Phosphate) and converted

to NaH2PO4 (Acid Phosphates).

? These acid phosphates then

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excreted out through kidneys as

acidic urine.

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? Thus Phosphate Buffer is

connected to Excretory system .

? Phosphate Buffer also termed as

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Urine Buffer.
? When an alkali enters it is

buffered by the acid phosphate

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NaH2PO4 which converted to

Na2HPO4 alkaline phosphate.

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? Excreted in urine making it

alkaline urine.

Protein Buffers

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? Includes hemoglobin, work in blood.
? Carboxyl group gives up H+
? Amino Group accepts H+
? The Imidazole group of Histidine

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present in Hb structure has buffering

capacity.

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Role of Respiratory Mechanisms

? Respiratory system plays

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second line of defense

mechanism of Acid Base

Balance.

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? Role of respiration in acid base

balance is short term

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regulatory process.

? H2CO3 formed from Bicarbonate Buffer, is

exhaled out through respiratory system.

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? Increased H2CO3 stimulates the respiratory

centre in Medulla Oblongata.

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? This in turn stimulates hyperventilation

which promptly removes H2CO3 from blood

by expiration.

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? Exhalation of H2CO3 is as carbon dioxide

by activity of enzyme Carbonic Anhydrase

of Lungs.

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? H+ + HCO - 3 H2CO3 CO2 + H20

? Respiratory mechanism is

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powerful, but only works with

volatile acids.

? Doesn't affect fixed acids like

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lactic acid.
? Blood pH can be adjusted

through respiratory

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mechanism

? By changing rate and depth

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of breathing.

? Low H2CO3 concentration in

blood depresses respiratory

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centre ,causes hypoventilation

i.e slow and shallow respiration.

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? This retains H2CO3 in blood.


?If Nervous centre /

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Respiratory system

fails.

?Acid Base Balance

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fails.

Generation of bicarbonate by RBC

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LACK OF AEROBIC ACTIVITY,DIFFUSION OF CARBONDIOXIDE,H+ BUFFERED BY HHb.

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Events in lungs and tissue

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lung

tissue

-

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HCO -

HCO

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3

3

HHb

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HHb

O

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O2

2

H+

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H+

H2CO3 HbO2

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HbO2

H2CO3

H2O CO2

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CO H

2

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2O

Isohydric transport

EXPIRED AIR

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of co2

METABOLISM

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Role of Renal Mechanism

? Renal mechanism is the third

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line of defense mechanism.

? Role of renal mechanism is

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long term regulatory process.

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? The acid and alkaline phosphates

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formed during phosphate buffering

mechanism are filtered from blood

and excreted out through urine.

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? Thus the phosphate buffer system is

directly connected to renal

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mechanism.

? Renal mechanism conserve and

produce Bicarbonate ions ( Alkali

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reserve).

? Renal Mechanism is the most

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effective regulator of blood pH.

? If kidneys fail, pH balance fails.

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? Renal System maintains Acid Base Balance

through:

? Reabsorption of Bicarbonate (HCO3-) ions.

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? Excretion of H+ ions

? Excretion of titrable acids(Acid Phosphates)

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? Excretion of Ammonium ions

(Glutaminase activity)

REABSORPTION OF BICARBONATE

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~Conservation of Bicarbonate
~Urine is free of HCO -3
~Simultaneous excretion of H+

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EXCRETION OF TITRABLE ACIDS

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~measure of acid excreated by kidney
~no. of mil ilitres of N/10 NaOH required to titrate 1 litre of urine to pH 7.4
~role of phosphate buffer

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Excretion Of H+ ions

~Elimination of nonvolatile acid
~Excretion of H+

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~Occurs in PCT
~Regeneration of bicarbonate
~H+ combine with non carbonate base and excreated

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EXCRETION OF AMMONIUM ION

NH3 is obtained from Deamination of Glutamine

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NH +4 cant diffuse back
2/3 of body acid load liberated in the form of NH +4

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Rates of correction

? Buffers function almost

instantaneously

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? Respiratory mechanisms take

several minutes to hours

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? Renal mechanisms may take

several hours to days

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MECHANISM FOR REGULATION OF

ACID BASE BALANCE

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? Buffer system: temporary solution
? Respiratory mechanism provide short time regulation
? Renal mechanism : permanent solution
? Urine pH < plasma pH ,4.5-9.5

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? Eliminate nonvolatile acid, buffered by cation

(principal y Na+)

? Maintain alkali reserve

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Acid Base Imbalance

OR

Conditions Of Acid Base

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Disturbances

The Body and pH

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? Homeostasis of blood pH is tightly

control ed by mechanisms of Acid

Base Balance.

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? Extracellular fluid = 7.4
? Blood pH regulated to = 7.35 ? 7.45

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Occurrence of Acid Base Imbalance

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? When Factors involved in

homeostatic mechanisms to

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regulate Acid Base Balance fails to

work efficiently.

? Does not maintain the altered pH of

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blood to normal constant range.

? Results into Acid Base Imbalance.

