L25 Lung Disease And Control Of Respiration Flashcards
What are the two categories of lung diseases?
- 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
What does a flow-volume relationship show you?
Shows the relationship between the airflow speed (flow) and lung volume during a forced exhalation and inhalation
What would a flow - volume graph look like?
- 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
What does FEV mean?
Forced expiratory volume - measures the amount of air a person can exhale during a forced breath within a second
What does VC mean?
Vital capacity- the maximum amount of air a person can expel from the lungs after a maximum inhalation
What would a volume time graph look like during FEV and CV?
Sharp increase for 1 second (this is FEV) and then a little increase and plateau for VC
What are the potential reasons for the narrowing of airways?
1) Inflammation
2) Excess secretions (mucus)
3) Bronchoconstriction (tightening of bronchi and bronchioles) - asthma
Increased resistance to the flow of air
What is the difference between normal and obstructive spirometry?
Decrease FEV1
FVC and FEV would be similar in a normal one but FEV in obstructive would approximately be half of the FVC
What would the difference be in a normal and an obstructive volume-time graph?
- 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
What would the difference be in a normal and an obstructive flow volume loops?
- 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
What part of the flow-volume loop is represented below the x axis (the negative deflection)?
Negative deflection represents inspiration
Negative flow: Represents air moving into the lungs
What is ‘flow’ in the lungs?
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
What does positive and negative flow mean?
- Positive flow: Represents air moving out of the lungs (exhalation)
- Negative flow: Represents air moving into the lungs (inhalation)
What are the most common obstructive diseases?
- Chronic Obstructive Pulmonary Disease (COPD) - structural changes
- Chronic Bronchitis - excessive mucus production
- Emphysema - alveoli walls damaged which leads to loss of elasticity
What is asthma?
Chronic lung diseasae that causes inflammation and narrowing of the airways in the lungs. Characterised by hyper-active airways
What can trigger asthma?
- Atopic (extrinsic) - contact with inhaled allergens
- Non- atopic (instrinsic) - Respiratory infections, cold air, stress, exercise, drugs
How does the body responds to an asthma trigger?
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
What are the short and long acting treatments for asthma?
- Short acting - β2-adrenoreceptor agonists - salbutamol. Causes dilation of airways
- Longer acting - Inhaled steroids. Glucocorticoids such as beclometasone, act to reduce the inflammatory responses
What are two features of restrictive lung disease?
- 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
How would a restrictive lung disease spirometry look different?
Reduction in VC because limits the ability of the lungs to fully expand
How would the volume-time curve differ for a restrictive lung disease?
- Reduction in FVC due to limited lung expansion but FEV1 ratio can remain unaltered or even increase
- Plataeu lower because less volume inhaled/exhaled
How would the flow-volume loop differ for a restrictive lung disease?
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)
What is asbestos?
Slow build-up of fibrous tissue leading to a loss of compliance
What does DRG stand for?
Dorsal respiratory group
What is Dorsal respiratory group?
Controls inspiration by sending signals to the inspiratory muscles
What does VRG stand for?
Ventral respiratory group
What is ventral respiratory group?
- Controls inspiration and expiration
- Inactive during quiet respiration
- During activation, it helps control forceful inspiration and expiration
When is there a sudden increase in the number of active inspiratory neurons?
During inspiration and dramatically drops during passive expiration
What are the two main respiratory control centres in the brain stem?
- Pons respiratory centers
- Medullary respiratory centers
What are the two main medullary respiratory centers?
- Dorsal respiratory group (DRG)
- Ventral respiratory group (VRG)
What are the two main pons respiratory centers?
- Pneumotaxic center
- Apneustic center
What does the pons respiratory centers do?
Two centers in the Pons send stimuli to the medulla to regulate rate and depth of breathing
What does pneuomotaxic center do?
Increases the rate by shortening inspirations
Inhibitory effect on inspiratory centre
What does the apneustic centre do?
Increases the depth and reduced the rate by prolonging inspirations
Stimulates inspiratory centre
Describe the feedback mechanism of the Hering-Breuer reflex
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
What do central chemoreceptors do?
Monitors carbon dioxide and pH
Increases ventilation
Where are peripheral chemoreceptors located?
Carotid body and aortic bodies
What do peripheral chemoreceptors respond to?
Increase in CO2
Decrease in pH
Decrease in oxygen
Increases ventilation
Where are the DRG and VRG located?
Medulla oblongata
