Pulmonary Blood Flow Gas Exchange And Transport 1

Question 1

What does A stand for

Answer 1

Alveolar

Question 2

What does a stand for

Answer 2

Arterial blood

Question 3

What does ṽ stand for

Answer 3

Mixed venous blood (e.g. in pulmonary artery)

Question 4

What does PaO2 stand for

Answer 4

Partial pressure of oxygen in arterial blood

Question 5

What does PACO2 stand for

Answer 5

Partial pressure of carbon dioxide in alveolar air

Question 6

What types of circulation are there

Answer 6

Bronchial circulation (nutritive)
Pulmonary circulation (gas exchange)

Question 7

What supplies bronchial circulation

Answer 7

The bronchial arteries that arise from systemic circulation

Question 8

What type of blood does bronchial circulation supply and to where

Answer 8

Supply oxygenated blood to the airway smooth muscle, nerves and lung tissues

Question 9

What does pulmonary circulation consist of

Answer 9

Left and right pulmonary arteries that originated from the right ventricle

Question 10

What does pulmonary circulation carry

Answer 10

The entire cardiac output from the right ventricle

Question 11

What does pulmonary circulation supply

Answer 11

The dense capillary network surrounding the alveoli and returns oxygenated blood to the left atrium through the pulmonary vein

Question 12

What type of system is pulmonary circulation

Answer 12

High flow, low pressure system

Question 13

What does air diffuse across

Answer 13

Membranes down partial pressure gradient

Question 14

What obeys the rules for simple diffusion

Answer 14

The diffusion of gases between the alveoli and the blood
Gases will move across a membrane which is permeable to that gas down its partial pressure gradient and shall continue to do so until equilibrium is reached

Question 15

State 5 features about the rate of diffusion across the membrane

Answer 15

Directly proportional to the partial pressure gradient.
Directly proportional to gas solubility
Directly proportional to the available surface area
Inversely proportional to the thickness of the membrane
Most rapid over short distances

Question 16

Why are alveoli efficient in gas exchange

Answer 16

They have a large surface area and a thin membrane with a short diffusion distance

Question 17

What is emphysema

Answer 17

The destruction of alveoli which reduces the surface area for gas exchange

Question 18

What are the Po2 levels in patients with emphysema

Answer 18

Normal or low Po2 in the alveoli and a low Po2 in the capillaries

Question 19

What is fibrotic lung disease

Answer 19

A thickened alveolar membrane which slows gas exchange

There is a loss of lung compliance which may decrease alveolar ventilation

Question 20

What are the Po2 levels in patients with fibrotic lung disease

Answer 20

Low Po2 in alveoli and a low Po2 in the capillaries

Question 21

What is pulmonary edema

Answer 21

When the fluid in the interstital space increases the diffusion distance

Question 22

Describe the Pco2 and Po2 levels

Answer 22

Arterial Pco2 could be normal due to a higher CO2 solubility in water
Po2 in alveoli = normal
Po2 in alveoli normal while Po2 in capillaries kow

Question 23

What does asthma cause

Answer 23

Increased airway resistance and decreases airway ventilation

Question 24

Describe the Po2 levels in asthma

Answer 24

Bronchioles are constricted which cause a low Po2 in the alveoli and capillaries.

Question 25

What is ventilation

Answer 25

Air getting to alveoli L/min

Question 26

What is perfusion

Answer 26

Local blood flow L/min

Question 27

What is the most optimal condition in the ventilation-perfusion releationship

Answer 27

When the ventilation in alveoli is matched to perfusion through the pulmonary capillaries

Question 28

What is blood flow distribution in the lung influenced by

Answer 28

Hydrostatic (blood) pressure (Pa) and alveolar pressure

Question 29

What is blood flow inverserly proportional to

Answer 29

Vascular resistance and declines with height across the lung.

Question 30

At the base of the lungs is blood flow high or low and why

Answer 30

High | The arterial pressure exceeds the alveolar pressure so vascular resistance is low

Question 31

At the apex of the lungs is blood flow high or low and why

Answer 31

Low The arterial pressure is less than the alveolar pressure which will compress the arterioles and vascular resistance is increased

Question 32

From what rib does ventilation exceed blood flow

Answer 32

About rib 3 upwards

Question 33

Why does the ratio of ventilation to perfusion in the upright position within the lung change from the base to apex

Answer 33

Gravity

Question 34

What are the 3 types of ratios which can occur

Answer 34

Perfectly matched Ventilation:Perfusion ratio = 1.0 Mismatch 1 Ventilation>Perfusion ratio > 1.0 Mismatch 2 Ventilation

Question 35

Where does most mismatching occur

Answer 35

Apex and then autoregulated to keep the ventilation perfusion ration close to 1.0

Question 36

What happens if ventilation decreases in a group of alveoli

Answer 36

Pco2 will increase and Po2 will decrease | The blood flowing past those alveoli will not be oxygenated

Question 37

What is a shunt

Answer 37

The dilution of oxygenated blood from better ventilated areas

Question 38

What does a decreased tissue Po2 around under-ventilated alveoli cause

Answer 38

Constriction of their arterioles, diverting the blood to better-ventilated alveoli

Question 39

What is the constriction in response to hypoxia specific to

Answer 39

Pulmonary vessels (systemic vessels will dilate)

Question 40

What will increased Pco2 cause

Answer 40

Mild bronchodilation

Question 41

When does autoregulation occur

Answer 41

When ventilation is greater than blood flow creating an alveolar dead space

Question 42

What happens when the alveolar Po2 increases in the alveolar dead space

Answer 42

Pulmonary vasodilation

Question 43

What happens when the alveolar Pco2 decreases in the alveolar dead space

Answer 43

Bronchial constriction

Question 44

What is a shunt

Answer 44

The passage of blood through areas of the lung that are poorly ventilated

Question 45

What is a shunt opposite to

Answer 45

Alveolar dead space

Question 46

What is the alveolar dead space

Answer 46

Alveoli that are ventilated but not perfused

Question 47

What is the anatomical dead space

Answer 47

Air in the conducting zone of the respiratory tract unable to participate in gas exchange as walls of airways in this region (nasal cavities, trachea, bronchi and upper bronchioles) are too thick

Question 48

Physiological dead space =

Answer 48

Alveolar DS + anatomical DS