The Digestive System

1. The Digestive System Alexander Ortega Keith Olejnik

2. Purpose • Digestion • Mechanical and chemical breakdown of foods • Supply nutrients to cells

3. Organs and Glands • Salivary glands • Liver • Gallbladder • Pancreas • Mouth • Pharynx • Esophagus • Stomach • Small/large intestine

4. Pathway: The Mouth • Food Begins digestion in the mouth • The mouth mechanically reduces food size through Saliva and teeth • The mouth the lips, cheeks, tongue, and the oral cavity

5. Pathway: Pharynx • The pharynx do not digest food but are important to transportation • The pharynx includes 3 parts • Nasopharynx: provides passagway for breathing • Oropharynx: Passageway for food to travel downward from the mouth • Laryngopharynx: Passageway to esophagus

6. Pathway: Esophagus • The esophagus does not digest food • 25 CM long • Begins at the base of the pharynx to the traveling to the stomach • Just above the stomach the lower esophageal sphincter forms which is a layer of thick smooth muscle preventing regurgitation to the esophagus

7. Pathway: Stomach • Capacity of about 1 liter • Mixes food with gastric juice to initiate protein digestion • 4 regions: Cardiac, fundic, body, and pyloric regions • Gastric pits line the stomach walls • Releasing many helpful digestive materials • Pepsin is the most important as it begins digestion of nearly all dietary protein into polypeptide • Gastric juice is regulated based on sight, smell, and taste of food entering the body

8. Stomach pt. 2 • Gastric enzymes break down proteins • The stomach wall can only absorb a small amount of water, salt, alcohol, and some lipid soluble drugs • Mixing of fluids cause creation of chyme which is a semifluid paste of food particles and gastric juice • Rate of digestion depends on fluidity of chyme • Such as fat foods may stay from 3-6 hours while protein high foods move quickly and carbohydrates will move through the quickest

9. Pancreas • Exocrine digestive fluid secretion called pancreatic juice • The juice digests carbohydrates, fats, nucleic acid, and proteins • The carbohydrate digesting enzyme is pancreatic amylase • The protein digesting enzyme is pancreatic lipase

10. Liver • Helps maintain normal blood glucose also regulates carbohydrate metabolism • Converts portions of carbohydrate and protein molecules into fat for energy and storage in the adipose tissue

11. Gallbladder • Stores bile between meals • Bile: yellowish green liquid includes water, bile salts, bile pigments, cholesterol, and electrolytes Releases bile into the small intestine to continue digestion

12. Pathway: Small intestine • The small intestine is a tubular organ which receives secretions from secretions from pancreas and liver, also transports material to the large intestine • Varies in size from 4.6 M to 9.8 M • The small intestine consists of three parts • Duodenum, Jejunum, ileum • The small intestine secretes mucous throughout breaking down food even further • Villi absorb many materials and nutrients from food traveling through

13. Pathway: Large intestine • The large intestine is the last part of the digestive system • The large intestine takes about 16 hours to finish the digestion of the food • It removes water and any remaining absorbable nutrients from the food before sending the indigestible matter to the rectum • The large intestine differs from the small intestine in being much wider • Little to no digestive function

14. Nutrition • Nutrition is the study of nutrients and how the body utilizes them • Carbohydrates, lipids, and proteins are macronutrients which are required in large amounts • Vitamins and nutrients are micronutrients which can be extracted to energy but are not a direct supply • Carbohydrates are the primary fuel source of the body • Protein supplies essential amino acids

15. Diseases and Disorders • Achalasia: esophageal motility disorder involving the smooth muscle layer of the esophagus and the lower esophageal sphincter (LES) It is characterized by incomplete LES relaxation • Symptoms: Difficulty swallowing, regurgitation, and sometimes chest pain • The most common form is primary achalasia, which has no known underlying cause • Cure: Drugs that reduce LES pressure are useful. These include calcium channel blockers such as nifedipine, Heller myotomy helps 90% of achalasia patients.

16. Diseases and Disorders • Dyspepsia: also known as indigestion • It is a medical condition characterized by chronic or recurrent pain in the upper abdomen, upper abdominal fullness and feeling full earlier than expected when eating • Symptoms: The characteristic symptoms of dyspepsia are upper abdominal pain, bloating, fullness and tenderness • Cure: natural herbs

17. Diseases and Disorders • Dysentery: an inflammatory disorder of the intestine • Symptom: Severe diarrhea containing blood and mucus in the feces with fever, abdominal pain • caused by any kind of infection. • Cure: Dysentery is initially managed by maintaining fluid intake using oral rehydration therapy. antibiotics, such as ciprofloxacin or TMP-SMX (Bactrim). However, many strains of dysentery shigella are becoming resistant to common antibiotics • The seed, leaves, and bark of the kapok tree have been used in traditional medicine by indigenous peoples of the rain forest regions in the Americas, West-Central Africa, and South East Asia to treat this disease.