Pearson's Comprehensive Medical Assistingftc-drthorson.weebly.com/uploads/5/5/4/4/55444029/beaman...Title Slide 1 Author Thomas Dunn Created Date 8/9/2015 12:39:06 PM

Pearson's ComprehensiveMedical Assisting

Administrative and Clinical Competencies

CHAPTER

THIRD EDITION

Pearson's Comprehensive Medical Assisting:Administrative and Clinical Competencies, 3/eBeaman | Routh | Papazian-Boyce | Sesser | Mills | Maly

Copyright © 2015, 2011 by Pearson Education, Inc.All Rights Reserved

The Digestive SystemLesson 1:Overview of the Digestive System

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Lesson Objectives

Upon completion of this lesson, students should be able to:

1. Define and spell the terms to learn for this chapter.

2. Describe the purpose and function of the digestive system.

3. Identify the primary organs of the digestive system and briefly explain the function of each.



Lesson Objectives

Upon completion of this lesson, students should be able to:

4. Describe the three main portions of a tooth.

5. Identify the accessory organs of the digestive system and briefly explain the function of each.



The Digestive System

• Three main functions

Digestion

Absorption

Elimination



FIGURE 30-1 The digestive system.



Critical Thinking Questions

1. What organs comprise the "tube" of the digestive system?

2. What are the accessory organs?



Organs of the Digestive System

• Digestive system

Series of hollow organs joined in long, twisting tube from mouth to the anus

• Wall of long tube composed of four layers:

Serosa (peritoneum)

Muscular layer

Submucosa

Mucosa




• Digestive enzymes

Protease

• Helps to digest proteins

Amylase

• Helps digest carbohydrates

Lipase

• Helps digest fats



FIGURE 30-2 The oral cavity: (A) sagittal section; (B) anterior view as seen through the open mouth.




• Mouth

Digestion begins in the mouth

Process of mastication (chewing) and secretion of saliva

Helps to form food into a bolus (ball) for swallowing

Cavity (oral cavity) formed by palate, lips and cheeks, and tongue




• Mouth

Cheeks form the lateral walls and are continuous with the lips

Hard and soft palates form roof of oral cavity

Tongue connected to floor of the cavity

Oral cavity contains teeth and salivary glands

Gingivae (gums) hold the teeth in place




• Mouth

Three pairs of salivary glands secrete saliva into oral cavity

• Parotid

• Sublingual

• Submandibular




• Mouth

Tongue is skeletal muscle covered with mucous membrane

• Rear portion

• Central body

• Pointed tip




• Mouth

Four types of taste buds

• Sweet

• Salty

• Sour

• Bitter



Critical Thinking Question

1. How do these four types of taste buds produce the many flavors of our food?




• Mouth

Posterior margin of soft palate supports muscular pharyngeal arches

Functions in swallowing and phonation

Uvula

• Tissue that looks like tiny punching bag dangling from center of pharyngeal arches



FIGURE 30-3 Deciduous and permanent teeth: (A) deciduous teeth, with the age at eruption given in months; (B) permanent teeth, with the age at eruption given in years.




• Teeth

Humans have two sets of teeth

• 20 deciduous teeth (baby teeth); 8 incisors, 4 canines (cuspids), 8 molars

• 32 permanent teeth; 8 incisors, 4 canines, 8 premolars,12 molars




1. If the deciduous teeth fall out, why is it important for young children to practice good dental hygiene?




• Teeth

Incisors

• Four front teeth of each dental arch

• Sharp, cutting edge

• Used for biting into food

• Upper incisors larger and stronger than lower ones




• Teeth

Canine teeth (cuspids)

• Have roots that reach deep into bones of the jaw

• Upper canines known as eye teeth are larger than lower canines

• Lower canines often called stomach teeth




• Teeth

Premolar teeth

• Behind canine teeth

• Known as bicuspid teeth

• Smaller and shorter than canines

• Four premolars in each arch




• Teeth

Molar teeth

• Largest teeth in permanent set

• Adapted to grinding and pounding food

• Adult has 12 molars, 6 in each arch, posterior to the premolars




1. How does the shape of each tooth allow it to do a different job in the chewing process?




• Teeth

Crown

• Part above the gum

Root

• Embedded in the gums

Neck

• Portion between the root and the crown



FIGURE 30-4 A diagrammatic section through a typical adult tooth.




