Control of ventilation Flashcards
Minute ventilation=?
breathing frequency x tidal volume
minus dead space
=about 3.5L/min at rest
What three situations might increase the amount of breathing?
- Exercise
- Altitude
- Disease
What makes up the respiratory centre?
The medulla oblongata and the pons
Does the pons regulate the medulla or does the medulla regulate the pons?
Pons regulates the medulla
What are the two parts of the pons?
Pneumotaxic centre and the apneustic centre
What are the two parts of the medulla?
Dorsal respiratory group and ventral respiratory group
What does the pneumotaxic centre do?
Inhibits the DRG
What does the apneustic centre do?
Stimulates the DRG
What does the DRG do?
Causes inspiration.
What does the VRG do?
Initiates inspiration and expiration, only in use during exercise/time of increased ventilation
What is the relationship between the DRG and VRG?
Reciprocal inhibition- they inhibit each other creating rhythmical breathing.
Which nerves run from the DRG and VRG to innervate the diaphragm and intercostal muscles?
Phrenic and intercostal nerves
What are 9 ways the respiratory centre can be controlled?
- Overriden by cortical control
- Hypothalamus- emotional or sensory reflex (pain/cold) stimuli
- Central chemoreceptors
- Peripheral chemoreceptors
- Pulmonary stretch receptors
- Irritant/cough receptors
- Muscle/joint stretch receptors
- Baroreceptors
- J-receptors
Where are pulmonary stretch receptors located?
Bronchi and trachea
Where are irritant/cough receptors located? What does stimulation of them do?
Throughout the airways. Cough receptor = cough (explosive exhalation) and irritant recpetor= hyperpnoea, airway constriction.
What afferent nerve runs from the pulmonary stretch receptors and irritant/cough receptors to the medulla?
Vagus nerve
Where are the muscle/joint receptors and proprioceptors located?
Diaphragm, intercostal and other muscles (exercise)
Where are baroreceptors located? What do they sense?
Blood vessels, sense blood pressure (high BP= low ventilation)
Where are J receptors located? What do they sense?
Next to alveolar capillaries, sense ‘trauma’ e.g. pneumonia, pulmonary oedema, inflammatory agents and increase ventilation in response.
Where are peripheral chemoreceptors located? What do they sense?
Carotid artery and aorta, sense hypoxia, hypercapnia and acidosis
Which cell senses hypoxia? How?
Glomus cell. Hypoxia causes an influx of Ca2+ via depolarisation. This triggers the release of neurotransmitters which stimulate an action potential in the afferent nerve.
Where are central chemoreceptors located? What do they measure?
Near the medulla and also near a rich blood supply. They measure H+ levels by measuring CO2 levels (as this can cross the BBB whereas H+ can’t)
