Respiratory Physiology II

Question 1

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

Answer 1

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

Question 2

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

Answer 2

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

35% non-elastic

Question 3

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

Answer 3

Increase in diameter = increase in flow and decrease in resistance

Decrease in diameter = decrease in flow and increase in resistance

Question 4

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

Answer 4

Compliance (Change in volume / Change in pressure)

Elastance (Change in pressure / Change in volume)

Question 5

What factors affect compliance?

Answer 5

Distensibility of lung, pulmonary and/or thoracic tissues.

Question 6

What is elastance of the lung the result of?

Answer 6

High content of elastin proteins.

Question 7

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

Answer 7

The elastic proteins.

Question 8

Where is reistance of lungs and chest wall greatest?

Answer 8

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

Chest wall exerts most of the resistance at lower volumes

Question 9

Where is potential energy stored in the lungs?

Answer 9

In the elastin/collagen proteins

Question 10

What provides most lung resistance at very low volumes?

Answer 10

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

Question 11

Does opposing surface tension result in any stored potential energy?

Answer 11

No

Question 12

P=2 x ST/Ralv

Answer 12

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

Question 13

What does surfactant do?

Answer 13

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

Question 14

What cells produce surfactant?

Answer 14

Type II alveolar cells

Question 15

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

Answer 15

10%

Question 16

What is surfactant made up of?

Answer 16

Dipalmitoyl-phosphatidylcholine (DPPC), apoproteins, and cholesterol

Question 17

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

Answer 17

No

Question 18

When does surfactant get produced in foetuses?

Answer 18

about 34 weeks in

Question 19

What condition results from lack of surfactant at birth?

Answer 19

Infant respiratory distress syndrome (IRDS)

Question 20

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

Answer 20

Eye shaped

Question 21

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

Answer 21

It is stiff with extra work required for normal inspiration.

Fibrosis can decrease pulmonary compliance

Question 22

What is characteristic of a high compliance lung?

Answer 22

It is floppy with extra work being required for expiration.

Question 23

What causes a high compliance lung?

Answer 23

Elastic tissue damage results in poor elastic recoil.

Question 24

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

Answer 24

Makes it really difficult to exhale air

Question 25

What conditions cause a highly compliant lung?

Answer 25

COPD/Emphysema

Question 26

What is the cause of non-elastic resistance?

Answer 26

Airflow 80% Viscous flow 20%

Question 27

What regulates mucous production?

Answer 27

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

Question 28

What is mucosal oedema?

Answer 28

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

Question 29

What conditions affect mucous secretion and how?

Answer 29

Chronic bronchitis (too much mucus produced by lungs) Cystic fibrosis [CFTR mutation aka Cystic Fibrosis Transmembrane Conductance Regulator)]( Cl- transport is constantly lost from the lungs and this results in hypertonic fluid in the lungs and thus an increase in mucus viscosity) Which makes ciliary clearance very difficult

Question 30

What controls air flow to airways?

Answer 30

Airway smooth muscle tone

Question 31

What receptor is activated to cause bronchodilation?

Answer 31

Beta-2 adrenergic receptor

Question 32

What receptor is activated to cause bronchoconstriction?

Answer 32

Muscarinic cholinergic receptor activation Histamine H1 receptor activation

Question 33

What controls bronchial resistance under normal circumstances?

Answer 33

Primarily the parasympathetic NS.

Question 34

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

Answer 34

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

Question 35

What causes airways to constrict reflexively?

Answer 35

Inhalation of smoke, dust, chemical irritants Arterial hypercapnia Cold Pulmonary emboli

Question 36

What causes airways to dilate reflexively?

Answer 36

Arterial hypertension (carotid sinus reflux)

Question 37

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

Answer 37

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

Question 38

What do beta 2 agonists do?

Answer 38

Cause bronchodilation

Question 39

What do beta 2 antagonists do?

Answer 39

Bronchoconstriction

Question 40

What local factos control bronchodilation?

Answer 40

O2 and CO2

Question 41

How is resistance measured in pulmonary tract?

Answer 41

Peak Expiratory Flow (FEV1) Forced Expiratory Volume in 1 second FEV1/FVC(Forced Vital Capacity) Flow-Volume Loops

Question 42

What is FVC?

Answer 42

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

Question 43

What measures are normal for FEV1/FVC?

Answer 43

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

Question 44

What is positive flow on a volume-flow plot?

Answer 44

Air coming into lungs

Question 45

What is negative flow on a flow-volume plot?

Answer 45

Air leaving the lungs

Question 46

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

Answer 46

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.

Question 47

What is PIF on the Flow-Volume Plot?

Answer 47

Peak inspiratory flow

Question 48

What can go wrong with ventilation?

Answer 48

Respiratory muscles can fail Restrictive diseases Obstructive diseases

Question 49

What do restrictive diseases do?

Answer 49

Decrease compliance

Question 50

What do obstructive diseases do?

Answer 50

Increase resistance

Question 51

What is the difference between restrictive lung disease and obstructive lung disease? MAKE SURE YOU KNOW THIS

Answer 51

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

Question 52

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

Answer 52

Yes

Question 53

What type of diseases are obstructive lung disorders?

Answer 53

Asthma COPD Cystic fibrosis Bronchiolitis Bronchiectasis

Question 54

What type of diseases are restrictive?

Answer 54

Having a lobectomy Pregnancy Pulmonary fibrosis

Question 55

What are some common features of restrictive lung defects?

Answer 55

Loss in lung volume Abnormalities of structures surrounding the lung Weakness of inspiratory muscles Abnormalities of lung parenchyma

Question 56

What does Flow-Volume look like in healthy individuals?

Answer 56

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

Question 57

What happens to the flow in obstructive lung disease?

Answer 57

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

Question 58

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

Answer 58

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

Question 59

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

Answer 59

Reduction in TLC

Question 60

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

Answer 60

Reduced FEV1/FVC