Lecture 2 Digestive System &Nutrition 1 Lecture 3 1. Introduction 2. Digestive System 3. Nutrition Basics 2 1
Introduction Some Ecology 3 Mr. Sun 4 2
Nuclear Fusion 5 Light energy from Sun radiates across space. 6 3
Light energy from Sun radiates across space. 7 A very small percentage strikes the Earth s surface 8 4
Light Energy Absorbed 9 Photosynthesis Energy stored here 10 5
Plants! Important! 11 Consumers 12 6
Digestive System Breaks down ingested food (large molecules) into small molecules, via mechanical and chemical means. The material is absorbed by the body and used for various functions where needed. Also, begins the process of harvesting the solar energy contained within chemical bonds Digestive System 14 7
Digestive System, Five Functions 1. Breaks up food into small pieces 2. Transports food through the alimentary canal (gut) via rhythmic muscular contractions (peristalsis) 3. Secrets digestive enzymes to breakdown food 4. Absorbs nutrients into the bloodstream 5. Excretes solid wastes of digestion Digestive System 1. Mouth (Buccal Cavity) 2. Pharynx (Throat) 3. Esophagus 4. Stomach 5. Small Intestines 6. Large Intestine (Colon) 7. Secretory Glands (Salivary Glands, Liver, and Pancreas) 8
Mouth Teeth, mechanical breakdown: incisors canines premolars & molars Salivary Glands - Saliva, mixes with food and begins chemical breakdown. Esophagus Connecting tube between the pharynx and the stomach, or between pharynx and intestine. Peristalsis 18 9
Esophagus Specialization: Egg Eating Snake 19 Peristaltic Contractions waves of rhythmic relaxation and contraction of the muscles in the alimentary canal that move along the canal and act to push the contents from the mouth toward the rectum. Muscles Contracted Muscles Relaxed 20 10
Stomach 21 Stomach Cardiac Sphincter Pyloric Sphincter 22 11
Lining of the Stomach: Gastric Pits Cells secrete Hydrochloric Acid (HCl) Lining of the Stomach: Goblet Cells Secrete Mucous protects the stomach lining 24 12
Stomach Cardiac Sphincter Pyloric Sphincter 25 Stomach Cardiac Sphincter Pyloric Sphincter 26 13
Stomach Cardiac Sphincter Pyloric Sphincter Chyme 27 Gastroesophogeal Reflux Disease (GERD) Cardiac Sphincter Pyloric Sphincter 28 14
Intestines 29 Intestines Serve Three Main Functions: 1. Continues the digestive process begun by the mouth and stomach 2. Selectively absorbs final products of digestion 3. Moves the food through the system via peristalsis. 30 15
Intestine Regions 1. Small Intestine where digestion and nutrient absorption takes place. 2. Large Intestine (Colon) reabsorb water and consolidate feces. Synthesizes Vitamin K which is necessary for blood clotting. 31 Small Intestine: Three Sections 1. Duodenum chemical digestion 2. Jejunum absorption 3. Ileum - absorption 32 16
33 Duodenum shortest part of the small intestine (~ 25-30 cm), site of most chemical digestion 17
Jejunum & Ileum Jejunum - Second longest part of the small intestine (~ 2-3 meters), Ileum - longest part of the small intestine (~ 2-4 meters), sites of absorption. 35 Large Intestine (Colon) 18
Large Intestine (Colon) 1. Primary Function water absorption and feces consolidation. 2. Vitamin K produced by bacteria What about the appendix? A thin tube about four inches long, located at the junction of the small intestine and large intestine in the lower right abdomen. 38 19
What about the appendix? Once thought to be a vestigial organ an organ that once served a purpose in our evolutionary past, but no longer serves any function. 39 What about the appendix? NOW, is believed to serve an important function a haven for useful gut bacteria when illness flushes those bacteria from the rest of the intestines. 40 20
What about the appendix? Appendicitis - for unclear reasons, the appendix often becomes inflamed, infected, and can rupture. This causes severe pain in the right lower part of the belly, along with nausea and vomiting. 41 Secretory Organs Salivary Glands, Liver, and Pancreas 42 21
Salivary Glands Saliva enzymes that begin carbohydrate digestion 43 Liver Does lots of different stuff! Produces Bile. Stored in the Gall Bladder. Bile aids in fat digestion. 44 22
Pancreas Produces digestive enzymes secrets into the duodenum. Also produces insulin regulates blood sugar 45? 46 23
Nutrition 47 Nutrition 1. the process of providing or obtaining the food necessary for health and growth. 2. food; nourishment. 3. the branch of science that deals with nutrients and nutrition, particularly in humans. 24
Why is Nutrition Important? Your food choices each day affect your health how you feel today, tomorrow, and in the future. Why is Nutrition Important? Good nutrition is an important part of leading a healthy lifestyle. Combined with physical activity, your diet can help you: reach and maintain a healthy weight, reduce your risk of chronic diseases (like heart disease and cancer), and promote your overall health. 50 25
Why is Nutrition Important? Unhealthy eating habits have contributed to the obesity epidemic in the United States: About one-third of U.S. adults (33.8%) are obese Approximately 17% (or 12.5 million) of children and adolescents aged 2-19 years are obese Too much sugar and not enough good nutrients Why is Nutrition Important? Even for people at a healthy weight, a poor diet is associated with major health risks that can cause illness and even death. Heart Disease Hypertension (high blood pressure) Type 2 diabetes Osteoporosis Certain types of cancer By making smart food choices, you can help protect yourself from these health problems. 52 26
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