1. The Digestive System & Body Metabolism

2.  The Alimentary Canal (or gastrointestinal, GI, tract) is the hollow tube where digestion occurs.  The organs include: mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.  It is ~30 feet long. http://www.google.com/imgres

3.  Digestion is the decomposition (breakdown) of food for the body’s use.  This is both chemical and mechanical.  Mastication: chewing food.

4. Mouth (Oral Cavity):  Digestion begins here.  Food is broken down mechanically and chemically.  Its accessory organs: ◦ Cheeks ◦ Lips ◦ Tongue ◦ Palate ◦ Teeth http://www.blogaholics.ca/wp/uploads/illu_mouth.jpg

5. Swallowing occurs in 3 stages: ◦ Voluntary: food is chewed & consciously swallowed ◦ Swallowing reflex is triggered: through a variety of steps, food is moved by peristalsis to the esophagus ◦ Peristalsis: food moves through the esophagus  While swallowing, breathing does not occur.

6. Pharynx:Esophagus:  From the stomach, food passes thru to the pharynx.  It contains 3 parts: ◦ Nasopharynx (air passageway) ◦ Oropharynx (food passageway) ◦ Laryngopharynx (passageway to the esophagus)  A tube that runs ~25cm (10”) long  Allows peristalsis to continue  Just before the esophagus meets the stomach is a circular section of smooth muscle called the cardiac sphincter (a.k.a. lower esophageal sphincter) which controls the movement of food into the stomach. Usually this sphincter is closed (until food reaches it).

7. ◦ Mucosa (mucous membrane): contains glands that secrete mucus & digestive enzymes  serves as protection (underlying tissues) ◦ Submucosa ◦ Muscular layer: smooth muscle and some nerves  function is movement. ◦ Serosa (serous layer)

8. Four Layers: http://www.web- books.com/elibrary/medicine/Physiology/Digestive/stomach.jpg

9.  J-shaped organ that is below the cardiac sphincter of the esophagus  It can hold ~1 liter or more  It contains mucosal and submucosal layers  Mixes food with gastric juices (that contain enzymes & acids) http://mywebpages.comcast.net/wnor/stomachinside.jpg

10. http://www.nfl.com/gamecenter?game_id=29294&displayPage=tab_gamecenter&season=2007&week=REG7

11.  Function: Finish digestion and begin absorption of digested particles Parts of the Small Intestine: ◦ Duodenum: first portion; ~25cm long ◦ Jejunum: second section ◦ Ileum: last section (not truly distinctive from the jejunum) Both the jejunum and the ileum are protected by the peritoneal membrane called the mesentery  Intestinal villi are tiny projections that come from the small intestines that increase the surface area and aid in absorption.  The small intestine is the most important absorbing organ of the alimentary canal.

12. Small Intestine: http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/1922 1.jpg

13. http://www.google.com/imgres

14.  Chyme moves from the small intestine into the large intestine  Much shorter than the small intestine but is larger in its diameter  “surrounds” the small intestine  absorbs water & electrolytes from chyme  the remaining material becomes feces. ◦ This is ~75% water while the remaining is anything that was not digested or absorbed (electrolytes, mucus, intestinal cells, bacteria & bile pigments which give feces its color). ◦ Its odor comes from bacteria products.

15.  Does not contain villi  Parts of the Large Intestine: ◦ Cecum: 1st part of the large intestine which is directly below the ileocecal sphincter.  Below this is the vermiform appendix (a.k.a. appendix). This has no known function but has been discovered to have some lymphatic tissue. ◦ Colon: has 4 portions:  Ascending colon: upward  Transverse colon: below the stomach; largest section  Descending colon: downward  Sigmoid colon: twists into an S-shape, becoming this; the sigmoid reaches the rectum.

16. ◦ Rectum: ends at ~5cm below the tip of the coccyx ◦ Anal Canal: an opening to the external environment; feces exits the body.  The anus is guarded by 2 sphincters: ◦ The internal anal sphincter muscle: involuntary control (smooth muscle) ◦ External anal sphincter muscle: voluntary control (skeletal muscle)

17. Large Intestine: http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/1922 0.jpg

19.  Function: masticate  Primary teeth (a.k.a. deciduous teeth) are the first set of teeth ◦ 20 teeth (10 in each jaw)  Secondary teeth (a.k.a. permanent teeth) are the second set of teeth ◦ 32 teeth (16 in each jaw) ◦ grow in at 6-25 years (3rd molars appear between 17- 25) http://www.cdha.ca/images/facts_baby_6.gif http://www.tela.co.in/images/permteeth.jpg

20.  incisors (front teeth) have sharp edges to bite off food  cuspids (eye teeth) are sharp, sometimes pointed for biting, grabbing & tearing food  biscuspids (behind cuspids) and molars (back teeth) are flat for grinding food

21. Crown (above the gum) Root (below the gum; anchors) Enamel (glossy white covering composed of calcium) Dentin (bone-like substance that surrounds the tooth’s interior pulp cavity) Pulp cavity (interior tooth composed of BVs, nerves & connective tissue) Root canal (BVs and nerves that run the center of the pulp cavity) http://apps.uwhealth.org/health/adam/graphics/images/en/1121.jpg

22.  secrete saliva (contains serous fluid & mucus)  Serous fluid contains a digestive enzyme, amylase which breaks down sugars.  Mucus lubricates & coats the food http://cache.eb.com/eb/image?id=74321&rendTypeId=4

23.  Endocrine AND an exocrine gland.  Produces pancreatic juice.  Pancreatic juice digests carbs, fats, nucleic acids and proteins. http://www.med.umich.edu/1libr/wha/pancreas.gif

24. Liver:Gallbladder:  Reddish-brown  2 lobes  Produces bile (which emulsifies fat)  Connected to liver & small intestine  Stores bile http://www.pbiv.com/images/nature/lbp/liver_diagram.gif

25.  Ingestion: to eat  Propulsion: to move food throughout the canal (peristalsis)  Mechanical digestion: to chew, churn; physical break down  Chemical digestion: to breakdown food with enzymes  Absorption: to transport products of digestion into blood stream  Defection: to eliminate waste

26.  Know the location and final product of each macromolecule digestion:..\..\..\..\A&P_files\macromolecule end product of digestion chart.docx http://www.buzzle.com/articles/list-of-digestive- enzymes.html  Polysaccharides (mostly starch) are broken down into disaccharides and monosaccharides (sugars.)  Proteins are broken down into amino acids.  Fats are broken down into glycerol and fatty acids.  Nucleic acids are broken down into nucleotides.

27.  Chyme takes 3-10 hours to move through the small intestine  A peristaltic rush can occur if the small intestine is irritated. ◦ This is a sweeping motion that empties the small intestine’s contents into the large intestines and continues that sweeping motion without nutrient absorption. ◦ Diarrhea may result.

28. Movements of large intestine: both mixing and peristalsis:  Slower than the small intestine  Peristalsis occurs 2-3 times daily  Peristaltic waves produce mass movements (irritation & inflammation, such as colitis, also stimulate these mass movements) ◦ Defecation reflex is the force of pushing feces out the anus

29.  Look up online or in text!  Know the following: appendicitis, gallstones, jaundice, hepatitis, cirrhosis, heartburn, hiatal hernia, vomiting, pancreatitis, peptic ulcers, diverticulosis, diarrhea, constipation, BMR, hyperthyroidism, hypothyroidism, hypothermia, frostbite, hyperthermia, heat stroke, heat exhaustion, & appendicitis