What is our system?

1. Our system involves…the intakeand digestion of food, absorption of nutrients, and elimination of solid waste. What is our system?

2. Gastro-Intestinal System Alexandra Ford, Jenna Volpe, Alexa Mastriano and Alexis Tomaszewski

3. Functions of the GI System • Digestion • Produces various chemicals to break down food molecules • Filters out harmful substances • Removes solid waste

4. What is Digestion? • The chemical breakdown of complex biological molecules into their component parts • The breakdown involves… • Lipids – Fatty Acids • Proteins – Amino Acids • Carbohydrates- Simple Sugars

5. 5 Stages of Digestion • Ingestion • Movement • Mechanical and Chemical Digestion • Absorption • Elimination

6. Two Different Types of Digestion…. • Mechanical Digestion • Chemical Digestion What do you think the difference is?

7. Mechanical Digestion • Changes the physical form of food EXAMPLES • Chewing • Tearing • Grinding • Mashing • Mixing

8. Chemical Digestion • Changes the chemical composition of food with the aid of digestive enzymes EXAMPLES • Carbohydrates • Proteins • Lipids

9. GI Tract

10. Parts of the GI Tract • Tube within a tube • Direct link/path between organs Structures • Pharynx • Esophagus • Stomach • Small intestine • Large Intestine • Rectum

11. Pharynx • Connects the nasal and oral cavities with the larynx and esophagus • There are 3 parts to the pharynx: • nasopharynx • oropharynx • laryngopharynx

12. Parts of the Pharynx Nasopharynx • provides a passageway for air when breathing Oropharynx • passageway for food to move from the mouth, and for air to move to and from the nasal cavity Laryngopharynx • provides a passageway to the esophagus

13. Esophagus • Approximately 10” long • Functions include: • Secrete mucus • Moves food from the throat to the stomach using muscle movement called peristalsis • If acid from the stomach gets in here that’s heartburn.

14. Stomach • J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces. • Mixes food with digestive juices that contain enzymes to break down proteins and lipids. • Acid in the stomach kills bacteria. • Food found in the stomach is called chyme.

15. Stomach • The stomach is divided into the fundus (upper, rounded part), body (main portion), and antrum (lower part). Rugae- the folds in the mucosa lining the stomach. Gastric Secretions: Thick mucus membrane forms the inner lining of stomach , studded with small openings (gastric pits) that are at the ends of gastric glands -Gastric glandshave 3 types of secretory cells; mucous, chief, and parietal cells • Chief secrete digestive enzymes • Parietal release hydrochloric acid • The digestive enzymes and the hydrochloric acid forms gastric juice.

16. Small Intestine • Small intestines are roughly 7 meters long • Lining of intestine walls has finger-like projections called villi, to increase surface area. • The villi are covered in microvilli which further increases surface area for absorption.

17. Small Intestine Digestion in Small Intestine Produces: 1) disaccharides 2) fatty acids 3) peptidesmonoglycerides Portions of the Small Intestine: 1) duodenum 2) jejunum 3) ileum

18. Small Intestine • Nutrients from the food pass into the bloodstream through the small intestine walls. • Absorbs: • 80% ingested water • Vitamins • Minerals • Carbohydrates • Proteins • Lipids • Secretes digestive enzymes

19. Large Intestine • About 5 feet long • Accepts what small intestines don’t absorb • Rectum (short term storage which holds feces before it is expelled).

20. Large Intestine Functions • Bacterial digestion • Ferment carbohydrates • Protein breakdown • Absorbs more water • Concentrate wastes

21. Large Intestine Movement • Slower than in the small intestine. Peristaltic waves happen 2-3 times a day. Intestinal wall constricts vigorously and forces the intestinal contents toward the rectum. • Defecation reflex: holding a deep breath and contracting the abdominal wall muscles increases internal abdominal pressure and forces feces into the rectum.

22. Feces from the Large Intestine Feces • Materials that were not absorbed or digested, and water (75%), electrolytes, mucus, and bacteria. • Odor is from a variety of compounds that bacteria produces. • Color is from pigments now altered by bacterialß action.

