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IMED3001 > Respiratory Physiology II > Flashcards

Respiratory Physiology II Flashcards

1
Q

What forces must be overcome to allow air into the lungs?

A

Elastic recoil of the lungs and chest wall
(the lungs are like balloons)

Resistance to air flow such as the straw like nature of the conduction system

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2
Q

What percentage of resistance is caused by elastic and nonelastic resistance?

A

65% elastic (comes back to us in the form of recoil)

35% non-elastic

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3
Q

What does changing diameter of respiratory tubes do to ventilation rate?

A

Increase in diameter = increase in flow and decrease in resistance

Decrease in diameter = decrease in flow and increase in resistance

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4
Q

What physical properties of the lung are important for its elasticity?

A

Compliance (Change in volume / Change in pressure)

Elastance (Change in pressure / Change in volume)

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5
Q

What factors affect compliance?

A

Distensibility of lung, pulmonary and/or thoracic tissues.

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6
Q

What is elastance of the lung the result of?

A

High content of elastin proteins.

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7
Q

What causes the plateau of increase in lung volume while increasing the pressure of the lungs?

A

The elastic proteins.

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8
Q

Where is reistance of lungs and chest wall greatest?

A

Lungs and chest wall together exert the most resistance against inhalation at high volumes.

Chest wall exerts most of the resistance at lower volumes

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9
Q

Where is potential energy stored in the lungs?

A

In the elastin/collagen proteins

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10
Q

What provides most lung resistance at very low volumes?

A

Surface tension at the air-alveolar surface (picture wetsuits when they are wet)

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11
Q

Does opposing surface tension result in any stored potential energy?

A

No

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12
Q

P=2 x ST/Ralv

A

As alveoli radius (Ralv) decreases, surfactant’s ability to lower surface tension increases

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13
Q

What does surfactant do?

A

Lowers surface tension by reducing attractive forces of hydrogen bonding between H2O molecules.

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14
Q

What cells produce surfactant?

A

Type II alveolar cells

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15
Q

What percentage of alveolar surface is covered by type II alveolar cells?

A

10%

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16
Q

What is surfactant made up of?

A

Dipalmitoyl-phosphatidylcholine (DPPC), apoproteins, and cholesterol

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17
Q

Do alveolar type II cells have any benefit to gas exchange directly?

A

No

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18
Q

When does surfactant get produced in foetuses?

A

about 34 weeks in

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19
Q

What condition results from lack of surfactant at birth?

A

Infant respiratory distress syndrome (IRDS)

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20
Q

How does the Lung-Chest wall pressure-volume curve look in healthy lungs?

A

Eye shaped

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21
Q

What is characteristic of a low compliance lung? What can cause this condition to occur?

A

It is stiff with extra work required for normal inspiration.

Fibrosis can decrease pulmonary compliance

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22
Q

What is characteristic of a high compliance lung?

A

It is floppy with extra work being required for expiration.

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23
Q

What causes a high compliance lung?

A

Elastic tissue damage results in poor elastic recoil.

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24
Q

What is the problem with high compliance inhalation is so easy?

A

Makes it really difficult to exhale air

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25
Q

What conditions cause a highly compliant lung?

A

COPD/Emphysema

26
Q

What is the cause of non-elastic resistance?

A

Airflow 80%

Viscous flow 20%

27
Q

What regulates mucous production?

A

Histamine (produced by mast cells) which increases mucous secretion and viscosity

28
Q

What is mucosal oedema?

A

Increased permeability leading to transudation of fluid and macromolecules through wide intercellular gaps

29
Q

What conditions affect mucous secretion and how?

A

Chronic bronchitis (too much mucus produced by lungs)

Cystic fibrosis CFTR mutation aka Cystic Fibrosis Transmembrane Conductance Regulator) Which makes ciliary clearance very difficult

30
Q

What controls air flow to airways?

A

Airway smooth muscle tone

31
Q

What receptor is activated to cause bronchodilation?

A

Beta-2 adrenergic receptor

32
Q

What receptor is activated to cause bronchoconstriction?

A

Muscarinic cholinergic receptor activation

Histamine H1 receptor activation

33
Q

What controls bronchial resistance under normal circumstances?

