© 2009 The McGraw-Hill Companies, Inc. All rights reserved The Digestive System PowerPoint® presentation to accompany: Medical Assisting Third Edition.

© 2009 The McGraw-Hill Companies, Inc. All rights reserved

The Digestive SystemThe Digestive SystemPowerPoint® presentation to accompany:

Medical AssistingThird Edition

Booth, Whicker, Wyman, Pugh, Thompson

33-2


Learning Outcomes33.1 List the functions of the digestive system.

33.2 Trace the pathway of food through the alimentary canal.

33.3 Describe the structure and functions of the mouth, teeth, tongue, and salivary glands.

33.4 Describe the structure and function of the pharynx.

33-3


Learning Outcomes (cont.)

33.5 Describe the swallowing process.

33.6 Describe the structure of the esophagus and tell how it propels food into the stomach.

33.7 Describe the structure and functions of the stomach.

33.8 List the substances secreted by the stomach and give their functions.

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33.9 Describe the structure and functions of the small intestine.

33.10 List the substances secreted by the small intestine and describe the importance of each.

33.11 Describe the structure and functions of the large intestine, including the anal canal and rectum.

33.12 Explain the structures and functions of the liver, gallbladder, and pancreas.

33-5



33.13 List the substances released by the liver, gallbladder, and pancreas into the small intestine and give the function of each secretion.

33.14 Tell what types of nutrients are absorbed by the digestive system and where they are absorbed.

33.15 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the digestive system.

33-6


Introduction Digestion

Mechanical and chemical breakdown of foods into forms that body cells can absorb

The organs of the digestive system carry out digestion

Two categories Alimentary canal organs Accessory organs

33-7


Characteristics of the Alimentary Canal Wall of alimentary canal

Mucosa Inner most layer; epithelial tissue Secretes enzymes and mucus into lumen Absorbs nutrients

Submucosa Inferior to mucosa; loose connective tissue, blood vessels,

glands, and nerves Blood vessels carries away absorbed nutrients

Muscular layer Just outside submucosa; layers of smooth muscle Contracts to move materials through the canal

33-8


Characteristics of the Alimentary Canal (cont.)

Serosa Double-walled outermost layer: peritoneum

Visceral peritoneum Innermost wall of serosa Secretes serous fluid to keep outside of canal moist

Parietal peritoneum Abdominal lining

Movements Churning – mixes substances in the canal Peristalsis – propels substances through the tract

33-9


Apply Your KnowledgeWhat are the layers of the wall of the alimentary canal and what do they do?

ANSWER: The layers are:

Mucosa: innermost layer; secretes enzymes and mucus into the canal and absorbs nutrients

Submucosa: inferior to the mucosa; carries away absorbed nutrients

Muscular layer: just outside the submucosa; contracts to move materials through the canal

Serosa: double-walled outer layer; secretes serous fluid to keep outside of canal moist

Bravo!

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The Mouth Buccal cavity Mechanical digestion

Takes in food and reduces its size by chewing

Starts chemical digestion Saliva contains enzyme

amylase, which breaks down carbohydrates

33-11


The Mouth (cont.)

Cheeks hold food in mouth Lips – sensory nerve fibers that judge temperature of

food Tongue

Skeletal muscles covered by mucous membrane Lingual frenulum – holds tongue to floor of mouth Mixes food, holds food between teeth, contains taste buds Lingual tonsils – lymphatic tissue destroys bacteria and

viruses on back of tongue

33-12


The Mouth (cont.)

Palate Roof of mouth Separates oral cavity from nasal cavity Uvula – portion of soft palate that hangs down in

throat Lymph tissue

Palatine tonsils (oropharynx) Pharyngeal tonsils – adenoids (nasopharynx)

33-13


The Mouth (cont.)

Teeth – decrease size of food particles Incisors – bite off

food pieces Cuspids – tear tough

food Bicuspids and

molars – grind food

Salivary glands Cells

Serous Mucous

Glands Parotid Submandibular Sublingual

33-14


Apply Your KnowledgeMatching:

___ Buccal cavity A. Saliva

___ Roof of mouth B. Mouth

___ Grind food C. Bolus

___ Adenoids D. Palate

___ Water, enzymes, and mucus E. Bicuspids

___ Mass of food mixed with saliva and mucus F. Pharyngeal gland

D

E

F

A

B

BANSWER:

33-15


Pharynx Throat Functions

Connects nasal cavity with oral cavity for breathing

Pushes food into esophagus

Divisions Nasopharynx

Behind nasal cavity

Oropharynx Behind oral cavity

Laryngopharynx Behind larynx Continues as

esophagus

33-16


Pharynx (cont.)

Swallowing – automatic process

1. Soft palate raises, uvula covers opening between nasal and oral cavity

2. Epiglottis covers larynx, keeping food out of it

3. Tongue presses against roof of mouth, forcing food into oropharynx

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Pharynx (cont.)

