Acid Base Study Guide

What is pH?

-degree of acidity or alkalinity

−Reflects H+ (hydrogen) ion concentration in fluid

−Cellular function is impaired if pH is abnormal

−Death likely if pH below 6.9 or above 7.8

-pH tells you the hydrogen ion content in the blood

What is normal pH?

7.35-7.45

Describe an acid. What is the relation to H⁺ (hydrogen) ions?

An acid is a substance with a large amount of H+ (hydrogen) ions. More H+ ions means more acidity and a lower pH.

Describe a base. What is the relation to H+ ions

A base is a substance with a few H+ (hydrogen) ions. Fewer H+ ions means less acidity and a higher pH.

What are the types of acid our bodies make during normal cellular metabolism?

-Carbonic acid

-Metabolic acid

Describe buffers-the FIRST line of defense. Thinking about the

Bicarbonate Buffer:

a. What is the weak base?

b. What is the weak acid?

c. What happens when there is too much or too much base

a. The weak base is HCO₃⁻ (bicarbonate).

b. The weak acid is H₂CO₃ (carbonic acid).

c. When there is too much acid, bicarbonate takes up the released H⁺ ions and becomes carbonic acid, which is excreted through the respiratory system. When there is too little acid (too much base), the bicarbonate system releases H⁺ ions.

Describe the respiratory system in normal acid base balance. This is the

SECOND line of defense.

a. What kind of acid do the lungs excrete?

b. What is the indicator of lung effectiveness?

c. What do the lungs do if the CO2 is high?

d. What do the lungs do it the CO2 is low?

The respiratory system is the second line of defense.

a. Carbonic acid
b. PaCO₂
c. The lungs increase the rate and depth of respiration to blow off CO₂.
d. The lungs decrease the rate and depth of respiration to retain CO₂.

HYPERVENTILATION

-PaCO2 above normal means carbonic acid has accumulated in the blood

-Rate and Depth of respiration will INCREASE

-BLOW OFF CO2

HYPOVENTILATION

-Not enough acid

-Rate and Depth of respiration will DECREASE

-Retain carbon acid

What does the renal system to do maintain acid base balance? This is out

THIRD line of defense.

a. What type of acids do the kidneys excrete?

b. What may the kidneys MAINTAIN to regulate acid base balance?

c. What is the indicator of renal effectiveness?

a.Metabolic acids

b. HCO₃ ^- (bicarbonate)

c.HCO₃ ^- (bicarbonate)

What happens if the lungs or kidneys become overwhelmed and can’t do their

job?

a. How do the lungs compensate for the kidneys?

b. How do the kidneys compensate for the lungs?

c. How do you know if compensation has been achieved? What value do

you examine?

a. The lungs compensate for metabolic acid imbalances by adjusting breathing.

• If there is too much metabolic acid, the lungs hyperventilate to blow off CO₂

• This helps bring the pH back toward normal.

b.The kidneys compensate for carbonic acid/respiratory imbalances by adjusting:

• H+

• HCO₃^- (bicarbonate)

• They can excrete H+ and retain HCO3- when the body needs to reduce acidity

c.Look at the pH.

• Normal pH= 7.35-7.45

• If the pH is back within the normal range, full compensation has been achieved.

Respiratory Acidosis

a. What is the cause---or what are the lungs doing to cause this problem?

b. What are some etiologies for this?

c. What are the clinical manifestations?

d. What system helps to compensate for the problem? How does it happen?

a. What is the cause?

Hypoventilation is the cause.

The lungs are not excreting carbonic acid properly, so carbonic acid builds up.

The slide says:

• Excess carbonic acid

• High PaCO₂ (partial pressure of carbon dioxide in arterial blood), called hypercapnia(high carbon dioxide in the blood)

• Respiratory excretion of carbonic acid is impaired

b. What are some etiologies?

Pulmonary:

• COPD

• Pulmonary edema

• Pneumonia

• Airway obstruction

• Laryngospasm

• Bronchospasm

• Aspiration

• Underventilation by mechanical ventilation

• Hypoventilation

• Obesity

• Postoperative pain

• Abdominal distention

• Use of abdominal binders

Nonpulmonary:

• Overdosage of anesthetics, sedatives, and narcotics

• Neuromuscular disorders:

  • Guillain-Barré

  • Myasthenia gravis

  • Advanced MS

• Severe spinal deformities

• CNS depression

• Cardiopulmonary arrest

c. What are the clinical manifestations?

• Hypercapnia

• Anxiety

• Restlessness

• Headache

• Lethargy

• Fatigue

• Shortness of breath

• Tachypnea

• Cough

• Dysrhythmias (hyperkalemia)

Advanced:

• Confusion

• Somnolence

• Coma

d. What system compensates, and how?

The renal system (kidneys) compensates.

It does this by:

• Increasing renal excretion of H⁺ (hydrogen ions)

• Retaining HCO₃⁻ (bicarbonate)

🧠 Super-short version to remember:

Respiratory acidosis = LOW pH

Cause: Hypoventilation → carbonic acid builds up

Compensation: Kidneys → excrete H⁺ + retain HCO₃⁻.

Metabolic Acidosis

a. What are some etiologies for this?

b. What are the clinical manifestations?

c. What system helps to compensate for the problem? How does it happen?

What K+ imbalance happens with acidosis? Why?

Respiratory Alkalosis

a. What is the cause---or what are the lungs doing to cause this problem?

b. What are some etiologies for this?

c. What are the clinical manifestations?

d. What system helps to compensate for the problem? How does it happen?

Metabolic Alkalosis

a. What are some etiologies for this?

b. What are the clinical manifestations?

c. What system helps to compensate for the problem? How does it happen?

Know your normal values

a. pH

b. PaCO2

c. HCO3

What is the cause of Respiratory Acidosis?

HYPOVENTILATION