Regulation of Respiration Flashcards
What are the 5 major respiratory centers
- Dorsal Respiratory group (DRG)
- Ventral Respiratory group (VRG)
- Pontine respiratory group (PRG)
- Botzinger complex (BotC)
- Pre-botzinger complex
What are the functions and locations of the medullary respiratory centers? What are they?
These center initiate breathing and are located in the reticular formation of the medulla
- Dorsal respiratory group (DRG)
- Located in the nucleus of the tractus solitarius
- The Ventral respiratory group (VRG)
What respiratory center is located in the nucleus of the tracts solitaries
The Dorsal Respiratory Group (DRG)
What are the two Pontine respiratory centers
(located in the pons)
- The Apneustic
- The Pneumotaxic center (Pontine respiratory group PRG)
The brain controls both the ______ of breathing and the ______
frequency, pattern
The two pontine respiratory centers mainly control
rate and depth of breathing
explain the inspiratory “ramp” signal
Established by the DRG (Dorsal Respiratory Group) the nervous signal that is transmitted to the inspiratory muscles is not an instantaneous burst of action potentials . Instead, it begins weakly and increases steadily in a ramp manner for about 2 seconds in normal respiration. Then it ceases abruptly for approximately the next 3 seconds, which turns off the excitation of the diaphragm and allows elastic recoil of the lungs and the chest wall to cause expiration.
The dorsal respiratory group is located in the
dorsal portion of the medulla
The Dorsal Respiratory group sets _______ of respiration
basic rhythm
Most of the neurons of the Dorsal respiratory group are in the
nucleus of the tractus solitarius (NTS) and medulla reticular substance
_____ is the sensory termination of both the vagal and glossopharyngeal nerves
NTS
NTS receives information from
- Peripheral chemoreceptors
- Baroreceptors
- Several types of receptors in the lungs
What are the principle initiators of the phrenic nerve activity
Dorsal respiratory group
Establishes ramp signal
Dorsal respiratory group
What is the primary function of the PRG (Pneumotaxic center)
Control the switch off point of the inspiratory ramp
A strong PRG signal results in ____ breaths per minute
30-40
A weak PRG signal results in _____ breaths per minute
3-5
Where is the Pneumotaxic center located
in the superior pons
lesions of the _____ influence respiratory timing
PRG
Lesion os the PRG result in
loss of the ability to turn off inspiration (without additional input from the vagus nerve)
Function of Pneumotaxic center
-mainly controls rate and depth of breathing
The Pneumotaxic center transmits signals to the
inspiratory center (DRG)
Where is the Apneustic respiratory center located
in the inferior pons
Loss of function to the apneustic center causes
prolonged inspiratory gasping (apneuses)
The normal function of the apneustic center may be to
limit lung expansion
______ is the failure to turn off inspiration
Apneusis
Where is the ventral respiratory center located
in the ventrolateral portion of the medulla
Neurons of the ventral respiratory center are found in the
retrofacial nucleus, nucleus ambiguous and nucleus retroambiguous
The postal part of the Ventral respiratory group is the ________ and may be associated with
Botzinger complex, coordinating VRG output
The intermediate part of the VRG is associated with
the dilation of the upper airway during inspiration
Neurons of the caudal region of the VRG synapse with motor neurons to the internal intercostal and other muscles used for
forced expiration
Neurons of the VRG are almost totally inactive during _________
normal quiet respiration
During increased pulmonary ventilation, respiratory signals spill over from the DRG into the VRG, which then contributes to the
increased respiratory drive
The rhetorical nucleus of the VRG contains expiratory neurons which form the ______
botzinger complex
What respiratory center neurons do not participate in the basic rhythmical oscillation that controls respiration
VRG
This is a small area in the rostral part of the VRG
Pre-Botzinger complex
Believed to be the site which generates the timing (frequency) of the respiratory rhythm (central pattern generator)
Pre-Botzinger complex
Deciding the length of _____ and _____ is important to determining frequency of respiratory rhythm
inspiration and expiration.
