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Chapter 39

Chapter 39. Digestive and Excretory Systems. FOOD PYRAMID. Fats, oils, and sweets (top of the pyramid) Use sparingly Milk, Yogurt, Cheese 2-3 servings a day Meat, Beans, Eggs, Nuts 2-3 servings a day Vegetables 3-5 servings a day Fruits 2-4 servings a day Grains, bread, cereal

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Chapter 39

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  1. Chapter 39 Digestive and Excretory Systems

  2. FOOD PYRAMID

  3. Fats, oils, and sweets (top of the pyramid) • Use sparingly • Milk, Yogurt, Cheese • 2-3 servings a day • Meat, Beans, Eggs, Nuts • 2-3 servings a day • Vegetables • 3-5 servings a day • Fruits • 2-4 servings a day • Grains, bread, cereal • 6-11 servings a day

  4. Regardless of the source, the excess calories you eat will be stored as either glycogen or body fat and you will gain weight • Obesity is being more than 20% heavier than your ideal body weight and significantly increases the risk of diabetes and heart disease.

  5. Vitamins are organic substances that occur in many foods in small amounts that are necessary for normal metabolic functioning and dissolve in water or fat. • Minerals are naturally occurring inorganic substances that are used to make certain body structures and substances, in normal nerve and muscle function, and maintain osmotic balances. Minerals are soluble in water.

  6. Digestion • The process of breaking down food into molecules the body can use is called digestion.

  7. The digestive system takes in food, breaks it down into molecules that can be absorbed, and gets rid of undigested molecules and wastes. • Food travels more than 8 m (26 ft) through your digestive tract. • Digestion begins: as soon as food is ingested • Saliva moistens and lubricates food and contains amylases which are enzymes that begin the breakdown of carbohydrates.

  8. Digestive tract includes: mouth, pharynx, esophagus, stomach, small intestine, large intestine, and rectum.

  9. Liver, pancreas, and gallbladder deliver secretions to digestive tract.

  10. Food moves past the pharynx, triggers a swallowing response which moves the epiglottis moving the food into the esophagus instead of the trachea. • Successive rhythmic waves of smooth muscle contractions in the esophagus is called peristalsis move the food into the stomach.

  11. Esophagus is a long tube that connects the mouth and stomach and is around 10 inches long. • The stomach is the saclike organ just below the diaphragm that stores food and chemically and mechanically break down food.

  12. Gastric juice is a combinations of hydrochloric acid and pepsin. • Swallowed food can spend 2 to 6 hours in the stomach. • A coating of mucus protects the lining of the stomach from gastric juices.

  13. Food passes from the stomach to the small intestine which is about 6m long and functions mainly in digestion and absorption of nutrients. • Food remains in the small intestine for 3 to 6 hours.

  14. The first part of the small intestine, called the duodenum, receives secretions from the pancreas, liver, and gallbladder. • Lipases from the pancreas digest fat.

  15. Lining of small intestine is covered with fingerlike projections called villi which increase the area available for absorption.

  16. Wastes then move into the large intestine. • Mostly mineral ions and water are absorbed in the large intestine.

  17. The final segment of the large intestine is the rectum; from here solid feces are eliminated through the anus. • Undigested material pass through the large intestine and are expelled in 12 to 24 hours.

  18. Liver’s role in digestion and metabolism: Secrets bile which aids in emulsification of fats Breaks down glycogen when its needed for energy

  19. Digestive System Disorders • Jaundice is a condition in which the eyes, skin and urine become abnormally yellow as a result of increased bile pigments in the blood. • Anorexia nervosa is an eating disorder in which people starve themselves. • Bulimia is an eating disorder in which people engage in frequent binging then purging.

  20. EXCRETION • Excretion is the process that rids the body of toxic chemicals, excess water, salts, and CO2, while maintaining osmotic and pH balances.

  21. Organs of excretion: • Lungs rid the body of CO2 • Kidneys rid the body of nitrogen wastes, salt, water, and urea. • Skin rids the body of water and salts

  22. Kidney • Each kidney is composed of roughly 1 million microscopic blood filtering units called nephrons. • 3 phases occur as blood flows through nephrons: filtration, reabsorption, and secretion.

  23. Urine that is excreted from the body is formed from water, urea, and salts that are left over after the reabsorption and secretion processes.

  24. Ureters are tubes that carry the urine from the kidneys to the urinary bladder which stores the urine and expands as it fills. • The urinary bladder can hold about 0.6L of urine. • Urine leaves the bladder and exits the body through a tube called the urethra. • Elimination of urine from the body through the urethra is called urination.

  25. Kidney dialysis or hemodialysis is a procedure for filtering blood by using a machine. • Kidney Transplant is a more permanent solution to kidney failure. Major problem is rejection of the organ.

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