PL3 - control of breathing :: brain stuff and chemoreceptors Flashcards
What area regulates volitional and emotional control of breathing?
Someone is having an anxiety attack and is hyperventilating which area is most likely causing this?
The supra-pontine sites
Located above the pons – can surpass the respiratory areas in the pons and the medulla and act on the muscles directly
Hyperventilation
Hypoventilation
Hyperventilation – breathing in excess of metabolic needs
Hypoventilation – Breathing thats insufficient to meet metabolic needs
What is the nucleus tractus solitarius closely associated with?
The dorsal respiratory group (DRG)
What are the main respiratory areas in the pons and the medulla?
Medulla – pneumotaxic and apneustic center
Pons – DRG and Ventral Respiratory Group (VRG)
What are the pneumotaxic and apneustic center responsible for?
Pneumotaxic – consists of parabrachial neurons. – helps with the transition from inspiration to expiration – inhibits inspiration so expiration can begin
Apneustic center – Responsible for prolonged inspiration (apneusis)
What are the structures associated with the DRG and the VRG and what is their role in respiration?
DRG:
- Nucleus tractus solitarius – receives info from a variety of receptors and sends signals to trigger inspiration.
VRG:
- Botzinger complex: controls expiration
- Pre-botzinger complex: Consists of pacemaker neurons. Sets the normal respiratory rate (eupnea = 12-16 bpm)
- Nucleus retroambiguus: Contains both inspiratory and expiratory neurons
- Nucleus Ambiguus: Responsible for inspiration. controls soft palate+uvula+some pharynx and larynx muscles
- Parafacial respiratory group (pFRG): Responsible for expiratory control especially during forced expiration
- RTN: Principle chemosensitive site
- Post inspiratory complex (PiCO) : located in ventromedial pons — involved in post-inspiratory rhythm generation
What is the function of the pontine respiratory group (PRG)?
Fine tune respiration and important in laryngeal motor control
What is the negative feedback control of the respiratory system dependent on?
Oxygen and acid-base homeostasis
_____________ can be adjusted on a breath-by-breath basis in tune with whole-body metabolism
Alveolar ventilation can be adjusted on a breath-by-breath basis in tune with whole-body metabolism
True or false:
The supra-pontine sites can surpass the respiratory centers when regulating control.
True – they can directly act on the muscles thru the motor neuron pathways
Hyperpnoea
Hyperpnoea – Increased breathing that matches metabolic needs such as during exercise
Tachypnoea
Tachypnoea – Increased resp rate above normal (12-20 breaths pm) often rapid and shallow
Dyspnea
Dyspnoea - Labored breathing (its a symptom with multiple causes)
Apnoea
Apnoea - Absence of airflow due to lack of respiratory effort or airway obstruction
When do abdominal muscles contribute to breathing?
They play a role during active breathing
– They contribute during the late expiratory phase
What are the 3 main oscillators that regulate respiration
- preBötzinger complex [preBötC],
- post-inspiratory complex [PiCo]
- parafacial respiratory group [pFRG]
Muscles modulating airway resistance during respiration and when do they fire during quiet breathing?
Located in the larynx:
- Posterior cricoarytenoid (dilation of airways)
- Thyroarytenoid (constriction of airways)
PCA fires in the inspiratory phase
TA fires in the post-inspiratory phase
Which resp. group (DRG/VRG) consists of:
- Only inspiratory neurons
- Both inspiratory and expiratory neurons
- DRG
- VRG
Which region in the brain is responsible for the following:
- Sets the inspiration rate
- Putative rhythm post-inspiratory generator
- drives active expiration
- Contains pacemaker neurons
- Fine tune respiration and are important in laryngeal motor control
- Principal chemosensitive site
- expiratory control especially during hypercapnia
- primary integrative site
- Prebotzinger complex
- PiCo (post-inspiratory complex)
- pFRG (parafacial respiratory group)
- Prebotzinger complex
- PRG (pontine respiratory group)
- RTN (retrotrapezoid nucleus)
- pFRG
- NTS (nucleus tractus solitarius) - (DRG)
Btozinger complex
expiratory complex
Pre-botzinger
Inspiratory
Principal rhythm generator
– has pacemaker neurons
– Sets principal inspiratory rate
PiCO
Post inspiratory complex
– post-inspiratory
– putative rhythm generator
RTN (retrotrapezoid nucelus)
principal chemosensitive site (for CO2 chemoreception)
PRG
Pontine respiratory group
– fine tunes respiration
– important in laryngeal motor control during breathing
pFRG
Parafacial respiratory group
– Main center in active respiration
– Quiescent rhythm generator
– active especially during hypercapnia
Inspiratory phase is critical for _________ .
Activates obligatory and accessory muscles.
Upper airway dilation facilitates airflow.
Early expiratory (post-inspiratory) phase is critical to the ________________.
____________ protects FRC.
Late expiratory phase is essential to ___________
________________________ facilitates large
tidal volume.
Inspiratory phase is critical for ventilation.
Activates obligatory and accessory muscles.
Upper airway dilation facilitates airflow.
Early expiratory (post-inspiratory) phase is critical to the “braking” of expiratory flow.
Laryngeal narrowing protects FRC.
Late expiratory phase is essential to active
breathing.
Abdominal muscle recruitment facilitates large
tidal volume.
_______ is a nexus in central CO2
chemosensitivity
RTN
What do central chemoreceptors respond to?
- Local increases in H+ conc.
- Increases in PCO2
—-> IN THE CEREBROSPINAL FLUID
What do peripheral chemoreceptors respond to?
Changes in PO2, PCO2 and pH (blood acidosis by metabolites)
Which chemoreceptors account for the majority of the ventilatory response to hypercapnia?
the central chemoreceptors (account for 70%)
While peripheral accounts for 10-30%
acidaemia
Blood acidosis
What are the 2 peripheral chemoreceptors - where located? Which one is more important? Which nerves do they send signals via?
- Carotid bodies and aortic bodies
- In carotid artery at dilation - carotid sinus
- In aortic arch
– carotid bodies more important
carotid - glossopharyngeal
Aortic – vagus
When is alveolar ventilation greater - sleep or awake? how does this affect PCO2?
Awake
- increases Pco2
Alveolar hypoventilation results in a respiratory _______
Alveolar hyperventilation results in a respiratory _______
acidosis
alkalosis
primary mechanism for defending the airway from aspiration of liquids?
The laryngeal chemoreflex
When is the laryngeal chemoreflex especially powerful? What is its response to liquid in larynx? What could it lead to?
in early-life
Central apnea and laryngeal adduction are key features of this reflex in response to liquid in the airways.
Can lead to fatal-apneoa – (sudden death syndrome)
Laryngeal chemoreflex?
- Defends airway against aspiration of liquids
- Causes laryngeal adduction and central apnoea
Laryngeal chemoreflex?
- Defends airway against aspiration of liquids
- Causes laryngeal adduction and central apnoea
Thermoreceptor, mechanoreceptor and
chemoreceptor afferent feedback is
relayed centrally via which nerves?
Trigeminal, vagus and glossopharyngeal
Which reflex prevents lungs from over inflating and signals start of expiration?
Hering-breuer reflex
Which receptors are triggered by fluid accumulation in the lungs/oedema?
The J-receptors
What is the result of a muscle reflex activated due to increased exercise on breathing? What is this reflex activated by?
Hyperpnea – increased breathing to match metabolic needs.
Stimulus: stretch of muscles, tendons, movement of joints
Sensors: GTO, Spindles, proprioreceptors.
