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Nutrient Absorption

Nutrient Absorption . How many different systems do you see? Digestive -Breaks down and absorbs nutrients 2. Respiratory -absorbs oxygen 3. Circulatory –transports nutrients. Evolutionary Trends of the Digestive System. Function of The Digestive System.

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Nutrient Absorption

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  1. Nutrient Absorption

  2. How many different systems do you see? Digestive-Breaks down and absorbs nutrients 2. Respiratory-absorbs oxygen 3. Circulatory –transports nutrients

  3. Evolutionary Trends of the Digestive System

  4. Function of The Digestive System • The function of the digestive system is to help convert foods into simpler molecules that can be absorbed and used by the cells of the body; eliminates waste.

  5. The Digestive System (aka. Alimentary Canal) Includes: • Mouth • Pharynx • Esophagus • Stomach • Small Intestine • Large Intestine • Rectum/colon • (Accessory organs: salivary glands, liver, gallbladder, pancreas)

  6. The Mouth • Teeth • Cutting, tearing, and crushing food into small fragments. • Begins the process of mechanical digestion or physical breakdown. • Saliva • Secreted by the salivary glands. • Helps moisten the food and make it easier to chew. • Contains amylase, a digestive enzyme that begins the breakdown of carbohydrates. • Begins the process of chemical digestion, where chemicals breakdown the large pieces into smaller pieces.

  7. The Esophagus • Bolus – Chewed clump of food. • From the throat, the bolus passes through the esophagus, or food tube, into the stomach. • Food travels through the esophagus to the stomach by smooth muscle contractions (wave-like) called peristalsis. • The epiglottis (small flap covering the trachea) separates the food from air when swallowing

  8. The Stomach • Food from the esophagus empties into a large muscular sac called the stomach. • The stomach continues the mechanical and chemical digestion of food. • Mechanical: Stomach muscles contract to churn and mix stomach fluids and food, gradually producing a mixture known as chyme. • Chemical: • Gastric glands release mucous to protect the stomach wall • Gastric glands produce hydrochloric acid and pepsin, which begins the complex process of protein digestion. • Amylase is denatured by the stomach acid so carbohydrate breakdown does not occur in the stomach.

  9. The Small Intestine • Most of the chemical digestion and beginning absorption of the food you eat occurs in the small intestines.

  10. The Small Intestine • Divided into three parts: • Duodenum • Jejunum • Ileum • Together average about 6 meters (19.7 ft) long.

  11. Duodenum • The first of three parts of the small intestine. • It is where almost all of the digestive enzymes enter the intestine. • The pancreas and the liver release digestive enzymes and fluids to help with digestion in the small intestine.

  12. Absorption in the Small Intestine • By the time chyme enters the jejenum and the ileum parts of the small intestine, much of the chemical digestion has been completed. • Chyme is now a rich mixture of medium and small nutrient molecules.

  13. Absorption in the Small Intestine • The small intestine is specially adapted for absorption of nutrients. • The folded surfaces of the small intestine are covered with fingerlike projections called villi. • Villi increases the surface area for absorption of nutrients

  14. Absorption of Nutrients in the Small Intestine Nutrients are absorbed through the wall of the small intestine directly into the capillaries (blood) by the process of diffusion. Diffusion – movement of substances from an area of high concentration to an area of low concentration

  15. Absorption in the Small Intestine • By the time food is ready to leave the small intestine, it is basically nutrient-free. • The complex organic molecules have been digested and absorbed, leaving only water, cellulose, and other undigestible substances behind.

  16. The Large Intestine • When the chyme leaves the small intestine, it enters the large intestine, or colon. • Primary Function: Remove water from the undigested material that is left. • The concentrated waste material (feces) that remains after the water has been removed passes through the rectum and is eliminated from the body.

  17. Click on picture

  18. Accessory Structures of Digestion • Pancreas • Liver • Gallbladder • Salivary Glands

  19. Pancreas • Located just behind the stomach. • Gland that serves three important functions: • Produces insulinthat regulate blood sugar levels. • Produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids. • Produces sodium bicarbonate, a base that neutralizes stomach acid so that these enzymes can be effective.

  20. Liver • Assisting the pancreas is the liver, a large organ located just above and to the right of the stomach. • Produces bile; to help digest fats • Bile acts like a detergent, dissolving and dispersing the droplets of fat found in fatty foods. • Makes it possible for enzymes to reach the smaller fat molecules and break them down. • Bile is stored in a small, pouch-like organ called the gallbladder.

  21. Gallbladder http://www.youtube.com/watch?v=iCyk-670bdw(dr. oz) • A pouch like organ that stores the bile • The bile is brought to the small intestine by the bile duct • 20 million ppl get gallstones, small hard mineral deposits due to excess cholesterol buildup

  22. Salivary Glands • There are 3 salivary glands: • Parotid gland – largest of the salivary glands that secretes saliva to assist with chewing and swallowing; located in the cheek area inferior to the ear • Submandibular gland – secretes amylase to help breakdown starches in the mouth; located below and inferior to the parotid gland • Sublingual gland – secretes mucous that helps coat the food being swallowed; located in front of the submandibular gland on the floor of the mouth

  23. Digestive System Levels of Organization Epithelial cells, Liver cell, stomach cell, pancreatic cell, etc…. epithelium, villi, smooth muscle Mouth, esophagus, stomach, small & large intestines, etc… digestive

  24. A. SALIVARY GLANDS B. MOUTH C. ESOPHAGUS D. STOMACH E. LARGE INTESTINE F. SMALL INTESTINE H. ANUS G. RECTUM

  25. Digestive System Disorders • Peptic Ulcer • Hole in the stomach wall • Most peptic ulcers are caused by bacteria and most can be cured by antibiotics. • Diarrhea or Constipation • If not enough water is absorbed by the large intestine, diarrhea occurs. • If too much water is absorbed from the undigested materials, constipation occurs.

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