neural control of breathing

Question 1

what do the neurons in the brain - motor cortex and limbic system control

Answer 1

Voluntary Control of Respiration (eg breath-hold, sighing etc)

Question 1

what do the neuron in brainstem/medulla, medulla rhythm generation control

Answer 1

Involuntary Control of Respiratory Rhythm

Question 2

what do the neurons hypoglossal nerve, laryngeal nerve, carotid sinus nerve control

Answer 2

Chemical Modulation of Respiratory Rhythm
(peripheral Chemoreceptor Feedback)
Breathing Frequency &Volume

Question 3

what does the neurons, vagus nerve, phrenic nerve, intercostal nerve, phrenic nerve control

Answer 3

Intercostal Respiratory Muscles
Diaphragm inspiration control
= Breathing Frequency &Volume

phrenic nerve controls contraction of diaphram

Question 4

what are the muscles involved in respiration and what are they innervated by

Answer 4

Sternocleidomastoid = exercise
scalene = exercise

external intercostals
parasternal intercostals
innervated by intercostal nerves

Question 5

Where does the diaphragm sit, and what is its shape? What nerves supply the diaphragm?

Answer 5

dome-shaped and sits above the liver.
phrenic nerves, originating from C3-5.

Question 6

How does the diaphragm move during inspiration?

Answer 6

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.

Question 7

What nerves supply the external intercostal muscles?

Answer 7

The intercostal nerves at “rib level”

Question 8

What are the accessory muscles involved in inspiration?

Answer 8

Sternocleidomastoid, scalenes, and others.

Question 9

when do we do forced expiration

Answer 9

exercise, voluntary (cough,
sneeze, defaecation

Question 10

what occurs during expiration

Answer 10

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

Question 11

what is the cranial motorneurones important for

Answer 11

opening/closing glottis, affecting upper airway diameter, flaring nostrils

Question 12

what 2 places does involuntarty breathing occur in the brain stem amd what are the neurons involved

Answer 12

pons respiratory centre - Pneumotaxic center
Apneustic center

medulla respiratory centre -
Pre-Bötzinger complex
Dorsal Respiratory Group (DRG)
Ventral Respiratory Group (VRG)

Question 13

where is the dorsal resp group located

Answer 13

within the Nucleus
tractus solitarius and is dorsal to the VRG

Question 14

What is the role of the dorsal resp group

Answer 14

PRIMARILY AFFERANT
- inspiratory control
- site of sensory information
- site of central chemoreceptor input
- some premotor neurons

Question 15

where is the ventral resp group located

Answer 15

Spans 3 regions within medulla – rostral, intermediate & caudal

Question 16

what does the ventral resp group do

Answer 16

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

Question 17

what is involved in the regulation of involuntary breathing rhythm

Answer 17

sensor -
Central Chemoreceptors
PeripheralChemoreceptorStretch receptors

effectors -
Respiratory
Muscles

Question 18

describe the sensor regulation - chemoreceptors

Answer 18

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)

Question 19

how does central chemoreceptors work

Answer 19

• 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

Question 20

what happens when there is small changes in alveolar partial pressure co2

Answer 20

there is a significant increase in total ventilation due to chemoreceptors being very sensitive to small changes in alveolar partial pressure co2