L11: Ventilation And Perfusion

Question 1

What is PAo2 (alveolar partial pressure)

Answer 1

13

Question 2

What is the pao2 (arterial partial pressure) when it leaves the left side of the heart

Answer 2

12

Question 3

What are the 2 reasons for the 1kpa difference in alveolar and arterial partial pressure

Answer 3

Shunts

Ventilation perfusion mismatch

Question 4

What is the shunting process

Answer 4

When deoxygnated blood reaches the lungs some alveoli do no oxygenate the blood this gives a mixture of deoxygenated and oxygenated blood leaving the left heart at 12kpa instead of 13kpa

Question 5

What is the ventilation perfusion ratio (V/Q) mismatch

Answer 5

The flow of blood is greater than the alveolar ventilation

Question 6

What is the fall in pao2 termed as

Answer 6

Hypoxia

Question 7

From which side to side does blood move from in the heart

Answer 7

Right to left

Question 8

Does the right side of the heart carry deoxygenated blood or oxygenated blood

Answer 8

Deoxygenated blood

Question 9

After leaving the right side of the heart where does the deoxygenated go

Answer 9

To the lungs

Question 10

What happens to the deoxygenated blood at the lungs

Answer 10

Blood becomes oxygenated

Question 11

Where does oxygenated blood travel to after the lungs

Answer 11

Left side of the heart

Question 12

After leaving the left side of the heart where does the oxygenated blood travel to

Answer 12

Rest of the body

Question 13

What happens to the oxygenated blood after reaching to the rest of the body

Answer 13

Blood becomes deoxygenated

Question 14

After the rest of the body where does deoxygenated blood go to

Answer 14

Right side of the heart

Question 15

What is right-left shunted blood

Answer 15

Blood that contains a mixture of oxygenated and deoxygenated blood

Question 16

Do we have natural right left shunts

Answer 16

Yes

Question 17

What are the natural shunts in the heart

Answer 17

Thebesian veins

Question 18

What are thebesian veins

Answer 18

Small valve-less venous channels that open directly into the heart

Arterial blood that has gone to supply the cardiac tissue but instead of draining back into the venous system it drains into the left ventricle

Question 19

What are the other natural right-left shunts

Answer 19

Bronchial circulation

Question 20

What is the bronchial circulation

Answer 20

Lungs has its only arterial supply from the thoracic aorta

Question 21

What happens to the blood in the bronchopulmonary veins of the bronchial circulation

Answer 21

The blood join the pulmonary vein, mixes with the oxygenated blood to go into the left atrium

Question 22

What are pathological right-left shunts

Answer 22

A greater alveolar-arterial pressure difference due to disease

Question 23

Name pathological right-left shunts

Answer 23

Pulmonary disease

Question 24

What does the pulmonary disease include

Answer 24

Airway blockage

Collapsed bronchi

Question 25

How does pulmonary disease cause an increase in alveolar-arterial difference

Answer 25

Pulmonary artery cannot receive oxygen

Question 26

What are left-right shunts

Answer 26

Cardiovascular anatomical abnormalities

Question 27

How does cardiovascular anatomical abnormalities occur

Answer 27

Occur in neonates with septal defects

Question 28

What happens in a left-right shunt

Answer 28

Oxygenated blood enters the deoxygenated areas

Question 29

In a normal lung what is the ventilation/perfusion (V/Q) ratio

Answer 29

0.8

Question 30

What are the main causes of ventilation in the lungs

Answer 30

Gravity | Compliance

Question 31

What happens to the alveolar ventilation as you go down from apex to base

Answer 31

Increase

Question 32

Why is there are greater ventilation at the base than apex

Answer 32

Base has a greater compliance and more negative intrapleural pressure

Question 33

What are the main causes of change in perfusion

Answer 33

Gravity

Question 34

What happens to the perfusion as you go down from apex to base

Answer 34

Increases

Question 35

What happens to the ventilation/perfusion ratio as you go down from apex to base

Answer 35

Decreases

Question 36

What are the 2 mechanisms that alter the ventilation/perfusion ratio (V/Q)

Answer 36

Bronchiole diameter | Arteriole diameter

Question 37

What does the bronchiole diameter alter

Answer 37

Ventilation

Question 38

What does arteriole diameter alter

Answer 38

Perfusion

Question 39

What does a high V/Q lead to

Answer 39

Hyperoxia | Hypocapnia

Question 40

What is hyperoxia

Answer 40

High oxygen in blood

Question 41

What is hypocapnia

Answer 41

Low carbon dioxide

Question 42

What does a low V/Q lead to

Answer 42

Hypoxia | Hypercapnia

Question 43

What is hypoxia

Answer 43

Low oxygen in blood

Question 44

What is hypercapnia

Answer 44

High carbon dioxide in blood

Question 45

How does the body respond to a high V/Q

Answer 45

Vasodilation | Bronchoconstriction

Question 46

How does the body respond to a low V/Q

Answer 46

Vasoconstriction | Bronchodilation

Question 47

What is hypoxic pulmonary vasoconstriction

Answer 47

During hypoxia vascoconstriction occurs to divert the blood away

Question 48

How does hypoxic pulmonary vasoconstriction occur

Answer 48

1) potassium channels of smooth muscle of bronchioles are inhibited by hypoxia 2) this leads to membrane depolarisation 3) voltage gated calcium channels open 4) calcium influx gives vasoconstriction

Question 49

Name a lung disease which results in a high V/Q mismatch

Answer 49

Bronchitis | Emphysema

Question 50

What equation do we use to find out hypoxia is due to alveolar ventilation

Answer 50

Alveolar gas equation