Human Digestive System

Digestive System

Functions Ingest food Break down food Move food through digestive tract Absorb digested food and water Eliminates waste materials

Mouth

Diagram of Teeth

Mouth Breaks down food into small pieces Begins starch digestion (amylase) Saliva produces amylase and lubricates food Moves food into esophagus Epiglottis covers trachea Peristalsis moves food to stomach

Esophagus Pushes food to Stomach

Motility: Peristalsis

Figure 14.3B Slide 14.5 Copyright © 2001 Benjamin Cummings, an imprint of Addison Wesley Longman, Inc. Peristalsis

Stomach Muscles churn food – mechanical digestion. Glands produce gastric juice = pepsin + HCl Pepsin breaks down proteins (only at pH 2) Food leaves after 2-4 hrs Pushes food through pyloric sphincter to small intestine

Stomach

Stomachh

Small Intestine Digestion is finished here –Peristalsis finishes mechanical digestion –Pancreatic juice produces enzymes to finish chemical digestion of fats, proteins and carbohydrates

Small Intestine

Digestive System

Pancreas Makes enzymes to break down fats, carbohydrates and proteins

Liver Produces bile Processes food for use by body Question: What is the function of bile? Bile is stored in the gallbladder.

19 Liver Location –R. Hypochondrium –Epigastric region 4 Lobes –Left –Quadrate –Caudate –Right Each lobe has lobules – Contains hepatocytes – Surround sinusoids – Feed into central vein

20 Liver Functions –Makes bile Detergent – emulsifies fats Release promoted by: –Vagus n. –CCK –Secretin Contains –Water –Bile salts –Bile pigments –Electrolytes –Cholesterol –Lecithin

21 Liver –Detoxifies/removes Drugs Alcohol –Stores Gycolgen Vitamins (A, D, E, K) Fe and other minerals Cholesterol –Activates vitamin D –Fetal RBC production –Phagocytosis –Metabolizes absorbed food molecules Carbohydrates Proteins Lipids

22 Liver Dual blood supply –Hepatic portal vein Direct input from small intestine –Hepatic artery/vein Direct links to heart

Liver

Large Intestine Absorbs water Bacteria live here (produce methane) Bacteria produce B vitamins and Vitamin K Stores solid waste in rectum until elimination.

Large Intestine

Digestive Endocrine Glands Pancreas – insulin = blood sugar Thyroid – thyroxine = metabolic rates Thyroid – calcitonin = blood calcium levels Parathyroid – PTH = calcium, phosphorus absorption rates and helps make Vitamin D