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Flashcards in 26 1-5 Deck (26):

List important sources of acids in the body.

Biggest source: CO2. Amino acids, fatty acids, lactic acids, acids of citric cycle, ketoacids


Four ways acids originate?

1. Breakdown of phosphorus containing proteins releasing phosphoric acid into ECF

2. Anaerobic respiration - lactic acid

3. Fat metabolism - Ketone bodies

4. Loading and transport of CO2 in the bloos HCO3- liberates H ions


List the three major chemical buffer systems

Bicarbonate buffer system, Phosphate buffer system, Protein buffer system


A chemical buffer is?

A system of one or more compounds that resist changes in pH when a strong acid or base is added.

This is done by binding to H+ when pH drops and releasing H+ when pH rises.


How does the bicarbonate buffer system resist pH changes. In what compartment?

Main and most important buffer of ECF (blood and interstitial fluid.)

Mixture of H2CO3 (carb acid) and NaHCO3 (sodium bicarbonate, a weak base).

When a strong acid is added, carbonic acid is mostly unchanged, but bicarbonate ions of the salt bind to excess H+ forming more carbonic acid.

When a strong base is added, the sodium bicarbonate remains relatively unaffected, but the carbonic acid dissociates donating more H+ to bind to excess hydroxide.


Stong acid added to bicarbonate buffer sys.

HCl + NaHCO3 -- H2CO3 + NaCl

(Strong acid + weak base = weak acid + salt)


Strong base added to bicarbonate buffer sys.

NaOh + H2CO3 -- NaHCO3 + H2O

(strong base + weak acid = Weak base + water)


What regulates the bicarbonate concentrations?

ECF - kidneys, Plasma - respiratory system


How does the Phosphate buffer system resist pH changes. In what compartment?

Urine and ICF.

Sodium dihydrogen is the weak acid, Monohydrogen is the weak base (operates like bicarb sys.)


How does the Protein buffer system resist pH changes. In what compartment?

Proteins in plasma and in cells.

Organic acids containing carboxyl groups can dissociate to release H+ or H+ can bind to an amino group if excess H+.

75% of buffering power of the body resides in cells/intracellular proteins.


Acids are _____________? Bases are ___________?

Proton donors, proton acceptors.

Acids dissociate from their H+. Bases tie up H+.


Lines of defense to maintain Acid-Base balance?

1. Chemical buffers (act in seconds)

2. Respiratory system (act in mins, 75% of capacity of acid/base balance)

3. Kidney (act in hours)

Buffers can tie up acids-bases temporarily, lungs can dispose of the volatile acid, carbonic acid, by eliminating CO2, only the kidney can rid the body of other acids: phosphoric/uric/lactic/ketone.

Kidneys can also renew chem buffers used in reg H+ in ECF.


Describe the influence of the respiratory system on acid-base balance.

CO2 + H2O = H2CO3 = H+ + HCO3-.

If Pco2 rises, medullary chemoreceptors ↑ resp rate/depth.

In addition, any rise in plasma H+ excites resp ctr via peripheral chemoreceptors to ↑ resp rate/depth. (reactions to the left in the lungs, h+ turned into h2o)

When blood pH rises, the respiratory center is depressed aloowing accumulation of CO2 in the blood (pushes to the right).


Describe how the kidneys regulate hydrogen and bicarbonate ion concentrations in the blood.

Kidneys can directly excrete or reabsorb H+.

Kidneys can indirectly alter pH by changing the reabsorption or excretions of HCO3- (bicarbonate ions can be conserved from filtrate when depleted and their reabsorption is dependent on H+ secretion)


Most important renal mechanism for regulating balance

Conserving (reabsorbing) or generating HCO3- and excreting HCO3-.

Intercalated A cells of renal tubules can synthesize new bicarbonate.

When the body is in alkalosis, intercalated B cells excrete bicarbonate and reclaim H+.

Ammonium ions/weak acid can also be excreted replenishing the alkaline reserve.


Respiratory acidosis

↓ pH/↑Pco2 - results from shallow breathing or respiratory diseases.


Respiratory alkalosis

CO2 is eliminated from the body faster than it is produced


Metabolic acidosis

↓ blood pH and ↓ bicarbonate levels from loss of bicarbonate ions or too much alcohol


Metabolic alkalosis

↑ blood pH and ↑ bicarbonate levels from vomiting or excessive base intake


Respiratory acidosis causes

impaired lung function,
impaired ventilatory movement,
narcotic or barbituate overdose,
injury to brainstem


Respiratory alkalosis causes

(least common)

strong emotions,
hypoxia (high altitude/asthma/pneumonia),
brain tumor or injury


Metabolic acidosis causes

renal disease,
untreated diabetes,
excess alcohol,
high ECF potassium


Metabolic alkalosis causes

Vomiting/gastric suctioning,
excessive antacid intake,
excess aldosterone


Normal range for pH

acid 7.35-7.45 alkaline


Normal range for Pco2

alkaline 35-45 acid mmHg


Normal range for HCO3-

acid 22-26 alkaline