The organs/parts shared by respiratory and digestive system are: –
Laryngo-pharynx- The part of pharynx contained by respiratory system is known as nasopharynx and that contained by digestive system is known as oropharynx. The nasopharynx receives air from nostrils or external nares and this air moves further towards laryngopharynx. Similarly, food in the oral cavity, moves through oropharynx into food pipe. Laryngopharynx is the common organ shared by respiratory and digestive system. Dorsally, food moves into the oesophagus through laryngopharynx and ventrally air moves into the larynx through laryngopharynx.
The functions/processes shared by the two systems are:-
Metabolism- Thyroid and parathyroid glands are present posterior to the larynx. These glands control metabolism. And metabolism can be related to digestive as well as respiratory system.
Peristalsis- Food moves through food pipe via the process of peristalsis. Now, when thoracic cavity expands and contracts, in the act of breathing, the process of peristalsis is supported further and food is pushed further. So, we can say that the process of peristalsis is shared by the two systems.
The structures shared by the two systems are:-
Thoracic/Anterior cavity – Body cavities are anterior and posterior. The parts of anterior cavity that contains lungs (of respiratory system) are known as pleural cavities. There are two pleura cavities: – right and left which house the right and left lung respectively. Besides this, the oesophagus, which is a part of digestive system, passes through the anterior cavity. So, anterior cavity is shared between the two systems.