Topic 34 - Respiratory tracts, respiratory movements, panting

Question 1

Words to include in respiratory tracts

Answer 1

Upper respiratory tract

• Nasal cavity
  
  • Defense
  • Air conditioning
  • Heat transfer
• Oral cavity
  
  • Ventilation
• Pharynx
  
  • Defensive function
    
    • Lymphatic system
• Larynx
  
  • Voice formation

Lower respiratory tract

• Filtering
• Protective function
• Upper part of lower respiratory tract
  
  • Trachea
  • Main bronchus
  • Gas exchange (ø)
  • Defensive role
    
    • Goblet cells
      
      • Mucin - IgA
• Trachea
  
  • Protection
  • Goblet cells
• Bronchus
  
  • Protection
  • Goblet cells
• Terminal bronchus
  
  • Cilitated epithelium (ø)
• Bronciolus respiratorius
  
  • Respiratory epithelium
• Alveolus
  
  • Ventilation
  • Gas-exchange
  • Layers:
    
    • ​Surfacant
    • Alveolar epithelium
    • Basal membrane
    • Capillary endothelium
• Alveolar wall
  
  • Pneumocytes
    
    • Epithel providing the actual gas exchange
    • Surfacant

Question 2

Words to include in respiratory movements

Answer 2

• Inspiration
  
  • Active process
  • Participants:
    
    • ​Diaphragm
    • Mm. intercostales externi
    • Abdominal muscles
  • Muscle work is needed to work against collapsing tendency
    Expitation
  • Passive process
  • Collapsing tendency of lungs
    
    • Surface tension of alveoli
    • Elastic elements of lung
    • Total collapse (ø)
      
      • Adhesional forces
        
        • Fluid-film
        • Visceral pleura → parietal pleura
• Active inspiration
  
  • Diaphragm
    
    • Expand inner space of chest
• Passive expiration
  
  • Collapsing tendency
    
    • Surface tension of alveoli
    • Elastic elements of the lung
• Pause of respiration
  
  • Chest in rest
  • Balanced status
  • Intrapleural pressure lower than atmospheric pressure
• Mouse-elephant curve
  
  • Breathing frequency depending on metabolic activity

Question 3

Words to include in panting

Answer 3

• Physological gas-exchange
• Heat exchange
  
  • Thermoregulation
• Parietal air flow
  
  • Slow
  • Gass pressure maintained
  • Ø increase in elimination of CO₂
• Central air flow
  
  • Fast
  • Perspiration
    
    • Heat exchange
    • Stimulates water release
• Hyperventilation (in other species)
  
  • Alkalosis
    
    • Loss of CO₂

Question 4

Respiratory tracts

Answer 4

• Separated into upper and lower respiratory tract

Upper respiratory tract

1. Nasal cavity
   
   • ​Defense
   • Air conditioning
   • Heat transfer
2. Oral cavity
   
   • ​Ventilation in case of increased respiration
3. Pharynx
   
   • ​Defensive functiondue to thelymphatic system
4. Larynx
   
   • ​Place of voice formation

Lower respiratory tract

• The upper part of the lower respiratory tract is composed of trachea and main bronchus
  
  • Lack gas exchange
  • Defensive role
    
    • ​The epithelium contains goblet cells which produces mucin - IgA

1. Trachea
   
   • ​Protection, goblet cells
2. Bronchus
   
   • ​​Protection, goblet cells
3. Terminal bronciole
   
   • ​Ø ciliated epithelium
4. Bronchiolus respiratorius
   
   • ​Respiratory epithelium
5. Alveolus
   
   • ​Basic unit of ventilation
   • Where gas-exchange takes place
   • 4 layers:
     
     1. ​Surfacant
     2. Alveolar epithelium
     3. Basal membrane
     4. Capillary endothelium

Question 5

Respiratory movements

Answer 5

• Two compartments:
  
  • Inspiration
  • Expiration

Inspiration

• Active process
• Participants:
  
  • Diaphragm (expands the inner space of the chest)
  • Mm. intercostales externi (raise the ribs)
  • Abdominal muscles
• During inspiration, active muscles work is needed against the collapsing tendency of the lungs

Expiration

• Passive process
• The lungs has a collapsing tendency
  
  • Due to:
    
    • Surface tension of alveoli
    • Elastic elements of the lung
  • Total collapse is pervented by adhesional forces:
    
    • ​A fluid film between the visceral pleura and parietal pleura
  • Returning of ribs to resting position and passive pressure from abdominal direction (diaphragm) help the process

Movements of respiration

• Respiration is separated into 3 movements

1. Active inspiration
   
   • ​Diaphragm has the major role (especially in large animals), expanding the inner space of the chest
2. Passive expiration
   
   • ​Driven by the collapsing tendency of the lung returning ribs to normal position
3. ​​Pause of respiration
   
   • ​Chest in rest, balanced status
   • The intrapleural pressure is lower than the atmospheric pressure

Question 6

Respiratory movements

Interspecies differences

Answer 6

• Diaphragm plays the most important role at inspiration in large animals
• The “mouse-elephant” curve
  • ​Relationship between body size and breathing frequency
  • The breathing frequency depending on metabolic activity is the greatest in animals of the smallest body size

Figure: the “mouse-elephant” curve

Question 7

Panting

Answer 7

• Physological gas-excange
• Primarily used for heat exchange - thermoregulation
• Occurs in eg. cat, dog and pig
• Separated into:
  
  1. Parietal air flow
     
     • ​Slow
     • Gas pressure is maintained, elimination of CO₂ will not increase despite the high panting frequency
  2. Central air flow
     
     • ​Fast
     • Heat excange and stimulates water release in the mouth (perspiration)
• Hyperventilation of this manner will cause serious alkalosis in other species, thanks to the loss of CO₂