What Is the Digestive System?

Susan Grindstaff

The digestive system describes organs and glands within the body that work together to bring about the digestion of food. With the help of these glands, the body is able to break down foods so that the nutrients within them can be absorbed into the bloodstream. After the body has taken all that it can use from the food, the digestive tract converts the remainder into waste that is eliminated from the body. Some of the more prominent organs within the digestive system include the mouth, stomach, intestines, and rectum.

An illustration of a human stomach, a major organ in the digestive system.
An illustration of a human stomach, a major organ in the digestive system.

Eating is the first step in digestion, and it is typically prompted by appetite. In most cases, appetite is stimulated by the reaction of salivary glands to the aroma of nearby food. Foods are first broken down within the mouth, by chewing. The swallowed food then moves through the esophagus, where it is finally deposited into the stomach. Once in the stomach, enzymes and acids work to break the food down into a liquid called chyme, so that it can easily move on to the intestines.

The abdomen houses organs related to digestion.
The abdomen houses organs related to digestion.

The intestinal portion of the digestive system includes the small and large intestines. Inside the small intestine, the pancreas, liver, and gallbladder act on food to help ease digestion and maximize nutrient absorption. A series of ducts allow these organs to interact with the contents of the small intestine. The small intestine also has millions of tiny outgrowths called villi, which help nutrients pass from the intestines into the bloodstream. Parts of foods that cannot be completely digested by the body leave the small intestine and are deposited into the large intestine.

The rectum is used to dispel waste at the end of the digestive system.
The rectum is used to dispel waste at the end of the digestive system.

Converting undigested food into waste is the primary function of the large intestine. This intestinal tract includes the rectum, colon, and cecum. The cecum is the part of the large intestine where the undigested food first arrives, before it moves on to the colon. Inside the colon, bacteria help transform undigested food into waste. Once foods are converted to waste, they move on to the rectum.

The small and large intestines are included in the intestinal portion of the digestive system.
The small and large intestines are included in the intestinal portion of the digestive system.

The body uses the rectum and anus to remove waste. Inside the rectum, waste stools are housed until they are expelled through the anus. This is brought about by both voluntary and involuntary muscle contractions that cause the stools to be pushed from the rectum out through the anal opening.

The collective of organs and glands responsible for digesting food is know as the digestive system.
The collective of organs and glands responsible for digesting food is know as the digestive system.

If the processes of the digestive system have gone properly, digestion typically takes about 24 hours. This tends to vary with each individual, and for some, the digestive process can take as many as 72 hours. When digestion takes longer than this, constipation usually occurs, and laxatives may be necessary to bring about evacuation.

Villi, which are tiny projections that line the walls of the intestines, absorb nutrients during the digestive process.
Villi, which are tiny projections that line the walls of the intestines, absorb nutrients during the digestive process.

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Discussion Comments

fify

@ysmina-- I'm not a doctor but my aunt had to have her gallbladder removed several years ago.

As far as I know, the gallbladder produces enzymes that help with food digestion, especially the digestion of fat. That's why people without gallbladders have to avoid fat or they will experience digestive problems like stomach pain and bloating.

My aunt takes an enzyme supplement that has enzymes that break down fat. This is has been very helpful and has reduced many of her indigestion symptoms.

You should ask your doctor for the most accurate information. This is all I know based on my aunt's experience.

ysmina

What types of digestive issues occur when the gallbladder is removed? Is it a very important organ for digestion?

fBoyle

I never took it seriously when my mother told me to chew my food properly growing up. I have a habit of eating very quickly and I barely chew my food. Lately, I started experiencing indigestion, bloating and stomach cramps. After some tests, my doctor found nothing wrong with me and told me that the indigestion is due to me not chewing my food as much as I need to.

Chewing is apparently very important for digestion. Our saliva has components that start breaking down food before it even reaches our stomach. The more we chew, the easier it is for our stomach to break down food further.

I learned my lesson and now I make a conscious effort to chew my food thoroughly before swallowing. My mother was right after all!

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