Digestive system Pages 516-527

What is the function of the digestive system? The digestive system has three main functions 1) Breaks down food into molecules that the body can use. 2) Molecules are absorbed into the blood and carried throughout the body. 3) Waste is eliminated from the body.

What is digestion? Digestion is the process by which your body breaks down food into small nutrient molecules. There are two ways this can occur 1) Mechanical 2) Chemical

Mechanical digestion Mechanical digestion is where you physically breakdown food particles. Example- chewing food *Your teeth help to physically breakdown the food in your mouth

Chemical digestions Chemical digestion occurs when the saliva in the mouth breaks down the food. The combination between the mechanical and chemical makes it possible to swallow our food. Example: Saliva/ spit in the mouth has an acid base that begins the digestive process.

Absorption After you have digested the food your body will absorb the nutrients from the food into your blood stream. Some nutrients are not absorbed by the body, they will then continue through the digestive track and be eliminated as waste.

Mouth Your mouth is where digestion begins. Within your mouth you have chemical and mechanical digestion taking place. Saliva = chemical Chewing = mechanical

Esophagus The esophagus is the tube that connects the mouth to the stomach. The esophagus is lined with mucus this allows the food particles to move easier down the tube. The esophagus is made of Smooth muscle, The esophagus contracts moving the food down towards the stomach.

Peristalsis When food particles move down the esophagus we call this involuntary wave of muscle contraction PERISTALSIS. http://www.westga.edu/~lkral/peristalsis/index.html

Epiglottis At the back of the mouth there are two openings one opens to the esophagus the other opens to the trachea (wind pipe). To prevent food from going down the wrong pipe (trachea) a flap of tissue covers the pipe it is called the EPIGLOTTIS.

Sometimes when you eat or drink to fast you can choke, this is due to particles going down the wrong pipe. The epiglottis prevents food particles from entering the trachea. Epiglottis- flap of tissue that prevents food from entering the windpipe.

Stomach The stomach is a J-Shaped muscular pouch that is located in the abdomen.

Stomach The stomach is located at the end of the esophagus. This is where mostly mechanical digestion and some chemical digestion takes place. What does mechanical digestion look like in the stomach? When the food enters the stomach the j-shaped pouch churns the food, it mixes in the stomach.

Stomach Some chemical digestion takes place in the stomach as well. Hydrochloric acid – is a very strong acid that breaks down food with in the stomach. This acid kills bacteria that might be within the food, it is a very strong acid, this is why you have a protective lining of mucus that prevents the acid from eating your stomach.

Stomach It takes a couple of hours for the stomach to turn all of your food into a liquid form. It does not leave the stomach until this point. After the food has been turned into a liquid form it leaves the stomach and continues on to the small intestines.

The liquid leaves the stomach and enters the small intestines The liquid leaves the stomach and enters the small intestines. This is where the majority of chemical digestion takes place. Small intestines

Small Intestines Almost all chemical digestion Almost all absorption takes place in the small intestines. Enzymes and secretions come into the small intestines from the liver and the pancreas.

The liver is a very large organ that is located under the rib cage and beside the stomach.

Liver The role of the liver is to produce BILE. What is bile? Bile is a substance that breaks up fat particles. Bile is made in the liver and stored in the gallbladder. You can think of bile like soap it does not get rid of fat it just breaks up large fat particles into smaller fat droplets.

Liver produces bile and the gallbladder stores the bile until your body needs it. Liver/ Gallbladder

Pancreas Pancreas is a triangular shaped organ that lies between your stomach and small intestines. The job of the pancreas is to supply the small intestines with an enzyme that breaks down starches, proteins, and fat. Also secrete hormones into the blood stream. The pancreatic hormone, insulin and glucagon, work together to maintain the proper level of sugar in the blood.

Pancreas supplies an enzyme that is secreted into the small intestines that helps by breaking down starches, fat, and protein molecules.

Absorption in the small intestine The small intestines is where the majority of the food molecules are absorbed by the body. The food is absorbed on tiny finger shaped structures called VILLI.

Villi are tiny finger like structures that have a blood supply just beneath the surface. This is where the nutrients from the food are absorbed into the blood stream. Villi- if you were to stretch out all the villi in the small intestine it would be as large as a tennis court.

Large Intestine The large intestine is about 1.5 meters long, it is the last section of the digestive track. This is where water is absorbed into the bloodstream. The remaining material is readied for elimination.

Large intestine= 1.5 meters long Large intestine is where water is absorbed into the blood stream. Waste is readied for elimination. Large intestine= 1.5 meters long