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ACIDOSIS / ALKALOSIS

?Two major disturbances

in Acid-Base balance

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?Acidosis
?Alkalosis
Conditions Of Acid Base Imbalance

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? Acidosis /Acidemia
( Decreased pH/Increased H+ ions)

? Alkalosis/Alkalemia
(Increased pH/Decreased H+ ions)

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? Acidosis (Acidemia) below 7.35
? Alkalosis (Alkalemia) above 7.45
? Blood pH < 6.8 or > 8.0 death

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occurs

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ACIDOSIS / ALKALOSIS

? Acidosis

? A condition in which the blood has too much acid (or

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too little base), frequently resulting in a decrease in

blood pH.

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? Alkalosis

? A condition in which the blood has too much

base (or too little acid), occasional y resulting in

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an increase in blood pH.

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Effect of Altered pH

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?Altered pH may seriously

disturbs the vital

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processes.

?Might lead to fatality.

? Most enzymes function only

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with narrow pH ranges.

? Extremes of pH affects the

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enzymatic action by

protonation or deprotonation

at the active sites of Enzymes.

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? Makes Enzymes inactive.
? Inactivated Enzymes affect

metabolic reactions and

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metabolic pathways.

? Metabolism gets deranged .
? Leads to metabolic syndromes.

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pH also affect excitability of

Nerve and Muscle cells

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pH

Excitability

pH

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Excitability

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ACID-BASE REGULATION

? Enzymes, Hormones and ion distribution

are all affected by Hydrogen ion

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concentrations

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ACIDOSIS / ALKALOSIS

? pH changes have dramatic effects on normal cell

function

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1) Changes in excitability of nerve and muscle

cells

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2) Influences Enzyme activity
3) Influences K+ levels/Retention of K+

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CHANGES IN CELL EXCITABILITY

? pH decrease (more acidic) depresses the

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central nervous system

? Can lead to loss of consciousness

? pH increase (more basic)causes over

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excitability of nervous system.

? Tingling sensations, nervousness, muscle

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twitches

INFLUENCES ON ENZYME ACTIVITY

? pH increases or decreases can alter the shape of

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the enzyme rendering it non-functional

? Changes in enzyme structure can result in

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accelerated or depressed metabolic actions

within the cell

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INFLUENCES ON K+ LEVELS

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? If H+ concentrations are high (acidosis) than H+ is

secreted in greater amounts

? This leaves less K+ than usual excreted.

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? The resultant K+ retention can affect cardiac

function and other systems

K+

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K

Na+

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Na

N

H+

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H

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Smal changes in pH can produce major

disturbances

? Acid-base balance can also

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affect Electrolytes (Na+, K+, Cl-)

? Can also affect Hormones

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ACID-BASE IMBALANCE

? Derangements of
? Hydrogen/Carbonic

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acid (H+/H2CO3)

? Bicarbonate
(HCO3-)

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concentrations

In body fluids are

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common in

conditions of Acid

Base Imbalance

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Acid-Base Imbalances

?pH< 7.35 Acidosis
?pH > 7.45 Alkalosis

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4 Types of Primary Acid-Base Disorders

Acid Base Imbalances

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Biochemical

Change

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Respiratory Acidosis

Increased H2CO3

Respiratory Alkalosis

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Decreased H2CO3

Metabolic Acidosis

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Metabolic Alkalosis

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RESPIRATORY ACIDOSIS

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Respiratory Acidosis

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? Primary Carbonic acid excess

? Increased H2CO3/Increased pCO2

? Defect in respiratory centre of brain

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? Defect in respiratory organ system

? Decreased elimination of H2CO3 by

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the lungs.

? Hypoventilation

? Increased blood levels of

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CO2 above 45 mm Hg.

? Hypercapnia ? high levels of

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pCO2 in blood

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RESPIRATORY ACIDOSIS

? Respiratory acidosis

develops when the lungs

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don't expel CO2

adequately.

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? This can happen in

diseases that severely

affect the lungs.

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? Chronic conditions:

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? Depression of respiratory center in brain that

controls breathing rate ? drugs or head trauma

? Paralysis of respiratory or chest muscles

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? Emphysema

? Asthma

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? Pneumonia

? Pulmonary edema

? Obstruction of respiratory tract

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? Congestive Cardiac Failure


HYPOVENTILATION

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Causes Respiratory Acidosis

? Hypo = "Under"

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Elimination of CO2

H+

pH

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RESPIRATORY ACIDOSIS

CO2

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CO2

-

HCO3

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CO2

CO2

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H CO

2

3

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2

:

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20

-breathing is suppressed holding CO2 in body

-pH = 7.1

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RESPIRATORY ACIDOSIS

? 1) Obstruction of air passages

? Vomit, Anaphylaxis, Tracheal Cancer

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RESPIRATORY ACIDOSIS

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? 2) Decreased Respiration

? Shallow, slow breathing

? Depression of the respiratory centers in the brain

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which control breathing rates

? Drug overdose

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RESPIRATORY ACIDOSIS

? 4) Col apse of lung

? Compression injury, open thoracic wound

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Left lung

col apsed

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Respiratory Acidosis

? Acute conditions:

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?Adult Respiratory Distress

Syndrome

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?Pulmonary edema
?Pneumothorax

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Compensation for Respiratory Acidosis

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?Kidneys eliminate

hydrogen ion and retain

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bicarbonate ions.

