BSN-ANPH-M3-CU10. Digestive System PDF

BACHELOR OF SCIENCE IN NURSING ANPH 111 (Anatomy and Physiology) COURSE MODULE COURSE UNIT WEEK 3 10 13 The Digestive System and Body Me...

BACHELOR OF SCIENCE IN NURSING ANPH 111 (Anatomy and Physiology) COURSE MODULE COURSE UNIT WEEK 3 10 13 The Digestive System and Body Metabolism ü Read course and unit objectives ü Read study guide prior to class attendance ü Read required learning resources; refer to unit terminologies for jargons ü Proactively participate in classroom discussions ü Participate in weekly discussion board (Canvas) ü Answer and submit course unit tasks. VanPutte, Cinnamon. Regan, Jennifer. Russo, Andrew (2016). Seeley’s Essentials of Anatomy & Physiology Penn Plaza, New York, New York, McGraw-Hill Education, 10th Edition Computer device or smartphone with internet access (at least 54 kbps; average data subscription will suffice) At the end of the course unit (CM), learners will be able to: Cognitive Identify the overall function of the digestive system as digestion and absorption of foodstuffs, and describe the general activities of each digestive system organ. Name the organs of the alimentary and accessory digestive organs, describing the general function of each Explain how the accessory organs contribute to the digestive processes. Describe how foodstuffs in the digestive tract are mixed and moved along the tract Affective Listen attentively during class discussions Demonstrate tact and respect of other students’ opinions and ideas Accept comments and reactions of classmates openly Psychomotor Participate actively during class discussions Follow class rules and observe compliance to Netiquette Use critical thinking to identify areas of care that could benefit from additional research or application of evidence-based practices Integrate knowledge of trends in Anatomy and Physiology Amylase - Enzyme contained in saliva that breaks down starch Appendix - Tubular organ attached to the lower end of the cecum; serves as a source for immune cells Bile - Yellow-green fluid secreted by the liver that aids in digestion Cecum - Blind pouch that serves as the beginning of the large intestine Chief cells - Cells in the gastric mucosa that secrete digestive enzymes Chyme - Semi-fluid mixture consisting of particles of food mixed with digestive juices Dentin - Firm, yellowish tissue forming the bulk of a tooth Duodenum - The first 10 inches of small intestine; the portion of intestine that performs most digestive processes Enteric nervous system - Network of nerves innervating the digestive system Enteroendocrine cells - Cells in the gastric mucosa that secrete the hormone ghrelin Esophagus - Muscular tube connecting the pharynx to the stomach Gallbladder - Sac attached to the liver that stores and concentrates bile Gastric pits - Depressions within the gastric mucosa containing glands that secrete components of gastric juice Gingiva - Tissue surrounding the necks of teeth; the gums Hard palate - Bony structure that separates the mouth from the nasal cavity Haustra - Pouches along the length of the large intestine Ileum - The third and last portion of the small intestine Jejunum - The second portion of the small intestine; location where many nutrients are absorbed Lacteal - Lymph vessel found inside the villi of the small intestine Lipase - Enzyme that digests fat Mastication - Process of chewing, which begins the digestion of food Mesentery - Sheet of connective tissue that suspends the digestive organs within the abdominal cavity Parotid gland - Salivary gland located just underneath the skin anterior to the ear Peristalsis - Wave-like muscular contractions that propel food along the digestive tract Proteases - Enzymes working in the stomach and small intestine to break peptide bonds Rugae - Folds of mucosa and submucosa in the stomach Salivary glands: Glands in the oral cavity that secrete saliva Segmentation - Type of contraction in the small intestine that involves ring-like constrictions Soft palate - Structure consisting mostly of skeletal muscle that forms an arch between the mouth and nasopharynx 10.1 GASTROINTESTINAL SYSTEM: AN OVERVIEW 10.1.1 Functions § Ingestion—taking in food § Digestion—breaking food into nutrient molecules § Absorption—movement of nutrients into the bloodstream § Defecation—excretes to rid the body of indigestible waste (Marieb & Keller, 2018) 10.2 TWO MAIN GROUP OF ORGANS 10.2.1 Alimentary canal § gastrointestinal, or GI, tract § continuous, coiled, hollow tube § These organs ingest, digest, absorb, defecate § Mouth § Pharynx § Esophagus § Stomach § Small intestine § Large intestine § Anus 10.2.2 Accessory digestive organs § Include teeth, tongue, and several large digestive organs § Assist digestion in various ways © 2018 Pearson Education, Inc. Figure 10.1 The human digestive system: Alimentary canal and accessory organs *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) 10.3 ORGANS OF THE ALIMENTARY CANAL 10.3.1 