Respiratory Control Flashcards
When it comes to breathing, what does the brain control?
- Frequency of breathing
- Pattern of breathing (depth of breathing)
PA is what?
alveolar blood pressure
Pa is what?
Arterial BP
What is the controller of our respiratory control?
Medullary centers
What are the effectors of our respiratory control?
Skeletal muscle
-Diaphragm, external intercostal muscles, internal intercostal m, abdominal m.
The effectors are regulated by what?
Controlled variables
Medullary centers control—> _________, which are regulated by _________. Changes are then determined by our ________ and sent to _________.
Medullary centers control effectors, which are regulated by our controlled variables. Changes are then picked up by our sensors and then sent back to the medullar centers.
What are our respiratory medullary centers?
- DRG- dorsal respiratory group
- VRG- ventral respiratory group
- PRG- pontine respiratory group
- Botzinger complex
5. Pre-botzinger complex.
—–All are bilateral——
Where is our VRG (ventral respiratory group) located?
What type of neurons does it consist of?
Located medullary: run from the begining of brain stem–> pons.
Consists of inspiratory and expiratory neurons .
Where is the DRG located and what type of neurons does our DRG consist of?
-Medullary
Inspiratory neurons
Where is the PRG located?
What type of neurons do our PRG consist of?
- Pons
-IE neurons
Where is the Botzinger complex located?
What type of neurons does it consist of?
it sits on top of the VRG
E neurons (expiratory neurons)
Where is the pre-betztinger complex located?
Medullary: between the rostral end of the VRG and the Botzinger complex.
What is the most important medullary respiratory center?
Pre-botzinger complex.
When we look at the respiratory control center, what must the brain determine?
- Timing (frequency of breathing)
- Depth of breathing (do we need to increase or decrease depth of breathing)
& convey these signals —> motor neurons.
What areas determine our frequency (timing of breathing)? What is their role?
Pre-botzinger–> generates our core rhythm
PRG–> controls how long we inspire for (activity –> turns off inspiration)
Another name for the pre-betzinger complex is what?
Central pattern generator
(generates our pattern of breathing)
Is the pre-botzinger region the only region that plays a role in determining the frequency of breathing?
No.
But in bbs and fetuses, it is the most important.
In determing the frequency of breathing, what factors are important?
- Determine how long inspiration and expiration are.
- Transition from expiration and inspiration
Damage of the pontine respiratory group (PRG) causes?
A problem with the transition of breathing called apneusis.
Apneusis–> we cannot turn off inspiration without activating our vagus nerve. Thus, we are stuck in apneusis.
Apneusis occurs when there is damage to the PRG and we are stuck in inspiration. How do we stop this?
Activate the vagus nerve.
What is the role of the PRG?
It determines the length of inspiration, under normal conditions.
So; what determines the timing (frequency of breathing)?
- Pre-botzinger complex
- PRG
What determines the depth (pattern) of breathing?
- VRG- depth
- DRG- depth of breathing (tidal volume)
Role of the DRG
- Controls depth of breathing (tidal volume)
- 95 of pre-motor neurons in the DRG sends sensory information –>
- phrenic nucleus* in the spinal cord–>
+ phrenic N motor neurons –>
CONTROL PATTERN OF BREATHING (ex. slow, deep breath, etc).
Role of VRG
Rostral part of VRG fire during inspiration; premotor neurons–> inspiratory muscles* and phrenic n-
Caudal part of the VRG will fire during expiration; premotor neuons –> upper airway and expiratory muscles
Name this disorder:
- Appearance: Maintain inspiratory discharge
- Results from:* pontine damage
- Effects*: Increase in CO2, decrease in O2;
Apneusis
What effects will we see with apneusis?
Increase CO2
Decrease O2
What is apnea?
- Appearance
- Results from
- Effects
Appearance- No respiratory effort (no inspiration)
Results from- damage from medullary or spinal cord
Effects: increase CO2 and decrease O2= drop in pH
What are our control variables in respiratory control
CO2
O2
pHa
How can we determine how changes in CO2, O2, pHa will affect respiratory control?
