Food’s journey through the . . .

Types of Digestion Mechanical – physically

breaking food down into smaller pieces This creates more surface

area, so enzymes can get to more molecules

Chemical – use of chemicals and enzymes to break food into substances that can be absorbed

Mouth

Teeth are used for mechanical digestion to break the food into smaller pieces, so it can be easilyswallowed. Saliva contains enzymes used in

chemical digestion, which breaks down starches into simple sugars

The tongue is your strongest muscle used to manipulate food during mastication

Esophagus

The tube the food travels down to get to the stomach Peristalsis is the motion that pushes the

food down the tube. The tube pinches off above the food pushing it toward the stomach

You have an epiglottis that covers your esophagus while you are breathing and covers your trachea while you are swallowing

This prevents food from “going down the wrong tube”

Stomach

The stomach performs mechanical and chemical digestion of food. The stomach secretes a powerful acid

(pepsin) that breaks food down It also churns mixing the food with the acid

and breaking it down mechanically Chyme is the mixture of stomach acid

(pepsin), broken down food, and saliva that flows from the stomach into the small intestine

Duodenum

This is the first section of the small instestine, where most of the chemical digestion of carbohydrates, lipids, and proteins occurs

Chyme is joined with enzymes from the liver and pancreas that reduce acidity of the chyme and chemically digest the food

Small Intestine The small intestine are

covered in little finger like projections called villi

Villi increase the surface area of the small intestine to increase absorption of nutrients The usable nutrients are removed from the chyme and travel across the villi into the blood vessels that are inside it

Large Intestine

When the food arrives in the large intestine it is nutrient free The large intestine pulls any excess water

out of the remaining indigestible material creating feces

The large intestine is filled with bacteria that help our digestion process

When the large intestine is not removing enough water, diarrhea will result

When the large intestine removes too much water, constipation will occur

Rectum

The rectum will store the feces until there is enough to pass out of the

body When the rectum is full, you feel the urge to

go to the bathroom There is a sphincter muscle at the bottom of

the rectum called the anus This squeezes shut to keep feces in the

rectum and expands to allow it out when passing a stool

Liver, Pancreas, & Gallbladder The liver and pancreas secrete enzymes and digestive fluids that mix with the chyme in the duodenum The pancreas secretes a fluid to

neutralize the acidity of the stomach acid The liver secretes bile, which is used to break down fatty acids (lipids) Bile is stored in the gallbladder

Appendix

Is located near the junction of the small and large intestine The appendix is a vestigial organ,

which means it was once used but shrunk in size as it became less useful

Some organisms use the appendix to help break down cellulose in very fibrous substances (leaves)

Common Diseases

Diarrhea Constipation Appendicitis GERD IBS Ulcers Cirrhosis

What diseases or problems do you think of when you think of the digestive system?

Diverticulitis Ulcerative

Colitis Hemorrhoids Celiac’s Lactose

Intolerance Stomach Ache

Diarrhea and Constipation

Diarrhea – too much fluid in the bowel movements Caused by the large

intestine not removing enough water

Can be caused by viruses, bacteria, etc.

Can lead to dehydration and eventually death

Constipation – too much water being removed from the bowel movements Can be caused by

poor diet or not taking in enough water

Symptoms can be alleviated by taking laxatives

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