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Respiratory System DO > Pulmonary Blood Flow Gas Exchange And Transport 1 > Flashcards

Pulmonary Blood Flow Gas Exchange And Transport 1 Flashcards

1
Q

What does A stand for

A

Alveolar

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2
Q

What does a stand for

A

Arterial blood

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3
Q

What does ṽ stand for

A

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

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4
Q

What does PaO2 stand for

A

Partial pressure of oxygen in arterial blood

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5
Q

What does PACO2 stand for

A

Partial pressure of carbon dioxide in alveolar air

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6
Q

What types of circulation are there

A 
Bronchial circulation (nutritive)
Pulmonary circulation (gas exchange)
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7
Q

What supplies bronchial circulation

A

The bronchial arteries that arise from systemic circulation

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8
Q

What type of blood does bronchial circulation supply and to where

A

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

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9
Q

What does pulmonary circulation consist of

A

Left and right pulmonary arteries that originated from the right ventricle

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10
Q

What does pulmonary circulation carry

A

The entire cardiac output from the right ventricle

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11
Q

What does pulmonary circulation supply

A

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

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12
Q

What type of system is pulmonary circulation

A

High flow, low pressure system

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13
Q

What does air diffuse across

A

Membranes down partial pressure gradient

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14
Q

What obeys the rules for simple diffusion

A

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

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15
Q

State 5 features about the rate of diffusion across the membrane

A

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

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16
Q

Why are alveoli efficient in gas exchange

A

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

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17
Q

What is emphysema

A

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

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18
Q

What are the Po2 levels in patients with emphysema

A

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

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19
Q

What is fibrotic lung disease

A

A thickened alveolar membrane which slows gas exchange

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

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20
Q

What are the Po2 levels in patients with fibrotic lung disease

A

Low Po2 in alveoli and a low Po2 in the capillaries

21
Q

What is pulmonary edema

A

When the fluid in the interstital space increases the diffusion distance

22
Q

Describe the Pco2 and Po2 levels

A

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

23
Q

What does asthma cause

A

Increased airway resistance and decreases airway ventilation

24
Q

Describe the Po2 levels in asthma

A

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

25
Q

What is ventilation

A

Air getting to alveoli L/min

26
Q

What is perfusion

A

Local blood flow L/min

27
Q

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

A

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

28
Q

What is blood flow distribution in the lung influenced by

A

Hydrostatic (blood) pressure (Pa) and alveolar pressure

29
Q

What is blood flow inverserly proportional to

A

Vascular resistance and declines with height across the lung.

30
Q

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

A

High

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

31
Q

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

A

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

32
Q

From what rib does ventilation exceed blood flow

A

About rib 3 upwards

33
Q

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

A

Gravity

34
Q

What are the 3 types of ratios which can occur

A

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

35
Q

Where does most mismatching occur

A

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

36
Q

What happens if ventilation decreases in a group of alveoli

A

Pco2 will increase and Po2 will decrease

The blood flowing past those alveoli will not be oxygenated

37
Q

What is a shunt

A

The dilution of oxygenated blood from better ventilated areas

38
Q

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

A

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

39
Q

What is the constriction in response to hypoxia specific to

A

Pulmonary vessels (systemic vessels will dilate)

40
Q

What will increased Pco2 cause

A

Mild bronchodilation

41
Q

When does autoregulation occur

A

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

42
Q

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

A

Pulmonary vasodilation

43
Q

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

A

Bronchial constriction

44
Q

What is a shunt

A

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

45
Q

What is a shunt opposite to

A

Alveolar dead space

46
Q

What is the alveolar dead space

A

Alveoli that are ventilated but not perfused

47
Q

What is the anatomical dead space

A

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

48
Q

Physiological dead space =

A

Alveolar DS + anatomical DS

Respiratory System DO (33 decks)

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