Acid-Base Balance (chapter 10)

Question 1

Function of Buffers

Answer 1

Absorb or release hydrogen ions in order to keep the pH within their narrow limits of stability.

Excess hydrogen ions are transported to the lungs for excretion.

Once buffers are used it takes time to replace them leaving the body less able to withstand further changes until replacement occurs.

Question 2

Buffers

Answer 2

Fast acting regulatory system which provides immediate protection against changes in hydrogen ion concentration in the ECF.

Question 3

Primary Buffer Systems in the ECF

Answer 3

1. Hemoglobin system
2. Plasma protein system
3. Carbonic acid - bicarbonate system
4. Phosphate buffer system

Question 4

Hemoglobin Buffer System

Answer 4

Red blood cells contain hemoglobin. System maintains an acid-base balance via chloride shift whereby chloride shifts in and out of cells based on the amount of O2 in the blood. When a chloride ion leaves the cell it is replaced by a bicarbonate ion.

Question 5

Plasma Protein Buffer System

Answer 5

System functions with the liver to vary the amount of hydrogen ions in the chemical structure of the plasma proteins which have the ability to attract or release hydrogen ions.

Question 6

Carbonic acid - bicarbonate system

Answer 6

Primary buffer system in the body.

Maintains a pH of 7.4 (20 bicarbonate : 1 carbonic acid (H2CO3).

System is controlled by excretion of CO2 in the lungs and changing rate, rhythm and depth of respirations in response to changing CO2 levels.

Kidneys control the bicarbonate concentration through excretion and reabsorption.

Question 7

Phosphate Buffer System

Answer 7

Present in the cells and body fluids, especially active in the kidneys.

System acts like bicarbonate to neutralize excess hydrogen ions.

Question 8

Acidosis

Answer 8

When the pH level in the body is lowered due to an increase in H+ ions. The respiratory rate and depth increase to promote exhalation of excess acid.
Carbonic acid is created by the neutralization of bicarbonate where it is carried to the lungs and reduced to C02 and water and exhaled.

Question 9

Alkalosis

Answer 9

When the pH in the body increases. The respiratory rate and depth decrease, C02 is retained and carbonic acid increases to neutralize and decrease the strength of excess bicarbonate.

Question 10

Arterial Blood Gas Chart

Answer 10

pH A——————————————-B
7.35 7.45

PCO2 B—————————————A RESPIRATORY
35 45

HC03 A—————————————B METABOLIC
22 26

Question 11

Respiratory Acidosis

Answer 11

The respiratory rate is depressed causing an increase in C02 in the lungs. This causes a pH below 7.35 and a PC02 above 45.

Question 12

Respiratory Alkalosis

Answer 12

The respiratory rate is increased causing a loss of C02 acid in the lungs. The pH is greater than 7.45 and the PC02 is lower than 35.

Question 13

Metabolic Alkalosis

Answer 13

The patient is vomiting and losing their acid causing the pH to rise and the HC03 to rise above 26.

Question 14

Metabolic Acidosis

Answer 14

The patient has diarrhea and is losing base therefore becoming acidotic. The pH falls below 7.35 and the HC03 falls below 22.

Question 15

The role of Potassium in the Acid-Base Balance

Answer 15

Potassium helps control the acid-base balance in the body by moving H+ ions in and out of cells.

Acidosis: H+ levels are high, therefore H+ move into the cells forcing K+ out of the cells and increasing the K+ levels.

Alkalosis: H+ levels are low, therefore H+ ions move out of the cells, forcing K+ into the cells and reducing the K+ levels.

Question 16

Causes of Respiratory Acidosis

Answer 16

1. Asthma
2. Atelectasis (partial collapse or incomplete inflation of the lung)
3. Brain trauma
4. Bronchiectasis (abnormal widening of the bronchi or their branches)
5. Bronchitis
6. CNS depressants
7. Emphysema
8. Hypoventilation
9. Pneumonia
10. Pulmonary edema
11. PE

Question 17

Atelectasis

Answer 17

Partial collapse or incomplete inflation of the lung

Question 18

Bronchiectasis

Answer 18

Abnormal widening of the bronchi or their branches

Question 19

Causes of Respiratory Alkalosis

Answer 19

1. Fever
2. Hyperventilation
3. Hypoxia
4. Hysteria
5. Overventilation by mechanical ventilator
6. Pain

Question 20

Tetany

Answer 20

A condition marked by intermittent muscular spasms, caused by malfunction of the parathyroid glands and a consequent deficiency of calcium.

Question 21

Metabolic acidosis

Answer 21

Condition where there is an increase in H+ ion concentration resulting from a loss of base or retention of acid.

Question 22

Causes of metabolic acidosis

Answer 22

1. Diabetes mellitus or diabetic ketoacidosis
2. Excessive ingestion of aspirin
3. High fat diet
4. Malnutrition
5. Renal insufficiency (AKI or CKD)
6. Severe diarrhea

Question 23

Metabolic alkalosis

Answer 23

A decrease in the H+ ion concentration due to accumulation of bases in the blood or loss of acids.

Question 24

Causes of metabolic alkalosis

Answer 24

1. Diuretics
2. Excessive vomiting or GI suctioning
3. Hyperaldosteronism
4. Ingestion of and/or infusion of excess sodium bicarbonate
5. Massive transfusion of whole blood

Question 25

Allen’s Test for ABG

Answer 25

For the Allen test, the health professional drawing your blood will apply pressure to the arteries in your wrist for several seconds. This will stop the blood flow to your hand, and your hand will become cool and pale. Blood is then allowed to flow through the artery that will not be used to collect the blood sample. This is usually the ulnar artery, which is found on the outer (little finger side) of your wrist. Arterial blood gases are usually taken from the radial artery, which is found on the inner (thumb side) of the wrist.

Allen test
Normal (positive)
Your hand quickly becomes warm and returns to its normal color. This means that one artery alone will be enough to supply blood to your hand and fingers.

Abnormal (negative)
Your hand remains pale and cold. This means that one artery is not enough to supply blood to your hand and fingers. Blood will not be collected from an artery in this hand.

Question 26

Kussmaul’s Breathing

Answer 26

Deep and labored breathing pattern often associated with severe metabolic acidosis, particularly diabetic ketoacidosis (DKA) but also kidney failure.

A abnormal respiratory pattern characteized by rapid, deep breathing, often seen in patients with metabolic acidosis.

Abnormally deep, regular and an increased rate.

Question 27

Atelectasis

Answer 27

Partial collapse or incomplete inflation of the lung

Question 28

Manifestations of Respiratory Alkalosis

Answer 28

• lethargy
• lightheadedness
• confusion
• tachycardia
• dysrhythmias
• nausea
• vomiting
• epigastric pain
• numbness and tingling of extremities
• hyperventilation