Respiratory Acidosis and Hypercapnia

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Questions and Answers

What is the normal pH of the body?

7.4 (correct)

7.9

7.1

7.7

What is the ratio that needs to be kept constant to maintain a pH of 7.4?

[H+] / pCO2

pCO2 / [HCO3]

[H+] x pCO2

[HCO3] / pCO2 (correct)

What is the Pka of the bicarbonate buffer system?

6.1 (correct)

6.3

6.2

6.0

What is the respiratory component of the equation?

pCO2 Signup and view all the answers

What is the metabolic component of the equation?

[HCO3] Signup and view all the answers

What is the reference range for pCO2?

4.5 – 6 kPa Signup and view all the answers

What is the reference range for [HCO3]?

20 – 30 mmol/l Signup and view all the answers

What is the equivalent hydrogen ion concentration of a pH of 7.4?

40 nmol l^-1 Signup and view all the answers

What is the main function of the buffering mechanism in the body?

To mop up excess hydrogen ions Signup and view all the answers

Which buffer system is responsible for approximately three-quarters of the body's buffering capacity?

The bicarbonate system Signup and view all the answers

What is the enzyme that catalyzes the reaction between hydrogen ions and bicarbonate ions?

Carbon anhydrase Signup and view all the answers

What is the result of uncontrolled generation of hydrogen ions in the body?

High blood levels of dissolved carbon dioxide and low levels of bicarbonate ions Signup and view all the answers

Which organs are responsible for controlling the pH of the body?

The kidneys and lungs Signup and view all the answers

What is the role of the kidneys in acid-base metabolism?

To remove hydrogen ions from the body Signup and view all the answers

What is the result of the interaction between the respiratory and metabolic components of acid-base balance?

Stable blood pH levels Signup and view all the answers

What can affect the acid-base balance, leading to an abnormal pH?

Diseases affecting the lungs or kidneys Signup and view all the answers

What is the term for the mechanism that restores pH within the reference range?

Respiratory compensation Signup and view all the answers

What is the outcome of excessive loss of bicarbonate ions?

Altered ratio of pCO2 and bicarbonate, leading to lower pH Signup and view all the answers

What is the consequence of high levels of hydrogen ions (low pH)?

Cardiac muscle contraction impairment Signup and view all the answers

What is the result of kidney diseases in acid-base balance?

Decreased excretion of acid Signup and view all the answers

What is the term for disorders of acid-base balance?

Acid-base balance disorders Signup and view all the answers

What is the outcome of respiratory compensation in metabolic acidosis?

Lower pCO2 levels Signup and view all the answers

In which condition is there an excess production of organic acids?

Diabetes mellitus Signup and view all the answers

What is the effect of low pH on calcium levels?

Enhanced mobilization of calcium from bones Signup and view all the answers

What is the primary cause of respiratory acidosis?

Decreased respiration rate Signup and view all the answers

What is the result of high levels of carbon dioxide in the blood?

Cerebral vasodilation Signup and view all the answers

How does the kidney compensate for respiratory acidosis?

By excreting more bicarbonate Signup and view all the answers

What is the result of metabolic alkalosis?

Increased pH of tissue Signup and view all the answers

What is the typical manifestation of moderate to severe metabolic alkalosis?

All of the above Signup and view all the answers

What is the primary organ responsible for compensating for metabolic alkalosis?

Lungs Signup and view all the answers

What is the result of alkalotic agents in the body?

Metabolic alkalosis Signup and view all the answers

What is the normal pH range of tissue?

7.35-7.45 Signup and view all the answers

What is the main reason for the increased release of glucose by the liver in diabetic ketoacidosis?

Lack of insulin leads to increased glucagon Signup and view all the answers

What is the result of the high glucose levels in the blood in diabetic ketoacidosis?

Osmotic diuresis, leading to polyuria and dehydration Signup and view all the answers

What is the energy source that can be used in the absence of insulin-mediated glucose delivery?

Ketone bodies Signup and view all the answers

What is the mechanism that initially buffers the acidosis caused by the ketone bodies?

Bicarbonate buffering system Signup and view all the answers

What is the result of the release of free fatty acids from adipose tissue in diabetic ketoacidosis?

Conversion into ketone bodies in the liver Signup and view all the answers

What is the term for the increased urine production and thirst in diabetic ketoacidosis?

Polyuria and polydipsia Signup and view all the answers

Why do ketone bodies have a low pH?

Because they have a low pKa Signup and view all the answers

What is the mechanism that helps to compensate for the acidosis caused by the ketone bodies?

Hyperventilation to decrease blood carbon dioxide levels Signup and view all the answers

Study Notes

pH Control and Buffering Mechanisms

The body has sophisticated buffering mechanisms to maintain a stable pH, with three main buffer systems: bicarbonate, proteins (mainly hemoglobin), and phosphate systems.
These buffer systems mop up excess hydrogen ions produced by cells.

Bicarbonate Buffering System

The bicarbonate buffering system is the most important, making up approximately three-quarters of the body's buffering capacity.
Hydrogen ions combine with bicarbonate ions to form carbonic acid, which dissociates to water and carbon dioxide.
The reaction is driven to the right, meaning that hydrogen ions produced in cells and buffered by the bicarbonate system generate carbon dioxide and reduce available bicarbonate.

Control of pH

Two organs control the pH of the body: the lungs and the kidneys.
The lungs excrete carbon dioxide, and the kidneys remove hydrogen ions from non-volatile and organic acids into the urine.
The blood transports acidic waste products from the site of production in the tissues to the site of excretion, namely the kidneys and lungs.

Acid-Base Balance

The normal pH of the body is 7.4, which is maintained by the balance between the respiratory and metabolic components of acid-base metabolism.
The respiratory component is controlled by the lungs, and the metabolic component is controlled by the kidneys.
The lungs and kidneys interact and balance to control the pH of the body.

Disorders of Acid-Base Balance

Disorders of acid-base balance can be divided into acidosis (low pH) and alkalosis (high pH), each having a metabolic and respiratory origin.
Metabolic acidosis is characterized by a low bicarbonate concentration and can be caused by increased acid production, decreased acid excretion, or excessive loss of bicarbonate ions.
Respiratory acidosis is characterized by a high pCO2 and can be caused by decreased respiration rate or lung disease.
Metabolic alkalosis is characterized by a high bicarbonate concentration and can be caused by loss of hydrogen ions or administration of alkalotic agents.

Compensation Mechanisms

Compensation for metabolic acidosis occurs through the respiratory pathway, where the lungs remove more carbon dioxide through hyperventilation.
Compensation for respiratory acidosis occurs through the kidney, where more acid is excreted and more bicarbonate is generated.
Compensation for metabolic alkalosis occurs mainly in the lungs, which retain carbon dioxide through slower breathing or hypoventilation.

Diabetic Ketoacidosis (DKA)

DKA is a potentially life-threatening complication of diabetes mellitus, characterized by a lack of insulin and corresponding elevation of glucagon.
It leads to increased release of glucose by the liver, high glucose levels in the urine, and dehydration.
The absence of insulin also leads to the release of free fatty acids from adipose tissue, which are converted into ketone bodies, causing metabolic acidosis.
The body initially buffers the change with the bicarbonate buffering system, but this system is quickly overwhelmed, and other mechanisms must work to compensate for the acidosis.

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Description

This quiz covers the causes and effects of respiratory acidosis, including decreased respiration rate and lung disease, and how it relates to high levels of carbon dioxide in the blood. Learn about the symptoms and consequences of hypercapnia.