Avian and Mammalian Respiratory System

Differences between the avian (Gallus gallus domesticus- chicken) and mammalian (Sus scrofa domesticus- swine) respiratory system

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Differences between the avian and mammalian respiratory system

Introduction

        Respiration is where an organism gets oxygen from the immediate environment so as to meet its metabolic requirements (Carvalho & Goncalves, 2012). It is the physical process of breathing in oxygen into the cell tissues and exhaling carbon dioxide from the body. It is also a metabolic process where an organism gets the energy to manage the cellular requirements (Carvalho & Goncalves, 2012) . Mammals and birds are a group of vertebrates that are capable of sustaining high oxygen consumption, yet they have a different respiratory system (West et. al., 2007a).

Evolution history

         Mammals and birds share a common ancestry as they both originated from reptiles 300 million years ago when they emerged from the water and began breathing in air (Maina, 2000; West et. al., 2007b). The reptiles were initially exothermic and could not maintain high levels of physical activity, but out of these reptiles, there developed two classes of vertebrates with maximal oxygen consumption (Maina, 2000; West et. al., 2007b). Mammals are believed to have originated from a group of carnivorous reptiles known as cynodonts, while the birds are believed to have originated from the theropod dinosaurs (West et. al., 2007b). It is noteworthy that these two groups of animals share similarities in their endocrine, renal, nervous, cardiovascular and gastrointestinal physiology, while their lungs and pulmonary system are completely different.  

This is interesting since both birds and mammals follow the same evolutionary path and it is evident that the avian lung developed further than that of the mammal, becoming superior and giving birds the ability to fly. It is possible that birds developed the ability to fly to overcome constraints present in the environment they were living in at the time, such as predation from other animals. Flying also enabled to occupy an environment that was less crowded compared to the terrestrial environment and with time they underwent adaptation and speciation to give rise to the current avian species (Hawkins et. al., 2012; Maina, 2000).

Similarities between mammals and birds

Birds and mammals share a number of similarities but some of the major ones include that they are both warm blooded tetrapods with a well-developed skeleton and a four-chambered heart (Harvey  Ben- Tal, 2016; West et. al. 2007a). Their digestive system is similar as both classes are omnivorous and they feed on both plant and animal material (Lavin et. al., 2008). In both birds and mammals, the parents care for their young ones until they are old and mature enough to fend for themselves, a characteristic that is unique to these two groups (Speakman et. al, 2008). Birds have been known to exhibit behavior that is similar to that of mammals which are associated with high levels of consciousness and cognition that is associated with mammals (Butler and Cotterill, 2006). It is possible that these two classes have some neuro- anatomical features in common such as the high brain: body ratios and in the brain circuitry which may have come about during evolution (Butler et. al., 2015). Studies have also shown that the avian immune system is similar to that of mammals. Research has been carried out on domestic chicken (Gallus gallus domesticus) and the findings have been applied successfully in humans, showing the similarities between the two classes (Tirziu and Seres, 2010). The blood composition of birds and mammals is also similar as both have the white and red blood cells and use hemoglobin to transport oxygen through- out the body.