Comparative Vertebrate Physiology

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Comparative Vertebrate Physiology

• Vertebrate Respiration Systems

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Respiration systems

• Gill
• External invagination
• High surface area

• Lung
• Internal invagination
• Ventilation

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Patterns of air flow

• Amphibians

Fishes
Countercurrent flow
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Patterns of air flow

• Mammals

Birds
Crosscurrent flow
Tidal flow
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Cutaneous respiration

• Increase skin surface area
• Ineffective above 1,000g
• When PO2 low use reduced lungs

Lake Titicaca in Peru
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Lamella gills

• Anatomy
• Gill arches, filaments, secondary lamellae

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Gill ventilation

• Mouth
• Buccal cavity (positive pressure)
• Operculum

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Countercurrent flow

• Is it more efficient?

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Ram ventilation

• Fast swimmers (i.e., tuna, some sharks)
• Forcing water across gill surface

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Aquatic respiration

• Physiological consequences

(ml/L)
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Aquatic respiraton

• Aquatic 1L water for 1 ml O2
• Terrestrial 25 ml of air for 1 ml O2
• Its harder to breathe under water

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Amphibians

• Varied respiratory systems
• Cutaneous, gills, lungs
• Positive pressure buccal pump
• IV phases

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Reptiles

• Negative intrapulmonary pressure
• All have ribs and intercostal muscles (except
  chelonians)
• Crocodiles
• Muscle contraction

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Reptiles

• Chelonians
• Rigid carapace (ribs?) and diaphragm
• Breathe by movement of girdles and muscle
  contraction

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Birds

• Air sac system
• Connected to trachea, lungs and long bones
• One way system

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Birds

• Two breaths to remove air from pathway

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Extremes of respiration

• 1. Increase in altitude
• PO2 at 5,800 m is 80 mmHg compared with 155 mmHg
  at sea level
• Birds migrate at 6,000 m
• Humans
• Short-term response Increase in depth of
  respiration (not rate), regulated by pH of CSF
• Long-term response Increase in erythropoietin
  and RBC count

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Extremes of respiration

• 2. Diving in air-breathing animals
• e.g.reptiles, mammals

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Extremes of respiration

• 2. Diving
• Cope with hypoxia by using all available oxygen
• High levels of Hb, myoglobin
• Blood shunt to brain and heart

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Extremes of respiration

• Preventing the bends
• Nitrogen narcosis caused by an increase in
  pressure

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Extremes of respiration

• Solution evacuate lungs of air