Mouth 10.3.1.1 Anatomy § Mouth (oral cavity)—mucous membrane–lined cavity § Lips (labia)—protect the anterior opening § Cheeks—form the lateral walls § Hard palate—forms the anterior roof § Soft palate—forms the posterior roof § Uvula—fleshy projection of the soft palate § Vestibule—space between lips externally and teeth and gums internally § Oral cavity proper—area contained by the teeth § Tongue—attached at hyoid bone and styloid processes of the skull, and by the lingual frenulum to the floor of the mouth § Tonsils § Palatine—located at posterior end of oral cavity § Lingual—located at the base of the tongue Figure 10.2 Anatomy of the Mouth (Oral Cavity) *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018)  10.3.1.2 Functions § Mastication (chewing) of food § Tongue mixes masticated food with saliva § Tongue initiates swallowing § Taste buds on the tongue allow for taste 10.3.2 Pharynx § Serves as a passageway for foods, fluids, and air § Food passes from the mouth posteriorly into the: § Oropharynx—posterior to oral cavity § Laryngopharynx—below the oropharynx and continuous with the esophagus § Food is propelled to the esophagus by two skeletal muscle layers in the pharynx § Longitudinal outer layer § Circular inner layer § Alternating contractions of the muscle layers (peristalsis) propel the food 10.3.3 Esophagus 10.3.3.1 Anatomy § About 10 inches long § Runs from pharynx to stomach through the diaphragm 10.3.3.2 Physiology § Conducts food by peristalsis (slow rhythmic squeezing) to the stomach § Passageway for food only (respiratory system branches off after the pharynx) 10.3.4 Swallowing 10.3.5 Layers of Tissue in the Alimentary Canal Organs 10.3.5.1 Mucosa § Innermost, moist membrane consisting of: § Surface epithelium that is mostly simple columnar epithelium (except for esophagus—stratified squamous epithelium) § Small amount of connective tissue (lamina propria) § Scanty smooth muscle layer § Lines the cavity (known as the lumen)  10.3.5.2 Submucosa § Just beneath the mucosa § Soft connective tissue with blood vessels, nerve endings, mucosa-associated lymphoid tissue, and lymphatic vessels 10.3.5.3 Muscularis Externa § Made up of smooth muscle § Inner circular layer § Outer longitudinal layer 10.3.5.4 Serosa § outermost layer of the wall; contains fluid-producing cells § Visceral peritoneum—innermost layer that is continuous with the outermost layer § Parietal peritoneum—outermost layer that lines the abdominopelvic cavity by way of the mesentery Figure 10.3 Basic Structure of the Alimentary Canal Wall *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018)  Figure 10.4 Peritoneal Attachments of the Abdominal Organs *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) (a) Anterior view; the greater omentum is shown in its normal position, covering the abdominal viscera. (b) Sagittal view of the abdominopelvic cavity of the female. 10.3.6 Alimentary Canal Nerve Plexuses § Alimentary canal wall contains two intrinsic nerve plexuses that are part of the autonomic nervous system § Submucosal nerve plexus § Myenteric nerve plexus § Regulate mobility and secretory activity of the GI tract organs 10.3.7 Stomach 10.3.7.1 Anatomy of the Stomach § C-shaped organ located on the left side of the abdominal cavity § Food enters at the cardioesophageal sphincter from the esophagus § Food empties into the small intestine at the pyloric sphincter (valve 10.3.7.1.1 Regions  § Cardial (cardia)—near the heart and surrounds the cardioesophageal sphincter § Fundus—expanded portion lateral to the cardiac region § Body—midportion § Greater curvature is the convex lateral surface § Lesser curvature is the concave medial surface § Pylorus—funnel-shaped terminal end Figure 10.5 Anatomy of the Stomach *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) Gross internal anatomy (a) Diagram (b) Photo § Stomach can stretch and hold 4 L (1 gallon) of food when full § Rugae—internal folds of the mucosa present when the stomach is empty § Lesser omentum § Double layer of the peritoneum § Extends from liver to the lesser curvature of stomach § Greater omentum § Another extension of the peritoneum § Covers the abdominal organs § Fat insulates, cushions, and protects abdominal organs  10.3.7.1.2 Structure of the stomach mucosa § Simple columnar epithelium composed almost entirely of mucous cells § Mucous cells produce bicarbonate-rich alkaline mucus § Dotted by gastric pits leading to gastric glands that secrete gastric juice, including: § Intrinsic factor, which is needed for vitamin B12 absorption in the small intestine § Chief cells—produce protein-digesting enzymes (pepsinogens) § Parietal cells—produce hydrochloric acid that activates enzymes § Mucous neck cells—produce thin acidic mucus (different from the mucus produced by mucous cells of the mucosa) § Enteroendocrine cells—produce local hormones such as gastrin 10.3.7.2 Functions § Temporary storage tank for food § Site of food breakdown § Chemical breakdown