69. Physiology - Acid Base II Compensation

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Questions and Answers

What is the most closely regulated pH range in the human body?

7.35 - 7.45

7.40 - 7.50

7.30 - 7.35

7.38 - 7.42 (correct)

Which of the following statements is true regarding normal arterial pCO2 levels at sea level?

Normal pCO2 levels remain unaffected by altitude.

Normal pCO2 is strictly 35 mmHg.

Normal pCO2 ranges from 30 to 35 mmHg.

Normal pCO2 is between 35 and 45 mmHg. (correct)

What is the definition of acidemia?

A condition resulting in a decrease of arterial pCO2.

A condition where pH is less than 7.35. (correct)

A situation with increased bicarbonate concentration.

A condition where pH is greater than 7.45.

Which organs are primarily involved in maintaining acid-base balance in the body?

Lungs and kidneys Signup and view all the answers

Which of the following is a common consequence of decreased excretion processes in acid-base balance?

Hypercapnia Signup and view all the answers

What distinguishes simple acid-base disorders from combined disorders?

Presence of a single primary disorder. Signup and view all the answers

Which of the following represents metabolic acidosis?

Decreased bicarbonate concentration. Signup and view all the answers

What indicates a primary disorder when pH is down and both pCO2 and [HCO3-] are down?

The primary disorder is metabolic acidosis. Signup and view all the answers

Which arrows represent compensation in acid-base physiology?

Dotted arrows Signup and view all the answers

In respiratory acidosis, what is the primary problem related to acid-base balance?

Excess of carbonic acid. Signup and view all the answers

What is the normal range for [HCO3-] in acid-base values?

24 mEq/L Signup and view all the answers

Which condition occurs when the body attempts to counteract acidosis?

Increased pH levels. Signup and view all the answers

Which of the following is NOT a characteristic of simple acid-base disorders?

They have multiple primary processes. Signup and view all the answers

Which biochemical response occurs rapidly in respiratory acidosis due to elevated pCO2?

Increase in [HCO3-] for buffering. Signup and view all the answers

What does a solid arrow signify in the context of acid-base disorders?

It represents the primary disorder. Signup and view all the answers

Which factors are important for understanding HCO3- reabsorption from the kidneys?

Hormonal regulation and blood flow to kidneys. Signup and view all the answers

What occurs in the kidney when metabolic acidosis is developing?

Increased secretion of H+ as NH4+ Signup and view all the answers

What characterizes the respiratory compensation in response to a metabolic acidosis?

It leads to a rapid decrease in pCO2. Signup and view all the answers

During the recovery phase after metabolic acidosis, what happens to the acid in the body?

It is excreted by the kidneys over a prolonged period. Signup and view all the answers

What characterizes the condition known as compensated hypercapnia?

pCO2 rises initially, then stabilizes as HCO3- increases Signup and view all the answers

What is the effect of a lower pCO2 on respiratory compensation during metabolic acidosis?

It inhibits the respiratory center's activity. Signup and view all the answers

Which of the following statements about renal compensation for chronic hypercapnia is true?

There is an upper limit to HCO3- reabsorption rates in the kidneys. Signup and view all the answers

Which of the following best explains the loss of buffering capacity during metabolic acidosis?

Approximately half of the strong acid is taken up by muscles and cells. Signup and view all the answers

What is incorrect regarding the definitions of compensated respiratory acidosis?

It implies two distinct primary diseases affecting respiratory function. Signup and view all the answers

Which of the following is NOT a characteristic of compensated hypercapnia?

The pCO2 can exceed 70 mmHg without consequences. Signup and view all the answers

In the context of respiratory alkalosis, what is primarily affected?

A decrease in pCO2 leading to lowered HCO3- levels. Signup and view all the answers

What does the reaction $CO_2 + H_2O ightleftharpoons H_2CO_3$ primarily illustrate?

The mass action effect following changes in carbon dioxide levels. Signup and view all the answers

What physiological change is immediate in response to decreased pCO2 in respiratory alkalosis?

