Chapter 17 The Digestive System

Alimentary canal aka GI tract Extends from mouth to anus –9 m (29 feet) Functions: –Digestion –Absorption –Metabolism

Mouth Hard palate Soft palate Uvula Tongue Papillae Taste buds Lingual frenulum

Teeth Names of teeth –Incisors –Cuspids –Bicuspids –Molars 20 primary; 32 permanent Crown, Neck, Root

Salivary Glands Parotid glands –Largest –in front of ear at angle of jaw Submandibular glands Sublingual glands

Saliva Carbohydrate digestion Amylase

UPPER GI TRACT

Pharynx

Layers of Digestive Tract Wall Mucosa— mucous epithelium Submucosa— connective tissue Muscularis— smooth muscle Serosa— –covers the outside of abdominal organs –mesentery

Esophagus Muscular, mucus-lined tube about 25 cm Connects pharynx with stomach Muscular walls help push food toward stomach Sphincters in GI tract help keep ingested material moving in one direction down the tube Each end of esophagus “guarded” by a sphincter—upper esophageal sphincter (UES) and lower esophageal sphincter (LES)

Stomach Expands after large meal Cardiac Region Pyloric Region Pyloric sphincter Rugae Functions in chemical digestion

Small Intestine About 7 meters (20 feet) long Divisions –Duodenum –Jejunum –Ileum Intestinal villi

Large Intestine Cecum –Appendix Colon –Ascending –Transverse –Descending –Sigmoid –Rectum –Anus

ACCESSORY ORGANS

Liver Fills upper right section of abd cavity Secretes bile Common bile duct –Hepatic duct –Cystic duct Helps maintain normal blood glucose level Removes toxins from the blood

Gallbladder Under the liver Concentrates and stores bile

Pancreas Located behind stomach Exocrine function –pancreatic juice into duodenum Endocrine function –Pancreatic islets (of Langerhans –Secrete glucagon and insulin into the blood

Peritoneum Serous membrane lining abdominal cavity and covering abdominal organs

Digestion Mechanical digestion –Chewing –Swallowing –Peristalsis Chemical digestion –Large molecules  smaller molecules

Carbohydrate Digestion Begins in mouth with amylase Intestinal juice enzymes Maltase—changes maltose to glucose Sucrase—changes sucrose to glucose Lactase—changes lactose to glucose

Protein Digestion Starts in stomach Gastric juice enzymes (rennin and pepsin) Finishes in small Intestine Peptidases and trypsin Proteins  amino acids

Fat Digestion Bile emulsifies fats Released from gall bladder as needed Small Intestine Pancreatic lipase Emulsified fats  fatty acids and glycerol

Absorption Food moves from intestine  blood/lymph Nutrients/water absorbed in small intestine Some water absorbed from large intestine

Chapter 18 Nutrition and Metabolism

Nutrition Food, vitamins, and minerals that are ingested and assimilated into the body

Metabolism Body making use of food molecules

Catabolism Releasing energy from food (breaking food down)

Anabolism Builds food molecules

Glycogenesis Glucose = sugar Glycogen = storage form of sugar

Adenosine Triphosphate (ATP) Stores energy Breakdown releases energy for the cells to do work

Vitamins Organic Needed for metabolism

Minerals Inorganic Required for normal body function

Metabolic Rates Basal Metabolic Rate (BMR) Total Metabolic Rate (TMR)