The Digestive System

by Jacob Villani

The digestive system is a group of organs working together to convert food into energy and basic nutrients to feed the entire body. Each organ has a different  function that contributes to the digestion of food. The picture below shows the organs that make up the entire digestive system.

Mouth and Esophagus

The Digestive system begins in the mouth.  In fact, digestion starts here as soon as you take the first bite of a meal. 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.

Food begins its journey through the digestive system in the mouth. Inside the mouth are many accessory or other organs that help in the digestion of food—the tongue, teeth, and salivary glands. Teeth chop food into small pieces, which are moistened by saliva before the tongue and other muscles push the food into the esophagus or throat. This processes is a chemical change. The esophagus, or throat, is a funnel-shaped tube connected to the posterior end of the mouth. The esophagus is responsible for the passing of masses of chewed food from the mouth to the esophagus.  It contains a flap of tissue that acts as a switch to route food to the esophagus.

Stomach/Liver/Pancreas/Gallbladder

The pancreas is a large gland located just inferior and posterior to the stomach. It is about 6 inches long and shaped like short, lumpy snake with its connected to the duodenum and its pointing to the left wall of the abdominal cavity. The pancreas secretes digestive enzymes into the small intestine to complete the chemical digestion of foods.The gallbladder stores bile between meals. When a person eats, the gallbladder squeezes bile through the bile ducts, which connect the gallbladder and liver to the small intestine. The bile mixes with the fat in food. The bile acids dissolve fat into the watery contents of the intestine, like how detergents dissolve grease from a frying pan. The cells in the lining of the stomach and small intestine produce and release hormones that control the functions of the digestive system. These hormones stimulate production of digestive juices and regulate appetite. This video will take you through the stomach.

Small Intestine

●Made up of three segments — the duodenum, jejunum, and ileum — the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver.

The duodenum is largely responsible for the continuous breaking-down process, with the contents of the small intestine start out semi-solid, and end in a liquid form after passing through the organ.

Water, bile, and enzymes contribute to the change in consistency. Once the nutrients have been absorbed and the leftover-food residue liquid has passed through the small intestine, it then moves on to the large intestine, or colon.

Large Intestine

●The colon (large intestine) is a 6-foot long tube that connects the small intestine to the rectum. The large intestine is made up of the cecum, the ascending colon, the adjacent colon, the descending 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 easy and conveniently.

●Stool, or waste left over from the digestive process, is passed through the colon, 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 colon until a "mass movement" empties it into the rectum once or twice a day. The stool is mostly leftover food and bacteria. These bacteria perform several useful functions, such as synthesizing vitamins, processing waste products and food particles, and protecting against harmful bacteria. When the descending colon becomes full of stool, it empties its contents into the rectum to begin the process of waste disposal. This picture is an example of inside a human body.

Steps

1.Uses saliva to break down food

2.Your teeth chew the food to make it smaller

3.The chewed up food goes down the esophagus/throat then into the stomach which has acid intestine. This long,twisting tube is almost 20 feet (6 meters) long!

4.From here, the soupy food moves to your small intestine

5.Other organs, such as your liver, send more acid. It breaks the food down even more.

6.Finally, the food has been broken into tiny pieces called nutrients.

7.These nutrients slip through the walls of the intestines and get carried by your blood to all the cells of your body

8.The waste from the food has been broken down and is ready to be disposed of through the rectum


The Excretory System

●You have toxic waste in your body! The excretory system keeps these out! The excretory system is the system of an organism's body that performs the function of excretion, the bodily process of discharging wastes.

●The Excretory system is responsible for the elimination of wastes. There are several parts of the body that are involved in this process, such as sweat glands, the liver, the lungs and the kidney system.

Kidneys

●The kidneys act as a filter. Eventually all of the blood in your body passes through the kidneys and they are able to do their filtering magic. The kidneys pull harmful molecules out of your bloodstream and leave the ones that are good for you.

●Nephrons are microscopic structures that help form urine. These are essential for the waste disposal process.

●The kidneys are also key players in the hydration (water) levels for your body. Let's say you are in the desert and you haven't been drinking much water. Chemical signals are sent to your kidneys to reabsorb as much water as possible. The result is less urine creation and your body loses less water. A normal day has you creating about one and a half liters of fluid.

Ureters

The ureters are long tubes that connect the kidneys to the bladder. The urine forms in the kidneys, travels through the ureters, and go to the bladder where the waste is ready to be disposed of.

Bladder

The urine is transported from the kidneys to the bladder. The bladder is a sack like organ that stores urine. Other muscles hold the urine until it is ready to be released. At that time, the muscles contract and squeeze urine out of the bladder

Urethra

In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. In humans, the urethra has an excretory function in both genders to get urine out of your bladder.

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