“From gum to bum”

In this section, you will:  identify the main structures and functions of the digestive system  describe the physical and chemical processing of food through the digestive system and into the bloodstream  identify enzymes and other chemicals involved in digestion  describe, in general terms, how digested molecules enter the bloodstream

 Ingestion (eating)  Teeth masticate  Salivary glands  Amylase

 The tongue  When the food is swallowed,  The epiglottis  The food

 The stomach is a J-shaped pouch that has three main roles:  Partially  The top of the stomach is  If this muscle is weak, it can lead to heartburn or acid reflux disorder.

 The normal stomach The normal stomach

 The stomach secretes 3 important substances into its lumen (interior): 1. Hydrochloric acid (HCl). 2. Mucous. 3. Pepsinogen  Stomach ulcer Stomach ulcer

 The mixture  Chyme  In the duodenum,  Bile,

 The pancreas secretes a number of important substances that aid in digestion. SecretionRoleFunction Bicarbonate (HCO 3 - ) Carbohydrases Lipases Erepsins Nucleases Trypsinogen Enterokinase

 Hormones are chemical messengers that travel through the blood stream.  Gastrin  Secretin.  CCK  Enterogastrone

 Nutrients are absorbed from the sm. intestine into the blood stream. The jejunum absorbs most nutrients, while the ileum absorbs lipids & fat soluble vitamins.  Finger-like projections called villi  Microscopic projections on the villi,  Capillaries in the villi absorb most nutrients,.

Top: Glucose is actively transported into cells of the intestinal wall to move into the bloodstream. Middle: Amino acids are actively transported into the cells of the intestinal wall to move into the bloodstream. Bottom: Glycerol and fatty acid molecules diffuse into the cells of the intestinal wall where they are resynthesized into fats, coated with proteins, and move into lymph vessels for eventual transport into the bloodstream.

 The colon is mainly responsible for  There are also bacteria (such as E. coli) in the colon that make vitamins for us (particularly B & K).  Solid wastes (feces)  Removal of colonal polyps (YouTube).

 The human body takes in matter from the environment in the form of food and water. The human digestive system processes the food and water in order to obtain the macromolecules it needs for survival.

 Food passes through the digestive tract—the mouth, pharynx, esophagus, stomach, small intestine, and large intestine—during physical digestion.  The accessory organs—the salivary glands, liver, gall bladder, and pancreas—supply chemicals that also contribute to the digestion of food as it passes through the digestive tract.  The stomach supplies chemicals to aid digestion as well as generating physical contractions to physically break down food.  The food is eventually liquefied into soluble units that can pass through cell membranes for transport via the circulatory system to all the cells in the body.  The waste materials from the digestive process leave the body via the large intestine.

 The nutrients that food supplies include carbohydrates, lipids (fats), protein, and nucleic acids.  Carbohydrates and lipids are broken down to supply energy; lipids also supply material for the cell membranes.  Proteins are more structurally and functionally diverse than carbohydrates and lipids. They assist in transport, immunity, and muscle action and are used to make up most cellular structures.  Nucleic acids direct growth and development. Enzymes speed up chemical reactions, particularly for the production of energy.  Vitamins and minerals are organic and inorganic substances that enable chemical reactions to occur and aid in tissue development and growth and immunity. These substances are needed for a healthy, functional human body.