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Signs and Symptoms of Respiratory

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Acidosis

? Breathlessness
? Restlessness

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? Lethargy and disorientation
? Tremors, convulsions, coma
? Respiratory rate rapid, then gradually

depressed

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? Skin warm and flushed due to vasodilation

caused by excess CO2

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Treatment of Respiratory Acidosis

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? Restore ventilation
? IV lactate solution
? Treat underlying

dysfunction or disease

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RESPIRATORY ALKALOSIS

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Respiratory Alkalosis

? Primary Carbonic acid deficit
? Decreased H2CO3

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? pCO2 less than 35 mm Hg (hypocapnea)

? Most common acid-base imbalance
? Primary cause is hyperventilation
? Washes out excessive quantity of H2CO3

--- Content provided by‌ FirstRanker.com ---

through expiration process of lungs.

105

--- Content provided by FirstRanker.com ---

? Stimulation of respiratory

centre in brain

? Hyperventilation

--- Content provided by FirstRanker.com ---

Respiratory Alkalosis

? Conditions that stimulate respiratory center:

--- Content provided by⁠ FirstRanker.com ---

? Oxygen deficiency at high altitudes
? Pulmonary disease and Congestive heart failure ?

caused by hypoxia

--- Content provided by⁠ FirstRanker.com ---

? Respiratory center lesions
? Acute anxiety
? Fever, anemia
? Early salicylate intoxication

--- Content provided by FirstRanker.com ---

? Cirrhosis
? Gram-negative sepsis/Meningitis

107

--- Content provided by⁠ FirstRanker.com ---

RESPIRATORY ALKALOSIS

? Anxiety is an

emotional disturbance

--- Content provided by‍ FirstRanker.com ---

? The most common

cause of

--- Content provided by‍ FirstRanker.com ---

hyperventilation, and

thus respiratory

alkalosis, is noted in

--- Content provided by FirstRanker.com ---

anxiety

108

--- Content provided by⁠ FirstRanker.com ---

--- Content provided by⁠ FirstRanker.com ---

--- Content provided by‍ FirstRanker.com ---

--- Content provided by⁠ FirstRanker.com ---

RESPIRATORY ALKALOSIS

--- Content provided by FirstRanker.com ---

? Respiratory center lesions

? Damage to brain centers

--- Content provided by‍ FirstRanker.com ---

responsible for

monitoring breathing

rates

--- Content provided by⁠ FirstRanker.com ---

? Tumors
? Strokes

109

--- Content provided by FirstRanker.com ---

RESPIRATORY ALKALOSIS

? High Altitude

--- Content provided by⁠ FirstRanker.com ---

? Low concentrations of O2 in the arterial blood

reflexly stimulates ventilation in an attempt to

obtain more O2

--- Content provided by FirstRanker.com ---

? Too much CO2 is "blown off" in the process

110

--- Content provided by⁠ FirstRanker.com ---

--- Content provided by‍ FirstRanker.com ---

--- Content provided by⁠ FirstRanker.com ---

--- Content provided by FirstRanker.com ---

RESPIRATORY ALKALOSIS

--- Content provided by⁠ FirstRanker.com ---

? Fever

? Rapid shallow breathing

--- Content provided by‌ FirstRanker.com ---

blows off too much CO2

111

RESPIRATORY ALKALOSIS

--- Content provided by FirstRanker.com ---

? Salicylate poisoning
(Aspirin overdose)

? Ventilation is stimulated

--- Content provided by FirstRanker.com ---

without regard to the status

of O2, CO2 or H+ in the body

--- Content provided by‌ FirstRanker.com ---

fluids

112

--- Content provided by​ FirstRanker.com ---

RESPIRATORY ALKALOSIS

? Kidneys compensate by:

--- Content provided by⁠ FirstRanker.com ---

? Retaining hydrogen ions
? Increasing bicarbonate excretion

HCO -3

--- Content provided by​ FirstRanker.com ---

-

H

--- Content provided by⁠ FirstRanker.com ---

HCO

+

3H+

--- Content provided by‍ FirstRanker.com ---

HCO -3

HCO -3

--- Content provided by​ FirstRanker.com ---

H+

H+

H+

--- Content provided by FirstRanker.com ---

HCO -3

HCO - H+

--- Content provided by​ FirstRanker.com ---

3

HCO -

H+

--- Content provided by‍ FirstRanker.com ---

3

HCO -3

--- Content provided by​ FirstRanker.com ---

H+

HCO -3

H+ HCO - H+

--- Content provided by​ FirstRanker.com ---

3

H+

--- Content provided by‌ FirstRanker.com ---

113

HYPERVENTILATION

Causes Respiratory Alkalosis

--- Content provided by‌ FirstRanker.com ---

? Hyper = "Over"

Elimination of CO2

--- Content provided by⁠ FirstRanker.com ---

H+

pH

114

--- Content provided by FirstRanker.com ---

Compensation of Respiratory Alkalosis

? If kidneys are functioning normal
? The conditions of respiratory

--- Content provided by‌ FirstRanker.com ---

acidosis or alkalosis are

compensated.