Rapid decreases in bicarbonate concentration. Signup and view all the answers

Which area of assessment would suggest improper compensation in chronic hypercapnia?

Stable pH levels exceeding the alkalemic range. Signup and view all the answers

What defines hypocapnia in the context of acid-base balance?

A decrease in pCO2 leading to abnormal acid-base ratios. Signup and view all the answers

What role does lactic acid play in the body's response to decreased pCO2?

It generates more CO2 and helps normalize pH. Signup and view all the answers

What physiological change occurs in the kidneys as a compensation mechanism during respiratory alkalosis?

Decreased HCO3- reabsorption and reduced NH4+ secretion. Signup and view all the answers

In a patient with chronic hypocapnia, what is expected to happen to pH levels over time?

pH will approach normal but not overshoot. Signup and view all the answers

Which condition is associated with excessive removal of CO2 from the lungs?

Respiratory alkalosis. Signup and view all the answers

What is the primary problem in metabolic acidosis?

Accrual of non-carbonic acids. Signup and view all the answers

What initial change occurs in arterial blood values during a state of acute hypocapnia?

Decrease in pCO2. Signup and view all the answers

How does increased ventilation due to aspirin intoxication initially affect blood gas levels?

It causes respiratory alkalosis. Signup and view all the answers

During the compensation for chronic hypocapnia, what happens to HCO3- levels?

They decrease over time. Signup and view all the answers

What type of acids primarily contribute to metabolic acidosis?

Non-carbonic acids. Signup and view all the answers

What is a common characteristic of conditions causing respiratory alkalosis?

Increased ventilatory rate. Signup and view all the answers

Study Notes

Acid-Base Imbalance

Acid-base disturbances are classified by pH
- Acidemia: pH < 7.40
- Alkalemia: pH > 7.40
Then sub-classified by carbonic acid or non-carbonic
- Respiratory imbalances: changes in pCO2
  - Respiratory acidosis: pCO2 excess
  - Respiratory alkalosis: pCO2 deficit
- Metabolic imbalances: changes in non-carbonic acid
  - Metabolic acidosis: base deficit
  - Metabolic alkalosis: base excess

Learning Objectives

Identify and classify acidemia vs alkalemia
Identify and classify respiratory vs metabolic imbalances
Define compensation for acid-base disorders
Learn the role of the lungs and kidneys in acid-base compensation
Develop proficiency in using the acid-base map to identify/categorize acid-base disorders
Know buffering systems involved in response to disturbance
Estimate expected compensatory response for acid-base disorders
Identify paradigm diseases associated with primary acid-base disorders

Acid-Base Definitions

Normal pH range: 7.35 - 7.45 (at sea level, 37°C)
Normal pCO2 range: 35 - 45 mmHg
Normal HCO3- range: 22 - 26 mEq/L

Acid-Base Regulation

Daily acid formation: 13,000 mmol/day CO2 + 70-100 mmol/day non-volatile acid
Lung excretion: 13,000 mmol/day CO2
Kidney excretion: 70-100 mmol/day H+ (5,000 total mmol H+)

Steps in Evaluating Acid-Base Problems

Obtain arterial blood sample
Measure pH, pCO2 and HCO3-
Plot values on Davenport diagram
Make a diagnosis based on the diagram's location.

Simple Acid-Base Disorders

Acidosis: pH decreases, pCO2 and/or HCO3- decrease
Alkalosis: pH increases, pCO2 and/or HCO3- increase
Primary disorder: solid arrows in diagram
Compensation: dotted arrows in diagram

Factors Affecting HCO3 Reabsorption

Carbonic anhydrase activity
Partial pressure CO2 (pCO2)
Amount filtered HCO3-
Amounts of filtered/secreted buffers (distal): NH3 and HPO42-

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Description

Test your knowledge on acid-base disturbances classified by pH. This quiz covers various imbalances including respiratory and metabolic disorders, as well as compensation mechanisms in the body. Learn to identify and classify these disorders effectively using the acid-base map.