Ventilation/Perfusion

Question 1

Respiration

Answer 1

Entire breathing process which includes both ventilation and oxygenation

Question 2

Ventilation

Answer 2

Exchange of gases in the lungs on a molecular level caused by moving air in and out of the body
O2 in CO2 out

Question 3

Oxygenation

Answer 3

Diffusion of oxygen from the air into the red blood cells where it is then delivered to the tissues

Question 4

Perfusion

Answer 4

Blood flow, to the alveoli and the tissues

Question 5

What drives ventilation?

Answer 5

High CO2

Question 6

What is CO2

Answer 6

Waste product of energy production during the Kreb’s cycle

Question 7

High levels of CO2 leads to formation of…

Answer 7

CO2 and water form carbonic acid, which is a weak acid that dissociates into bicarbonate and H+ ions

Question 8

Increase of H+ leads to

Answer 8

Decrease in pH (More acidic)

Question 9

Increase in CO2 leads to a/an _________ in pH

Answer 9

Decrease, more acidic from formation of H+ ions

Question 10

Normal rage of pH

Answer 10

7.35 - 7.45

Question 11

Chemoreceptors

Answer 11

Monitor the pH of the blood and can then trigger change in ventilation to alter amount of CO2 in the body which in turn can increase or decrease pH

Question 12

Minute ventilation

Answer 12

Respiratory rate x tidal volume
RR x VT = MV
# of breaths x volume of each breath

Question 13

Result of increase in tidal volume or RR

Answer 13

Increase amount of CO2 expelled, so decrease in amount of H+ ions and increase in pH (more basic)

Question 14

Hypercapnia (hypercarbia)

Answer 14

CO2 retention
Elevation in PaCO2 (amount of CO2 in the blood) over 45 mmHg

Question 15

Hypocapnia

Answer 15

A decrease in PaCO2 (CO2 in the blood) below 35 mmHg

Question 16

Equation to determine acidity from CO2

Answer 16

Question 17

Regulation of pH with respirations time

Answer 17

Seconds to minutes
Just breathing more or less to change CO2

Question 18

Regulation of pH with kidneys time

Answer 18

Days to weeks

Question 19

How respirations change the pH equation

Answer 19

Change the amount of CO2 by breathing more or less
Left side

Question 20

How kidneys control pH equation

Answer 20

Right side of equation
Changing retention or excretion of bicarbonate and H+ into the urine

Question 21

Hypoventilation

Answer 21

Less breathing, so retaining CO2, not increased production
Decreases acidity

Question 22

Impact of chronic CO2 elevation

Answer 22

Down regulates chemoreceptors which makes it so they don’t respond to the consistent difference pH
Hypercapnia
Hypoxia becomes primary stimulus for ventilation

Question 23

Hypoxemia

Answer 23

Decrease amount of O2 in the blood
PaO2 is low (under 75 mmHg)

Question 24

Oxygen saturation

Answer 24

How much oxygen is currently bound to hemoglobin
Measured by pulse oximetry

Question 25

Hypoxia

Answer 25

When the tissue oxygen level is impaired (Tissues now have decreased O2 amount)

Question 26

Anoxic

Answer 26

No oxygen delivery to a tissue (Infarction, tissue death)

Question 27

Most common cause of hypoxia

Answer 27

Due to low oxygen available in the blood

Question 28

Hypoxemia without hypoxia

Answer 28

Means there is a decrease amount of O2 in the blood but not in the tissues Increased delivery of O2 to compensate for low PaO2 (Increase in CO to maintain perfusion or hypothermia so tissues don't need as much O2)

Question 29

Hypoxia without hypoxemia

Answer 29

O2 is in the blood but there is insufficient oxygen supply at the tissue level Tissues are unable to use O2 effectively O2 delivery is impaired (MI)

Question 30

V/Q mismatch used in cases of

Answer 30

Hypoxemia So decrease amount of O2 in the blood

Question 31

V/Q mismatch

Answer 31

Ventilation/perfusion mismatch occurs when the ratio of ventilation to perfusion is abnormal in one or more areas of the lung. This can lead to a decrease in oxygen delivery to the tissues and an increase in carbon dioxide retention. Ventilation/perfusion mismatch is diagnosed by measuring the ratio of ventilation to perfusion in different areas of the lung.

Question 32

V/Q mismatch equation

Answer 32

1 = V divided by Q

Question 33

V =

Answer 33

Alveolar ventilation Air entering lungs into alveoli

Question 34

Q =

Answer 34

Perfusion Blood flow in capillaries past the alveoli

Question 35

What is V/Q mismatch looking at

Answer 35

Hypoxemia can occur when ventilation and perfusion aren't matched Seeing which is the cause

Question 36

Hypoxic pulmonary vasoconstriction

Answer 36

Try to maintain proper V/Q ratios by sensing areas of hypoxia and poor gas exchange and vasoconstricting flow to these poorly functioning areas Healthy areas get the blood flow Max out though when thinking about chronic disease issues

Question 37

5 most common causes of hypoxemia (V/Q mismatch)

Answer 37

Asthma COPD Pulmonary embolism Cystic fibrosis Interstitial lung disease

Question 38

Asthma V/Q mismatch

Answer 38

Bronchoconstriction = lower V (.75) Blood flow is the same = Q of 1 .75 / 1 = .75 Low mismatch

Question 39

Pulmonary embolism V/Q mismatch

Answer 39

Blood clot is decreasing blood flow in artery so Q is lower = .5 Ventilation is the same so V= 1 1/.5 = 2 High mismatch

Question 40

Right to left shunt

Answer 40

When blood travels from the RV to the LA without ever being oxygenated Extreme form of low ratio V/Q mismatch

Question 41

Diffusion limitation

Answer 41

Difficulty in getting oxygen from the alveolus into the capillary Often due to scaring/fibrosis of the alveolar - capillary membrane or of reduced surface tension in the alveoli

Question 42

FiO2

Answer 42

Fraction of inspired oxygen Room air is 21% If less then less O2 for gas exchange leading to hypoxemia

Question 43

Carbon monoxide and Hb

Answer 43

Has 250X greater binding affinity for Hb than O2

Question 44

CO + O2 Hb

Answer 44

CO is a competitive antagonist When CO binds it changes Hb shape to make it more difficult to unload oxygen into the tissues