1. pH is a measure of how acidic or alkaline a solution is, defined as the negative logarithm of the hydrogen ion concentration. Normal pH values in the body are 7.35-7.45. 2. Deviations from normal pH can result in acidosis or alkalosis. Acidosis is an increase in hydrogen ions causing a pH below 7.35, while alkalosis is an increase in bicarbonate ions causing a pH above 7.45. 3. Common causes of acid-base imbalances include respiratory or metabolic disorders that affect carbon dioxide or bicarbonate levels in the blood and can lead to respiratory acidosis, respiratory alkalosis, metabolic acidosis, or

1. Changes in pH of body 1
Presented byPresented by
Pratiksha BhandariPratiksha Bhandari
B.Sc. Nursing 2013 BatchB.Sc. Nursing 2013 Batch
College of Nursing, BPKIHSCollege of Nursing, BPKIHS

2. General objectives
• At the end of the session, students will be able to know
about changes in pH of body.
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3. Specific objectives
• At the end of the session, students will be able to:
1.Define pH.
2.List normal pH values.
3.Differentiate between acid and base.
4.List the effects of pH change.
5.Enlist deviations from normal acid base status.
3

4. pH
• It is the negative logarithm of concentration of
solution.
• Optimal pH: The pH value at which maximum range
of enzyme reaction occurs.
• pH = -log [H++
]]
• Normal pH = 7.35-7.45Normal pH = 7.35-7.45
4

5. pH values
• Arterial blood: 7.41
• Venous blood: 7.35
(due to H2CO3)
• Interstitial fluid: 7.35
5

6. pH scale 6

7. Acids
• Acids are hydrogen containing substances which
dissociate in solution to release HH++
• Acids can be defined as a proton (HH++
) donor.
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8. Acids
• Physiologically important acids include:
• Carbonic acid (HCarbonic acid (H22COCO33))
• Phosphoric acid (HPhosphoric acid (H33POPO44))
• Pyruvic acid (CPyruvic acid (C33HH44OO33))
• Lactic acid (CLactic acid (C33HH66OO33))
• These acids are dissolved in body fluids.
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9. Acids
• Sources of Hydrogen Ions.
oCell metabolism (CO2)
oFood products: Yoghurt, Citric acid in fruits
oMetabolic Intermediate by-products: Lactic acid, Pyruvic
acid, Acetoacetic acid and fatty acids.
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10. Acids
• Some disease processes: diabetes causes improper
metabolism of fats which results in the generation of
a waste product called a Keto Acid.
• Proteins (red meat products): Breakdown leads to
productions of sulfuric acid and phosphoric acid.
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11. Base
• A proton (HH++
) acceptor.
• Molecules capable of accepting a hydrogen ion.
• Physiologically important bases include:
o Bicarbonate (HCOBicarbonate (HCO33
--
))
o Biphosphate (HPOBiphosphate (HPO44
-2-2
))
11

12. Acidity Vs Alkalinity
• The normal blood pH range is 7.35 to 7.45.
• When the pH is below 7.35, the blood is said to be acidic.
• When the pH is above 7.45, the blood is said to be alkalotic.
• Significant changes in the blood pH above 7.8 or below 6.8 will
interfere with cellular functioning, and if uncorrected, will lead
to death.
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13. Acidity Vs Alkalinity 13

14. Effects of PH changes
• pH changes have dramatic effects on normal
cell function
1)Changes in excitability of nerve and muscle
cells
2)Influences enzyme activity
3)Influences KK++
levels
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15. 1. CHANGES IN CELL EXCITABILITY
a. pH decrease (more acidic) depresses the
central nervous system
• Can lead to loss of consciousness
b. pH increase (more basic) can cause over-
excitability
a. Tingling sensations, nervousness
muscle twitches
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16. CHANGES IN CELL EXCITABILITY 16
p
H
p
Excitabilit
y
Excitabili

17. 2. INFLUENCES ON ENZYME ACTIVITY
• pH increase or decrease can alter the shape of the enzyme .
• Enzyme then become inactive or it can cause the enzyme to
completely break apart. (Substrate is specific substance on
which a given enzyme acts).
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18. 3. Influences of PH on K+
level
• Acidosis may lead to hyperkalemia by two
mechanism:
1.Hydrogen ions are exchanged with potassium in the
cells.
2.Hydrogen ions leaves less potassium from renal
tubules.
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19. Acidosis leads to Hyperkalemia
• Acidosis leads to hyperkalemia .ThisAcidosis leads to hyperkalemia .This
causes a shift of potassium ions out of thecauses a shift of potassium ions out of the
cells.cells.
19
H+
H+
H+
H+
H+
H+
H+
H+
H+
K+
K+K+
K+
K+
K+
ACIDOSIS

20. INFLUENCES ON K+
LEVELS
• Normally : When NaNa++
is reabsorbed from the filtrate
of the renal tubules , KK++
or HH++
is secreted
(exchanged).
• KK++
is secreted in much greater amounts than HH++
in
normal condition.
20

