BIOD 121 (Portage): Module 2 Latest Update Graded A+

BIOD 121 (Portage): Module 2 Latest Update Graded A+ Digestion process of transforming food into basic nutrients that can be absorbed and used by the body Without the process, the nutrients we initially consume in food would be useless: digestion Before food even enters the mouth, a cascade of events involving the nervous system and a variety of hormones are set off based on a variety of stimulus: cognition, sound, odor, appearance, and taste cognition thoughts about food can start the flow of saliva sound hearing a description of the meal odor smells stimulate a hunger response and influence its taste appearance seeing the food taste begins as the food enters your mouth and also how it feels Once food enters the mouth it begins to break down into smaller units in both mechanical and chemical processes Mechanical process begins in the mouth with chewing peristalsis involuntary muscle contractions are used to move food mixtures along the tract Enzymes, acid, bile, and mucus chemical means the body has at its disposal to further aid in breaking down food enzymes proteins that catalyze (speed up) chemical reactions. They catalyze the chemical reactions required to break down food particles into smaller parts, which prepares the nutrients for absorption gastrointestinal (GI) tract a long hollow tube consisting of several layers of tissue that begins with the mouth and ends at the anus nutrient absorption occurs across the wall of the gastrointestinal (GI) tract mucosa (intestinal wall) is the inner-most layer, and it is made of absorption cells and glands circular and longitudinal muscles comprise the outer layers, both of which function to mix and move food along the GI tract Circular bands of muscle most often found where one part of the tract connects to another, serving as valves to control the flow of the food particles 3 processes the body can use to move nutrients from the GI tract into the blood/lymph system and eventually into the cells: Passive diffusion, Facilitated diffusion, and Active transport Passive diffusion substances move easily in and out of cells without the use of energy. Nutrients move from high to low concentration. Facilitated Diffusion no energy is required, but a special protein carrier is required to help substances cross in or out of the cell. Nutrients move from high to low concentration. 2 processes that move from high to low concentrations and require no energy passive and facilitated diffusion Active transport energy is required to move substances in or out of the cell. Nurtients move from low to high concentrations Moves nutrients against the natural gradient: active transport Does not require a special protein carrier/transport molecules: passive transport GI tract can be divided into six main parts: 1) mouth 2) esophagus 3) stomach 4) small intestine 5) large intestine 6) rectum