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Digestive and Excretory Systems By the end of this unit, I should be able to… 1. List and describe the sequence of organs in the gastrointestinal (G.I.) tract. 2. Describe how the general physiology of each organ in the G.I. tract aids in it’s function. 3. Compare and contrast Nutrients, Vitamins, and Minerals. The Digestive System The Digestive System • A long hollow tube- called the Gastrointestinal Tract (GI Tract) • Purpose: to break down macromolecules into unit molecules that our body then absorbs The Processes of Digestion 1. Ingestion- taking food in 2. Digestion- break down of food 3. Movement- from one segment of the tract to the next 4. Absorption- when nutrients cross the wall of the GI tract and enter the cells lining the tract and then enter into the blood stream. 5. Elimination- undigested molecules are removed The pathway that food follows? mouth pharynx esophagus stomach small intestine large intestine rectum anus The Digestive Tract 1. Mouth– Teeth are well adapted for chewing many kinds of food – Saliva - a mixture of water, mucus, and a digestive enzyme called salivary amylase (breaking down starches into sugars) 2. Pharynx- The location where the GI tract and the respiratory system crossover 3. Esophagus- long muscular tube that connects the pharynx with the stomach – muscles in the Esophagus wall move food toward the Stomach. – Waves of muscular contractions called peristalsis move food through the digestive tract 4. Stomach- J shaped muscular organ that lies on the left side of the body beneath the diaphragm – Stores food – Stomach acid and gastric enzymes begin the breakdown of protein – Pepsin- the enzyme that begins protein digestion 5. Small Intestine– Digests carbohydrates, fats, and completes the digestion of proteins. – ABSORBS nutrients 6. Large Intestine– Absorb water to prevent dehydration – Absorbs vitamins (B complex and K) produced by intestinal flora – Forms and rids the body of feces through the anus Accessory Organs Pancreas- secretes Pancreatic Fluid into the Small Intestine. – Lipase enzymes - break down fat molecules to free fatty acids, diglycerides, and monoglycerides – Emulsification of fats- broken down into smaller droplets Liver- produces bile, destroys old blood cells, detoxifies blood, stores iron, and helps regulate blood cholesterol levels Bile- produced by liver and stored in the furthers the process of digestion Gall bladder- stores bile Review Nutrient Absorption Nutrients • Part of food that performs a function in the body – provides energy – promote growth and development – regulate metabolism Polymers Carbohydrates Proteins Lipids Monomers glucose amino acids free fatty acids Minerals • Inorganic (nonliving) substance that occurs naturally in the ground • Living organisms require them for parts of cells, body fluids and structural components of tissues • ExamplesCalcium- Bones and muscle contraction Phosphourous - Bone, phospholipids, ATP Vitamins • Organic compounds that the body uses for metabolic purposes, but is unable to produce enough on its own • Many are co-enzymes (enzyme helpers) • Examples Vitamin D, B, C