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SISTIM PENCERNAKAN Zaenal M. SOFRO Bagian Ilmu Faal FK.UGM What is Homeostasis? Homeostasis – a steady state of bodily functioning and equilibrium What does “environment” mean? External to Internal environment ..a hint of integration? - John Hughlings Jackson (1835-1911) Father of English Neurology Quoted by Stephen Porges 11/01 Social Sympathetic Parasympathetic Freeze The Human Nervous System Cardiovascular system Central Nervous System Autonomic Nervous System Immune system Urogenital tract Homeostasis Gastrointestinal tract PARASYMPATHETIC CRANIAL OUTFLOW SYMPATHETIC THORACOLUMBAR OUTFLOW SACRAL OUTFLOW Tongue Teeth Sublingual gland Trachea Liver Gall bladder Parotid gland Pharynx Submaxillary gland Larynx Esophagus Spleen Stomach Duodenum Ascending colon Cecum Appendix Rectum Pancreas Transverse colon Descending Colon Ileum Sigmoid colon Anus Prehospital Emergency Care The Human Body 4-71 5 basic processes: 1. Ingestion 2. Movement of food 3. Digestion 4. Absorption 5. Defecation Mechanical Digestion: movement of food that reduces the size of the food particles Chemical Digestion: breaks proteins, carbohydrates, and lipids into simple molecules Digestive System: made of the gastrointestinal tract and accessory structures (teeth, tongue, salivary glands, liver, gall bladder, and pancreas) 1. Mouth (oral or buccal cavity) A. lips - keep food between the teeth and assist in speech B. tongue - maneuvers food for chewing; pushes food to back of mouth for swallowing; important for speech C. teeth - 1) incisors - cut food 2) cuspids - tear and shred food 3) premolars - crush and grind food 4) molars - crush and grind food 2. Salivary Glands Secrete saliva which is primarily water with the enzyme salivary amylase a. water dissolves food b. mucus lubricates food c. lysozyme destroys bacteria Mechanical: mastication (chewing) breaks food down and mixes it with saliva reducing it into a soft bolus Chemical: 1) salivary amylase begins digestion of starches into simpler sugars until stomach acid inactivates it 2) lingual lipase from glands on tongue reduces some triglycgerides into fatty acids and monoglycerides 3. Pharynx - oropharynx and laryngopharynx contract to move food into the esophagus 4. Esophagus - transports food to the stomach and secretes mucus 3 Stages of Swallowing 1) voluntary stage: bolus is moved into the oropharynx 2) pharyngeal stage: involuntary movement from pharynx into the esophagus; epiglottis blocks glottis 3) esophageal stage: involuntary movement through the esophagus to the stomach through rhythmic contractions called peristalsis 5. Stomach A. has 4 areas 1) cardia: surrounds upper opening 2) fundus: curve above and to the left of the cardia 3) body central portion 4) pylorus: narrow, lower region B. pyloric sphincter: controls opening between the stomach and duodenum C. rugae: folds in empty stomach D. gastric glands: in stomach lining, contain 4 types of secreting cells 1) chief cells: secrete pepsinogen 2) parietal cells: secrete HCl and intrinsic factor which, with pepsinogen, make up gastric juice 3) mucous cells: secrete mucus which is also part of gastric juice 4) G cells: secrete the hormone gastrin Mechanical: peristaltic waves mix food with gastric juices and change it into a thin liquid called chyme Chemical: protein digestion begins in stomach Pepsinogen secreted by chief cells is changed into the active form pepsin by HCl. Pepsin breaks proteins into peptides. Gastric lipase aids in the breakdown of large lipids. Absorption: The stomach absorbs some water, electrolytes, some drugs, and alcohol 6. Pancreas A. exocrine glands produce pancreatic juice which is made of water, some salts, sodium hydrogen carbonate (NaHCO3), and enzymes B. NaHCO3 increases the pH of chyme to 7.1 - 8.2 stopping the action of pepsin. C. The enzymes that are present breakdown carbohydrates, proteins, lipids, and nucleic acids. 7. Liver: secretes bile which causes the emulsification of fats into a suspension of small droplets. Other Liver Functions - page 424 8. Gall Bladder: concentrates and stores bile which is emptied into the duodenum through the common bile duct. 9. Small Intestine A. made of 3 sections: duodenum - shortest jejunum - middle portion ileum - longest, final part; joins the large intestine at the ileocecal sphincter B. Intestinal glands in the lining secrete intestinal juice with a pH of 7.6 C. Duodenal glands secrete alkaline mucus D. Inner lining contains villi, microvilli, and circular folds which provide more surface area for digestion and absorption Mechanical: segmentation moves food back and forth; peristalsis mixes chyme through the small intestine Chemical: Carbohydrates - Pancreatic amylase produces the disaccharides maltose, sucrose, and lactose. Sucrase breaks sucrose into glucose and fructose. Maltase breaks malatose into 2 glucose molecules. Lactase breaks lactose into glucose and galactose. More chemical digestion in the small intestine. Proteins: Pancreatic enzymes break peptide bonds making small peptides. Peptidase that is made by the small intestine completes the digestion into amino acids Lipids: Most digestion of lipids occurs in the small intestine. Bile emulsifies fats into tiny droplets. Pancreatic lipase breaks triglycerides into 2 fatty acids and a monoglyceride. Nucleic Acids: Ribonuclease (RNA) and deoxyribonuclease (DNA) convert nucleic acids into nucleotides Monosaccharides, amino acids, glycerol, monoglycerides, water, electrolytes, and vitamins are absorbed in the small intestine. Vitamin B12 requires intrinsic factor to be absorbed. 10. Large Intestine Sections: A. cecum - pouch below the ileocecal sphincter B. appendix - attached to the cecum C. colon - above the cecum - 6 parts 1) ascending colon - up right side of abdomen 2) transverse colon - across top of abdomen 3) descending colon - down left side of the abdomen 4) sigmoid colon - curved portion between the descending colon and rectum 5) rectum - lower portion 6) anus - opening to the outside with internal and external sphincter Bacterial digestion breaks down remaining carbohydrates and proteins and is responsible for the production of some B vitamins and vitamin K. Vitamins, electrolytes, and most water is absorbed in the large intestine. Remaining substances make up feces which is eliminated. Maintaining a Healthy Weight is a Balancing Act Calories In = Calories Out How long will you have to walk in order to burn those extra 305 calories?* *Based on 130-pound person