Lecture 30. Control of Respiration Flashcards
What is external respiration?
Exchange of oxygen and carbon dioxide between an organism and external environment
What is breathing?
The act of muscle contraction/relaxation to move air in and out of the lung
What is ventilation?
Movement air from outside to inside the body for exchange of gas between air in the lungs and blood in capillaries within the alveoli
What are ventilation and breathing different aspects of?
External respiration
What are the 3 aspects to the central control of breathing?
Voluntary/behavioural
Reflex/automatic
Emotional
What generates inspiratory rhythm?
preBötzinger Complex
What generates expiratory rhythm?
Parafacial respiratory group
What coordinates the reflex/automatic control of breathing?
Ventral respiratory column
Where does voluntary control of breathing originate from?
Motor complex
When can voluntary control not be maintained?
When stimuli such as PCO2 or H⁺ become too intense
When can emotional control of breathing still occur?
In sufferers of locked in syndrome
What type of control does not occur in locked in syndrome?
Volitional control
Where does emotional control of breathing arise?
Through corticospinal projections
How is feedback patterned?
Via feedback mechanisms
What does excess CO₂ lead to?
Acidification
What is a potent regulator of breathing?
Hypercapnia
What modulates breathing to a lesser degree than hypercapnia?
Hypoxia
What do peripheral chemoreceptors detect?
Alterations in blood gases – predominantly oxygen
Where are carotid bodies situated?
Close to bifurcation of common carotid arteries in the neck
Where are aortic bodies situated?
Close to aortic arch
What do central chemoreceptors detect?
Alterations in blood gases – predominantly carbon dioxide
Where are central chemoreceptors mainly located?
In medulla oblongata but can be in other brain structures
What do central chemoreceptors respond to?
Changes in cerebrospinal fluid
What monitors lung inflation?
Slowly adapting pulmonary stretch receptors
What monitor irritants?
Rapidly adapting pulmonary stretch receptors
What are examples of monitoring irritants?
Promote cough in trachea and larynx
Promote sighing due to gradual collapse of lungs (atelectasis): ~5 minutes.
Why do lungs require compliance?
So that they may inflate and deflate
What is compliance?
Ability to expand lungs at any given change in (Pₜₚ)
What are the two major determinants of lung compliance?
- “Stretchability” of tissues
- Surface tension within alveoli
What lowers surface tension and increases compliance?
Pulmonary surfactant within alveoli
When is pulmonary surfactant released and where?
Pulmonary surfactant is released from type II alveolar cells during sighing
What do deficiencies in the foetal lung in premature babies result in?
Respiratory distress syndrome of the newborn
What are protective reflexes?
Responses that protect the respiratory system from irritants
What causes the cough reflex?
Due to receptors in epithelial cells of upper airway
Air speed of 960 km·h⁻¹
What causes the sneeze reflex?
Due to receptors in epithelial cells of nose or pharynxAir speed of 160 km·h⁻¹