4. Muscles in pharynx contract, moving food toward esophagus

5. Esophagus opens

6. Food is pushed into esophagus by muscles of pharynx

33-18


The Esophagus Muscular tube connecting pharynx to stomach

Esophageal hiatus – hole in diaphragm through which esophagus passes

Cardiac sphincter Circular band of muscle at the opening of the

stomach controls movement of food into stomach

33-19


Apply Your Knowledge

Matching:

___ Connects nasal cavity with oral cavity A. Cardiac sphincter

___ Covers the opening of larynx B. Esophageal hiatus

___ Hole in diaphragm C. Sphincter

___ Controls movement of food into stomach D. Epiglottis

___ Circular bands of muscle E. PharynxC

A

B

D

E

ANSWER:

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The Stomach Below the diaphragm in

the upper left quadrant of the abdominal cavity

Functions Receive food from

esophagus Mix bolus with gastric juice Start protein digestion Move food into small

intestine

Sections Cardiac region Fundus Body Pylorus

Pyloric sphincter Controls movement of

substances into small intestine Stomach

33-21


The Stomach (cont.)

Lining of stomach Rugae – folds of the inner lining Gastric glands

Mucous cells – secrete mucus to protect the lining Chief cells – secrete pepsinogen pepsin, which

digests protein Parietal cells

Hydrochloric acid needed to convert pepsinogen to pepsin Intrinsic factor needed for vitamin B12 absorption Stomach

33-23


The Stomach (cont.)

Gastric glands stimulated by Parasympathetic nervous system Gastrin (hormone)

Cholesystokinin (hormone) secreted by the small intestine inhibits gastric glands

Stomach absorbs alcohol, water, and some fat-soluble drugs

Chyme – mixture of food and gastric juices

33-24



What are the functions of the stomach?

ANSWER: The stomach’s functions are to receive the bolus of food, mix it with gastric juice, start protein digestion, and move food into the small intestine. It also absorbs alcohol, water, and some drugs.

Right Answer!

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The Small Intestine Tubular organ

extending from the stomach to the large intestine

Functions Digestion Absorption of nutrients

Small Intestine

Duodenum C-shaped Short

Jejunum Coiled Majority of small

intestine

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The Small Intestine Ileum

Attached to large intestine Mesentery

Fan-like tissue that holds jejunum and ileum in the abdominal cavity

Attaches to the posterior wall of the abdomen Ileocecal sphincter

Controls movement of chyme from the ileum to the cecum of the large intestine Small

Intestine

33-27


The Small Intestine (cont.)

Lining of small intestine Microvilli – increase surface area Intestinal glands

Mucus and water Enzymes

Peptidases – digest proteins Sucrase, maltase, and lactase – digest sugars Intestinal lipase – digests fats

Primary controls Parasympathetic nervous system Stretching of intestinal wall

33-29



ANSWER: She cannot produce lactase and cannot digest lactose, which is the sugar in dairy products.

Your patient states that she is lactose intolerant. What does that mean?

33-30


The Large Intestine Extends from the ileum to the anus

Cecum Beginning of large intestine Veriform appendix

Ascending colon Portion that goes up the right side of the

abdominal cavity Large Intestine

33-31


The Large Intestine (cont.)

Transverse colon Crosses abdominal cavity from right to left

Descending colon Down left side of abdominal cavity

Sigmoid colon S-shaped portion in pelvic cavity

Absorbs water and electrolytes Large Intestine

33-32


The Rectum and Anal Canal Rectum – off sigmoid colon

Anal canal Last few centimeters of rectum Opening to outside of body is the anus

Large Intestine

33-33


The Rectum and Anal Canal Feces

Leftover chyme Consists of undigested solid materials, little

water, ions, mucus, cells of intestinal lining, and bacteria

Defecation reflex Triggered by periodic contractions of large

intestine Allows anal sphincters to relax

33-35


Apply Your KnowledgeMatching:

___ Vermiform appendix A. Feces

___ Crosses the abdomen B. Ascending colon

___ Up right side of abdomen C. Anal canal

___ S-shaped tube D. Defecation reflex

___ Down left side of abdomen E. Sigmoid

___ Leftover chyme F. Transverse colon

___ Last section of rectum G. Cecum

___ Allows anal sphincters to relax H. Descending colon

H

G

F

E

D

C

B

A

ANSWER: Super!

33-36


The Liver Lobular organ in right upper quadrant

Large right lobe and smaller left lobe Hepatic lobules – contain macrophages Hepatocytes – process nutrients in blood and

make bile

Part of liver’s function Store vitamins and iron

33-37


The Liver (cont.)

Hepatic portal vein – carries blood from digestive organs to hepatic lobules

Hepatic duct – bile from liver Hepatic duct merges with cystic

duct from gallbladder and forms common bile duct

Common bile duct – delivers bile to duodenum

33-38


The Gallbladder Small sac-like structure

located beneath the liver

Only function is to store bile

Cholecystokinin causes the gallbladder to release bile

Gallbladder

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Apply Your KnowledgeWhat is the route of bile through the liver and gall bladder?

ANSWER: Bile is made in the hepatocytes and leaves the liver through the hepatic duct. The hepatic duct merges with the cystic duct from the gall bladder to form the common bile duct, which delivers bile to the duodenum.