of protein begins § Delivers chyme (processed food) to the small intestine Figure 10.6 Anatomy of the Stomach *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) Gross internal anatomy (left) Enlarged view of gastric pits and glands (longitudinal section) (right) Pepsinogen produced by the chief cells is activated (converted to pepsin) by HCl secreted by the parietal cells 10.3.8 Small intestine 10.3.8.1 Anatomy of the Small Intestine § The body’s major digestive organ § Longest portion of the alimentary tube (2–4 m, or 7–13 feet, in a living person) § Site of nutrient absorption into the blood § Muscular tube extending from the pyloric sphincter to the ileocecal valve § Suspended from the posterior abdominal wall by the mesentery 10.3.8.1.1 Subdivision § Duodenum § Jejunum § Ileum § Chemical digestion begins in the small intestine § Enzymes produced by intestinal cells and pancreas are carried to the duodenum by pancreatic ducts § Bile, formed by the liver, enters the duodenum via the bile duct § Hepatopancreatic ampulla is the location where the main pancreatic duct and bile ducts join Figure 10.7 The duodenum of the small intestine and related organs *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018)  10.3.8.1.2 Structural modifications § Increase surface area for food absorption § Decrease in number toward the end of the small intestine § Villi—fingerlike projections formed by the mucosa § House a capillary bed and lacteal § Microvilli—tiny projections of the plasma membrane (brush border enzymes) § Circular folds (plicae circulares)—deep folds of mucosa and submucosa § Peyer’s patches § Collections of lymphatic tissue § Located in submucosa § Increase in number toward the end of the small intestine § More are needed there because remaining food residue contains much bacteria Figure 10.8 Structural Modifications of the Small Intestine *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) (a) Several circular folds (plicae circulares), seen on the inner surface of the small intestine. (b) Enlargement of a villus extension of the circular fold. (c) Enlargement of an absorptive cell to show microvilli (brush border). 10.3.9 Large Intestines § Larger in diameter, but shorter in length at 1.5 m, than the small intestine § Extends from the ileocecal valve to the anus § Subdivisions § Cecum § Appendix § Colon § Rectum § Anal canal 10.3.9.1 Cecum—saclike first part of the large intestine § Appendix § Hangs from the cecum § Accumulation of lymphoid tissue that sometimes becomes inflamed (appendicitis) 10.3.9.2 Colon § Ascending—travels up right side of abdomen and makes a turn at the right colic (hepatic) flexure § Transverse—travels across the abdominal cavity and turns at the left colic (splenic) flexure § Descending—travels down the left side § Sigmoid—S-shaped region; enters the pelvis § Sigmoid colon, rectum, and anal canal are located in the pelvis § Anal canal ends at the anus § Anus—opening of the large intestine § External anal sphincter—formed by skeletal muscle and is voluntary § Internal anal sphincter—formed by smooth muscle and is involuntary § These sphincters are normally closed except during defecation § The large intestine delivers indigestible food residues to the body’s exterior § Goblet cells produce alkaline mucus to lubricate the passage of feces § Muscularis externa layer is reduced to three bands of muscle, called teniae coli § These bands of muscle cause the wall to pucker into haustra (pocketlike sacs)  Figure 10.9 The Large Intestine *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) A section of the cecum is removed to show the ileocecal valve. 10.4 ACCESORY DIGESTIVE ORGANS 10.4.1 Teeth § Teeth masticate (chew) food into smaller fragments 10.4.1.1 Humans have two sets of teeth during a lifetime § Deciduous (baby or milk) teeth § A baby has 20 teeth by age 2 § First teeth to appear are the lower central incisors § Permanent teeth § Replace deciduous teeth between ages 6 and 12 § A full set is 32 teeth (with the wisdom teeth)  Figure 10.10 Deciduous and Permanent Teeth *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) Approximate time of tooth eruption is shown in parentheses. The same number and arrangement of teeth exist in both upper and lower jaws, so only the lower jaw is shown in each case. The shapes of individual teeth are shown on the right. 