21. INFLUENCES ON K+
LEVELS
• IfIf HH++
concentrations are high ( as in acidosis), thisconcentrations are high ( as in acidosis), this
leaves lessleaves less KK++
than usual excreted result in retentionthan usual excreted result in retention
of Kof K++
..
• The resultantThe resultant KK++
retention can affect cardiac functionretention can affect cardiac function
and other systems.and other systems.
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22. ACIDOSIS / ALKALOSIS
• Acidosis and alkalosis are not diseases but rather are the results
of a wide variety of disorders.
• A relative increase in hydrogen ions results in acidosis.acidosis.
• A relative increase in bicarbonate results in alkalosis.alkalosis.
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23. Summary
AlkalosisAlkalosis
23
H+
OH-
AcidosisAcidosis
H+ OH-

24. ACIDOSIS / ALKALOSIS
• Normal base to acid ratio = 20:1
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25. ACIDOSIS / ALKALOSIS
• Deviations from normal Acid-Base status are
divided into four general categories;
• Respiratory Acidosis
• Respiratory Alkalosis
• Metabolic Acidosis
• Metabolic Alkalosis
25

26. 1. Respiratory acidosis
• Characterized by a pH decrease and an increase in
COCO22.
• Causes :
- Obstruction of air passages: Vomit
- Decreased respiration
- Disease of lungs
- Collapse of lung
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27. Nursing management
• Treatment of underlying causes
• Pulmonary and oral hygiene: Frequent clearing of
mucus and discharge from the respiratory tract.
• Positioning: Upright/ semi-flowers position
(facilitates maximum lung expansion).
• Teach breathing technique.
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28. Nursing management
• Mechanical ventilation use/ adjustment to gradually
decrease Carbondioxide
• Monitor GCS
• Monitor respiratory rate/ depth/ pulse rate/
regularity/ cyanosis.
• Frequent evaluation of ECG changes and CXR
changes.
• Brochodilators use.
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29. 2. Respiratory alkalosis
• A primary disorder where the first change is a
lowering of PaCO2, resulting in an elevated pH .
• Due to hyperventilation.
• Causes :
• Anxiety
• Fever
• High altitude
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30. Nursing management
• Relaxation technique and adequate rest.
• Assist client to breathe more slowly.
• In case of hypoxia: Oxygen inhalation
• Anti-anxiety drugs, sedatives.
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31. 3. Metabolic acidosis
• A primary disorder where the first change is a
lowering of HCO3¯ , resulting in decreased pH.
• Causes :
- Acute or chronic renal failure
- Diabetic ketoacidosis
- Poisonings: Aspirin, methanol, CO, Cyanide
- Diarrhoea
- Renal tubular acidosis
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32. Nursing management
• Adequate hydration and electrolyte balance
• Strict I/O charting and daily weighing.
• Frequent ABG monitoring
• Mechanical ventilation
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33. 4. Metabolic alkalosis
• A primary disorder where the first change is an
elevation of HCO3¯ , resulting in increased pH.
• Causes :
- Ingestion of alkaline substance (antacids: The extra
bicarbonate is absorbed in plasma, increasing pH of
plasma.)
- Vomiting (HCl loss, loss of hydrogen ion)
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34. Nursing management
• Maintain fluid balance.
• Potassium supplementation.
• Monitor vital signs and neurological status.
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35. Summary
• pH is the negative logarithm of concentration of
solution.
• A relative increase in hydrogen ions results in
acidosis.acidosis.
• A relative increase in bicarbonate results in
alkalosis.alkalosis.
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36. 36

37. MCQ
1. All are the causes of metabolic acidosis except
a.Diuresis
b.Diabetic ketoacidosis
c.Starvation
d.Methanol poisoning
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38. MCQ
2. All are the causes of respiratory alkalosis except
a.Anxiety
b.Fever
c.High altitude
d.Poliomyelitis
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39. MCQ
3. Normal pH value is
a.<7.35
b.>7.45
c.7.35-7.45
d.All
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40. SAQ
• Define pH. What are the effects of pH changes?
• Enlist the causes of respiratory acidosis.
• Describe management of patient with acid-base
imbalances.
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41. 41

42. 42

43. References
• J. Roshan, J. Rijuta, J and J Health Science, Body fluid, 4th
edition, 2016, page no 22-26
• Mandal G.N. A textbook of Adult Nursing, 2nd
Edition, Makalu
Publication House, August 2013, Page no. 123-127
• C. Carroll, Conn’s current therapy, Acid-Base, W.B Saunders
Company, 1st
edition, 1986, Page no 929.
• F. Sandra, Clinical, pH changes, 4th
edition, 1996, page no 815,
822, 823.
• Cited on https://en.wikipedia.org/wiki/pH , assessed on 23rd
May,
2017.
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