There is a high chance that you might have heard of fecal transplant, where doctors take feces from a patient with a healthy microbe and transfer them to a patient who doesn't have those healthy microbes. We usually do not look at feces as an important part of our lives. When we discuss animals and their metabolism we usually look at getting food and removing waste, and or minds goes to food all through looking at the nutrient that gets into our body but do not take into consideration other things like bacteria, maintaining gas pressure in the body.
All organism needs a way to get resources and dispose off waste and when it comes to vertebrates, the digestive system, the urinary system, and the respiratory system do great jobs. The respiratory system gets in oxygen and releases carbon dioxide and oxygen is a key ingredient in cell energy reaction along side the glucose we get from eating food. We cannot go for more than 10 minutes without oxygen and this is why we cannot stay under water for long unlike fishes that uses gills to absorb oxygen from water. When oxygen is taken into the body, they are transported to cells from the lungs via the blood. This oxygen goes to places where it is less available while carbon dioxide which is much in the body is diffused out of the blood to the lungs and gas exchange occurs.
While the lungs is working on gaseous exchange balance since the high presence of both oxygen and CO2 is bad, other system works to balance other things and one of those system is the digestive system. It is important in maintaining the balance of sugar, protein, fats, and vitamins. This starts from ingestion, to digestion which happens almost immediately from the mouth mechanically by chewing or chemically from saliva and other chemical process of digesting in the stomach. To mention, digestion also happens in the stomach and small intestine where microbes assists with the job.
While there are few exceptions, most vertebrates digest food the way we do. Absorption is important with nutrient transfer. The broken down food that have been digested is moved from the digestive tract to the bloodstream, and this sometimes happen with the help of diffusion or active transport. In the large intestine, more absorption is done although not as much as the small intestine, and in this case, more water is absorbed. When the absorption process is done, they are transported to the liver where so many toxins are inactivated.
Propulsion is another step in this process and this is the process of swallowing and peristalsis which is the process where muscles move food to the stomach. The next process after absorption is excretion or defecation. In human's in begins in the large intestine which includes the colon. In excretion, the kidney and the urinary tract are needed. Water is filtered out from the blood into the urinary tubule. The kidney also releases Renin which helps regulate blood pressure and the amount of calcium in the bones.
Understanding these processes highlights the importance of every step in maintaining our health. From oxygen intake to nutrient absorption and waste elimination, each system works in harmony to ensure our bodies function properly. Acknowledging the role of fecal transplants and the intricate balance maintained by our digestive, urinary, and respiratory systems can help us appreciate the complex yet efficient nature of our body's waste management
Reference
https://guides.hostos.cuny.edu/bio140/5-16
https://www.ncbi.nlm.nih.gov/books/NBK544242/
https://courses.lumenlearning.com/suny-ap2/chapter/digestive-system-processes-and-regulation/
https://www.hopkinsmedicine.org/health/wellness-and-prevention/anatomy-of-the-urinary-system
https://www.cancer.gov/publications/dictionaries/cancer-terms/def/urinary-system
https://www.niddk.nih.gov/health-information/urologic-diseases/urinary-tract-how-it-works
https://my.clevelandclinic.org/health/body/22506-renin
