The Role Of Digestive System And Respiratory System In Environmental Exchange

Natural selection is the evolution of our planet’s life. Natural selection dictated to us that we must adapt to coexist and survive as living organisms. Six kingdoms are co-existing in our world. Symbiosis is the basis of many of our relationships. Interdependence exists between plants and animals. Plants provide oxygen and nutrients to us, and we need them as animals. We provide them with carbon dioxide that they turn into glucose. We extract the chemicals above from our environment using two organs: the digestive tract and the respiratory tract. It is called “environmental interchange”.

For life to continue, all living creatures must consume nutrients from the environment. For a large, complex organism like the human body, a complex, large system is required to digest and absorb nutrients from food. We require a digestive system. The digestive system might not be as beautiful or strong, but it’s just as vital. The digestive organs include the gastrointestinal lining and accessory organs. The digestive system is a muscular tube that passes food through, where it gets broken down, absorbed, and becomes waste. The six steps of the digestive process are: ingestion, mechanical preparation, chemical preparation (digestion), ejection, absorption, excretion. The digestive system, for instance, will absorb as much carbohydrate as possible if, as an example, a marathon-trained runner decides that he wants to eat two bananas with oatmeal and a glass orange juice.

In order to prepare the food for swallowing (mechanical processing), the food must be chewed. The food is then mixed with saliva from the parotid gland, submandibular gland, and sublingual gland. These secretions contain enzymes like salivary beta amylase and water. As soon as the food and saliva mix, the bolus is formed, which begins the chemical reaction. By swallowing, the bolus is transported from the pharynx to the esophagus. In the esophagus the nerve system stimulates the smooth and striated muscles, causing peristalsis. The stomach, which is J-shaped, has four regions: the cardia and fundus. Gastric juice is mostly produced in the stomach’s body. Gastric juice is made up of hydrochloric acids, water, enzymes and mucus. The enzymes lipase, alpha-amylase, and pepsin continue the chemical breakdown. The antrum forms chyme by mixing the bolus along with gastric liquids. Through peristalsis the antrum can also stimulate gastric emptying. The chyme is then pumped into the small intestines where, due to their large surface area, most chemical absorption and nutrient digestion occurs. The brush borders of the small intestinal cells are present. Enterocytes are responsible for a large amount of enzymes including alpha-dextrinase.

In the small intestine, the pancreas and liver help to facilitate digestion and absorption. The pancreas secretes many digestive enzymes into the pancreatic duct, including pancreatic beta amylase. The main pancreatic joins the common bile to form bile-pancreatic duct. This empties into the duodenum. The liver produces bile, which is stored in the gallbladder. When required, bile enters the bile-pancreatic duct. The liver converts and excretes nutrients that are absorbed through the small intestine.

The pancreas secretes enzymes that hydrolyze partially digested carbohydrates. As the chyme travels through the small intestinal tract, including the duodenum and jejunum, nutrients such as monosaccharides or disaccharides are reduced to dimers. Intestinal mucosa is able to absorb the newly released carbohydrate through active and facilited transport. Once carbohydrates have entered the bloodstream, they are transported to the organs that need them, such as the skeletal muscles, brain or liver.

The nutrients, which were not digested, continue to move along the digestive tract until they reach the large colon. In the large intestinal tract, nutrients pass through the colon, rectum, cecum and other parts. They are mixed in with waste products and dehydrated.

Our marathon runner will distribute the glucose he ate before the race throughout his body. Due to his training for endurance exercise, some of the glucose will be stored as glycogen in the liver, skeletal muscles, and brain, while others will be converted into fat by the liver through de novo lipogenesis. The body begins to “adapt” when the marathon race starts. As the skeletal muscles consume glucose, oxygen, and lipids at a faster rate, they release carbon dioxide which reduces blood pH. During your first 15-20 minutes, the muscle will use stored glucose and glycogen as their primary energy source. It is oxygen that is required for the aerobic respiration of glucose. The respiratory system is how we get oxygen.

The respiratory system includes the nasal and oral cavities, larynxes, tracheas, bronchis and lungs. In collaboration with other systems, it regulates blood pH and exchanges gases with the external environment. Respiration is a process that involves the exchange of gas between the body and its external environment.

As our marathoner continues to run, his blood levels of oxygen will decrease, while carbon dioxide will rise. The central chemoreceptors are located in chemosensitive brainstem areas. They sense the changes. They then send a signal to the respiratory area (also medulla oblangata), which will increase respiratory volume and rate. In response, the muscles that are associated with inspiration, such as those of the diaphragm and intercostals (and abdominals), become stimulated. This increases pulmonary ventilation, which increases oxygen intake and carbon dioxide exhalation.

The alveoli in the lungs diffuse oxygen into the blood via the respiratory membrane. Carbon dioxide diffuses from the blood out into the alveoli. Gas exchange is carried out by diffusion. Each gas diffuses away from an area of high concentration into a zone of low concentration. In the lungs there is both an external and internal respiration. Internal respiration happens at the tissue that is metabolizing oxygen: carbon dioxide diffuses through the tissue.

As you may have noticed, the runner’s breathing increased slightly during the race compared to before. It is because the CO2 and oxygen production have increased and the respiratory system has adjusted. You can increase your respiratory rate and/or tidal size when the oxygen requirement increases. A medical expert can diagnose COPD and other pulmonary problems using complex mathematical equations.

Cited sources

Martini, F. H., Ober, W. C., Garrison, C. W. (2004). Fundamentals of Anatomy & Physiology 6th Edition.

Gropper, S. S., Smith, J. L. (2013). Advanced Nutrition & Human Metabolism Sixth Ed.

Ameer, F., Scandiuzzi, L., Hasnain, S. (2014). Lipogenesis Occurring for the First Time in Health and Illness. Metabolism, 63(7), 895-902.

Shier, D., Butler, J., Lewis, R. (2009). Hole’s Essentials Human Anatomy & Physiology Tenth Edition.

(2019). External and Internal Lung Respiration: Definition & process. (2019). Retrieved from: definition-process.html


  • calvinmerritt

    Calvin Merritt is an educational bloger who specializes in writing about educational topics. He has been writing for over a decade and has written for a variety of different platforms. His work has been featured on various websites and he has also been published in various magazines.