The Digestive System Chapter 11

The Digestive System The process of breaking down food into forms that the body can use.

Mouth 1. Saliva – smelling, seeing, or thinking can begin digestion a. glands in mouth and throat start producing saliva b. clear liquid in mouth contains enzymes (help break down food) c. makes food soft and wet (easier to swallow) 2. Teeth a. front teeth – tear b. side and back - grind 3. Tongue a. pushes food around inside the mouth b. forms a ball and pushes it into the back of the throat

Mouth – continued 4. Taste buds – on tongue – about 10,000 √ special clusters of cells that react to chemicals in food √ sensory cells √ gather information and send it to the brain √ Your brain tells you how your food tastes √ Taste buds only work when the food is wet a. 4 basic tastes  1. Sweet2. Sour  3. Salty4. Bitter b. Savory taste – cheeses, tomatoes, and meats  UMAMI– is in the flavoring MSG – it does not taste good by itself. It brings out the taste in other foods.  Taste and smell closely related  Taste buds identify taste  Sensory cells in nose identify smell  Both messages are sent to brain where it combines the information to identify and appreciate different flavors.

Throat Once you swallow the food you no longer choose your body takes over. 1. connects to two passageways a. trachea – passageway for air that leads to lungs b. esophagus – for food lead to stomach 2. epiglottis – flap of tissue that covers the opening to the trachea

Esophagus 1. connects throat to stomach (tube – 25 centimeters long X 2.5 cm wide) a. peristalis contracts or squeezes the food in waves to move the food along b. sphincter ring of muscles at the bottom of the esophagus control an opening to stomach After food is in stomach it closes so that no food can rise up when you bend over. Travel time from mouth to stomach – less than 30 seconds.

Stomach 1. stretchy storage bag – 30cm long (12 in.) a. located under rib cage b. Works on food in two ways 1. mechanically- mixes food by peristalsis ( The involuntary constriction and relaxation of the muscles of the intestine )  Mashes and churns – smaller and smaller pieces 2. chemically – gastric juices are a mixture of enzymes, water and hydrochloric acid.

Stomach Stomach – continued  These juices help break down food, which forms…  chyme - a liquid-like mixture  Gastric juices also kill harmful bacteria  Hydrochloric acid – inside the walls of the stomach is very harmful by itself.  Mucus – is special coating that protects the walls (lining of the stomach).  Stomach usually takes 3-4 hours in the digestion process

Stomach – acid reflux Embed

Small Intestine  Pyloric Sphincter – “Gate Keeper”  Every time the “gate watcher” opens and closes a spoon full of chyme travels from the stomach to the small intestine.  Nutrients  from food is absorbed  is the substance the body needs to live and grow  Villi  Tiny fingerlike structures within the small intestine.  Roughly 5 million!!!!!  Blood vessels in the villi carry the nutrients to the body  Takes about 4 hours 20 ft. long! Small intestine = 6 meters or 20 ft. long!

Large Intestine

1.5 meters 5ft long Body absorbs any water and salts still in the chyme. Digestion is now complete. Only waste is left. We cannot use waste so we eliminate it. Whole process takes 1-4 days.

Other Digestive Organs

Pancreas 1. Makes enzymes, which break down food into nutrients for the body. 2. Produces insulin a. helps the bodies cells use the sugar that the body absorbs b. Diabetes –the body does not produce enough insulin, preventing the body from getting the sugar it needs.

Liver  Produces Bile, a green liquid that helps break down fats. (dish soap vs. grease on dishes)  Cleans Blood – filters poisons, wastes, and other harmful substances from the blood.

Gallbladder  Stores excess bile and releases this bile at the appropriate times.

Nutrition

Receiving the proper nutrients the body needs.

Nutrients  Proteins – build and repair the body  Muscles contain a lot of protein  Enzymes that help with digestion  Examples: meats, eggs, nuts, beans, and dairy products  Fats – help insulate the body  Stored energy  Too many fats can damage the body (especially meats)  Examples: meats, nuts, weeds, fish  Carbohydrates – very important to the body  Not all carbohydrates are the same  Sugar – fruit  Starches – corn, potatoes  Broken down comes sugars that your body needs  Examples: grains, fruits, vegetables

Other Nutrients  Vitamins & Minerals  Water