Function of Digestive Organs

Function of Digestive Organs

The human digestive system supports essential functions of life, often through nutrition to fuel the body systems and the building blocks of the body. It contains a series of various organs across a long tract extending from the mouth to the rectum.


Digestion begins at the mouth with the mechanical breakdown of foods into small chunks known as bolus. The chewing process mixes food with the saliva and marks the onset of the chemical digestion of starch due to the amylase. Its purpose is to moisten the food for lubrication and maximize the surface area to allow the further breakdown of complex food materials into beneficial nutrients required by the body (Welcome, 2019).


After swallowing the bolus, it travels through the esophagus to the stomach, where it mixes and churns bolus with gastric juices. The content consists of a semi-fluid mixture of partly digested food and digestive juices known as chyme. Gastric juices also stimulate the digestion of proteins and the absorption of fat-soluble nutrients (Khan Academy, 2019). Because of the high acidity levels, the stomach is covered with a layer of mucous to protect gastric walls against acidic content.

Small Intestine

The stomach then releases the chyme into the small intestine. Here, the chyme will travel first in the duodenum, then the jejunum, and lastly into the ileum. In the duodenum, pancreatic juices act on fat, carbohydrates, and proteins. Bile from the gall bladder facilitates further breakdown and absorption of fats (Khan Academy, 2019). The movement of food materials in the small intestine is often slower to optimize nutrient digestion and nutrient absorption. This component also contains villi, finger-like projections, which provide a large surface area for nutrient absorption. Major organs that support small intestinal digestion include the pancreas, gallbladder, and liver (Khan Academy, 2019). Pancreatic juices contain bicarbonate content to neutralize gastric acids from within the chyme, thus creating optimal conditions for enzymatic functions.

Large intestine

Once essential nutrients are absorbed, the small intestine release food residuals from the colon or large intestine, further breakdown and absorption of remnant water, vitamins from enteric bacteria, and electrolytes. The large intestine provides transient storage of residuals to allow the accumulation of waste materials before propelling them toward the rectum for elimination as feces (Molnar & Gair, 2015 ). It also secretes mucus to facilitate the passage and elimination of fecal matter.


Peristalsis encompasses sequential and interchanging waves of relaxation and contraction that propel the food along the digestive tract. The waves begin in the esophagus and facilitate the mixing and churning of food content in the stomach. The process is very powerful and automatic, thus ensuring the continuous movement of food along the digestive tract. The motion also includes the movement of enzymatic juices through the ducts (Welcome, 2019). This is evident in the release of bile from the gallbladder into the small intestine.

Bacterial contaminants can fasten peristalsis as the body attempts to expel contaminated content from the stomach. An example of such a disease is irritable bowel movement. Another condition that can slow peristalsis is intestinal obstruction. It develops when a blockage prevents food from passing through the small intestine or colon. A possible reason for the condition might be attributable to the lack of sufficient fiber content in the diet. Constipation can also signify intestinal blockage or slow peristalsis movements. Laxatives are mostly used to quicken the peristalsis and manage or prevent constipation.


Khan Academy. (2019). The digestive system | Crash Course biology| Khan Academy. [YouTube Video].

Molnar, C., & Gair, J. (2015). Concepts of Biology: 1st Canadian Edition. Creative Commons

Welcome, M. O. (2019). Gastrointestinal physiology: development, principles and mechanisms of regulation.

Reply 2

  1. Describe the role of the following organs in processing food:
    • Mouth- The mouth breaks down the food, as stated in the video provided in module 3, the mouth uses saliva, as well as our teeth to break down food. Enzymes and acid help make this process smoother too.
    • Stomach- The stomachs job is to break, and smush everything, using something called gastric juice which is made up of Hydrochloric Acid, Pepsin, Water And Mucus this acid pretty much breaks down any  bacteria on our food that reaches our stomach. The pepsin breaks down protein into amino acids. Our mucus keeps our stomach from digesting itself. The water helps produce chyme so that by the time the food leaves our body it is liquidity.
    • Small intestine- The small intestine is where all absorption and secretion happens also the cellular exchange of nutrients, and breakdown of fats. Capillaries located on the villi help absorb nutrients.
    • Large intestine- The Large Intestines job is to remove most of the water and bio-salts from the chyme so that we don’t have diarrhea. Large Intestine contains Appendix which is known as a safe house for all the good bacteria that we may need to help us digest our food. If we have a virus or food poisoning large intestine helps get all that bad stuff or waste product out. Appendix has a little gut sample that helps our digestive system recolonize basically get back to norma after your illness. Lastly the large intestine reabsorbs excess water from the chyme preparing our poop.

1.) What is peristalsis and how does it help in the digestion of food?

Ans:As stated “Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract. … In the large intestine peristalsis helps water from undigested food be absorbed into the blood stream. Then, the remaining waste products are excreted through the rectum and anus” (

2.) Can you think of a disorder or medication that would speed up or slow down peristalsis?

Ans: Diphenoxylate and atropine, these two medications act on intestinal muscles to inhibit peristalsis and slow intestinal motility.

Work Cited

1.) U.S. National Library of Medicine. (n.d.). Peristalsis – Health Video: Medlineplus medical encyclopedia. MedlinePlus. Retrieved November 2, 2021, from,food%20through%20the%20digestive%20tract.&text=In%20the%20large%20intestine%20peristalsis,through%20the%20rectum%20and%20anus (Links to an external site.).

2.) Mia L Manabat, D. O. (2021, April 3). Intestinal motility disorders medication: Cholinergic agonists, prokinetic agents, opioid reversal agents, antidiarrheals, antibiotics, acetylcholinesterase inhibitors, secretagogues. Intestinal Motility Disorders Medication: Cholinergic Agonists, Prokinetic Agents, Opioid Reversal Agents, Antidiarrheals, Antibiotics, Acetylcholinesterase Inhibitors, Secretagogues. Retrieved November 2, 2021, from (Links to an external site.).

3.) Tatum, J. (2021, July 5). The digestive system” Assignment Ninjas. Retrieved November 2, 2021, from (Links to an external site.).

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