Buffer-It is a solution of weak acid/base & it’s corresponding salt which resists a change in pH when a small amount of acid or base is added to it. By buffering mechanism, a strong acid (or base) is replaced by a weaker one. pH, quantitative measure of the acidity or basicity of aqueous or other liquid solutions Blood buffer- 1. A chemical buffer is a system of one or two molecules that acts to resist changes in pH by binding H+ when the pH drops, or releasing H* when the pH rises. 2. The bicarbonate buffer system is the main buffer of the extracellular fluid, and consists of carbonic acid and its salt, sodium bicarbonate. H2CO3+NaHCO3 a. When a strong acid is added to the solution, carbonic acid is mostly unchanged, but bicarbonate ions of the salt bind excess H+, forming more carbonic acid. b. When a strong base is added to solution, the sodium bicarbonate remains relatively unaffected, but carbonic acid dissociates further, donating more H+ to bind the excess hydroxide. c. Bicarbonate concentration of the extracellular fluid is closely regulated by the kidneys, and plasma bicarbonate concentrations are controlled by the respiratory system. 3. The phosphate buffer system operates in the urine and intracellular fluid similar to the bicarbonate buffer system: sodium dihydrogen phosphate (NaH,PO) is its weak acid, and monohydrogen phosphate (Na,HPO,) is its weak base. 4. The protein buffer system consists of organic acids containing carboxyl groups that dissociate to release H+ when the pH begins to rise, or bind excess H+ when the pH declines. Respiratory regulation of PH-The lungs have the ability to exhale CO, which is the substrate for H2CO3 and HCO3. Thus, by regulating the rate of pulmonary ventilation through chemoreceptors, PCO, is regulated by lungs. So, a high PCO, leads to decrease in pH and low PCO, increase in pH. High PCO, stimulates ventilation which results in removal of CO₂ by expiration. Renal Mechanisms of Acid-Base Balance- 1. Only the kidneys can rid the body of acids generated by cellular metabolism, while also regulating blood levels of alkaline substances and renewing chemical buffer components. a. Bicarbonate ions can be conserved from filtrate when depleted, and their reabsorption is dependent on H+ secretion Conservation of Bicarbonate lons b. Type A intercalated cells of the renal tubules can synthesize new bicarbonate ions while excreting more hydrogen ions. Synthesis of New Bicarbonate/Excretion of BufferedH* c. Ammonums are weak acids that are excreted and urine, replenishing the alkaline reserve of the blood. NH4+, Excretion d. When the body is in alkalosis, type B intercalated cells excrete bicarbonate, and reclaim hydrogen ions. Acid base disorder-1. When arterial blood pH rises above 7.45, the body is in alkalosis; when arterial pH falls below 7.35, the body is in acidosis. 2. Most hydrogen ions originate as metabolic by-products, although they can also enter the body via ingested foods. Metabolic acidosis:

4.  It is a solution of weak acid/base & it’s
corresponding salt which resists a change in
pH when a small amount of acid or base is
added to it.
 By buffering mechanism, a strong acid (or
base) is replaced by a weaker one.

5.  pH, quantitative measure of the acidity or
basicity of aqueous or other liquid solutions

7.  1. A chemical buffer is a system of one or two molecules
that acts to resist changes in pH by binding H+ when the pH
drops, or releasing H* when the pH rises.
 2. The bicarbonate buffer system is the main buffer of the
extracellular fluid, and consists of carbonic acid and its salt,
sodium bicarbonate.
 H2CO3+NaHCO3
 a. When a strong acid is added to the solution, carbonic
acid is mostly unchanged, but bicarbonate ions of the
salt bind excess H+, forming more carbonic acid.
 b. When a strong base is added to solution, the sodium
bicarbonate remains relatively unaffected, but carbonic
acid dissociates further, donating more H+ to bind the
excess hydroxide.

8.  c. Bicarbonate concentration of the extracellular fluid
is closely regulated by the kidneys, and plasma
bicarbonate concentrations are controlled by the
respiratory system.
 3. The phosphate buffer system operates in the urine
and intracellular fluid similar to the bicarbonate buffer
system: sodium dihydrogen phosphate (NaH,PO) is its
weak acid, and monohydrogen phosphate (Na,HPO,)
is its weak base.
 4. The protein buffer system consists of organic acids
containing carboxyl groups that dissociate to release
H+ when the pH begins to rise, or bind excess H+
when the pH declines.

