DIGESTIVE SYSTEM Mr. Z’s Cool Science Classes

Digestive System Digestion- process by which foods are changed into forms the body can use

MOUTH Our teeth tear and crush food into a fine paste to be swallowed Chewing begins the process of mechanical digestion

What role does our mouth play? Mechanical Digestion- the physical breakdown of large pieces of food into smaller pieces. As we chew our food, digestive enzymes breakdown our food this is called chemical digestion.

Just Checking…. Are the teeth involved in mechanical or chemical digestion? MECHANICAL!!!

SALIVA As the teeth cut and grind food, the salivary glands secrete saliva, which moisten food and make it easier to chew. Saliva begins the process of chemical digestion Saliva not only eases the passage of food through the digestive system but also begins the process of chemical digestion

SALIVA Saliva contains an enzyme called amylase that breaks the chemical bonds in starches and releases sugars. Chemical Digestion- large molecules are broken down into smaller food molecules.

Chew on this for a second… Take a bite out of your cracker Chew on the soda cracker for 5 seconds –w/o sharing w/ anyone record how it tastes on paper. Continue chewing on your cracker for 5 minutes.

Results? What did your cracker taste like after 5 seconds? –5 minutes? How and Why did the taste of the cracker change?

Aha! Saliva contains an enzyme called_____. Amylase If you chew on a starchy food like a cracker long enough, it will begin to taste sweet. The sweet taste is a sign that sugar has been released from starch by the action of amylase.

Esophagus A Chewed clump of food is called a bolus. As we swallow, the bolus passes through the esophagus into the stomach. Peristalsis-contractions that squeeze food through the esophagus into the stomach.

STOMACH Food from the esophagus empties into a large muscular sac called the stomach. Chyme-mixture of stomach fluids and food produced by contracting stomach muscles.

Small Intestine As chyme is pushed through the pyloric valve, it enters the duodenum. Most of the chemical digestion and absorption of the food you eat occurs in the small intestine.

SMALL INTESTINE Just behind the stomach is the pancreas The pancreas has 3 main functions –To produce hormones that regulate blood sugar –Produces enzymes that break down carbohydrates, proteins, lipids, & nucleic acids –Produces sodium bicarbonate, base that neutralizes stomach acid.

Accessory Structures of Digestion Pancreas Liver-a large organ located above and to the left of stomach. Produces bile- fluid, acts like a detergent (dissolving and dispersing fats found in fatty foods)

Large Intestine When chyme leaves the small intestine, it enters the large intestine, or colon. Primary function: –Remove water from the undigested material that is left.

Digestive System Disorders

To help us organize the information, let’s create a graphic organizer!! PartsFunctionLocation MouthTasteUpper body Esophagus StomachMixes & stores food Small Intestine Large Intestine

Vocabulary Digestive system: set of organs involved in the digestion of food. Pharynx: part of the digestive tract between the mouth and the esophagus. Esophagus: part of the digestive tract between the larynx and the cardia of the stomach. Stomach: pocket-like part of the digestive tract, where food is mixed and stored. Pancreas (tail): gland connected to the digestive tract which produces digestive enzymes. Duodenum: beginning of the small intestine. Small intestine: part of the digestive tract between the stomach and the large intestine. Descending colon: part of the large intestine in which food travels downward. Sigmoid: last part of the descending colon. Anus: end of the large intestine, through which the human body expels solid waste. Rectum: last part of the large intestine, between the sigmoid colon and the anus. Appendix: hollow diverticulum fastened to the caecum. Cecum: blind gut formed by the part of the large intestine between the small intestine and the ascending colon. Ascending colon: part of the large intestine where food travels upward. Transverse colon: part of the large intestine where food travels horizontally. Gallbladder: small sac that contains the bile. Liver: digestive gland that produces bile. Tooth: organ set in the jaws and used to cut and crush food. Tongue: organ of taste.