The document discusses acid-base balance in the arterial plasma and disorders that can disrupt this balance. It maintains that blood pH is important to regulate at 7.4 for metabolic processes. Respiratory and renal systems work to balance pH levels through carbonic acid buffering. Respiratory acidosis and alkalosis involve the lungs not eliminating carbon dioxide properly, while metabolic versions stem from other causes like lactic acid production. The lungs and kidneys each compensate differently, with the kidneys slowly adjusting bicarbonate and the lungs rapidly modulating carbon dioxide levels. Case studies are used to analyze how the body responds to initial pH changes through compensated steady states of related values over time.

1. Lab 11: Acid - Base Balance of the Arterial
Plasma

2. Lab 11 - Carbonic Acid Buffering System
Important to maintain blood pH at intermediate set point (pH = 7.4)
- For metabolic processes and systems to work well
- Lot of the proteins are pH-dependent
: Homeostatic mechanism in which the lungs and/or
kidneys will maintain arterial blood pH approximately at 7.4.

3. Lab 11 - Causes of Blood pH Imbalance
(in arterial plasma)
Blood pH is mainly determined by the in the plasma.

4. Lab 11 - Acidosis and Alkalosis Disorders
Respiratory acidosis: a disorder where the respiratory system fails to eliminate
CO2 as fast as it is produced thus H+ concentration in the arterial plasma is
increased above normal (pH < 7.35).
Respiratory alkalosis: a disorder where the respiratory system eliminates CO2
faster than it is produced thus H+ concentration in the arterial plasma is
decreased below normal (pH > 7.45).
Metabolic acidosis: a disorder where there is an increase of arterial H+
concentration due to some cause other than a primary change in PCO2 (pH <
7.35).
Metabolic alkalosis: a disorder where there is a decrease of arterial H+
concentration due to some cause other than a primary change in PCO2 (pH >
7.45).

5. Lab 11 - Respiratory Acid-Base Disorders –
Cause and Compensatory Mechanism
Cause: Respiratory system (PCO2)
•
• Increase CO2 production to alveolar
ventilation (Net gain of plasma CO2)
•
• Decrease CO2 production to alveolar
ventilation (Net loss of plasma CO2)
Compensatory: Kidneys slowly adjust HCO3
-
• via secretion of H+
(No net gain of plasma HCO3
-)
• (Net gain of plasma HCO3
-)
• Binding to filtered nonbicarbonate
buffer via secretion of excess H+
• Glutamate breakdown and secretion of
NH4
+
• (Net loss of plasma HCO3
-)
• Insufficient secretion of H+
Respiratory Acidosis
Respiratory Alkalosis

6. Lab 11 - Metabolic Acid-Base Disorders – Cause
and Compensatory Mechanism
• Respiratory rate
• Tidal volume
Influence net gain or loss of plasma CO2
Cause: Any situation other than the
respiratory system
• Excessive production of lactic acid
• Excessive diarrhea
• Persistent vomiting
Compensatory:
Secondary: Kidneys
slowly adjust HCO3
-
Primary: Lungs quickly
adjust PCO2
• “Reabsorption” of
filtered HCO3
-
• New HCO3
-
•
Metabolic acidosis
Metabolic alkalosis
• • Excretion of
HCO3
-

7. Lab 11 – Goals (aka Learning Outcomes)
• Explain the homeostatic regulation of arterial pH using the
carbonic acid buffering system.
• Examine respiratory and metabolic acidosis and alkalosis
under various conditions.
o Predict and justify the cause of the acid-base disorder.
o Predict and justify the compensatory system and
mechanisms to correct pH imbalances.

8. Lab 11 – Experimental Setup for Part 1
Animal model: None, but there is an
inanimate model
Experimental Setup: PhysioEx simulation
Renal Responses to Respiratory Acidosis and Alkalosis

9. Lab 11 – Experimental Setup for Part 2
Metabolic Acidosis and Alkalosis
Animal model: Unknown
Experimental Setup: Case study
Initial pH
change
Values before compensation Compensated state (steady state)
pH
Arterial
PCO2
(mmHg)
Alveolar
ventilation
(ml/min)
Arterial
HCO3
-
(mMol/L)
pH
(log
molar)
Arterial
CO2
(mmHg)
Alveolar
ventilation
(breaths/min)
Arterial
HCO3
-
(mMol/L)
How these variables change 5
minutes after compensation
relative to before compensation