= Blood supply, gas exchange, ventilation & perfusion Flashcards

1
Q

What does the bronchial circulation supply?

A

Supplies oxygenated blood via bronchial arteries from the systemic circulation to airway smooth muscle, nerves and lung tissue.

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2
Q

Where do the Left and right pulmonary arteries arise from?

A

The right ventricle

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3
Q

What does the Left and Right pulmonary artery carry?

A

Entire cardiac output from RV

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4
Q

What does the pulmonary artery supply?

A

The dense capillary network surrounding the alveoli

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5
Q

Where does the blood travel after the capillary network surrounding the alveoli?

A

Travels to the left atrium via the pulmonary vein

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6
Q

How is the pulmonary circulation described?

A

High flow low pressure system.

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7
Q

What is the partial pressure of Oxygen in the alveoli?

A

100mmHg

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8
Q

What is the partial pressure of CO2 in the alveoli?

A

40 mmHg

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9
Q

How does the air diffuse across the membranes between the alveoli and the blood circulation?

A

Diffusion across the partial pressure gradient

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10
Q

What does A stand for?

A

Alveolar

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11
Q

What does a stand for?

A

Arterial blood

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12
Q

What does ṽ stand for?

A

Mixed venous blood (e.g pulmonary artery)

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13
Q

What are the missing values from the table?

A
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14
Q

What is the rate of diffusion across the membrane directly proportional to?

A

Partial pressure gradient

Gas solubility

Available surface area

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15
Q

What is rate of diffusion across the membrane indirectly proportional to?

A

The thickness of the membrane

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16
Q

When is the rate of diffusion of gas across the membrane most rapid?

A

Over short distances

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17
Q

Look at this slide

A
18
Q

What is the surface area of an alveoli in emphysema?

A

Reduced surface area

19
Q

What are the features of Fibrotic lung disease?

A

Thickened alveolar membranes slows gas exchange. Loss of lung compliance may decrease alveolar ventilation.

20
Q

What are the features of pulmonary edema?

A

Fluid in interstitial space increases diffusion distance. Arterial pCO2 may remain normal due to higher solubility in water.

21
Q

Describe asthma

A

Increased airway resistance decreases airway ventilation

22
Q

Which picture represents fibrotic alveoli, normal alveoli and pulmonary oedema?

A

Fibrotic, normal, oedema

23
Q

What is ventilation linked to?

A

Perfusion - (local blood flow L/min)

24
Q

What is distribution of blood flow in the lung influenced by?

A

Hydrostatic pressure and alveolar pressure

25
Q

Why is blood flow at the base of the lungs high?

A

Arterial pressure exceeds alveolar pressure and vascular resistance is therefore low.

26
Q

Why is blood flow low at the at the apex of the lung? (in pulmonary capillaries?)

A

Arterial pressure is less than alveolar pressure. This compresses the arterioles and vascular resistance is increased.

27
Q

What is the optimal condition for ventilation?

A

Ventilation = blood flow

28
Q

Which of the mismatches has

  1. Under oxygenated blood
  2. Too much breathing taking place compared to the rate of blood flow
A
  1. Mismatch 2
    1. Mismatch 1
29
Q

Where does majority of the mismatch take place?

A

Apex of the lung

Over 75% of the height the healthy lung performs quite well in matching blood and air

30
Q

What happens if ventilaiton decreases in a group of alveoli?

A

PCO2 increases and PO2 decreases. Blood flowing past those alveoli does not get oxygenated.

31
Q

What decreased PO2 around underventilated alveoli cause?

A

Constricts their arterioles, diverting their blood to better ventilated alveoli

Constriction in response to hypoxia is particular to pulmonary vessels (systemic vessels dilate)

32
Q

What does increased PCO2 cause?

A

Mild bronchdilation

33
Q

Ultimately this response increases perfusion and, to a lesser extent, decreases ventilation, bringing the ratio back towards 1.What happens when you get ventilation > blood flow?

A
34
Q

What is shunt?

A

Shunt is a term used to describe the passage of blood through areas of the lung that are poorly ventilated (ventilation << perfusion

Shunt is the opposite of alveolar dead space

35
Q

What are is alveolar dead space?

A

Alveolar Dead Space refers to alveoli that are ventilated but not perfused.

36
Q

What is anatomical dead space?

A

Anatomical Dead Space refers to 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.

37
Q

What is physiological dead space?

A

Physiological Dead Space = Alveolar DS + Anatomical DS

38
Q

What does the low pressure circuit cause?

A

More susceptible to the effects of gravity and this gives rise to a great degree of variability in blood flow within the lung.

39
Q

Why are the overall rates of equilibrim between O2 and CO2 similar? Despite the fact CO2 is more soluble?

A

Because of the greater pressure difference for O2

40
Q
A