Control of Respiration Flashcards
What directly determines the respiratory rate?
The interval between the discharges of successive groups of respiratory neural and innervation of respiratory muscles
What directly determines the depth of respiration?
The frequency of action potentials, duration of discharges and number of motor units activated
Where are the centers that regulate breathing located?
Located in the reticular formation of the medulla beneath the floor of the 4th ventricle
The dorsal respiratory neurons are located in what neural structure? What is the main functional type of neuron?
nucleus tractus solitaries; consists mainly of inspiratory neurons
What is the primary target of dorsal respiratory neurons? What is the general speculated function of the DRG?
Contralateral diaphragm; The DRG is probably the initial integratin site for many cardiopulmonary reflexes that affect respiratory rhythm
What are the components of the ventral respiratory groups?
The retrofacial nucleus, nucleus ambiguous, nucleus paraambigualis, and the nucleus retroambigualis
What is contained in the retrofacial nucleus? What is its function?
It mainly contains expiratory neurons in a group of cells called the Botzinger complex; Shown to inhibit the DRG inspiratory neurons
What are the targets of the nucleus ambiguous and nucleus para-ambigualis?
ambiguous- vagal motor neurons that innervate ipsilateral laryngeal, pharygeal, and tongue muscles; para- innervate contralateral inspiratory muscles
What are the targets of the nucleus retroambigualis?
One group mainly projects contralaterally to external intercostal muscles and diaphragm; another group projects within the medulla to other inspiratory and expiratory cells
What is the hypothesized location of the respiratory pacemaker? The “inspiratory cut-off switch”?
PreBotzinger complex in the ventral respiratory groups; apneustic center
What is apneusis? How could it be reproduced?
A breathing pattern with prolonged inspiratory efforts interrupted by occasional expirations; occurs with transection through the pons and vagal nerves
What is the function of the pontine respiratory groups
modulation of apneustic center activity— fine tuning of the breathing pattern
What three reflexes can be elicited by stimulation of the pulmonary stretch receptors? What is their afferent pathway?
The Hering-Breuer inflation reflex, Hering-Breuer deflation reflex and paradoxical reflex of Head; Vagus
What are the effects of the heuring-breuer inflation reflex?
Cessation of inspiratory effort, apnea or decreased breathing frequency; bronchodilation, Increased heart rate, slight vasoconstriction
What are the effects of the heuring-breuer deflation reflex?
Hyperpnea
What is the stimulus and effect of the paradoxical reflex of Head?
Lung inflation– inspiration
What is the response to negative pressure in the upper airway?
Contraction of pharyngeal dilator muscles
What is the response to mechanical or chemical irritation of airways?
Cough/sneeze; bronchoconstriction; increased blood pressure
What is the respiratory response to a pulmonary embolus?
Apnea or tachypnea
What is the respiratory response to pulmonary vascular congestion?
Tachypnea, possibly the sensation of dyspnea
What is the response to low PaO2, high PaCO2, or low pHa?
Hyperpnea, bronchoconstriction, dilation of the upper airway, decreased HR, vasocontriction
What is the respiratory response to increased systemic blood pressure?
Apnea, bronchodilation
What is the effect of increasing CO2 on alveolar ventilation? how does hypoxia affect this?
Increases ventilation; hypoxia potentiates this response
What is the stimulus that drives us to take the next breath?
High CO2
Which of the following can easily diffuse through the BBB: CO2, H+, HCO3-?
CO2
To what fluid are central chemoreceptors exposed?
CSF
What is the typical pH and PCO2 of CSF?
7.32; 50 mmHg
Why does arterial hypercapnia lead to greater changes in CSF [H+] than arterial blood?
Bicarbonate is the only buffer of consequence in the CSF
To what stimuli do central chemoreceptors respond?
Local increases in H+ or PCO2
Which chemoreceptors are responsible for establishing most of the resting ventilatory level?
Central
Which chemoreceptors are resposible for eliciting min to min adjustments in ventilation due to CO2?
Peripheral
How do arterial chemoreceptors monitor alveolar ventilation?
By detecting arterial PCO2, pH, and PO2
How would initial acidosis affect central and peripheral chemoreceptor ventilatory drive?
Increased peripheral drive and normal central drive
How does changes in plasma H+ concentration affect ventilation? What chemoreceptors are responding?
Ventilation increases almost linearly with increases in [H+]
Which specific chemoreceptors are most important in the ventilatory response to hypoxia?
Carotid body peripheral
