Human Digestive System

Function – converts food into simpler molecules that can be absorbed and used by cells of the body. Nutrients – substances needed for growth, repair and maintenance. ex: water, carbohydrates, fats, proteins, vitamins and minerals (pg 974) ex: water, carbohydrates, fats, proteins, vitamins and minerals (pg 974) Heterotrophic Nutrition – we must obtain our food from outside sources

Organs of the Digestive System 1. Mouth 1. Mouth - Mechanical digestion begins with teeth. - Mechanical digestion begins with teeth. - Chemical digestion begins with saliva. Contains enzyme amylase that digests starch. - Chemical digestion begins with saliva. Contains enzyme amylase that digests starch. 2. Esophagus – food tube to stomach. 2. Esophagus – food tube to stomach.

- food (bolus) moves down tube due to wave-like muscle contractions called peristalsis - food (bolus) moves down tube due to wave-like muscle contractions called peristalsis peristalsis uncovered peristalsis uncovered stomach endoscope stomach endoscope

3. Stomach 3. Stomach - mechanical digestion continues by muscle contractions. Mixes contents to make chyme - mechanical digestion continues by muscle contractions. Mixes contents to make chyme - chem digestion HCL and enzymes break food down, mainly proteins - chem digestion HCL and enzymes break food down, mainly proteins

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4. Small Intestine – 4. Small Intestine – most chemical digestion takes place ( carbs, proteins, fats) most chemical digestion takes place ( carbs, proteins, fats) ***Nutrients are absorbed here along little finger-like villi that have huge surface area ***Nutrients are absorbed here along little finger-like villi that have huge surface area

5. Large Intestine – water and undigestible material enter here. 5. Large Intestine – water and undigestible material enter here. - water reabsorbed - water reabsorbed - bacteria work on undigested stuff and some produce vitamin K that we need. - bacteria work on undigested stuff and some produce vitamin K that we need. - what’s left passes through rectum and out - what’s left passes through rectum and out - diarrhea results when water not reabsorbed - diarrhea results when water not reabsorbed

Accessory Organs

Food does not pass through these organs. They secrete digestive juices. Food does not pass through these organs. They secrete digestive juices. 1. Liver – makes and secretes bile that breaks down fats. 2. Gall bladder – stores bile and secretes it into small intestine 3. Pancreas – makes digestive juice containing: protease – for protein lipase – for lipids lipase – for lipids amylase – for starch amylase – for starch

Diseases of Digestive System 1. Ulcers – sores on lining of stomach or intestine 2. Diarrhea 3. Crohn’s Disease – inflammation of digestive tract 4. Celiac Disease – body reacts to gluten in wheat and barleys and destroys villi in small intestine.