10.4.1.2 Teeth are classified according to shape and function § Incisors—cutting § Canines (eyeteeth)—tearing or piercing § Premolars (bicuspids)—grinding § Molars—grinding 10.4.1.3 Two major regions of a tooth § Crown - exposed part of tooth above the gingiva (gum) § Enamel—covers the crown § Dentin—found deep to the enamel and forms the bulk of the tooth, surrounds the pulp cavity § Pulp cavity—contains connective tissue, blood vessels, and nerve fibers (pulp) § Root canal—where the pulp cavity extends into the root 10.4.1.4 Root § Cement—covers outer surface and attaches the tooth to the periodontal membrane (ligament) § Periodontal membrane holds tooth in place in the bony jaw Note: The neck is a connector between the crown and root § Region in contact with the gum Figure 10.11 Longitudinal Section of a Canine tooth *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) 10.4.2 Salivary Gland 10.4.2.1 Three pairs of salivary glands empty secretions into the mouth § Parotid glands § Found anterior to the ears § Mumps affect these salivary glands § Submandibular glands § Sublingual glands § Both submandibular and sublingual glands empty saliva into the floor of the mouth through small ducts 10.4.2.2 Saliva § Mixture of mucus and serous fluids § Helps to moisten and bind food together into a mass called a bolus § Contains: § Salivary amylase—begins starch digestion § Lysozymes and antibodies—inhibit bacteria § Dissolves chemicals so they can be tasted 10.4.3 Pancreas § Soft, pink triangular gland § Found posterior to the parietal peritoneum § Mostly retroperitoneal § Extends across the abdomen from spleen to duodenum § Produces a wide spectrum of digestive enzymes that break down all categories of food § Secretes enzymes into the duodenum § Alkaline fluid introduced with enzymes neutralizes acidic chyme coming from stomach § Hormones produced by the pancreas § Insulin § Glucagon 10.4.4 Liver § Largest gland in the body § Located on the right side of the body under the diaphragm § Consists of four lobes suspended from the diaphragm and abdominal wall by the falciform ligament § Digestive role is to produce bile § Bile leaves the liver through the common hepatic duct and enters duodenum through the bile duct § Bile is yellow-green, watery solution containing:  § Bile salts and bile pigments (mostly bilirubin from the breakdown of hemoglobin) § Cholesterol, phospholipids, and electrolytes § Bile emulsifies (breaks down) fats 10.4.5 Gallbladder § Green sac found in a shallow fossa in the inferior surface of the liver § When no digestion is occurring, bile backs up the cystic duct for storage in the gallbladder § While in the gallbladder, bile is concentrated by the removal of water § When fatty food enters the duodenum, the gallbladder spurts out stored bile 10.5 FUNCTIONS OF THE DIGESTIVE SYSTEM 10.5.1 Overview of Gastrointestinal Processes & Controls § Digestion § Absorption 10.5.2 Essential Processes 10.5.2.1 Ingestion § placing of food into the mouth 10.5.2.2 Propulsion § movement of foods from one region of the digestive system to another § Peristalsis—alternating waves of contraction and relaxation that squeeze food along the GI tract § Segmentation—movement of materials back and forth to foster mixing in the small intestine Figure 10.12 Peristaltic and segmental movements of the digestive tract *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) 10.5.2.3 Mechanical Breakdown § Food breakdown: mechanical breakdown § Examples § Mixing of food in the mouth by the tongue § Churning of food in the stomach § Segmentation in the small intestine § Mechanical digestion prepares food for further degradation by enzymes  10.5.2.4 Digestion § Digestion occurs when enzymes chemically break down large molecules into their building blocks § Each major food group uses different enzymes § Carbohydrates are broken down to monosaccharides (simple sugars) § Proteins are broken down to amino acids § Fats are broken down to fatty acids and glycerol 10.5.2.5 Absorption § End products of digestion are absorbed in the blood or lymph § Food must enter mucosal cells and then move into blood or lymph capillaries 10.5.2.6 Defecation § Elimination of indigestible substances from the GI tract in the form of feces Figure 10.13 Flowchart of digestion and absorption of foodstuffs (1 of 3) *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018)  Figure 10.14 Flowchart of digestion and absorption of foodstuffs (2 of 3) *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) Figure 10.15 Flowchart of digestion and absorption of foodstuffs (3 of 3) *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) Figure 10.16 Schematic summary of gastrointestinal tract activities *Photo and content taken from Essentials of Human Anatomy & Physiology by Marieb & Keller (2018) Marieb, E. N., & Keller, S. M. (2018). Essentials of Human Anatomy & Physiology. New York, New York: Pearson Education, Inc.. Rizzo, D. C. (2016). Fundamentals of Anatomy and Physiology (Fourth ed.). Boston, Massachussetts: Cengage Learning. Thompson, G. S. (2015). Understanding Anatomy & Physiology: A Visual, Auditory, Interactive Approach,2nd Edition. Philadelphia: F. A. Davis Company. Tortora, G. J., & Freudenrich, C. C. (2011). Visualizing Anatomy & Physiology. John Wiley & Sons, Inc. VanPutte, C., Regan, J., & Russo, A. (2016). Seeley's Essentials of Anatomy & Physiology. New York, New York: McGraw-Hill Education. To set the tone right, we will help each other in the appreciation of the initial phase of Anatomy and Physiology by accomplishing the Course Task/s in Canvas