The document discusses acid-base balance and buffer systems in the human body. It describes how the body maintains a slightly basic pH between 7.35-7.45 through various systems like the lungs, kidneys, and important buffer systems. The major buffer system is the bicarbonate-carbonic acid buffer system, which functions to instantly buffer changes in pH. Disorders that disrupt acid-base balance like metabolic acidosis, alkalosis, respiratory acidosis and alkalosis are explained along with their causes and compensatory mechanisms.

2. • Acid-Base Balance
• The body's maintenance of a healthy pH
range for blood and tissues that is slightly
basic (pH between 7.35 - 7.45).
• This balance is achieved through the use
of systems in the blood (which help to
minimize pH changes) and by the lungs
and kidneys, which eliminate excess
amounts of acids or bases from the body.

3. • Normally because of metabolic, there
is daily a hug amount of
H ion 40 mmoles/day and
CO2 15,000 mmoles/day, which should be
effectively deal with in order to maintain
normal acid – base state .

4. • A buffer solution
• is an aqueous solution consisting of a
mixture of a weak acid and its conjugate
base or a weak base and its conjugate
acid.
• It has the property that it resist the
change in pH when a small amount of
strong acid or base is added to it.
• Buffers found in all body fluids .

5. • Strong acids are poor buffers because
they make the system more acid .
• Weak acids good buffers since they
can tilt a reaction in the other
direction .
•Function
• Maintains pH homeostasis .
• Maintenance of H+ concentration .

6. • Why do we need Buffer Systems ?
• If the acids produced in the body from
the catabolism of food and other cellular
processes are not removed or buffered,
the body’s pH would drop
• Significant drops in pH interferes with cell
enzyme systems.
• Change in PH below 6.8 or above 8.0 may
result in death .
• Acid-base balance can also affect
electrolytes (Na+, K+, Cl-) .

7. The most important buffer for
maintaining acid-base balance
in the blood is the carbonic-
acid-bicarbonate
buffer.

8. As shown in the above equation, the pH of the buffered solution (i.e.,
the blood) is dependent only on the ratio of the
amount of CO2 present in the blood to the amount of HCO3
- (bicarbonate ion) present in the blood (at a given
temperature, so that pK remains constant). This ratio remains relatively
constant, because the concentrations of
both buffer components (HCO3
- and CO2) are very large, compared to the amount of H+ added to the
blood
during normal activities and moderate exercise .

10. This figure shows the major organs
that help control the blood
concentrations of CO2 and HCO3
-, and
thus help control the pH of the blood.
Removing CO2 from the blood helps
increase the pH.
Removing HCO3
- from the blood helps
lower the pH.

11. • The major buffers system in man
Four Major Buffer Systems
1 - Bicarbonate-carbonic acid Buffer.
• H2CO3 H+ + HCO3¯(major )
2 - Phosphate Buffer system
( Major intracellular buffer )
H2PO4 H+ + HPO4 ¯2

12. Protein Buffer systems
3 - Hemoglobin Buffer system .
HPr H+ + Pr¯
4 - Amino acids
NH4
+ H++ NH3

13. Buffer Systems in Body Fluids
Figure 27.7

16. • Phosphate Buffer System
• Has a major role in the elimination of H+ via
the kidney
• Assists in the exchange of sodium for
hydrogen
• It participates in the following reaction
• HPO-2
4 + H+ H2PO –
4
• Essential within the erythrocytes .

17. • Protein Buffer System
Roles
• Originates from amino acids .
• ALBUMIN- primary protein due to high
concentration in plasma .
• Buffer both hydrogen ions and carbon
dioxide .

18. • Hemoglobin Buffer System
Roles
• Binds CO2 .
• Binds and transports hydrogen and
oxygen .
• Participates in the chloride shift .
• Maintains blood pH as hemoglobin
changes from oxyhemoglobin to
deoxyhemoglobin .

19.  Bicarbonate/carbonic acid buffer
system
 Function almost instantaneously
 Cells that are utilizing O2, produce CO2,
which builds up. Thus, more CO2 is found in
the tissue cells than in nearby blood cells.
This results in a pressure (pCO2).
 Diffusion occurs, the CO2 leaves the tissue
through the interstitial fluid into the capillary
blood .

