Chapter 25,26,27 Digestion and Nutrition

General Characteristics of the Alimentary Canal Approximately 27 feet Structure of the wall – 4 layers –Mucosa - protects –Submucosa- nourishes –Muscular – propel food –Serosa - secretes serous fluid – lubrication Movements of the tube (peristalsis) –Mixing –Propelling Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Peristalsis

Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mouth - oral cavity Cheeks and lips Tongue – held down by frenulum Palate –Hard palate –Soft palate Teeth –Primary –Secondary –Incisors, cuspids, bucuspids, molars

teeth

Salivary Glands Salivary secretions –Serous cells –Amylase - digests carbohydrates –mucous Major salivary glands –Parotid –Submandibular –Sublingual

Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Salivary glands

Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pharynx Structure –Nasopharynx –Oropharynx –Laryngopharynx Swallowing mechanism –Food mixed and forced into pharynx –Sensory receptors trigger swallowing reflex –peristalsis

Esophagus Collapsible passageway leading to stomach Mucous glands Esophageal sphincter

The stomach Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stomach Parts of the stomach –Cardiac, fundic, body, pyloric –Pyloric sphincter Gastric secretions - mucus, pepsin, hydrochloric acids, intrinsic factor Regulation of gastric secretions –Parasympathetic impulses, gastrin (increases secretions of gastric glands Gastric absorption Mixing and emptying actions (chyme)

pancreas Produces pancreatic juices which aid in digestion Located in association with the small intestine Structure of the pancreas –Acinar cells – produce pancreatic juices. –Travel through Pancreatic duct –Controlled by Hepatopancreatic sphincter

Pancreatic juice –Digest organic compounds –Amylase, lipase, chymotrypsin (trypsin), carboxypeptidase, nucleases Regulation of pancreatic secretions –Secretin - stimulates release of pancreatic fluid –cholecystokinin

The Pancreas Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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The liver Location Structure –Hepatic lobules, sinusoids –Hepatic portal vein –Kupfer cells Function - metabolism of glucose from noncarbohydrates, storage of vitamin D, filter blood, digestion

Bile Functions of bile salts-emulsify fat Made in liver Gallbladder - stores bile Composition of bile- water, bile salts, bile pigments, cholesterol, electrolytes Regulation of bile release - cholecystokinin, hepatopancreatic sphincter

Small Intestine Function –Receives pancreas and liver secretion, completes digestion of nutrients, absorbs products of digestion, transports residues to large intestine. Parts of the small intestine –Duodenum, jejunum, ileum –Duodenum – shortest, fixed portion –Suspended by mesentery Small intestinal wall –Lined with villi – connective tissue and capillaries –4 layers Secretions –Goblet cells – secrete mucous –Intestinal gland – watery fluid –Digestive enzymes Regulation of secretion – mechanical and chemical stimulation – release of mucous Absorption of nutrients –Monosacharides – facilitated diffusion –Amino acids – active transport –Fatty acids – encapsulated then absorbed Movement - peristalsis

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Large intestine Parts – ascending colon, transverse colon, descending colon Structure of wall –4 layers –No villi Functions - reabsorption of water from chyme Movements accomplished by peristalsis Feces – waste products –Contain undigested material, mucous, water, bacteria –Color – bile salts –Smell – bacterial action

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Nutrition and Nutrients A.Nutrition is the process by which the body takes in and uses nutrients. B.Essential nutrients are those that cannot be synthesized by human cells. Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Carbohydrates Sources Utilization requirements

Lipids Sources Utilization Requirements

proteins Sources requirements

vitamins Fat soluble Water soluble

minerals Characteristics Major minerals Trace elements