• Teeth

Dentin

• Calcified, largely mineral tissue that forms bulk of tooth

Enamel

• Hardest and most compact part of tooth; covers exposed part of the crown




• Teeth

Cementum

• Thin layer of bone that covers the dentin of the root, providing protection and anchoring to periodontal ligament




1. What structures are affected if a cavity in the enamel is left untreated and penetrates to the pulp of the tooth?

2. What is the result to the patient?




• Teeth

Bound to bony sockets in maxillary and mandible jawbones by fibers of periodontal ligament

Teeth erupt through gums during childhood when they are sufficiently calcified to tolerate the stress they will be subjected to later




1. What is the result when gingivitis (gum disease) destroys these structures?




• Pharynx

Lies posterior to the mouth

Beginning of tubal component that leads to the stomach

Passageway for both air and food

Belongs to respiratory and digestive systems

Both larynx and esophagus begin in pharynx




• Pharynx

Once food is swallowed, bolus passes through pharynx into esophagus reflexively

Muscular contractions move bolus of food into esophagus while closing larynx to prevent food from entering the trachea




1. What happens when food accidentally goes into the trachea?




• Esophagus

Collapsible tube about 10 inches long

Starts at pharynx and ends at the stomach




• Esophagus

Food and liquids carried down esophagus by muscular contractions (peristalsis)

Involuntary wavelike contractions continue to move bolus of food through entire digestive system




• Stomach

Large, muscular, saclike organ

Can hold 1 to 1.5 liters of food and fluid

Secretes hydrochloric acid and gastric juices

Converts food into chyme, a semiliquid that is then passed into small intestine for further digestion



FIGURE 30-5 Stomach.




1. What nutrient is digested in the stomach?




• Stomach

Fundus is upper rounded portion and can store undigested food for up to one hour

Inside has rugae (gastric folds) that allow inside surface area of stomach to expand as food is ingested




• Stomach

Cardiac sphincter

• Opens and closes allowing food and liquid to enter the stomach

Pyloric sphincter

• Facilitates passage of food and liquid out of the stomach




1. What would happen without sphincters?

2. Which structure is faulty when acid reflux occurs?




• Small Intestine

21 feet long and about 1 inch in diameter

Coiled within lower abdomen

First 12 inches constitute duodenum

Next 8 feet make up jejunum

Last 12 feet are the ileum



FIGURE 30-6 Small intestine.




• Small Intestine

Chyme moves into small intestine from stomach through pylorus

Mixes with bile from liver and gallbladder and pancreatic juice from pancreas




• Small Intestine

Nutrients absorbed into tiny capillaries and lymph vessels in walls of small intestine

Transmitted to body cells via circulatory system




1. What nutrients are digested in the small intestine?




• Large Intestine

Begins at ileocecal orifice

About 5 feet long and 2.5 inches in diameter

Functions

• Complete digestion

• Complete absorption



FIGURE 30-7 Large intestine.




• Large Intestine

Cecum

• Small pouch about 3 inches long that forms beginning of large intestine

• Receives fecal (solid) material from small intestine

Appendix

• Small appendage attached to cecum

• Has no known function in humans




• Large Intestine

Colon

• Bulk of large intestine

• Divided into ascending colon, transverse colon, descending colon, and sigmoid colon, which leads to the rectum

• Waste products of digestion eliminated from body via rectum and anus (external opening of rectum)




• Accessory Organs of Digestion

Salivary glands

Gallbladder

Liver

Pancreas




1. What is the general function of the accessory organs?



FIGURE 30-8A Salivary glands



FIGURE 30-8B Gallbladder, liver, and pancreas.





Salivary Glands

• Located in and near mouth

• Saliva produced in response to sight, smell, taste, or mental image of food

• Three pairs: parotid, submandibular, sublingual

• Saliva contains digestive enzyme, amylase





Liver

• Largest glandular organ

• Essential role in metabolism of carbohydrates, fats, and proteins





Liver

• In carbohydrate metabolism, it changes glucose to glycogen and stores it for future use

• To metabolize fat, liver produces bile, which emulsifies fats before releasing products into bloodstream




1. What substances does the liver detoxify?





Liver

• In protein metabolism, liver stores components of proteins so body can break down or build up proteins as required

• Bile

• Digestive juice that emulsifies fats

• Fibrinogen and prothrombin

• Essential for blood clotting





Liver

• Heparin

• Prevents clotting of blood

• Blood proteins: albumin, gamma globulin

• Stores iron and vitamins B12, A, D, E, and K

• Produces body heat

• Detoxifies substances potentially harmful to body (drugs and alcohol)





Gallbladder

• Membranous sac in which bile stored and concentrated

• Bile six to ten times more concentrated than bile produced by liver

• Components of bile can build up and form gallstones (cholelithiasis)




1. How does the concentration of bile in the gallbladder contribute to the formation of gallstones?




• Pancreas

Elongated gland, 6 to 9 inches in length

Situated behind stomach

Secretes pancreatic juice into small intestine

Contains cells that produce digestive enzymes

Also has cells that secrete hormones insulin and glucagon



Questions?

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Pearson's Comprehensive Medical Assistingftc-drthorson.weebly.com/uploads/5/5/4/4/55444029/beaman...Title Slide 1 Author Thomas Dunn Created Date 8/9/2015 12:39:06 PM