9.  The lungs have the ability to exhaleCO,
which is the substrate for H2CO3 and HCO3.
 Thus, by regulating the rate of pulmonary
ventilation through chemoreceptors, PCO, is
regulated by lungs.
 So, a high PCO, leads to decrease in pH and
low PCO, increase in pH.
 High PCO, stimulates ventilation which
results in removal of CO₂ by expiration.

11. 1. Only the kidneys can rid the body of acids
generated by cellular metabolism, while also
regulating blood levels of alkaline substances
and renewing chemical buffer components.
a. Bicarbonate ions can be conserved from
filtrate when depleted, and their reabsorption
is dependent on H+ secretion
Conservation of Bicarbonate lons

12. b. Type A intercalated cells of the renal tubules can
synthesize new bicarbonate ions while excreting
more hydrogen ions.
Synthesis of New Bicarbonate/Excretion of
BufferedH*
c. Ammonums are weak acids that are excreted
and urine, replenishing the alkaline reserve of
the blood.
NH4+, Excretion
d. When the body is in alkalosis, type B
intercalated cells excrete bicarbonate, and
reclaim hydrogen ions.

13. A. 1. When arterial blood pH rises above 7.45, the body is
in alkalosis; when arterial pH falls below 7.35, the
body is in acidosis.
B. 2. Most hydrogen ions originate as metabolic by-
products, although they can also enter the body via
ingested foods.
1. Metabolic acidosis: Decrease in bicarbonate (HCO3)
concentration.
2. Respiratory acidosis: Increase in H,CO, concentration.
3. Metabolic alkalosis: Increase in bicarbonate
(HCO,)concentration.
4. Respiratory alkalosis: Decrease in H,CO,
concentration.

15.  Severe diarrhea: bicarbonate-rich intestinal (and pancreatic)
secretions rushed through digestive tract before their solutes can
be reabsorbed; bicarbonate ions are replaced by renal
mechanisms that generate new bicarbonate ions
 Renal disease: failure of kidneys to rib body of acids formed by
normal metabolicprocesses
 Untreated diabetes mellitus: lack of insulin or inability of tissue
cells to respond to insulin, resulting in inability to use glucose; fats
are used as primary energy fuel, andketoacidosis occours
 Starvation: lack of dietary nutrients for cellular fuels; body
proteins and fat reserves are used for energy - both yield acidic
metabolites as they are broken down for energy
 Excess alcohol ingestion: results in excess acids in bloodHigh ECF
potassium concentrations: potassium ions compete with H for
secretion inrenal tubules; when ECF levels of K are high, H
secretion is inhibited

16.  Vomiting or gastric suctioning: loss of stomach HCO
requires that H be withdrawn from blood to replace
stomach acid; thus H decreases and HCO, increases
proportionately
 Selected diuretics: cause K depletion and H2O loss.
Low K directly stimulates the tubule cells to secrete H.
 Ingestion of excessive sodium bicarbonate
(antacid): bicarbonate moves easily into ECF, where it
enhances natural alkline reserve
 Excess aldosterone (e.g., adrenal tumors): promotes
excessive reabsorpation of Na+, which pulls increased
amount of H into urine. Hypovolemia promotes the
same relative effect because aldosterone secretion is
increased to enhance Nat (and H₂O) rebsorption.

17.  Impaired lung function (e.g., in chronic
bronchitis, cystic fibrosis, emphysema):
impaired gas exchange or alveolar PCO,
ventilation
 Impaired ventilatory movement: paralysis of
respiratory muscles, chest injury, extreme
obesity
 Narcotic or barbiturate overdose or injury to
brain stem: depression of respiratory centers,
resulting in hypoventilation and respiratory
arrest

18.  Strong emotions: pain, anxiety, fear, panic
attack
 Hypoxia: asthma, pneumonia, high altitude;
represents effort to raise PO, at the exof
excessiveCO, excretion
 Brain tumor or injury: abnormality of
respiratory controls