A

Primarily the parasympathetic NS.

34
Q

Why isn’t the sympathetic NS as influential on bronchial resistance?

A

The bronchioles don’t have many receptors for the sympathetic NS

35
Q

What causes airways to constrict reflexively?

A

Inhalation of smoke, dust, chemical irritants

Arterial hypercapnia

Cold

Pulmonary emboli

36
Q

What causes airways to dilate reflexively?

A

Arterial hypertension (carotid sinus reflux)

37
Q

How do the bronchioles respond to symapthetic nervous system when required?

A

It has beta 2 adrenergic receptors that are activated by adrenaline which is an endocrine effect.

38
Q

What do beta 2 agonists do?

A

Cause bronchodilation

39
Q

What do beta 2 antagonists do?

A

Bronchoconstriction

40
Q

What local factos control bronchodilation?

A

O2 and CO2

41
Q

How is resistance measured in pulmonary tract?

A

Peak Expiratory Flow

(FEV1) Forced Expiratory Volume in 1 second

FEV1/FVC(Forced Vital Capacity)

Flow-Volume Loops

42
Q

What is FVC?

A

Forced Vital Capacity which is the gas forcibly expelled after a deep breath

43
Q

What measures are normal for FEV1/FVC?

A

Better than 80% is normal and better than 70% is normal for older people

44
Q

What is positive flow on a volume-flow plot?

A

Air coming into lungs

45
Q

What is negative flow on a flow-volume plot?

A

Air leaving the lungs

46
Q

Why is flow-volume plot shaped the way it is?

A

During exhalation lung volume drops rapidly due to recoil.

During inhalation there is a lot of difficulty overcoming initial surface tensionand then peak inspiratory flow plateau then a build up of resistance caused by elasticity of both the chest wall and the lung.

47
Q

What is PIF on the Flow-Volume Plot?

A

Peak inspiratory flow

48
Q

What can go wrong with ventilation?

A

Respiratory muscles can fail

Restrictive diseases

Obstructive diseases

49
Q

What do restrictive diseases do?

A

Decrease compliance

50
Q

What do obstructive diseases do?

A

Increase resistance

51
Q

What is the difference between restrictive lung disease and obstructive lung disease?

MAKE SURE YOU KNOW THIS

A

Restrictive:
Restriction in how much lung can be inflated.

Compliance of the lung is reduced which means stiffness of the lung limits expansion.

Problem is a change in lung volume

In restrictive lung disease more pressure is required for the same volume.

Obstructive lung disease:

Airway obstruction = more resistance

Slower flow of air into the lungs

No difference in P-V relationship but more work is required to overcome the R to flow

A decrease in expiratory airflow/time could result

Air may be trapped in lungs due to incomplete emptying and as a result there is an increase in lung residual volume

52
Q

Do restrictive and obstructive lung disorders typically happen at the same time?

A

Yes

53
Q

What type of diseases are obstructive lung disorders?

A

Asthma

COPD

Cystic fibrosis

Bronchiolitis

Bronchiectasis

54
Q

What type of diseases are restrictive?

A

Having a lobectomy

Pregnancy

Pulmonary fibrosis

55
Q

What are some common features of restrictive lung defects?

A

Loss in lung volume

Abnormalities of structures surrounding the lung

Weakness of inspiratory muscles

Abnormalities of lung parenchyma

56
Q

What does Flow-Volume look like in healthy individuals?

A

Inspiratory limb is symmetric and convex, expiratory limb is linear.

57
Q

What happens to the flow in obstructive lung disease?

A

Although all airflow is diminished the expiratory flow is diminished and ir doesn’t decrease linearly.

58
Q

How does the restrictive lung disorder flow-volume curve differ from the normal flow-volume curve?

A

The loop is narrowed because of diminished lung volumes

Airflow is greater than normal at comparable lung volumes because the increased elastic recoil of the lungs holds airways open

59
Q

What is absolutely necessary for a diagnosis of restrictive lung disorder?

A

Reduction in TLC

60
Q

What is absolutely necessary for a diagnosis of obstructive lung disorders?

A

Reduced FEV1/FVC

IMED3001 (46 decks)

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