Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slides 14.1 – Seventh Edition Elaine N. Marieb Chapter 14 The Digestive System and Body Metabolism Lecture Slides in PowerPoint by Jerry L. Cook

The Digestive System and Body Metabolism Slide 14.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Ingestion – taking in food  Digestion  Breakdown of food; Absorpt.of nutrients into blood stream  Chemically (enzymes)/Mechanically  Metabolism  Production of cellular energy (ATP)  Constructive and degradative cellular activities

Organs of the Digestive System Slide 14.2a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Two main groups  Alimentary canal – continuous coiled hollow tube  Accessory digestive organs  Ex. Liver, gall bladder, pancreas

Organs of the Digestive System Slide 14.2b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.1

Organs of the Alimentary Canal Slide 14.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mouth  Pharynx  Esophagus  Stomach  Small intestine  Large intestine  Anus

Mouth (Oral Cavity) Anatomy Slide 14.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Lips (labia), Cheeks  Hard palate – forms the anterior roof  Soft palate – forms the posterior roof  Uvula – fleshy projection of the soft palate Figure 14.2a

Mouth (Oral Cavity) Anatomy Slide 14.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Oral cavity – area contained by the teeth  Tongue – attached at hyoid and styloid processes of the skull, and by the lingual frenulum Figure 14.2a

Mouth (Oral Cavity) Anatomy Slide 14.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Tonsils  Palatine tonsils  Lingual tonsil Figure 14.2a

Processes of the Mouth Slide 14.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mastication (chewing) of food  Mix food w/ saliva  *Salivary Amylase – Enzyme digest Starches (bread,potato,etc)  Tongue initiates swallowing  Sense of taste

Esophagus Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Runs from pharynx to stomach through the diaphragm  Conducts food by peristalsis (slow rhythmic squeezing)  Passageway for food only

Stomach Anatomy Slide 14.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  left side of the abdominal cavity  Food enters at the esophageal sphincter  Holds about 1 gallon of food (Full)

Stomach Anatomy Slide 14.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Rugae – internal folds of the mucosa  External regions  Fundus  Pyloris  Lesser curvature  Greater curvature

Stomach Anatomy Slide 14.16b  Layers of peritoneum attached to the stomach:  Lesser/Greater omentum – hangs like a curtain over small/Lg. intestines - Contains fat- insulates, cushion, protect  Mesenteries: Binds abdomin. Organs together and attaches them to back wall of body

Stomach Anatomy Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.4a Layers of muscles at different angles allow food to be churned and PUMMELED!

Stomach Functions Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Acts as a storage tank for food  Some food breakdown,  gastric glands = gastric juice  Chem.digest. Of protein begins (pepsinogen/pepsin)  HCl (hydrocholoric Acid!)..  Acidic Environ. – Activates pepsinogen & hostile to microorganisms

The only absorption that occurs in the stomach is of alcohol and aspirin Delivers chyme (processed food) to the small intestine…”looks like heavy cream” Stomach Functions

Propulsion in the Stomach Slide 14.56b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The pylorus sends out chyme to small intestine (30 ml at a time)  The stomach empties in four to six hours Figure 14.14

Small Intestine Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  *major digestive organ, only process small amounts at a time.  *Site of nutrient absorption into the blood  Suspended from the posterior abdominal wall by the mesentery

Subdivisions of the Small Intestine Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Duodenum = 1 st section off stomach  10 inches; Curves around pancreas  Bile & pancreatic ducts enter  Jejunum = 2 nd section  8 ft long.  Ileum= 3 rd section ends at Lg intest. (12ft)

Chemical Digestion in the Small Intestine Slide 14.23a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Enzymes are mixed with chyme  From: Gall Bladder (bile=lipid digest.)  Intestinal cells  *Pancreas  (lipid/protein enzymes)

Digestion in the Small Intestine Slide 14.57b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Pancreatic enzymes play the major digestive function (continued)  Responsible for fat digestion (lipase)  Digest nucleic acids (nucleases)  *Alkaline content neutralizes acidic chyme *Why is this important!?!

Absorption in the Small Intestine Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Water is absorbed along the length of the small intestine-90% of H20 intake absorbed in small intest.  End products of digestion  Most substances are absorbed by active transport through cell membranes  Lipids are absorbed by diffusion  Substances are transported to the liver by the hepatic portal vein or lymph

Chemical Digestion in the Small Intestine Slide 14.23b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.6

Small Intestine – digestion/absorption Slide  Villi - Fingerlike structures give the sm. Intest.more surface area  Microvilli – small projections of plasma membrane on absorptive cells

Structures Involved in Absorption of Nutrients Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Absorptive cells  Blood capillaries Figure 14.7b

Large Intestine Slide Larger diameter, but shorter length! (than small intestines)

Functions of the Large Intestine Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Absorption of water  Eliminates indigestible food from the body as feces  Does not participate in digestion of food  Goblet cells produce mucus to act as a lubricant

Rectum Last section of colon (large intestines) eliminate feces undigested materials – extracellular waste »mainly cellulose from plants » roughage or fiber masses of bacteria