Control of Breathing

Question 1

Respiratory control system: Sensors

Answer 1

• Chemoreceptors
  
  • Co2, O2, pH
• Pulmonary Stretch Receptors:
  
  • make smooth respiratory cycle
  • stretch slows respiratory frequency
• Pain Receptors:
  
  • few

Question 2

Respiratory Control System: Central Control-Integrator

Answer 2

• Pons & Medulla
  
  • Inspiratory center
    
    • intrinsic rhythmic breathing
      
      • basic rhythm of breathing
  • Expiratory center
    
    • quiescent during normaling breathing
    • important when we alter breathing
• Cortex
  
  • voluntary control center of breathing

Question 3

Respiratory Control System: Effectors

Answer 3

• Muscles of respiration
  
  • diaphragm
  • intercostal m.

Question 4

Ventilatory control consists of:

Answer 4

• Ventilatory control center
  
  • Central Pattern Generator (CPG)
  • medulla
  • generates rhythym of breathing
• Central Chemoreceptors:
  
  • Medulla
  • sense changes in PCo2 and pH in CSF
• Peripheral Chemoreceptors:
  
  • Aortic Bodies and Carotid Bodies
  • Sense changes in:
    
    • PaCo2, PaO2, pH
• Pulmonary Mechanoreceptors and irritant receptors

Question 5

Cross Talk

Answer 5

• Brain can effect the pulmonary and CV systems
  
  • Thoughts
  • Pain
  • emotions
  • temperature

Question 6

Thoracic Cavity: Innervation

Answer 6

All go to Medulla Respiratory Centers

• Chest wall: Thoracic Nerve
  
  • intercostal muscle
• Lungs: Vagus Nerve (CN10)
  
  • Stretch Receptors
  • Irritant receptors
• Heart/Cardiovascular system:
  
  • Chemoreceptors:
    
    • Aortic arch-Aortic bodies
      
      • CN10
    • Carotid arteries-Carotid Bodies
      
      • CN9 (hypoglossal nerve)
  • Baroreceptors:
    
    • can also stimulate ventilatory response
    • found in same area as chemoreceptors
      
      • same nerve
    • sense changes in BP

Question 7

Autonomous and Voluntary Control of breathing

Answer 7

• Autonomoous control overrides voluntary control when out of homeostasis
  
  • PCO2, pH, O2
• Automatic Rhythmic Respiratory Pathway
  
  • Ventrolateral tract
    
    • expiratory tract-medial
    • Inspiratory tract-lateral
• Voluntary Respiratory Pathway:
  
  • Corticospinal Tract
• Motor Neurons
  
  • Cervical Spiinal Cord
    
    • C345–>Phrenic Nerve–>Diaphgram
  • Thoracic Spial Cord
    
    • intercostal muscles
  • Lumbar Spinal Cord
    
    • Abdominal Muscles (Forced expiration)

Question 8

Hypothesis of Respiratory Control in Brainstem

Answer 8

• Basic pattern originates in medulla
• Inspiratory Cutoff switch in pons

Question 9

System Diagram for Rhythmic Breathing

-define

Answer 9

• Rhythm Generation is in the medulla
• Apneustic Center
  
  • located in pons
  • inspiratory off signal
• PRG
  
  • Pontine Respiratory Group
  • modulates behavior of apneustic center
  • contains pneumotaxic center
• DRG:
  
  • Primarily inspiratory neurons
  • contralateral diaphgram (NTS-nucleus tractus solitarius)
• VRG:
  
  • Mixed inspiratory and expiratory neurons
  • Acessory muscles (voluntary breathing) and upper airways (Forced expiration)
    
    • NA and NRA

Question 10

Systemic Diagram for Rhytmic Breathing

-Draw Diagram

Answer 10

• A Neurons:
  
  • Tonic Activity
  • send output to respiratory muscles=tells us to inhale
• B Neurons:
  
  • Receive info from stretch receptors in chest wall and compare to stimulation from A neurons
  • Stimulate Group C neurons
• C Neurons:
  
  • internous
  • omjobot tpmoc actovotu pf A meirpsm

Question 11

Chemoreceptors: Location vs what they sense

Answer 11

• Central Chemoreceptors:
  
  • Medulla
  • sense pH and CO2 of CSF and interstitial fluid
• Peripheral Chemoreceptors:
  
  • Aortic Arch-Aortic Bodies
    
    • pH and CO2
  • Carotid Sinus-Carotid bodies
    
    • pH, CO2, Hypoxemia=Low O2 levels

Question 12

What nerve innervates aortic bodies vs carotid bodies

Answer 12

• Aortic Bodies
  
  • CN10=Vagus
• Carotid Bodies
  
  • CN9=Hypoglossal Nerve

Question 13

Carotid Bodies

Answer 13

• CN9=hypoglossal nerve
• Detects pH, CO2, hpoxemia (low o2 levels)
  
  • CO2 sensor=more sensitive
  • O2 sensor=least sensitve
    
    • Very Low O2=Increase Ventilation
• Oxygen Sensors
  
  • Type 1 cells
    
    • aka Glomus Cells
    • Contain oxygen sensitive K+ channels
    • steps:
      
      • Decrease O2 levels
      • Decrease flux of K+
      • Depolarization
      • Release Ach
      • Ach Binds to Sensory Nerved Endings
      • Increase Nerve Firing
      • CN9 sends info to integration center in brainstem

Question 14

Ventilatory Regulation: Peripheral Chemoreceptors

Answer 14

• CO2 (most sensitive)
  
  • Linear
  • Increase PaCo2=Increase Alveolar Ventilation
  • Ventilatory Response to CO2 is greater @ low Arterial PO2
• H+
  
  • Linear
  • Increase arterial H+=Increase Alveolar Ventilation
    
    • (pH drops)
• O2 (least Sensitive)
  
  • Ventilatory response to low O2 is greater at greater alveolar CO2 (Blood CO2)
  • When PaCO2 is normal (40mmHg), not sensitive to drop in O2 until 60mmHg
  • Increase PaCO2-sensitive to drop in higher O2

Question 15

Central Chemoreceptors:

Answer 15

• Medulla
• Sense pH of CSF and PCO2
  
  • Respond to high levels of Blood CO2, but dont respond to low pH in the blood, because H+ Cant cross BBB
• Account for majority of CO2 induced Ventilation
  
  • most sensitive to acute changes in increase PCO2 (Acute Hypercapnia)
  • Chronic Hypercapnia-1 to 2 day-densitize
• Dominant role in Respiratory Disturbances

Question 16

Peripheral Chemoreceptors:

Answer 16

• Aortic Bodies
• Carotid Bodies
• sense PCO2, pH, and O2 (carotid bodies)
  
  • most sensitive to CO2
  • Least sensitive to O2
• Dominant role in metabolic disturbances