? Kidneys conserve hydrogen ion

--- Content provided by‌ FirstRanker.com ---

? Excrete bicarbonate ion

115

Treatment of Respiratory Alkalosis

--- Content provided by‍ FirstRanker.com ---

? Treat underlying cause
? Breathe into a paper bag
? IV Chloride containing solution

--- Content provided by FirstRanker.com ---

Cl- ions replace lost

bicarbonate ions

116

--- Content provided by​ FirstRanker.com ---

METABOLIC ACIDOSIS

117

--- Content provided by‌ FirstRanker.com ---

Metabolic Acidosis

? Primary Alkali deficit

--- Content provided by FirstRanker.com ---

? Bicarbonate deficit - blood concentrations of

bicarbonate drop below 22mEq/L

? Causes:

--- Content provided by⁠ FirstRanker.com ---

? Loss of bicarbonate through diarrhea or renal

dysfunction.

--- Content provided by FirstRanker.com ---

? Overproduction production of acids (lactic acid or

ketones)

? Failure of kidneys to excrete H+

--- Content provided by FirstRanker.com ---

118

--- Content provided by⁠ FirstRanker.com ---

--- Content provided by FirstRanker.com ---

METABOLIC ACIDOSIS

? Occurs when there is a decrease in the normal

20:1 ratio

--- Content provided by‍ FirstRanker.com ---

? Decrease in blood pH and bicarbonate level

? Excessive H+ or decreased HCO -3

--- Content provided by⁠ FirstRanker.com ---

H

O - -

2CO3

--- Content provided by‌ FirstRanker.com ---

HHCCO33

H CO

--- Content provided by‍ FirstRanker.com ---

2

3

=

--- Content provided by⁠ FirstRanker.com ---

= 7.4

1

--- Content provided by‌ FirstRanker.com ---

:

210

119

--- Content provided by⁠ FirstRanker.com ---

METABOLIC ACIDOSIS

? Any acid-base imbalance

--- Content provided by​ FirstRanker.com ---

not attributable to CO2 is

classified as metabolic

? Metabolic production of

--- Content provided by‍ FirstRanker.com ---

Acids

? Or loss of Bases

--- Content provided by‌ FirstRanker.com ---

120

--- Content provided by‌ FirstRanker.com ---

--- Content provided by⁠ FirstRanker.com ---

METABOLIC ACIDOSIS

--- Content provided by‍ FirstRanker.com ---

? The causes of metabolic acidosis can be grouped

into five major categories

? 1) Ingesting an acid or a substance that is

--- Content provided by‍ FirstRanker.com ---

metabolized to acid

? 2) Abnormal Metabolism
? 3) Kidney Insufficiencies

--- Content provided by⁠ FirstRanker.com ---

? 4) Strenuous Exercise
? 5) Severe Diarrhea

121

--- Content provided by FirstRanker.com ---

METABOLIC ACIDOSIS

? 1) Ingesting An Acid

? Most substances that cause acidosis when

--- Content provided by FirstRanker.com ---

ingested are considered poisonous

? Examples include

--- Content provided by⁠ FirstRanker.com ---

wood alcohol

(methanol) and

antifreeze

--- Content provided by‍ FirstRanker.com ---

(ethylene glycol)

? However, even an overdose

--- Content provided by FirstRanker.com ---

of aspirin (acetylsalicylic acid)

can cause metabolic acidosis

122

--- Content provided by‌ FirstRanker.com ---

--- Content provided by​ FirstRanker.com ---

METABOLIC ACIDOSIS

? 2) Abnormal Metabolism

--- Content provided by⁠ FirstRanker.com ---

? The body can produce excess acid as a result of several

diseases

? Ketoacidosis

--- Content provided by‍ FirstRanker.com ---

? Type I Diabetes Mellitus
? Uncontrol ed Diabetes mellitus
? Prolonged Starvation
? Lacticacidosis
? Shock