23. Accessory Organs • Include: Liver, gall bladder, and pancreas • Not part of the path of food, but play a critical role.

24. Liver • Directly affects digestion by producing bile • Bile helps digest fat • filters out toxins and waste including drugs and alcohol

25. Liver Functions Carbohydrate metabolism- helps maintain concentration of blood glucose Lipid metabolism-oxidizes fatty acids at a high rate, synthesizing lipoproteins, phospholipids, and cholesterol, and converting portions of carbohydrate and protein molecules into fat molecules Protein metabolism-deaminated amino acids, synthesizing plasma proteins, and converting certain amino acids to other amino acids

26. Gall Bladder • Stores bile from the liver, releases it into the small intestine. • Fatty diets can cause gallstones

27. Gall Bladder Functions • Stores bile between meals, reabsorbs water to concentrate bile, and contracts to release bile into small intestine • Functions of Bile Salts -Aid digestive enzymes -Break down fat globules into smaller droplets (emulsification) -Then they mix with water so the fat molecules can be digested more effectively

28. Pancreas • Produces digestive enzymes to digest fats, carbohydrates and proteins • Regulates blood sugar by producing insulin

29. Pancreas • Pancreatic Juice- Contains enzymes that digest carbohydrates, fats, nucleic acids, and proteins • Pancreatic amylase -splits molecules of starch or glycogen into double sugars • Pancreatic lipase- breaks triglyceride molecules to fatty acids and glycerol -Two nucleases, which are enzymes, break down nucleic acid molecules into nucleotides -Trypsin, chymotrypsin, and carboxypeptidase (protein splitting enzymes) split the bonds between certain amino acids in proteins

30. Oral Cavity

31. Mouth • Teeth mechanically break down food into small pieces. Tongue mixes food with saliva (contains amylase, which helps break down starch). • Epiglottis is a flap-like structure at the back of the throat that closes over the trachea preventing food from entering it.

32. Salivary Glands 2 types of secretory cells: • serous cells: produce a watery fluid that is rich in proteins and glycoproteins as well as amylase (split starch and glycogen molecules into disaccharides) • mucous cells: secrete a thick mucus which lubricates the food before it is swallowed Salivation: occurs when one prepares to eat, and nerve signals activate salivary glands to moisten the mouth The amount of saliva secreted depends on how appealing the particular food is to the individual

33. Three Types of Salivary Glands

34. Salivary Glands partoids • large • secrete 25% of saliva (watery) • front of ears extending to jaw bone (1 on each side) • drains into mouth near upper teeth submandibular • secrete 70% of saliva (mucus) • drains into mouth from under tongue sublingual • smallest • secrete 5% of saliva (mucus) • drains into floor of mouth

35. Lips and Cheeks • LIPS • sensory receptors and provide information about food before its in the mouth • few differences between lips and skin on body • no sebaceous glands- keep moisturized with saliva • no hair follicles

36. Cheeks • Does anyone remember the scientific name for cheeks? -stratified squamous epithelium -inside of cheek is lined by mucous membrane

37. Tongue • guides and molds food in the mouth • composed of skeletal muscle fibers (willingly controlled) • mucous membrane protects it from microbes and pathogens • lingual frenulum connects tongue to floor of mouth • perceives taste and texture • over 10,000 taste buds (change with age)

38. Palate • forms the roof of the oral cavity and consists of a bony anterior part and a muscular posterior part • palatine tonsils- two lymphatic tissue masses, located on either side of the pharynx • help protect the body against infection (respiratory)

39. Fun Facts • HOW LONG ARE YOUR INTESTINES? At least 25 feet in an adult. Be glad you're not a full-grown horse -- their coiled-up intestines are 89 feet long! • Food drying up and hanging out in the large intestine can last 18 hours to 2 days! • In your lifetime, your digestive system may handle about 50 tons!!

40. On a sheet of paper, write the name of each colored organ: • Green: • Red: • Pink: • Brown: • Purple: • Green: • Yellow:

41. How’d you do? • Green: Esophagus • Red: Stomach • Pink: Small Intestine • Brown: Large Intestine • Purple: Liver • Green: Gall Bladder • Yellow: Pancreas