Comparative Vertebrate Physiology

Control of Respiration in Aquatic and Terrestrial vertebrates

Alveolar ventilation rate

 AVR = frequency x tidal volume (breaths/min.) (ml/breath) Human AVR = 4.2 - 6 L (12 x 350 - 500)

Alveolar ventilation

 Which variable enhances AVR more?

 Tidal volume S ub ject Tidal v olume (ml/b reath) 1 2 3 150 500 1000 Frequency (b reaths/min) 40 12 6 Total v entilation (ml/min) Dead sp ace v entilation (ml/min) AV (ml/min) 6,000 6,000 6,000 150x 40=6,000 150x 12=1,800 150x 6=900 0 4,200 5,100

Medulla control

 Pre-B ötzinger complex, parafacial respiratory group (amphibians, mammals)

Hering-Breuer reflex

Chemoreceptors

 Early detection   Central (brain) Peripheral (other areas)

Gases in the environment

 Aquatic  Fluctuations in pO 2 : hypoxia  Terrestrial  Fluctuations in pCO 2 : hypercapnia

Reptiles and birds

Mammals