--- Content provided by FirstRanker.com ---

? Haemorrhage
? Violent Exercise-

METABOLIC ACIDOSIS

--- Content provided by⁠ FirstRanker.com ---

? Unregulated diabetes

mellitus causes

ketoacidosis

--- Content provided by⁠ FirstRanker.com ---

? Body metabolizes fat

rather than glucose

--- Content provided by⁠ FirstRanker.com ---

? Accumulations of

metabolic acids (Keto

Acids) cause an

--- Content provided by​ FirstRanker.com ---

increase in plasma H+

124

--- Content provided by​ FirstRanker.com ---

--- Content provided by FirstRanker.com ---

METABOLIC ACIDOSIS

--- Content provided by​ FirstRanker.com ---

? 3) Kidney Insufficiencies

? This type of kidney malfunction is called renal

--- Content provided by FirstRanker.com ---

tubular acidosis or uremic acidosis and may

occur in people with kidney failure or with

abnormalities that affect the kidneys' ability

--- Content provided by‌ FirstRanker.com ---

to excrete acid

METABOLIC ACIDOSIS

--- Content provided by⁠ FirstRanker.com ---

? 3) Kidney Insufficiencies

? Kidneys may be unable to rid

the plasma of even the

--- Content provided by‍ FirstRanker.com ---

normal amounts of H+

generated from metabolic

--- Content provided by FirstRanker.com ---

acids

? Kidneys may be also unable to

conserve an adequate

--- Content provided by⁠ FirstRanker.com ---

amount of HCO -3 to buffer the

normal acid load

--- Content provided by‍ FirstRanker.com ---

126

--- Content provided by⁠ FirstRanker.com ---

METABOLIC ACIDOSIS

--- Content provided by‌ FirstRanker.com ---

? 4) Strenuous Exercise

? Muscles resort to anaerobic glycolysis during

--- Content provided by FirstRanker.com ---

strenuous exercise

? Anaerobic respiration leads to the production

of large amounts of lactic acid

--- Content provided by‍ FirstRanker.com ---

C

Enzymes

--- Content provided by‌ FirstRanker.com ---

6H12O6

2C3H6O3 + ATP (energy)

Lactic Acid

--- Content provided by⁠ FirstRanker.com ---

127

METABOLIC ACIDOSIS

--- Content provided by‌ FirstRanker.com ---

? 5) Severe Diarrhea

? Fluids rich in HCO -3 are released and reabsorbed

during the digestive process

--- Content provided by‌ FirstRanker.com ---

? During diarrhea this HCO -3 is lost from the body

rather than reabsorbed

--- Content provided by‍ FirstRanker.com ---

--- Content provided by FirstRanker.com ---

METABOLIC ACIDOSIS

? 5) Severe Diarrhea

--- Content provided by​ FirstRanker.com ---

? The loss of HCO -3 without a corresponding loss of

H+ lowers the pH

--- Content provided by⁠ FirstRanker.com ---

? Less HCO -3 is available for buffering H+

? Prolonged deep (from duodenum) vomiting can

result in the same situation

--- Content provided by‌ FirstRanker.com ---

Symptoms of Metabolic Acidosis

? Headache, lethargy
? Nausea, vomiting, diarrhea

--- Content provided by‍ FirstRanker.com ---

? Coma
? Death

130
Compensation for Metabolic Acidosis

--- Content provided by‌ FirstRanker.com ---

? Increased ventilation.
? Renal excretion of hydrogen ions

if possible.

--- Content provided by​ FirstRanker.com ---

? K+ exchanges with excess H+ in

ECF.

--- Content provided by‍ FirstRanker.com ---

? H+ into cells, K+ out of cells.

131

Treatment of Metabolic Acidosis

--- Content provided by FirstRanker.com ---

? IV lactate solution

132

--- Content provided by FirstRanker.com ---

METABOLIC ALKALOSIS

133

--- Content provided by FirstRanker.com ---

Metabolic Alkalosis

? Bicarbonate Excess - concentration in blood is

greater than 26 mEq/L

--- Content provided by‌ FirstRanker.com ---

? Causes:

? Excess vomiting = loss of stomach acid

--- Content provided by‌ FirstRanker.com ---

? Excessive use of alkaline drugs

? Certain diuretics

? Endocrine disorders

--- Content provided by⁠ FirstRanker.com ---

? Heavy ingestion of antacids

? Severe dehydration

--- Content provided by FirstRanker.com ---

? Cushings Syndrome

? Prolonged exposure to x rays and UV rays

134

--- Content provided by⁠ FirstRanker.com ---

--- Content provided by​ FirstRanker.com ---

METABOLIC ALKALOSIS

--- Content provided by FirstRanker.com ---

? Elevation of pH due to an increased 20:1 ratio

? May be caused by:

? An increase of bicarbonate

--- Content provided by FirstRanker.com ---

? A decrease in hydrogen ions

? Imbalance again cannot be due to CO2

? Increase in pH which has a non-respiratory

--- Content provided by FirstRanker.com ---

origin

7.4

--- Content provided by‌ FirstRanker.com ---

135

METABOLIC ALKALOSIS

? Can be the result of:

--- Content provided by​ FirstRanker.com ---

? 1) Ingestion of Alkaline Substances
? 2) Vomiting ( loss of HCl )

136

--- Content provided by‍ FirstRanker.com ---

--- Content provided by​ FirstRanker.com ---

METABOLIC ALKALOSIS

--- Content provided by‌ FirstRanker.com ---

? Baking soda (NaHCO3) often used as a remedy

for gastric hyperacidity

? NaHCO

--- Content provided by⁠ FirstRanker.com ---

-

3 dissociates to Na+ and HCO3

--- Content provided by FirstRanker.com ---

137

Compensation for Metabolic Alkalosis

? Alkalosis most commonly occurs

--- Content provided by FirstRanker.com ---

with renal dysfunction, so can't

count on kidneys.

--- Content provided by​ FirstRanker.com ---

? Respiratory compensation

difficult ? hypoventilation limited

by hypoxia.

