Digestive System Living Environment

What is it? The digestive system is a group of organs working together to convert food into energy and basic nutrients to feed the entire body. Everything you eat needs to be broken down into smaller molecules that your cells can use to make energy for your body. Proteins  amino acids Fruits, vegetables, grains, starches simple sugars Fatty foods  fatty acids

Six Major Functions Ingestion of food Secretion of fluids and digestive enzymes (ex. saliva, mucus, stomach acid, bile) Mixing and movement of food and wastes through the body (ex. swallowing) Digestion of food into smaller pieces Absorption of nutrients (stomach & small intestines) Excretion of wastes

Parts of the Digestive System Mouth Pharynx Esophagus Stomach Small Intestine Liver Gallbladder Pancreas Large Intestine

Mouth Food begins its journey through the digestive system in the mouth, also called the oral cavity The tongue, teeth, and salivary glands all help in the digestion of food

Teeth The teeth are 32 small, hard organs that cut and grind food into smaller pieces They are made of dentin which is a bone-like substance They are covered in a layer of enamel which is the hardest substance in the body They are living organs and contain blood vessels and nerves

The Tongue The tongue is a small organ made up of several pairs of muscles covered in a thin, bumpy, skin-like layer. The outside of the tongue has many papillae for gripping food and moving it around the mouth. Taste buds on the surface of the tongue detect taste molecules in food and connect to nerves to send taste information to the brain The tongue pushes food to the back of the mouth

Salivary Glands There are 3 sets of salivary glands that surround the mouth They are accessory organs that produce saliva Saliva moistens food and begins the digestion of carbohydrates. Saliva also lubricates food so it passes easier through the mouth, pharynx, and esophagus

Pharynx Also known as the throat It is connected to the back of the mouth The pharynx’s job is to pass masses of chewed food from the mouth to the esophagus It also is a pathway for air to the lungs A flap of tissue known as the epiglottis acts as a switch to route food to the esophagus and air to the lungs

Esophagus The esophagus is a muscular tube connecting the pharynx to the stomach that is part of the upper gastrointestinal tract It carries swallowed masses of chewed food into the stomach A muscular ring, called the sphincter, is located at the bottom of the esophagus and makes sure that food stays in to stomach once it passes through

Stomach The stomach is a muscular sac located on the left side of your abdomen, right under the diaphragm The stomach is about the size of two fists placed next to each other It acts as a storage tank for food so that the body has time to digest large meals properly It contains hydrochloric acid and digest enzymes that continue the digestion of food that started in the mouth

Small Intestine The small intestine is a long, thin tube about 1 inch in diameter and about 10 feet long. It is located right under the stomach and takes up most of the space in the abdomen. It is coiled up like a hose and its inside surface is full of ridges and folds The folds maximize the digest of food and absorption of nutrients By the time food leaves the small intestine, about 90% of all nutrients have been taken out of the food

Liver The liver is roughly triangular accessory organ of the digestive system located to the right of the stomach, under the diaphragm, and above the small intestine It weighs about 3 pounds and it is the 2nd largest organ in the body Its main function in digestion and the production of bile and its secretion into the small intestine

What’s Bile? Bile is a fluid that is made and released by the liver and stored in the gallbladder Bile helps with digestion It helps the enzymes in your body to break down fats into fatty acids which can then be taken into the body

What are enzymes? Enzymes are usually proteins that help to start chemical reactions within the body They initiate change In the digestive system they help to break down food into smaller macromolecules that can be used by the body for energy

Gallbladder The gallbladder is a small, pear-shaped organ located right behind the liver It is used to store and recycle excess bile from the small intestine so that it can be reused for the digestion of future meals

Pancreas The pancreas is a large gland located just below and behind the stomach It’s about 6 inches long and shaped like a short, lumpy snake It secretes digestive enzymes into the small intestine to complete the chemical digestion of foods

Large Intestine The large intestine is a long, thick tube about 2 ½ inches in diameter and about 5 feet long It’s located right under the stomach and wraps around the small intestine Its function is to absorb water and contains many symbiotic bacteria that aid in the breaking down of wastes to get any remaining nutrients that weren’t absorbed in the small intestine Feces in the large intestine exit the body through the anal canal