Nutrition, Digestion, & Excretion Chapter 18

Class objectives Understand the overall function of the digestive system. Identify the function of the parts of the digestive system. Compare mechanical and chemical digestion and identify the organs responsible for each type.

Digestive System Ingestion, digestion, absorption, and elimination. Ingestion is the intake of food, digestion is the breakdown of these food particles into useable nutrients. Mechanical digestion -is the physical breakdown of food by chewing. Chemical digestion -occurs in your digestive track by enzymes that break food down chemically. Absorption is the body taking in the nutrients into the blood stream. Elimination is the removal of food products that could not be used.

What are the parts of the digestive tract? stomach, mouth, small intestine, large intestine, sophagus ,rectum , anus What is the correct order of the digestive organs from start to finish? -mouth -esophagus -stomach Sm. Intestine -lg. intestine rectum anus

Organs of the Digestive System -Mouth- Takes solid food and mechanically breaks it down into a bolus, or ball of food. Q:What is the scientific name for chewing? A:Mastication -The tongue pushes this bolus down the esophagus. Esophagus- flexible tube that connects the mouth to the stomach. And passes the bolus to the stomach through peristalsis, or involuntary muscle movement of the esophagus. Stomach- J-shaped hollow organ has 2 sphincters, a cardiac and a pyloric sphincter. Food enters the stomach and is ground up by the strong walls of the stomach into a watery substance called chyme.

Really creepy picture of the salivary glands Esophagus

Organs of the Digestive System Small Intestine- accepts chyme from the stomach through the pyloric sphincter. Here digestion of solid food occurs as well as absorption of nutrients. 3 major sections: -Duodenum -Jejunum -ileum These nutrients are absorbed through the small intestines villi, or small folds in the small intestine. Large intestine- Here water from the undigested food is absorbed. 4 major sections: -Ascending, transverse, descending, sigmoid colon

Accessory Organs of the Digestive System Pancreas- attached to the first section of the Small intestine and secretes amylase, protease, lipase and insulin into the sm. Intestine for aid in break down of food and removal of glucose from the blood. Liver & Gall Bladder- makes bile and send it to the gall bladder which is also attached to the sm. Intestine and allows the easier emulsification of fats.

Name 2 digestive disorders or problems per organ of the digestive system. (don’t use the ones we spoke about already!)