--- Content provided by​ FirstRanker.com ---

138
Symptoms of Metabolic Alkalosis

? Respiration slow and shallow

--- Content provided by‍ FirstRanker.com ---

? Hyperactive reflexes ; tetany

? Often related to depletion of

--- Content provided by‌ FirstRanker.com ---

electrolytes

? Atrial tachycardia

? Dysrhythmias

--- Content provided by FirstRanker.com ---

139

Treatment of Metabolic Alkalosis

--- Content provided by‌ FirstRanker.com ---

? Electrolytes to replace

those lost

? IV chloride containing

--- Content provided by‍ FirstRanker.com ---

solution

? Treat underlying disorder

--- Content provided by‍ FirstRanker.com ---

140
Acidosis

? Principal effect of acidosis is depression of the CNS through

--- Content provided by​ FirstRanker.com ---

in synaptic transmission.

? Generalized weakness

? Deranged CNS function the greatest threat

--- Content provided by‍ FirstRanker.com ---

? Severe acidosis causes

? Disorientation

--- Content provided by​ FirstRanker.com ---

? Coma

? Death

141

--- Content provided by‌ FirstRanker.com ---

Alkalosis

? Alkalosis causes over excitability of the central and

--- Content provided by‌ FirstRanker.com ---

peripheral nervous systems.

? Numbness

? Light headedness

--- Content provided by‌ FirstRanker.com ---

? Severe Alkalosis causes :

? Nervousness

--- Content provided by FirstRanker.com ---

? muscle spasms or Tetany

? Convulsions

? Loss of consciousness

--- Content provided by‍ FirstRanker.com ---

? Death

142
Compensation Of

--- Content provided by‍ FirstRanker.com ---

Acid Base Imbalance

? The body response to acid-base imbalance is

--- Content provided by‌ FirstRanker.com ---

called compensation

? May be complete compensation if altered pH

brought back within normal limits

--- Content provided by‍ FirstRanker.com ---

? Partial compensation if pH range is still

outside norms.

--- Content provided by‌ FirstRanker.com ---

? Uncompensated if pH range is very out from

norms.

? If underlying problem is respiratory, renal

--- Content provided by‍ FirstRanker.com ---

mechanisms can bring about metabolic

compensation.

--- Content provided by‌ FirstRanker.com ---

? If underlying problem is metabolic,

hyperventilation or hypoventilation can help :

respiratory compensation.

--- Content provided by⁠ FirstRanker.com ---

ACIDOSIS

decreased

--- Content provided by FirstRanker.com ---

failure of

metabolic

--- Content provided by FirstRanker.com ---

production

absorption of

prolonged

--- Content provided by FirstRanker.com ---

removal of

kidneys to

--- Content provided by​ FirstRanker.com ---

acid

of keto acids

metabolic acids

--- Content provided by‌ FirstRanker.com ---

diarrhea

CO2 from

--- Content provided by FirstRanker.com ---

excrete

from GI tract

lungs

--- Content provided by FirstRanker.com ---

acids

accumulation

--- Content provided by⁠ FirstRanker.com ---

accumulation

excessive loss

of CO2 in blood

--- Content provided by‌ FirstRanker.com ---

of acid in blood

of NaHCO3

--- Content provided by⁠ FirstRanker.com ---

from blood

deep

vomiting

--- Content provided by FirstRanker.com ---

respiratory

metabolic

--- Content provided by​ FirstRanker.com ---

from

GI tract

increase in

--- Content provided by‍ FirstRanker.com ---

acidosis

plasma H+

--- Content provided by⁠ FirstRanker.com ---

acidosis

concentration

kidney

--- Content provided by FirstRanker.com ---

disease

(uremia)

--- Content provided by FirstRanker.com ---

depression of

145

nervous system

--- Content provided by⁠ FirstRanker.com ---

ALKALOSIS

anxiety

--- Content provided by FirstRanker.com ---

overdose

high

prolonged

--- Content provided by FirstRanker.com ---

ingestion of

excess

--- Content provided by‍ FirstRanker.com ---

of certain

altitudes

vomiting

--- Content provided by‌ FirstRanker.com ---

excessive

aldosterone

--- Content provided by FirstRanker.com ---

drugs

alkaline drugs

hyperventilation

--- Content provided by‌ FirstRanker.com ---

loss of acid

accumulation

--- Content provided by‍ FirstRanker.com ---

loss of CO2 and

of base

H2CO2 from

--- Content provided by FirstRanker.com ---

blood

respiratory

--- Content provided by​ FirstRanker.com ---

metabolic

alkalosis

alkalosis

--- Content provided by‌ FirstRanker.com ---

decrease

in plasma H+

--- Content provided by‌ FirstRanker.com ---

concentration

overexcitability

of nervous

--- Content provided by‌ FirstRanker.com ---

146

system
Organ dysfunction

--- Content provided by​ FirstRanker.com ---

And

Acid Base Imbalance

--- Content provided by FirstRanker.com ---

? CNS ? respiratory acidosis (suppression) and alkalosis

(stimulation)

? Pulmonary ? respiratory acidosis (COPD) and

--- Content provided by‌ FirstRanker.com ---

alkalosis (hypoxia, pulmonary embolism)

? Cardiac ? respiratory alkalosis, respiratory acidosis,

--- Content provided by‌ FirstRanker.com ---

metabolic acidosis (pulmonary edema)

? GIT ? metabolic alkalosis (vomiting) and acidosis

(diarrhea)