Gas exchange
VE= f *VT
What are our sensors in respiratory control?
Chemoreceptors
What is a chemoreceptor?
a neuron specific to chemicals: CO2, O2, H+.
Changes in the concentration of these will alter the firing rate of the chemoreceptor.
How will a increase in CO2 affect firing?
Increase firing
How will a decrease in O2 affect firing?
Increase firing
How will a increase in H+ ions affect firing?
Increase firing
What is the NORMAL response of a respiratory neuron to an increase in CO2 or a decrease in O2?
Shut down: decrease activity and decrease ventillation.
Ex. when a little kid holds in breath, they will pass would
Chemoreceptors act to override this
How do chemoreceptors act, compared to our normal respiratory neurons?
They are designed to act the exact opposite: they will increase their rate of activatity during hypoxia or hypercapnia.
–> Activate respiratory centers
–> + respiration
What are the 2 sets of chemoreceptors?
- Central chemoreceptors (in the brain)
- Peripheral chemoreceptors (in carotid and the aorta)
Each has a different role when controlling ventillation.
Central chemoreceptors
- Where are they located?
- What are they sensitive to?
- Ventral surface of the medulla
- Respond indirectly to changes in Co2 in the blood. They are directly sensitive to H+ because as CO2 crosses the BBB, it reacts with water and carbonic anhydrase to form H+ and HCO3-.
This causes a decrease in pH.
-They make us breathe regularly-
Peripheral chemoreceptors. Tell me about them
2 locations: carotid body and aortic arch. The main ones are located in the carotid body (where dopamine plays an important role). If damaged, the peripheral receptors in the aortic arch werk.
Sensitive to: O2, CO2, H+.
Are changes in O2 detected by central chemoreceptors?
No
What do peripheral chemoreceptors send signal to?
They relay message to the brain and increase firing in pre-botzinger and DRG.
INCREASING f and Vt
How do CO2 and pH stimulate central and peripheral chemoreceptors differently?
Cause the same response,
but it is quicker than central .
Besides our chemoreceptors, what are other sensors?
Pulmonary stretch receptors - respond to changes in the lung volume and are mostly concerned with changes in tidal volume
Slowly adapting pulmonary receptors
Located:
Sensitive to:
Fibers go to:
Effect:
Located: airways
Sensitive to: stretch of the airway (Directly prop to lung volume)
Fibers go to: brain via vagus n.
Effect: inhibit inspiration and prolong expiration
Slowly adapting pulmonary stretch receptors are important for controling respiration (tidal volume) in:
Infants (all the time)
Adults during excersise (NOT active at rest)
Rapidly adapting pulmonary receptors
Located:
Sensitive to:
Fibers go to:
Effect:
Located: airways
Sensitive to: irritation, foreign bodies in the airway, EXCESSIVE stretch
Fibers go to: brain via vagus nerve
Effect: COUGH to get ride of the irritant
IMPORTANT FOR PROTEXTING THE GAS EXCHANGE SURFACES
Is cough elicited by the receptors in the larynx the same from this reflex?
no.
v. different .
J (juxtacapillary) receptors
Located:
Sensitive to:
Fibers go to:
Effect:
Located: near BV of alveoli
Sensitive to: pulmonary edema
Fibers go to: brain via vagus nerve
Effect: dry cough, tachypnea
Why are RAR and Jreceptors important for survival?
They cause PROTECTIVE reflexes that overide the normal respiratory control system.
What is our fail safe is something goes wrong with the medullary ?
Cortical influences
What is the role of cortex on breathing.
Control breathing (talking, holding breath).
It bypasses the medullary centers completley and send input DIRECTLY to muscles of respiration.
How can we solve for apneusis (damage to our PRG, which causes prolonged expiration)?
We want to turn off inspiration. To do so, we want to activate our vagus nerve.
To solve, we want to activate our SLOW-ADAPTING PULMONARY RECEPTORS (inhibit inspiration and prolong expiration).
