DIGESTIVE SYSTEM

FUNCTIONS Digestion Absorption Elimination

DIGESTION Digestion – the mechanical and chemical breakdown of foods for use by the body’s cells. Types of digestion include: Mechanical Digestion – when teeth or the stomach break up food into smaller pieces Chemical Digestion – when food is broken down into simpler substances due to the action of enzymes.

ABSORPTION Absorption – the passage of digested food from the digestive tract into the bloodstream or cardiovascular system. Nutrients are absorbed into the blood and delivered to all the cells of the body through the cardiovascular system *Nutrients absorbed – Carbohydrates, Proteins, Fats, Vitamins, Minerals

ELIMINATION Elimination – the expulsion of undigested food or body wastes

STRUCTURES OF THE DIGESTIVE SYSTEM Teeth are used to break up food, a process called chewing or mastication. MASTICATION = chewing Salivary Glands – produce saliva in the mouth that contain enzymes that start to break down certain foods in the mouth Saliva also lubricates food making it easier to swallow

STRUCTURES The tongue forms and pushes chewed food towards the throat or pharynx. As you swallow, muscular contractions force food into the pharynx. The uvula, a small flap of tissue in the back of the throat, closes the opening to the nasal passages. The epiglottis, another flap of tissue covers the windpipe, also known as your trachea.

DIGESTIVE TRACT Alimentary Canal – takes in food, digests it, extracts nutrients, and expels water 30 foot long tube that opens at both end; food passes through

PARTS OF THE DIGESTIVE TRACT Mouth – forms bolus Bolus – ball shaped through chewing and swallowing food; mixed with saliva Voluntary and Involuntary Physical and chemical breakdown of food by process of chewing

PARTS CONTINUED Pharynx – located in the neck and throat Food and air pass through here Transports food to stomach Involuntary

PARTS Esophagus – 10 inch tube transports food to stomach Peristalsis – contraction of muscles to propel food down (bolus)

PARTS Stomach Chemical and Physical breakdown of food Chyme – mixture of gastric juices and food Food stays in the stomach for about 3 – 5 hours

PARTS Small Intestine – 20 foot long tube 3 parts: Duodenum – first 10 inches of the small intestine; extract nutrients Jejunum Ileum Absorption – nutrients absorbed into the blood stream

SMALL INTESTINE PARTS

PARTS Large Intestine – 5 – 6 foot long tube Organization of wastes and feces Undigested food turns into feces Appendix – about 4 inch thin tube; no known function Cecum – beginning of the large intestine; receives fecal matter from the Ileum

LARGE INTESTINE

PARTS Rectum – stores feces Anus – releases feces Ring of muscle, expelling unwanted solid matter Sphincter – circular muscle that normally maintains constriction of a natural body passage

ORGANS THAT HELP IN DIGESTION Liver – produces bile Bile – dark green to yellowish brown fluid that aids in digestion in the small intestine Stores glucose (sugar) and iron Pancreas – digests sugar Produces enzymes that break down carbohydrates, fats, and proteins in food Enzymes – any proteins that cause a chemical reaction

ORGANS CONTINUED Gallbladder – stores bile in between meals At meal time, bile is secreted into the bile duct to reach the small intestine (duodenum) and mix with the fats in foods Bile dissolves fats into watery contents After dissolved, its digested by the enzymes made in the pancreas

FUN FACTS Carbohydrates digest first, proteins next, and fats last It takes about 12 – 72 hours to digest food, depending on what type of food you eat Water helps in digestion