--- Content provided by⁠ FirstRanker.com ---

? Liver ? respiratory alkalosis, metabolic acidosis (liver

failure)

--- Content provided by FirstRanker.com ---

? Kidney ? metabolic acidosis (RTA) and alkalosis (1st

Aldosterone)

Organ Dysfunction

--- Content provided by‍ FirstRanker.com ---

? Endocrine

? Diabetes mellitus ? metabolic acidosis

--- Content provided by⁠ FirstRanker.com ---

? Addisons Disease/Adrenal insufficiency ? metabolic

acidosis.(Decreased H+ ions excretion)

? Cushing's Syndrome ? metabolic alkalosis

--- Content provided by⁠ FirstRanker.com ---

(Increased Cortisol- Increased H+ ions excretion)

? Primary aldosteronism ? metabolic alkalosis

--- Content provided by‌ FirstRanker.com ---

? Drugs/toxins

? Toxic alcohols ? metabolic acidosis

? ASA/Aspirin ? metabolic acidosis and respiratory alkalosis(

--- Content provided by‍ FirstRanker.com ---

Causes Hyperventilation)

? Theophylline overdose ? respiratory alkalosis

--- Content provided by⁠ FirstRanker.com ---

ACID ? BASE DISORDERS

Clinical State

--- Content provided by⁠ FirstRanker.com ---

Acid-Base Disorder

Pulmonary Embolus

Respiratory Alkalosis

--- Content provided by‍ FirstRanker.com ---

Cirrhosis

Respiratory Alkalosis

--- Content provided by‌ FirstRanker.com ---

Pregnancy

Respiratory Alkalosis

Diuretic Use

--- Content provided by​ FirstRanker.com ---

Metabolic Alkalosis

Vomiting

--- Content provided by‍ FirstRanker.com ---

Metabolic Alkalosis

Chronic Obstructive Pulmonary Disease

Respiratory Acidosis

--- Content provided by‌ FirstRanker.com ---

Shock

Metabolic Acidosis

--- Content provided by‌ FirstRanker.com ---

Severe Diarrhea

Metabolic Acidosis

Renal Failure

--- Content provided by‌ FirstRanker.com ---

Metabolic Acidosis

Respiratory Alkalosis,

--- Content provided by‍ FirstRanker.com ---

Sepsis (Bloodstream Infection)

149

Metabolic Acidosis

--- Content provided by​ FirstRanker.com ---

150
Anion Gap

? Sum of anion and cations is always equal

--- Content provided by‌ FirstRanker.com ---

? Sodium and Potassium accounts for 95% of

cations

? Chloride and bicarbonate accounts for 68% of

--- Content provided by‌ FirstRanker.com ---

anions

? There is difference between measured anion

--- Content provided by‍ FirstRanker.com ---

and cation

? The unmeasured anions constitute the

ANION GAP.

--- Content provided by⁠ FirstRanker.com ---

? They are protein anions ,sulphates ,phosphates

and organic acid(Unmeasured Anions)

? AG can be calculated as (Na+ + K+)--(HCO -3 + Cl-)

--- Content provided by‍ FirstRanker.com ---

? High anion gap acidosis: renal failure, DM
? Normal anion gap acidosis: diarrhea
? Hyperchloremic acidosis

Calculation Of Anion Gap

--- Content provided by FirstRanker.com ---

? Na ++ K+ = Cl- + HCO3 - + A-
? 136+ 4 = 100 + 25
? A- = 15 mEq/L
? Normal AG is typically 12 ? 4

--- Content provided by FirstRanker.com ---

mEq/L.

? If AG is calculated using K+, the

--- Content provided by‌ FirstRanker.com ---

normal AG is 16 ? 4 mEq/L

Significance of Anion Gap Calculation

? Calculation of Anion gap

--- Content provided by‌ FirstRanker.com ---

and its values help in

diagnosing conditions of

--- Content provided by​ FirstRanker.com ---

Acid Base Balance and

Imbalance.
? The anion gap is increased in conditions

--- Content provided by FirstRanker.com ---

such as metabolic acidosis:

? That result from elevated levels of

metabolic acids (metabolic acidosis)

--- Content provided by​ FirstRanker.com ---

?Lactic acidosis
?Diabetic Ketoacidosis
?Renal Failure

--- Content provided by‌ FirstRanker.com ---

? A low anion gap occurs in conditions

that cause a fall in unmeasured

anions

--- Content provided by‌ FirstRanker.com ---

? (primarily albumin) OR a rise in

unmeasured cations

--- Content provided by⁠ FirstRanker.com ---

Calculate the Anion Gap

? 1. Calculate the anion gap as described.
? 2. An anion gap ,over 25 suggests a severe

--- Content provided by‍ FirstRanker.com ---

metabolic acidosis.

? 3. Causes of an high anion gap: ethylene

--- Content provided by‌ FirstRanker.com ---

glycol, lactic acid, methanol, paraldehyde,

aspirin, renal failure, ketoacidosis (diabetic or

ethanol).