33-40


The Pancreas

Pancreatic amylase – digests carbohydrates

Pancreatic lipase – digests lipids

Nucleases – digestsnucleic acids

Trypsin, chymotrypsin, and carboxypeptidase – digest proteins

Located behind the stomach Acinar cells produce pancreatic juice, which contains these enzymes:

33-41


The Pancreas (cont.)

Also secretes bicarbonate ions into duodenum Neutralize acidic chyme

Enzyme release stimulated by Parasympathetic nervous system Hormones secretin and cholecystokinin (from

small intestine)

33-42



What are the pancreatic enzymes and what do they do?

ANSWER: They are:

Pancreatic amylase – digests carbohydrates

Pancreatic lipase – digests lipids

Nucleases – digest nucleic acids

Trypsin, chymotrypsin, and carboxypeptidase – digest proteins

Good Job!

33-43


The Absorption of Nutrients Nutrients are necessary food

substances Carbohydrates Proteins Lipids Vitamins Minerals Water

33-44


The Absorption of Nutrients (cont.)

Carbohydrates – provide energy Polysaccharides – starches Monosaccharides and disaccharides – simple sugars Cellulose – provides fiber or bulk

Lipids – used for energy when glucose levels are low Triglycerides Cholesterol – essential for cell growth and function

33-45


The Absorption of Nutrients (cont.)

Protein – used for growth and repair of tissue Essential amino acids body can not make

Vitamins Fat-soluble Water-soluble

Minerals – used to make enzymes, cell membranes, and proteins

33-46


Apply Your KnowledgeTrue or False:

___ Carbohydrates are starches, simple sugars, and cellulose.

___ Excess glucose is stored in the gallbladder as glycogen.

___ Triglycerides are the least abundant lipids

___ Linoleic acid is an essential fatty acid.

___ A, D, E and K are water-soluble vitamins.

___ Minerals are used by cells to make enzymes.

F

F

F

T

T

ANSWER:

Tliver

most

fat-soluble

33-47


Aging and the Digestive System Decreased motility –

GERD

Decreased absorption

More likely to develop ulcers and cancers

Decreased ability to detoxify blood

Sense of taste altered

Dietary changes due to Isolation Depression

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Common Diseases and Disorders

Disease / Disorder Description

Appendicitis Inflammation of the appendix; can be life-threatening if not treated promptly

Cirrhosis Chronic liver disease; normal tissue is replaced with nonfunctional scar tissue

Colitis Inflammation of the large intestine; can be acute or chronic

Colorectal cancer Arises from lining of rectum or colon; curable if treated early

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Common Diseases and Disorders (cont.)


Constipation Difficult defecation

Crohn’s disease Inflammatory bowel disease; typically effects small intestine

Diarrhea Watery and frequent feces; usually self-limiting

Diverticulosis Abnormal pouches in the intestinal wall; no inflammation present

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Diverticulitis Inflammation of diverticuli (abnormal pouches in intestinal wall) of the intestine

Gastritis Inflammation of the stomach lining; “upset stomach”

Heartburn Gastroesophageal reflux disease (GERD); stomach acids push into esophagus

Hemorrhoids Varicose veins of rectum or anus

Hepatitis Inflammation of the liver; various types

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Hiatal hernia Portion of stomach protrudes into the chest through an opening (usually the esophageal hiatus) in the diaphragm

Inguinal hernia Portion of large intestine protrudes in the inguinal canal (where thigh and trunk meet) or, in males, into the scrotum

Oral cancer Usually involves the lips or tongue but can occur anywhere in the mouth; tends to spread rapidly

33-52




Pancreatic cancer Fourth leading cause of cancer deaths in the U.S.

Stomach cancer Commonly in cardiac portion of the stomach; occurs more frequently in Japan, Chili, and Iceland

Stomach ulcers Breakdown in lining of the stomach; can be caused by bacteria (H. pylori) or smoking, alcohol, excessive aspirin use, and hypersecretion of stomach acid

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Matching:

___ Inflammation of the large intestine A. Heartburn

___ Inflammatory bowel disease B. Hemorrhoids

___ Watery and frequent feces C. Constipation

___ Difficult defecation D. Chron’s disease

___ Inflammation of the stomach lining E. Colitis

___ Inflammation of pouches in the intestinal wall F. Diarrhea

___ GERD G. Gastritis

___ Varicose veins of rectum H. Diverticulitis

H

G

F

D

C

B

A

E

ANSWER:

33-54


In Summary Purpose of the digestive system is to provide

nutrients to the body Organs of alimentary canal are responsible for

mechanical and chemical breakdown of food Accessory organs

Assist in breakdown of food Eliminate waste

Medical assistant must have knowledge of this system Assist with procedures Patient education

33-55


End of Chapter

Take all that is given whether wealth, love or language; nothing

comes by mistake and with good digestion all

can be turned to health.

~ George Herbert

© 2009 The McGraw-Hill Companies, Inc. All rights reserved The Digestive System PowerPoint® presentation to accompany: Medical Assisting Third Edition.

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