Acid Base Imbalance Flashcards
(25 cards)
How does the body maintain Acid/Base Homeostasis
- BUFFERS
- RESPIRATORY SYSTEM
- RENAL SYSTEM
Buffers in the body
Chemicals in the body that combine with acid or base to change the pH
- Accept or release a H+
- Almost instantaneous
- Short-lived
3 Main Buffer Systems in the body
- Bicarbonate – Carbonic Acid Buffer
- Phosphate Buffer
- Protein Buffers - Hemoglobin
What is Bicarbonate – Carbonic Acid ?
- *ECF location
- Main ECF buffer
- CO2 byproduct of cellular metabolism
How does Bicarbonate – Carbonic Acid buffer?
- Combines with H2O in serum to form carbonic acid
- Carbonic anhydrase breaks down carbonic acid
- In the lungs - H2O + CO2
- In the kidneys - H+ + HCO3-
What is the Acid/Base buffer formula?
Bicarbonate – Carbonic Acid Equation
Carbonic Acid Equations
Phosphate Buffer
Main intracellular buffer
- H+ + HPO4-2 = H2PO4-
- Hydrogen + hydrogen phosphate = dihydrogen phosphate ion
Protein Buffers
Nearly all proteins can function as buffers
- Amino group (NH2-)
- Carboxyl group (COOH)
- Hemoglobin
Carboxyl Group Buffer
- Carboxyl group (COOH) is a weak acid that gives up H+
- Amino acid
- Acetic acid
Amino Group Buffer
Amino group (NH2-) accept H+
- Amino acids have both a carboxyl group and an amino group
- Ammonia NH3
Hemoglobin Group Buffer
•’picks’ up CO2 at the cellular level
Cellular Compensation
- H+ - positively charged ions
- K+ - positively charged ion, mostly found inside the cell
- Increase in [H+] (concentration)
- pH decreases – more acidic
- H+ move into the cell
- More positively charged ions in the cell
- K+ moves out of the cell
- Electrical neutrality is restored inside the cell
Is Cellular Compensation Permanent?
- A temporary correction of the pH
- Process will reverse as the pH returns to normal
- HOWEVER, if the kidneys are working, they will excrete the excess K+
- Body can have a depletion of K+
Respiratory Mechanisms for Compensation of Acid/Base imbalance
- Body produces CO2
- CO2 and H2O creates carbonic acid
- H2CO3 = H2O + CO2
- Exhalation excretes carbonic acid
- Doesn’t affect fixed acids (non-volatile) like lactic acid
- Body pH can be adjusted by changing rate and depth of breathing
Kidney Mechanisms for Compensation of Acid/Base balance
- Can eliminate large amounts of acid except carbonic acid
- Can also excrete base
- Can conserve and produce bicarb ions
- Most effective regulator of pH
- If kidneys fail, pH balance fails
- Depends on normal functioning of renal system
How long does it take for Buffers to compensate Acid/Base imbalance?
•Buffers (in the blood) function almost instantaneously
How long does it take respiratory mechanisms to compensate Acid/Base imbalance?
several minutes to hours
How long does it take kidneys to correct Acid/Base imbalance?
several hours to days
What is considered Acid/Base Imbalance?
- pH< 7.35 acidosis
- pH > 7.45 alkalosis
What is it called when the body corrects Acid/Base imbalance?
Compensation
- May be complete if brought back within normal limits
- Partial compensation if range is still outside norms
If the Acid/Base imbalance is Metabolic how does the body try to correct it?
Respiratory Compensation
•Lungs are the primary controller of H²CO³ ( H+/acid) supply
- Hyperventilation = CO2 blown off (increases pH)
- Hypoventilation = CO2 retained (decreases pH)
If the Acid/Base imbalance is Respiratory how does the body try to correct it?
Metabolic
- Renal mechanisms
- Kidneys control pH by adjusting the amount of HCO3 (bicarb) that is:
- Reabsorbed into the bloodstream
- Excreted in the urine