20. CO2 transport in the blood

21. Regenerate of bicarbonate by the kidny

22. Excretion of H ion by the kidny
1-Ammonium buffer

23. 2- Phosphate buffer

24. •Acid – Base disorder
•1-Metabolic acidosis
•2- Metabolic alkalosis
•3-Respiratory acidosis
•4-Respiratory alkalosis

25. • metabolic acidosis is a condition that occurs
when the body produces too much acid or
when the kidneys are not removing enough
acid from the body. If unchecked, metabolic
acidosis leads to acidemia, i.e., blood pH is
low (less than 7.35) due to increased
production of hydrogen by the body or the
inability of the body to form bicarbonate
(HCO3-) in the kidney. Its causes are diverse,
and its consequences can be serious,
including coma and death.

26. • Causes :
• A – Increase H+ production :
• 1 - Diabetic ketoacidosis .
• 2 - Alcoholic ketoacidosis .
• 3 - Starvation ketoacidosis .
• B – Decreased H+ excretion :
• 1 - Renal Failure .
• 2 - Renal tubular acidosis .
• 3 - Carbonic anhydrase inhibitors .
• C – Lose of HCO3_ ( GIT Causes ) :
• 1- Severe diarrhea .
• 2- Small bowel fistula .

27. • Biochemical features
• PCO2 H+ HCO3¯
• Befor compensation N ↑ ↓
• After compensation ↓ ↑ 𝑜𝑟 ↓
• ℎ𝑖𝑔ℎ 𝑛𝑜𝑟𝑚𝑎𝑙
• Compensation is done by the lungs by
Increased ventilation .

28. • Metabolic alkalosis is a metabolic
condition in which the pH of tissue is
elevated beyond the normal range (
7.35-7.45 ).
• This is the result of decreased
hydrogen ion concentration, leading
to increased bicarbonate, or as a
direct result of increased bicarbonate
concentrations.

29. • Bicarbonate excess
• Causes:
• Excess vomiting = loss of stomach acid .
• Excessive use of alkaline drugs .
• Certain diuretics .
• Endocrine disorders .
• Heavy ingestion of antacids .
• Severe dehydration .

30. • Biochemical features
• PCO2 H+ HCO3¯
• Befor compensation N ↓ ↑
• After compensation ↑ ↑ 𝑜𝑟 ↑
• low 𝑛𝑜𝑟𝑚𝑎𝑙
• Compensation is done by the lungs by
decreased ventilation .

31. • Respiratory alkalosis
• is a condition marked by low levels of
carbon dioxide in the blood due to
lung disease that leads to shortness
of breath can also cause respiratory
alkalosis(breathing excessively ).

32. • Causes
• Primary cause is hyperventilation .
• Oxygen deficiency at high altitudes .
• Pulmonary disease and Congestive heart failure –
caused by hypoxia .
• Acute anxiety .
• Fever, anemia .
• Cirrhosis .
• Gram-negative sepsis .

33. • Biochemical features
• PCO2 H+ HCO3¯
• Befor compensation ↓ ↓ ↓N
• or slightly lower
• After compensation ↓ ↑𝑜𝑟 ↓
• low 𝑛𝑜𝑟𝑚𝑎𝑙
• Compensation is done by Kidneys which conserve
hydrogen ion and excrete bicarbonate ion .

34. Respiratory acidosis is a medical condition
in which decreased ventilation
(hypoventilation) causes increased blood
carbon dioxide concentration and
decreased pH .

35. • Causes :
• Chronic conditions:
• Depression of respiratory center in brain
that controls breathing rate – drugs or
head trauma .
• Paralysis of respiratory or chest muscles .
• Emphysema .
• Pulmonary edema .
• Pneumothorax .

36. Biochemical features
• PCO2 H+ HCO3¯
• Befor compensation ↑ ↑ ↑N
• or slightly higher
• After compensation ↑ ↑𝑜𝑟 ↑
• high 𝑛𝑜𝑟𝑚𝑎𝑙
• Compensation is done by Kidneys which eliminate
hydrogen ion and retain bicarbonate ion .

37. • Normal value
• HCO3¯ 24 -28 mmol / l
• H+ 35 – 46 nmol/l
• PCO2 35 – 45 mmHg
• PH ( Blood ) ---- 7.36 – 7.44