Pulmonary 8 - Lecture 30 Flashcards
What are the 3 phases of breathing?
- Inspiratory Airflow
- Expiratory Airflow
- Expiratory Apnea
What happens to the frequency of breathing during exercise? Tidal Volume?
Frequency increases due to a decrease in pause time
- Tidal Volume increases by accessing the inspiratory reserve and expiratory reserve capacities
Is breathing automatic or voluntary?
BOTH
Automatic via Medulla
Voluntary via Motor Cortex (CST)
ex: hypo/hyperventilation
Where is the respiratory control center located?
The medulla
What respiratory group of the MEDULLA controls inspiratory neurons only? Both inspiratory and expiratory?
- Dorsal Respiratory Group (DRG)
= inspiration only
- N. Solitarius - Ventral Respiratory Group
- BOTH inspiration & expiration
What part of the brain GENERATES the breathing Pattern? What part of the brain CONTROLS the breathing pattern?
- Medulla
2. Pons
What are the functions of the
- Apneustic Center
- Pneumotaxic Center
Which part of the brainstem do these neurons belong to?
- Apneustic = excitatory effect on DRG (inspiration)
2. Pneumotacic = inhibits DRG
suppresses inspiration
Describe the following for CENTRAL chemoreceptors:
- Location
- Sensitive to changes in what?
- Insensitive to changes in what?
BBB:
- Permeable to
- Impermeable to
- Ventrolateral surface of Medulla Oblongata
- Sensitive to CO2 changes via pH changes in CSF
- Insensitive to pO2 changes
- permeable to CO2
- Impermeable to H+ and HCO3-
Why is the CSF so sensitive to changes in pCO2?
CSF has relatively low protein concentration so the decrease in pH and increase in CO2 is easily detected by the CSF chemoreceptors (more favorable environment than arterial CO2)
- pCO2 changes within minutes
Reducing the pH of CSF increases or decreases firing rate?
Increases firing rate
Describe the following for PERIPHERAL chemoreceptors:
- Location
- Sensitive to changes in what?
- Insensitive to changes in what?
- Aortic/Carotid Bodies
- Sensitive to:
decrease in pO2
decrease in pH
increase in pCO2 - Hb concentration does not change the firing of peripheral chemoreceptors, only change sin partial pressures of dissolved O2 or CO2 generate a response
- low proportion of total ventilation response to CO2 (only 20-40%)
What are the only receptors that respond to changes in pO2?
When does robust firing of pCO2 occur? (what pO2 level)
Peripheral Chemoreceptors
- firing begins at small changes in pO2
ROBUST firing begins when pO2< 70-80 mmHg
Where are Pulmonary Stretch Receptors Located?
What inhibits and initiates respiratory activity in the Receptors?
(Hering- Breuer Inflation/Deflation Reflex)
How is this response generated? (via what nerve)
- Smooth muscle cells of airways
- INFLATION of lung inhibits activity of inspiratory muscles
DEFLATION of lung INITIATES activity
- Respond via VAGAL NERVE
- Hering- Breuer Inflation & Deflation Reflex*
- -> largely inactive in adults, except at HIGH TIDAL VOLUMES
- important in newborns
Describe the following for Irritant Receptors:
1. Location
2. Stimulated by
3. What nerve does the impulse travel via?
Clinical correlates?
- Between airway epithelial cells
- Stimulated by NOXIOUS gases, cigarette smoke, dust, and cold air
- Impulse via VAGUS nerve (just like the stretch receptors)
- May play a role in ASTHMA
What do J (Juxtacapillary) Receptors & Bronchial C fibers respond to?
Respond to chemicals injected into the pulmonary (J receptors) & Bronchial (C fiber circulation)