respiratory and digestive system

In a post of at least 300 words, respond to the following:
Compare and contrast the structures of the respiratory and digestive systems by tracing pathways for: how an oxygen molecule enters the body and travels to the alveolar capillary beds; and
food as it is converted into a bolus and further processed.
Examine how histological features of these two organ systems contribute to their proper functioning.
Respond to at least 2 of your peers.
All references must be cited using APA Style format. Please refer to the CCCOnline APA Citation Toolkit.