reflex that is a protective mechanism to prevent excess inflation of the lungs. it begins with stretch receptors in the muscular portions of the walls of the bronchi and bronchioles
Hering-Breuer inflation reflex
The Hering-Breuer inflation reflex pathway
stretch receptors in muscular portions of walls of bronchi and bronchioles —-> dorsal Respiratory group neurons —> cessation of inspiratory ramp
what is hypercapnia
increase in carbon dioxide levels
What is hypoxia
a decrease in oxygen levels
Hypercapnia and hypoxia lead to ______ activity in most neurons
decreased
Chemoreceptors _____ their rate of activity when hypoxia or hypercapnia occur
increase
What are the two types of chemoreceptors
- Central
- Peripheral
Central chemoreceptors are located
bilaterally 0.2 mm beneath the ventral surface of medulla
Sensitivity of central chemoreceptors
- Sensitive to H+
- H+ does not easily cross the blood-brain barrier
- CO2 does easily cross the blood-brain barrier
thus they are Indirectly sensitive to carbon dioxide levels in blood (based on pH)
Peripheral chemoreceptors include
- Receptors in the aortic arch
- Carotid body receptors
Peripheral chemoreceptors are sensitive to
concentrations of oxygen (especially), carbon dioxide, and hydrogen ions
Central chemoreceptors heightened sensitivity to increased levels of CO2 last for several hours but then begins to decline due to ____ adjustment to plasma pH
Renal
Heightened sensitivity to CO2 in central nervous system leads to what in the kidneys
kidneys will increase blood bicarbonate levels:
- reduces plasma and CSF {H+}
- Bicarbonate ions diffuse through the blood-brain barrier
Peripheral receptors are more sensitive to changes in ______ levels in the blood and less sensitive to changes in plasma concentration of ____ and _____
oxygen, carbondioxide and hydrogen ions
Locations of peripheral chemoreceptors
- Aortic arch (aortic bodies)
- At the bifurcation of the common carotids (Carotid bodies)
- (these are not the same as carotid baroreceptors)
What are the two types of carotid bodies
- Type I (glomus) cells
- Type II (sustentacular cells)
Type I (glomus) Carotid body cells
- chemosensors
- PO2 dependent K+ channels result in K+ efflux when PO2 is high, leading to hyper polarization of the cells
- decrease in PO2 closes channels and results in a depolarization that opens calcium channels, leading to neurotransmitter release
- located close to fenestrated capillaries
Type II (sustentacular) carotid body cells
-play a support role similar to glial cells
Carotid body receptors pathway
decrease pO2 leads to depolarization onto hering nerves—–> CN IX—–> DRG
Aortic bodies pathway
CNX—-> DRG
Chemoreceptors are exposed to PO2 of ______ blood not ____ blood
arterial blood not venous blood
___ and ____ are mainly responsible for regulating ventilation (at sea level) for PO2 between 60 and 80 mmHg
PCO2 and H+
where are slow-adapting pulmonary stretch receptors located
within the airways of the lungs
Slow-adapting pulmonary stretch receptors signals travel in the _____ to the ______
vagus nerves, medulla
Signals from slow-adapting stretch receptors actions
- terminate inspiration
- prolong expiration
Are slow-adapting pulmonary stretch receptors important in controlling tidal volume in adults at rest
probably not
slow adapting pulmonary stretch receptors are important in controlling respiration in
infants and adults during exercise
Where are rapidly-adapting pulmonary stretch receptors found
Within the airways of the lungs
Rapidly-adapting pulmonary stretch receptors are sensitive to
irritation, foreign bodies in airway, and stretch
Signals from the rapidly-adapting pulmonary stretch receptors travel in the _____ to the brain
vagus nerve
These stretch receptors override the normal respiratory control mechanisms and elicit cough
Rapidly-adapting pulmonary stretch receptors
Thesauri are sensory endings (C fibers) in the alveolar wall in juxtaposition to pulmonary capillaries
J Receptors
J receptors are sensitive to
Pulmonary edam (i.e. CHF)
Signals from J receptors travel to the brain via the
vagus nerve
stimulation of J receptors elicits
cough
Tachypnea
Does J receptor override the normal respiratory control mechanisms
Yes
