Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings DIGESTIVE SYSTEM NOTES  Directions:  Read each slide & take notes as you would in class.  Study the diagrams throughout & pay particular attention to highlighted regions. You will need to know these structures for the quiz.  Any underlined terms WILL be on the quiz, so notate accordingly in your notes!

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Digestive System Functions  Ingestion  taking in food  Digestion  breaking food down both physically & chemically  Absorption  movement of nutrients into the bloodstream  Defecation  rids the body of indigestible waste

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Organs of the Digestive System  Two main groups:  Alimentary canal  AKA gastrointestinal tract or GI tract  continuous coiled hollow tube  Accessory digestive organs  Teeth  Salivary glands  Liver  Gall bladder  Pancreas

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Organs of the Alimentary Canal  Mouth  Pharynx  Esophagus  Stomach  Small intestine  Large intestine  Anus

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Organs of the Digestive System – Book page 470 Figure 14.1

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mouth Physiology  Mastication (chewing) of food  Bolus  Mixture of masticated food & saliva in mouth  Initiation of swallowing by the tongue  Allows for the sense of taste

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mouth (Oral Cavity) Anatomy Figure 14.2a

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Esophagus Anatomy and Physiology  Anatomy  About 10 inches long  Runs from pharynx to stomach through the diaphragm  AKA “Food Chute”  Physiology  Conducts food by peristalsis (smooth muscle contractions to propel food)  Passageway for food only (respiratory system branches off to trachea after the pharynx)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stomach Anatomy  Located on the left side of the abdominal cavity  Food enters stomach from the esophagus at the cardioesophageal sphincter  Food empties from the stomach into the small intestine at the pyloric sphincter (valve)  When empty, stomach collapses inward on itself & its mucosa (inner layer) form large folds called rugae

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stomach Anatomy Figure 14.4a

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stomach Physiology  Temporary storage tank for food  Site of food breakdown  Pepsin = enzyme that breaks down protein in the stomach  Chyme = mixture of food & gastric juices in the stomach

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Small Intestine  The body’s major digestive organ  Site of nutrient absorption into the blood  Sections/subdivisions of the small intestine:  Duodenum  Attached to the stomach  Curves around the head of the pancreas  Jejunum  Attaches anteriorly to the duodenum  Ileum  Extends from jejunum to large intestine

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Small Intestine Anatomy  Peyer’s Patches  Collections of lymphatic tissue found on the intestines to prevent bacteria from spreading to bloodstream  Microvilli  Tiny projections of the plasma membrane that increases surface area for absorption

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14.7c Small Intestine Anatomy

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Large Intestine  Functions:  Gets rid of indigestible waste  Reduces water loss  Larger in diameter, but shorter in length, than the small intestine  Frames the internal abdomen  No villi present  Haustra  Pocket-like sacs resulting from bands of muscle in intestinal wall

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Large Intestine Anatomy  AKA “Colon”  4 Sections:  Ascending —travels up right side of abdomen  Transverse —travels across the abdominal cavity  Descending —travels down the left side  Sigmoid —enters the pelvis

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Large Intestine Figure 14.8

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Large Intestine Anatomy  Rectum & Anal Canal—downward descent of colon in pelvis  Anus —opening of the large intestine  External anal sphincter—formed by skeletal muscle and under voluntary control  Internal involuntary sphincter—formed by smooth muscle  These sphincters are normally closed except during defecation

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Large Intestine Figure 14.8

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Digestive Organs  Teeth  Salivary glands  Pancreas  Liver  Gallbladder

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Teeth  Function is to masticate (chew) food  Humans have two sets of teeth:  Deciduous (baby or “milk”) teeth  20 teeth are fully formed by age two  Permanent teeth  A full set is 32 teeth  Some people do not have wisdom teeth

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Salivary Glands  Three pairs of salivary glands empty secretions into the mouth:  Parotid glands  Submandibular glands  Sublingual glands

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14.1 Salivary Glands

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Saliva  Mixture of mucus and serous fluids  Helps to form a food bolus  Contains salivary amylase to begin starch digestion in the mouth  Dissolves chemicals so they can be tasted

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Pancreas  Produces a wide spectrum of digestive enzymes that break down all categories of food  Releases enzymes into small intestine

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Pancreas Figure 14.1

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Liver  Largest gland in the body  Located on the right side of the body under the diaphragm  Produces Bile  Secreted by gall bladder  Digests lipids (fats)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Liver Figure 14.1

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Gallbladder  Sac found on posterior side of liver  Secretes bile for lipid digestion

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Appendix  Located on your lower right side at the beginning of the colon  Usually twisted so ideal location for bacteria to accumulate & multiply  Appendicitis = inflammation of the appendix

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spleen  Located on your left side lateral to the stomach  Filters blood

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs Figure 14.1