neural control of breathing Flashcards
what do the neurons in the brain - motor cortex and limbic system control
Voluntary Control of Respiration (eg breath-hold, sighing etc)
what do the neuron in brainstem/medulla, medulla rhythm generation control
Involuntary Control of Respiratory Rhythm
what do the neurons hypoglossal nerve, laryngeal nerve, carotid sinus nerve control
Chemical Modulation of Respiratory Rhythm
(peripheral Chemoreceptor Feedback)
Breathing Frequency &Volume
what does the neurons, vagus nerve, phrenic nerve, intercostal nerve, phrenic nerve control
Intercostal Respiratory Muscles
Diaphragm inspiration control
= Breathing Frequency &Volume
phrenic nerve controls contraction of diaphram
what are the muscles involved in respiration and what are they innervated by
Sternocleidomastoid = exercise
scalene = exercise
external intercostals
parasternal intercostals
innervated by intercostal nerves
Where does the diaphragm sit, and what is its shape? What nerves supply the diaphragm?
dome-shaped and sits above the liver.
phrenic nerves, originating from C3-5.
How does the diaphragm move during inspiration?
It flattens on contraction (increases chest volume) and moves 1 cm during quiet breathing, but can move up to 10 cm.
chest expands, and intrapleural pressure falls.
What nerves supply the external intercostal muscles?
The intercostal nerves at “rib level”
What are the accessory muscles involved in inspiration?
Sternocleidomastoid, scalenes, and others.
when do we do forced expiration
exercise, voluntary (cough,
sneeze, defaecation
what occurs during expiration
The abdominal wall muscles, including the Transverse abdominis and Rectus abdominis, push the guts up against the diaphragm.
The internal intercostals also assist in forced expiration
what is the cranial motorneurones important for
opening/closing glottis, affecting upper airway diameter, flaring nostrils
what 2 places does involuntarty breathing occur in the brain stem amd what are the neurons involved
pons respiratory centre - Pneumotaxic center
Apneustic center
medulla respiratory centre -
Pre-Bötzinger complex
Dorsal Respiratory Group (DRG)
Ventral Respiratory Group (VRG)
where is the dorsal resp group located
within the Nucleus
tractus solitarius and is dorsal to the VRG
What is the role of the dorsal resp group
PRIMARILY AFFERANT
- inspiratory control
- site of sensory information
- site of central chemoreceptor input
- some premotor neurons
where is the ventral resp group located
Spans 3 regions within medulla – rostral, intermediate & caudal
what does the ventral resp group do
PRIMARILY EFFERENT
- contains neuron clusters that regulate expiration and inspiration
- Rostral: Nucleus retrofacialis or Bötzinger complex. Expiration control
- Intermediate: Pre-Bötzinger complex plus
nucleus ambiguus, nucleus para-ambigualis.
Inspiration control. Pre-Bötzinger is thought to
be site for generating fundamental respiratory
rhythm (Respiratory Pattern Generator) - Caudal: Nucleus retroambigualis. Expiration control
what is involved in the regulation of involuntary breathing rhythm
sensor -
Central Chemoreceptors
PeripheralChemoreceptorStretch receptors
effectors -
Respiratory
Muscles
describe the sensor regulation - chemoreceptors
central chemoreceptors-
located in medulla
Monitor pCO2 in
cerebral spinal fluid (CSF).
CO2 + H2O → H2CO3↔HCO3- + H
peripheral chemoreceptor - arch of aorta, both sides of neck and ears
Monitor PO2, PCO2 and pH in blood and mixed lung gases.
* Carotid Body (blood)
* Neuroepithelial Bodies (airway)
stretch receptors -
Hering-Breuer reflex:
* Inhibition of lung over-inflation (>50% resting tidal)
* Increased breathing frequency following rapid lung deflation
PREVENT LUNG FOR OVERINFLATING
(exhalation→ pant)
how does central chemoreceptors work
- co2 carried as HCO3- in blood
- blood HCO3- and H+ cant cross blood brain barrier so reversal reaction of HCO3- and H+ —> H2CO3 —> CO2
- dissolved CO2 in blood is in gaseous state and can diffuse across the blood brain barrier to the CFS
- the reaction then happens in reverse SLOW NON carbonic anhydrase catalytic reaction CO2–> H2CO3 —> slow accumulation of HCO3- and H+
- since no pH buffering in brain, small changes detected and central chemoreceptors on medulla surface detect decrease in pH due to protons and send info to DRG which then increases fires neurons which then increases tidal volume and frequency of breathing and increase ventilation
what happens when there is small changes in alveolar partial pressure co2
there is a significant increase in total ventilation due to chemoreceptors being very sensitive to small changes in alveolar partial pressure co2
