Class 21 review

Question 1

Ventilation definition

Answer 1

The process of inhaling oxygen into the lungs and exhaling carbon dioxide from the lungs. Ventilation may be impaired by the unavailability of oxygen as well as by any disorder affecting the nasopharynx and lungs. Inadequate bone, muscle, or nerve function can reduce inhalation, prevent full thoracic expansion, or limit the movement of the diaphragm (Giddens, 2021).

Question 2

Transport definition

Answer 2

Transport refers to the availability of hemoglobin and its ability to carry oxygen from alveoli to cells for metabolism and to carry carbon dioxide produced by cellular metabolism from cells to alveoli to be eliminated (Giddens, 2021).

Question 3

Perfusion definition

Answer 3

Perfusion refers to the ability of blood to transport oxygen-containing hemoglobin to cells and return carbon dioxide-containing hemoglobin to the alveoli. Inadequate or impaired perfusion can be caused by decreased cardiac output as well as by thrombi, emboli, vessel narrowing, vasoconstriction, or blood loss (Giddens, 2021).

Question 4

pH definition

Answer 4

Refers to the balance of hydrogen ions in the arterial blood. A high pH indicates a solution is alkaline (low H+ concentration) and a low pH indicates a solution is acidic (high H+ concentration)

Question 5

pH normal values

Answer 5

7.35 - 7.45

Question 6

PaCO2 definition

Answer 6

Measures the amount of carbon dioxide in the arterial blood. Indicates how well the lungs are excreting carbonic acid.

Question 7

PaCO2 normal values

Answer 7

35 - 45 mmHg

Question 8

HCO₃⁻ definition

Answer 8

Measures the amount of bicarbonate in the arterial blood. Indicates how well the kidneys are excreting metabolic acid.

Question 9

HCO₃⁻ normal value

Answer 9

21 - 28 mmol/L

Question 10

PaO2 definition

Answer 10

Measures the amount of oxygen in the arterial blood. Lets us know what is happening at the level of the tissue.

Question 11

If the pH is above 7.45

Answer 11

they are in an alkalotic state

Question 12

If the pH is below 7.35

Answer 12

they are in an acidotic state

Question 13

Acids…

Answer 13

are produced as end products of metabolism, they contain hydrogen ions and are hydrogen ion donors, this means that they give up hydrogen ions to neutralize or decrease the strength of an acid or to form a weaker base

Question 14

Bases…

Answer 14

contain no hydrogen ions, they are hydrogen ion acceptors, they accept hydrogen ions from acids to neutralize or decrease the strength of a base or to form a weaker acid

Question 15

Cellular metabolism generates

Answer 15

carbonic acid (H2CO3) in the form of CO2 and H2O and metabolic acids

Question 16

What is a buffer?

Answer 16

A buffer will absorb or release a hydrogen ion as needed. Once a primary buffer system reacts, they are consumed, leaving the body less able to withstand further stress until the buffers are replaced.

Question 17

Hemoglobin System

Answer 17

Red blood cells (RBC) contain hemoglobin. This system maintains acid-base balance from a process called the chloride shift. Chloride is an electrolyte that shifts in and out of cells in response to the level of O2 in the blood. For each chloride molecule that leaves an RBC, a bicarbonate ion enters. For each chloride molecule that enters an RBC, a bicarbonate ion leaves.

Question 18

Plasma Protein System

Answer 18

This system functions along with the liver (where many plasma proteins are made) to vary the number of hydrogen ions in the chemical structure of plasma proteins. Plasma proteins can attract or release hydrogen ions.

Question 19

Phosphate Buffer System

Answer 19

This system is present in cells and body fluids, it is especially active in the kidneys. The system acts like bicarbonate and neutralizes excess hydrogen ions.

Question 20

Carbonic Acid-Bicarbonate System

Answer 20

This is the primary buffer system in the body. The system maintains a pH of 7.4 with a ratio of 20 parts bicarbonate (HCO3 -) to 1 part carbonic acid (H2CO3). This 20:1 ratio determines the hydrogen ion concentration of body fluid. Carbonic acid concentration is controlled by the excretion of CO2 in the lungs, the rate and depth of respiration change in response to the changes in CO2. The kidneys control the bicarbonate concentration and selectively retain or excrete bicarbonate in response to bodily needs.

Question 21

Lungs maintaining acid-base balance

Answer 21

The best thing about the lungs is that the process of correcting an acid-base deficit or excess takes only 10-30 seconds to complete! The lungs do this by either holding hydrogen ions (in states of alkalosis) or by changing hydrogen ions to water molecules to be exhaled with CO2 (in states of acidosis).

Question 22

Kidneys maintaining acid-base balance

Answer 22

The renal correction of an acid-base imbalance is slower but is provides a more inclusive corrective response. Compensation (correcting) can take a few hours to several days, however, it is more selective. Selective regulation of bicarbonate occurs in the kidneys. The kidneys restore bicarbonate by excreting hydrogen ions and retaining bicarbonate ions. Excess hydrogen ions are excreted in the urine in the form of phosphoric acid. The alteration of certain amino acids in the renal tubules results in a diffusion of ammonia into the kidneys, the ammonia combines with excess hydrogen ions and is excreted in the urine.

Question 23

Potassium in acidosis

Answer 23

the body protects itself from the acidic state by moving hydrogen ions into the cells. Therefore potassium moves out to make room for hydrogen ions and the potassium levels increase

Question 24

Potassium in alkalosis

Answer 24

the cells release hydrogen ions into the blood in an attempt to increase the acidity of the blood, this forces the potassium into the cells, and potassium levels decrease.

Question 25

Risk factors for acid-base imbalances:

Answer 25

• Excessive production or intake of metabolic acid
• Altered acid buffering due to loss or gain of bicarbonate
• Altered acid excretion
• Abnormal shift into H + into cells

Question 26

Respiratory acidosis

Answer 26

Too much carbonic acid
Cause: often hypoventilation
Correction of acidosis: via hyperventilation
Kidneys will increase secretion of H+ and produce more ammonia

Question 27

Metabolic acidosis

Answer 27

Too much metabolic acid
Cause: more metabolic acid then the kidneys can excrete
Correction: increased secretion of H+, more NH3 production
Respiratory compensation results in hyperventilation

Question 28

Respiratory alkalosis

Answer 28

Too little carbonic acid
Cause: often hyperventilation
Correction by system: hypoventilation
Kidneys compensate by decreasing secretion of H+, less NH3 production

Question 29

Metabolic alkalosis

Answer 29

Too little metabolic acid
Cause: more bicarbonate than kidneys can exert (too little metabolic acid)
Correction: decreased secretion of H+, less NH3 production

Question 30

Hypercapnia

Answer 30

carbon dioxide in the blood. Measured by arterial blood gas (PaCO2)

Question 31

Hypercapnia mechanisms of failure:

Answer 31

1. abnormalities of airways and alveoli
2. abnormalities of CNS
3. abnormalities of chest wall
4. neuromuscular conditions

Question 32

Effects of hypercapnia:

Answer 32

• Respiratory acidosis
• Altered electrolytes
• Arrhythmias
• intracranial pressures
• Somnolence
• Coma
• Headache
• Hypoxemia

Question 33

Hypercapnic value

Answer 33

(ventilatory failure)

PaCO2 greater than 45 mmHg and pH less than 7.35

Question 34

Hypoxemia value

Answer 34

(oxygenation failure)

PaO2 less than 60 mmHg on 60% oxygen