Digestive System

May 17, 2020

University Affiliation

The digestive system isconstructed to perform special functions of converting food intoenergy needed for survival by organisms and at the same timepackaging the residues for waste disposal. The basic structure of thedigestive system entails the mouth, the esophagus, the stomach, thesmall intestines, the pancreas, the gallbladder, the liver, the largeintestines, the rectum, and the anus. Each of the above parts has aunique function to facilitate the normal functioning of the digestivesystem. The mouth serves as the inlet for food into thegastrointestinal tract. In the mouth, food is broken down into moreeasily digestible pieces serving the purpose of mechanical digestion.Additionally, food is mixed with saliva from the salivary glandslocated in the mouth walls that begins breaking it down into anabsorbable form. Saliva has an enzyme called ptyalin that breaks downstarch (Cascone et al., 2016). The breakdown of starch takes place inthe mouth since the action of ptyalin is inhibited by the acidity inthe stomach due to hydrochloric acid. The chewed food is thenswallowed into the stomach through a pipe called esophagus.

The stomach then holds the foodas it is mixed with enzymes that break down the food. The stomachwalls are lined with cells that secrete hydrochloric acid. The acidensures that all the harmful bacteria that could have been ingestedare deactivated. The chyme from the stomach gets into the smallintestines that have three parts namely the duodenum, jejunum, andthe ileum. The duodenum breaks down food further using the enzymessecreted by the pancreas and liver. The enzymes secreted by thepancreas digest proteins, fats, and carbohydrates. The liver producesbile juice which is then stored in the gallbladder for use in themetabolism of lipids (Cascone et al., 2016). The bile has bile saltsthat break down fat forming micelles used to transport fatty acidsand monoglycerides for absorption.

The jejunum and ileum arespecialized to absorb the digested food with the absorption areabeing increased by the presence of finger-like projections referredto as villi. Lymphatic vessels ensure that the interstitial fluid isreturned into the blood stream. Gastrin,&nbspsecretin,&nbspandCCK control digestion with gastrin causing the gastric glands tosecrete HCL and pepsinogen, secretin stimulating the pancreas andbile ducts to release the acid neutralizers, and CCK stimulating therelease of digestive enzymes from the pancreas (Nigamand Knight, 2017).Peristalsis ensures thatfood is moved through the intestines and mixed with the digestivesystem. The large intestines then absorb water from the food residuesback into the body. The rectum holds the stool before it is evacuatedthrough the anus.

There are homeostatic deviationsthat result from the process of digestion. The fluctuations of theglucose in the plasma are detected by the pancreas. However, whenfood is absorbed into the bloodstream, and blood glucose rises in theplasma creating a homeostatic imbalance (Nigam and Knight, 2017). Theconcentration gradients of the plasma change and call for acorrective action else the whole body will malfunction especially inthe movement of fluids and nutrients through osmosis.

The digestive systems respond toattempt to return to homeostasis. First, when there is not foodintake over time, the plasma glucose level lowers. As a result, thepancreas releases glucagon that breaks down glycogen into glucose.Second, when the food has been taken and absorbed, the plasma glucoserises creating a homeostatic imbalance. The pancreas secretes insulinto convert excess glucose into glycogen.

Sample Questions

  1. Differentiate between mechanical and chemical digestion detailing which is more complex.

  2. What explanation is given to the color found in stool?

  3. Why are the functions of the hydrochloric acid produced in the stomach?

References

Cascone, S., Dalmoro, A.,Lamberti, G., Titomanlio, G., d’Amore, M., &amp Barba, A. A.(2016). In Vitro Simulation of Human Digestion: Chemical andMechanical Behavior.

Nigam, Y., &amp Knight, J.(2017). The anatomy and physiology of aging 3-The digestive system.Benefits,&nbsp10,32.

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