Question

Use the Guiding Principles document provided in the main menu. Select 3 guiding principles and explain how they can be applied to the digestive system. For each of them, provide specific examples of structures or physiological processes that exemplify the principle.

Please provide 3 detailed paragraphs, one for each. Thanks

Guiding Principles of A&P

• Cells form the foundation of body structure and function

• The body is organized into a hierarchy of increasing complexity

• Body systems are functionally integrated

• Structure and function are closely related

• Rela7vely stable internal conditions are maintained despite changing external conditions

• Informa7on flow coordinates body functions

• Energy input is needed to sustain life

Answer 1

Digestive system is the collection of organs that help taking food, digesting it and absorbing the nutrients from it. The digestive system starts from our mouth, teeth and tongue which help in processing of the food. Then the food goes down through gastrointestinal tract and into the stomach. Food is digested partly inside stomach then it goes down to small intestine. Here food is fully digested and absorbed into our blood stream. Then the undigested portion is dumped inside large intestine which excretes it out of our body. Along these organs, liver, pancreas and gall bladder are also part of digestive system as their secretion helps digest the food completely.

Three of the guiding principles that can be suited to describe digestive system are:

‘Cells form the foundation of body structure and function’

Cells are microscopic structure, which are the structural and functional unit of life. When cells unite and work in harmony they create a complex structure. Our body is no different. From the tip of hair to toe nails everything is created by cells. Every organs, every tissue is the result of complex cell architecture and their coordinating function. Cells of different characteristics give rise to different parts of digestive system. Most of our digestive system is made of epithelial cells. They form the inner lining of the digestive tract. Also they functionally support the system. They are responsible for smooth movement of foods from mouth to stomach, intestine. They created special structures inside intestine, microvillus, which is responsible for nutrient absorptions. The same way liver cells, pancreatic cells are responsible for their specific structures and functions. The epithelial cells of these organs have different properties; they are made to secrete enzymes, hormones which assist food digestion and nutrient absorption. So in general the foundation of digestive system, in fact the whole body foundation is the cells.

‘Body systems are functionally integrated’

Our body is coordinated by several organ systems. Nervous system, cardiovascular system, respiratory system, digestive system, excretory and endocrine system are some of the important ones. They might be differentially named, but their functions overlap with each other. The main function of digestive system is to break down food and absorb nutrients from it. The main energy source of our body is glucose, which comes from the food. Glucose is absorbed from the wall of small intestine. In fact all the necessary building molecule of our body comes from food. The three basic food type proteins, fats and carbohydrate, all are taken by digestive system from food. Then the job to circulate the nutrients to every tissue is taken up by cardiovascular system. Respiratory system then provides oxygen to burn the glucose to produce energy to every cell even for cells of digestive system. Nervous system innervates the digestive system to control the food intake, hunger, excretion etc. by central nervous system. In conclusion all the major organs in our body are functionally linked; failure to function by one system will break down the whole system eventually.

‘Structure and function are closely related’

The structure of our body is the way evolved so that it can be functionally optimal. We have five fingers so that we can grab properly. Our eyes are in front of our face so that our viewing angle is maximum. Our skeletons are arranged in a way that it can support our body weight. So it seems that structures and functions are correlated. Digestive system is also developed in that way. Our mouth is in front our face. The teeth are arranged at the start of our digestive system so that it can process food in smaller bits for the next steps of the food digestion. Our GI tract is long and vertically situated. This helps food come down wards naturally to the other organs. The other organs of digestive system is kept inside abdominal cavity, so the more important organs like respiratory system and cardiovascular system can be in thoracic cavity. Now the stomach is made in a way so that it can hold the food much longer to chemically break down food further inside its acidic environment. Then the small intestine, which is a long tube but it is folded inside the abdomen. It is long to maximize the nutrient absorbance. Then comes the large intestine which is also a tubular structure wraps around the small intestine. It is optimally build to create feces out of undigested food. Same can also be said for liver and pancreas. They are secretory organs, so they are positioned in a way that the secretory juice can mix with small intestine. So it is clear that the structures of the organs were developed in such a way it can functionally be optimal and can support each other’s function.