L25 Lung Disease And Control Of Respiration

Question 1

What are the two categories of lung diseases?

Answer 1

• Obstructive - Aiways have become narrowed or blocked, making it harder to breathe out
• Restrictive - These conditions limit the expansion of the lung, reducing the amount of air that can be inhaled

Obstructive - struggle to breathe out
Restrictive - struggle to breath in

Question 2

What does a flow-volume relationship show you?

Answer 2

Shows the relationship between the airflow speed (flow) and lung volume during a forced exhalation and inhalation

Question 3

What would a flow - volume graph look like?

Answer 3

• Exhalation = positive. Steep increase until it reaches peak expiratory flow and then slow decreases
• Inhalation = negative, steady decrease and then sharp increase back to 0

Question 4

What does FEV mean?

Answer 4

Forced expiratory volume - measures the amount of air a person can exhale during a forced breath within a second

Question 5

What does VC mean?

Answer 5

Vital capacity- the maximum amount of air a person can expel from the lungs after a maximum inhalation

Question 6

What would a volume time graph look like during FEV and CV?

Answer 6

Sharp increase for 1 second (this is FEV) and then a little increase and plateau for VC

Question 7

What are the potential reasons for the narrowing of airways?

Answer 7

1) Inflammation
2) Excess secretions (mucus)
3) Bronchoconstriction (tightening of bronchi and bronchioles) - asthma

Increased resistance to the flow of air

Question 8

What is the difference between normal and obstructive spirometry?

Answer 8

Decrease FEV1

FVC and FEV would be similar in a normal one but FEV in obstructive would approximately be half of the FVC

Question 9

What would the difference be in a normal and an obstructive volume-time graph?

Answer 9

• Shape in obstructive would be less steep compared to normal graph
• Takes longer to exhale a given volume of air
• FVC is unaltered but decrease in FEV1

Question 10

What would the difference be in a normal and an obstructive flow volume loops?

Answer 10

• Negative side of the graph would be the same since it represents inhalation
• Positive side of the graph would be a sharper decrease for obstructive flow

Volume on X
Flow on Y

Question 11

What part of the flow-volume loop is represented below the x axis (the negative deflection)?

Answer 11

Negative deflection represents inspiration

Negative flow: Represents air moving into the lungs

Question 12

What is ‘flow’ in the lungs?

Answer 12

Flow refers to the speed at which air moves in and out of the lungs

• Inhalation: Air flows into the lungs
• Exhalation: Air flows out of the lungs

Question 13

What does positive and negative flow mean?

Answer 13

• Positive flow: Represents air moving out of the lungs (exhalation)
• Negative flow: Represents air moving into the lungs (inhalation)

Question 14

What are the most common obstructive diseases?

Answer 14

• Chronic Obstructive Pulmonary Disease (COPD) - structural changes
• Chronic Bronchitis - excessive mucus production
• Emphysema - alveoli walls damaged which leads to loss of elasticity

Question 15

What is asthma?

Answer 15

Chronic lung diseasae that causes inflammation and narrowing of the airways in the lungs. Characterised by hyper-active airways

Question 16

What can trigger asthma?

Answer 16

• Atopic (extrinsic) - contact with inhaled allergens
• Non- atopic (instrinsic) - Respiratory infections, cold air, stress, exercise, drugs

Question 17

How does the body responds to an asthma trigger?

Answer 17

The movement of inflammatory cells into the airways, triggers immune system to release inflammatory mediators such as histamine and subsequent bronchoconstriction to minimise any extra inhaled ammount of allergens

Question 18

What are the short and long acting treatments for asthma?

Answer 18

• Short acting - β2-adrenoreceptor agonists - salbutamol. Causes dilation of airways
• Longer acting - Inhaled steroids. Glucocorticoids such as beclometasone, act to reduce the inflammatory responses

Question 19

What are two features of restrictive lung disease?

Answer 19

• Reduced chest expansion: Causes: chest wall abnormalities or muscle contraction deficiencies
• Loss of compliance: Causes: normal aging process, increase in collagen and exposure to environmental factors

Question 20

How would a restrictive lung disease spirometry look different?

Answer 20

Reduction in VC because limits the ability of the lungs to fully expand

Question 21

How would the volume-time curve differ for a restrictive lung disease?

Answer 21

• Reduction in FVC due to limited lung expansion but FEV1 ratio can remain unaltered or even increase
• Plataeu lower because less volume inhaled/exhaled

Question 22

How would the flow-volume loop differ for a restrictive lung disease?

Answer 22

The shape of the relationship tends to be normal but there is a reduction in the volumes of air inhaled/exhaled so line would intersect x axis closer to origin than normal since less volume (volume is on x axis)

Question 23

What is asbestos?

Answer 23

Slow build-up of fibrous tissue leading to a loss of compliance

Question 24

What does DRG stand for?

Answer 24

Dorsal respiratory group

Question 25

What is Dorsal respiratory group?

Answer 25

Controls inspiration by sending signals to the inspiratory muscles

Question 26

What does VRG stand for?

Answer 26

Ventral respiratory group

Question 27

What is ventral respiratory group?

Answer 27

• Controls inspiration and expiration
• Inactive during quiet respiration
• During activation, it helps control forceful inspiration and expiration

Question 28

When is there a sudden increase in the number of active inspiratory neurons?

Answer 28

During inspiration and dramatically drops during passive expiration

Question 29

What are the two main respiratory control centres in the brain stem?

Answer 29

• Pons respiratory centers
• Medullary respiratory centers

Question 30

What are the two main medullary respiratory centers?

Answer 30

• Dorsal respiratory group (DRG)
• Ventral respiratory group (VRG)

Question 31

What are the two main pons respiratory centers?

Answer 31

• Pneumotaxic center
• Apneustic center

Question 32

What does the pons respiratory centers do?

Answer 32

Two centers in the Pons send stimuli to the medulla to regulate rate and depth of breathing

Question 33

What does pneuomotaxic center do?

Answer 33

Increases the rate by shortening inspirations

Inhibitory effect on inspiratory centre

Question 34

What does the apneustic centre do?

Answer 34

Increases the depth and reduced the rate by prolonging inspirations

Stimulates inspiratory centre

Question 35

Describe the feedback mechanism of the Hering-Breuer reflex

Answer 35

1) Stretch receptor in lungs during inhalation
2) Receptor sends signals via the vagus nerve
3) Inhibit the inspiratory centre which leads to shortening of inspiration and prolongs expiration
4) Lungs deflate during exhalation so stretch receptors are deactivated

Helps prevent overinflation of the lungs

Question 36

What do central chemoreceptors do?

Answer 36

Monitors carbon dioxide and pH

Increases ventilation

Question 37

Where are peripheral chemoreceptors located?

Answer 37

Carotid body and aortic bodies

Question 38

What do peripheral chemoreceptors respond to?

Answer 38

Increase in CO2
Decrease in pH
Decrease in oxygen

Increases ventilation

Question 39

Where are the DRG and VRG located?

Answer 39

Medulla oblongata