The Structure and Function of the
Digestive System
OVERVIEW
What organs make up the digestive system?
Your digestive system is uniquely constructed to perform its specialized function of
turning food into the energy you need to survive and packaging the residue for waste
disposal. To help you understand how the many parts of the digestive system work
together, here is an overview of the structure and function of this complex system.
Mouth
The mouth is the beginning of the digestive tract; and, in fact, digestion starts here
when taking the first bite of food. Chewing breaks the food into pieces that are more
easily digested, while saliva mixes with food to begin the process of breaking it down
into a form your body can absorb and use.
Esophagus
Located in your throat near your trachea (windpipe), the esophagus receives food
from your mouth when you swallow. By means of a series of muscular contractions
called peristalsis, the esophagus delivers food to your stomach.
Stomach
The stomach is a hollow organ, or "container," that holds food while it is being mixed
with enzymes that continue the process of breaking down food into a usable form. Cells
in the lining of the stomach secrete a strong acid and powerful enzymes that are
responsible for the breakdown process. When the contents of the stomach are
sufficiently processed, they are released into the small intestine.
,Small intestine
Made up of three segments the duodenum, jejunum, and ileum the small intestine is a
22foot long muscular tube that breaks down food using enzymes released by the
pancreas and bile from the liver. Peristalsis also is at work in this organ, moving food
through and mixing it with digestive secretions from the pancreas and liver. The
duodenum is largely responsible for the continuous breakingdown process, with the
jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream.
Contents of the small intestine start out semisolid, and end in a liquid form after passing
through the organ. Water, bile, enzymes, and mucous contribute to the change in
consistency. Once the nutrients have been absorbed and the leftoverfood residue liquid
has passed through the small intestine, it then moves on to the large intestine, or colon.
Pancreas
The pancreas secretes digestive enzymes into the duodenum, the first segment of the
small intestine. These enzymes break down protein, fats, and carbohydrates. The
pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the
chief hormone for metabolizing sugar.
Liver
The liver has multiple functions, but its main function within the digestive system is to
process the nutrients absorbed from the small intestine. Bile from the liver secreted
into the small intestine also plays an important role in digesting fat. In addition, the
liver is the body's chemical "factory." It takes the raw materials absorbed by the
intestine and makes all the various chemicals the body needs to function. The liver
also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs.
Gallbladder
The gallbladder stores and concentrates bile, and then releases it into the duodenum
to help absorb and digest fats.
Colon (large intestine)
The colon is a 6foot long muscular tube that connects the small intestine to the rectum.
The large intestine is made up of the cecum, the ascending (right) colon, the transverse
(across) colon, the descending (left) colon, and the sigmoid colon, which connects to the
rectum. The appendix is a small tube attached to the cecum. The large intestine is a
highly specialized organ that is responsible for processing waste so that emptying the
bowels is easy and convenient.
Stool, or waste left over from the digestive process, is passed through the colon by
means of peristalsis, first in a liquid state and ultimately in a solid form. As stool passes
, through the colon, water is removed. Stool is stored in the sigmoid (Sshaped) colon until
a "mass movement" empties it into the rectum once or twice a day. It normally takes
about 36 hours for stool to get through the
Digestive System
OVERVIEW
What organs make up the digestive system?
Your digestive system is uniquely constructed to perform its specialized function of
turning food into the energy you need to survive and packaging the residue for waste
disposal. To help you understand how the many parts of the digestive system work
together, here is an overview of the structure and function of this complex system.
Mouth
The mouth is the beginning of the digestive tract; and, in fact, digestion starts here
when taking the first bite of food. Chewing breaks the food into pieces that are more
easily digested, while saliva mixes with food to begin the process of breaking it down
into a form your body can absorb and use.
Esophagus
Located in your throat near your trachea (windpipe), the esophagus receives food
from your mouth when you swallow. By means of a series of muscular contractions
called peristalsis, the esophagus delivers food to your stomach.
Stomach
The stomach is a hollow organ, or "container," that holds food while it is being mixed
with enzymes that continue the process of breaking down food into a usable form. Cells
in the lining of the stomach secrete a strong acid and powerful enzymes that are
responsible for the breakdown process. When the contents of the stomach are
sufficiently processed, they are released into the small intestine.
,Small intestine
Made up of three segments the duodenum, jejunum, and ileum the small intestine is a
22foot long muscular tube that breaks down food using enzymes released by the
pancreas and bile from the liver. Peristalsis also is at work in this organ, moving food
through and mixing it with digestive secretions from the pancreas and liver. The
duodenum is largely responsible for the continuous breakingdown process, with the
jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream.
Contents of the small intestine start out semisolid, and end in a liquid form after passing
through the organ. Water, bile, enzymes, and mucous contribute to the change in
consistency. Once the nutrients have been absorbed and the leftoverfood residue liquid
has passed through the small intestine, it then moves on to the large intestine, or colon.
Pancreas
The pancreas secretes digestive enzymes into the duodenum, the first segment of the
small intestine. These enzymes break down protein, fats, and carbohydrates. The
pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the
chief hormone for metabolizing sugar.
Liver
The liver has multiple functions, but its main function within the digestive system is to
process the nutrients absorbed from the small intestine. Bile from the liver secreted
into the small intestine also plays an important role in digesting fat. In addition, the
liver is the body's chemical "factory." It takes the raw materials absorbed by the
intestine and makes all the various chemicals the body needs to function. The liver
also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs.
Gallbladder
The gallbladder stores and concentrates bile, and then releases it into the duodenum
to help absorb and digest fats.
Colon (large intestine)
The colon is a 6foot long muscular tube that connects the small intestine to the rectum.
The large intestine is made up of the cecum, the ascending (right) colon, the transverse
(across) colon, the descending (left) colon, and the sigmoid colon, which connects to the
rectum. The appendix is a small tube attached to the cecum. The large intestine is a
highly specialized organ that is responsible for processing waste so that emptying the
bowels is easy and convenient.
Stool, or waste left over from the digestive process, is passed through the colon by
means of peristalsis, first in a liquid state and ultimately in a solid form. As stool passes
, through the colon, water is removed. Stool is stored in the sigmoid (Sshaped) colon until
a "mass movement" empties it into the rectum once or twice a day. It normally takes
about 36 hours for stool to get through the