--- Content provided by‌ FirstRanker.com ---

Anion Gap Acidosis:

? Anion gap >12 mmol/L; caused by a decrease

in [HCO3 -]

--- Content provided by​ FirstRanker.com ---

? Balanced by an increase in an unmeasured

acid ion from either endogenous production

--- Content provided by​ FirstRanker.com ---

or exogenous ingestion (normochloremic

acidosis).

Me

--- Content provided by​ FirstRanker.com ---

M t

e abolic

--- Content provided by⁠ FirstRanker.com ---

t



abolic Ac

--- Content provided by FirstRanker.com ---

A idos

c

--- Content provided by​ FirstRanker.com ---

is and t

and he

t

--- Content provided by‍ FirstRanker.com ---

he Anion

A

--- Content provided by‌ FirstRanker.com ---

g

nion ap

g

--- Content provided by‌ FirstRanker.com ---

1. Normal gap

2. Increased gap

--- Content provided by FirstRanker.com ---

1. Acid

1. Renal "HCO

2. Acid

--- Content provided by​ FirstRanker.com ---

3" 2. GI "HCO3"

prod

--- Content provided by⁠ FirstRanker.com ---

losses

elimination

losses

--- Content provided by‌ FirstRanker.com ---

Lactate

Renal disease

--- Content provided by⁠ FirstRanker.com ---

Proximal RTA

DKA

Distal RTA

--- Content provided by‌ FirstRanker.com ---

Diarrhea

Ketosis

--- Content provided by FirstRanker.com ---

Toxins

Alcohols

--- Content provided by‍ FirstRanker.com ---

Salicylates

Iron
Henderson Hasselbalch Equation

--- Content provided by‌ FirstRanker.com ---

? pH= pka +log [HCO3-]/[H2CO3]

? At pH 7.4 the ratio of HCO3-/H2CO3

--- Content provided by‍ FirstRanker.com ---

is 1:20.

? A buffer is most effective when

pH=pKa

--- Content provided by​ FirstRanker.com ---

? When concentration of salt and acid

are equal.
Significance of Henderson Hasselbalch

--- Content provided by⁠ FirstRanker.com ---

Equation

? The equation helps in

--- Content provided by FirstRanker.com ---

calculating pH of Buffers.

? The equation helps in

assessing status of Acid

--- Content provided by⁠ FirstRanker.com ---

Base balance.

Stepwise Approaches

--- Content provided by‍ FirstRanker.com ---

? History & physical examination

? Arterial blood gas for pH, pCO2, (HCO3)

? Use the HCO3 from ABG to determine compensation

--- Content provided by⁠ FirstRanker.com ---

? Serum Na, K, Cl, CO2 content

? Use CO2 content to calculate anion gap

--- Content provided by​ FirstRanker.com ---

? Calculate anion gap

? Anion gap = {Na - (Cl + CO2 content)}

? Determine appropriate compensation

--- Content provided by FirstRanker.com ---

? Determine the primary cause
DIAGNOSTIC LAB VALUES

&

--- Content provided by FirstRanker.com ---

INTERPRETATION

? Arterial Blood

--- Content provided by‍ FirstRanker.com ---

Gas(ABG )Analyzer

determines Acid Base

Balance and Imbalance.

--- Content provided by‌ FirstRanker.com ---

Diagnosis of Acid-Base Imbalances

1. Note whether the pH is low (acidosis) or high

(alkalosis)

--- Content provided by‌ FirstRanker.com ---

2. Decide which value, pCO

-

--- Content provided by​ FirstRanker.com ---

2 or HCO3 , is

outside the normal range

3. If the cause is a change in pCO2,/H2CO3 the

--- Content provided by‍ FirstRanker.com ---

problem is respiratory.

4. If the change is in HCO -3 the problem is

--- Content provided by⁠ FirstRanker.com ---

metabolic.

169

Normal Arterial Blood Gas (ABG)

--- Content provided by‍ FirstRanker.com ---

Lab Values:

? Arterial pH: 7.35 ? 7.45
? HCO -3: 22 ? 26 mEq/L

--- Content provided by FirstRanker.com ---

? PCO2: 35 ? 45 mmHg

? TCO2: 23 ? 27 mmol/L

--- Content provided by‍ FirstRanker.com ---

? PO2: 80 ? 100 mmHg

? Base Excess: -2 to +2
? Anion Gap: 12 ? 14 mEq/L
Example

--- Content provided by⁠ FirstRanker.com ---

? A patient is in intensive care because he

suffered a severe myocardial infarction 3 days

--- Content provided by FirstRanker.com ---

ago. The lab reports the following values from

an arterial blood sample:

? pH 7.3

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? HCO3- = 20 mEq / L ( 22 - 26)
? pCO2 = 32 mm Hg (35 - 45)

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Diagnosis

? Metabolic acidosis
? With compensation

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Questions

? Long Essays.

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? What is acid-base balance? Describe the homeostatic mechanism

by which the blood pH is regulated.

? Short Notes

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? Blood Buffer System.

? Role of Kidney in acid-base balance.

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? Hb as Buffer system.

? Acid-Base imbalance.

? Metabolic Acidosis.

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? Difference between acidosis & alkalosis.

? Anion Gap.

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END

ACID - BASE BALANCE

THANKS

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