Download Chapter 33: The Digestive System LEARNING OUTCOMES After

Chapter 33: The Digestive System
LEARNING OUTCOMES
After completing Chapter 33, students should be able to:
33.1 Describe the organs of the alimentary canal and their functions.
33.2 Explain the functions of the digestive system’s accessory organs.
33.3 Identify the nutrients absorbed by the digestive system and where they are absorbed.
33.4 Describe the causes, signs and symptoms, and treatments of various common diseases and disorders
of the digestive system.
Lecture Outline
Learning Outcome 33.1: Describe the organs of the alimentary canal and their functions.
•
Lecture Topics
•
Teach your students that digestion is the mechanical and chemical breakdown of foods into forms
that your body cells can absorb. (Refer to PowerPoint Slide 4.)
•
Begin the discussion of the digestive tract with the alimentary canal,
distinguishing it from the accessory digestive organs. (Refer to PowerPoint Slides 5 – 7.)
•
•
•
•
•
•
Ask your students to name the organs that make up the alimentary canal: mouth, pharynx,
esophagus, stomach, small intestine, large intestine, rectum, and anal canal. (Refer to
PowerPoint Slides 8 – 16.)
•
Explain that the alimentary canal consists of four layers and discuss the
function of each layer:
Mucosa: innermost layer that secretes enzymes and mucus, allowing for the absorption of
nutrients.
Submucosa: layer lined with blood vessels, connective tissue, nerves, and gland, which
carries away the absorbed nutrients
•
Muscular layer: consists of smooth [visceral] muscle that contracts to move
material through the system.
•
Serosa: outermost layer also known as the visceral peritoneum, which
secretes serous fluid to keep organs from sticking to the alimentary canal. (Refer to Figure
33-2.)
Review the functions of the following salivary glands:
Parotid glands
•
Submandibular glands
•
Sublingual glands (Refer to Figure 33-6 and PowerPoint Slide 11.)
Teach your students that the esophagus is a muscular tube that connects the pharynx to
the stomach and explain the role of sphincters in digestion. (Refer to Figures 33-7 and
33-8 and PowerPoint Slide 17.)
•
Review the anatomy of the stomach. Remind your students that the
beginning portion of the stomach that is attached to the esophagus is called the cardiac
region. The portion of the stomach that balloons over the cardiac region is the fundus.
The main part of the stomach is called the body, and the narrow portion connected to the
small intestine is the pylorus. The pyloric sphincter controls the movement of substances
from the pylorus of the stomach into the small intestine. (Refer to Figures 33-8 and 33-9
and PowerPoint Slides 18 - 21.)
•
Teach your students that eventually, the sigmoid colon straightens out to become the rectum.
Note that the last few centimeters of the rectum are known as the anal canal, and the opening of
the anal canal to the outside of the body is called the anus (Refer to Figure 33-10 and
PowerPoint Slides 26 – 28.)
•
Discussion Points
•
Ask students to list the organs of the digestive system and write the responses on the
board: mouth; pharynx; esophagus; stomach; small intestine; large intestine; rectum; anal
canal; the accessory organs of the liver, gallbladder, and pancreas. Use these answers to
prompt a discussion on the function of each organ.
•
Explain to students that without a properly functioning digestive system,
cells will not receive the nutrients needed to survive. (Refer to Figure 33-1.)
•
Ask a volunteer to describe peristalsis: the movement or propulsion of
substances through the alimentary canal. (Refer to Figure 33-2.)
•
Remind your students that humans have 32 teeth—16 on the upper jaw
and 16 on the lower jaw—which work to decrease the size of food particles. Discuss the
functions of the following types of teeth: cuspids, bicuspids, and molars. (Refer to
Figures 33-4 and 33-5 and PowerPoint Slide 12.)
•
Discuss the role of the pharynx: to push food into the esophagus. Point out
the divisions of the pharynx: nasopharynx, oropharynx, and laryngopharynx. (Refer to
Figure 33-7.)
•
Ask your students to describe the enzymes secreted by the small intestine:
peptides, sucrose, maltase, lactase, and intestinal lactase. Remind them that the
parasympathetic nervous system triggers the intestine to secrete these enzymes. (Refer to
PowerPoint Slides 22 – 25.)
•
•
Learning Activities
Place the following words on the blackboard: buccal cavity, amylase, palate, lingual
frenulum, uvula, pharynx, oropharynx, nasopharynx, and palatine tonsils. Ask your
students to write a brief report on how mechanical and chemical digestion begin in the
mouth using these words. Pick a few volunteers to read their reports to the class during a
class discussion. (Refer to Figure 33-3.)
•
Arrange your students into small groups and provide poster board and
markers to each group. Ask you students to work together to create a poster that depicts
the process that occurs when food is eaten, processed, and finally expelled from the body
as feces. For fun, the students could vote on the best poster and a small award could be
given to the group that created the poster.
Learning Outcome 33.2: Explain the functions of the digestive system’s accessory organs.
Lecture Topics
•
Emphasize the fact that although they do not form part of the alimentary canal, the
digestive system’s accessory organs play important roles in digestion. That is, they
deliver enzymes and other substances to the alimentary canal to assist with the digestive
process.
•
Discussion Points
•
Ask your students to name the accessory organs of the digestive system. Place these
labels on the board and have your students to describe the function of each organ: liver,
gallbladder, and pancreas. (Refer to Figures 33-11 and 33-12 and PowerPoint Slides 32
– 38.)
•
•
•
Learning Activities
Invite a radiologist or gastroenterologist to speak to the class about diagnosing liver and
gallbladder diseases seen on MRIs. Ask the speaker to bring some films in to show the
class the abnormalities and to speak about how studies of these organs are prepared for
the patient.
Learning Outcome 33.3: Identify the nutrients absorbed by the digestive system and where they are
absorbed.
•
Lecture Topics
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Tell your students that Harvard Medical International states a connection has been made
between higher-fiber diets and a decrease in colon diseases, including cancer. Have your
students explain why this connection might be made. (Fiber increases water absorption
and bulk, causing more rapid emptying of the colon and decreasing the production of
benign growths like adenomas or polyps, which increase the risk of cancer. Fiber may
also neutralize toxins produced by GI (gastrointestinal) tract bacteria.)
•
Teach your students that foods rich in protein include meats, eggs, milk,
cheese, fish, chicken, turkey, nuts, seeds, and beans. Point out that the body uses proteins
for growth and tissue repair.
•
Discussion Points
•
•
•
Ask students to define nutrients (necessary food substances) and to provide some
examples of nutrients: carbohydrates, proteins, lipids, vitamins, minerals, and
water. (Refer to PowerPoint Slide 41.)
•
Discuss the three types of carbohydrates that humans ingest:
starches (polysaccharides), simple sugars (monosaccharides and disaccharides),
and cellulose. Brainstorm with the class to make a list of foods that are good
sources of carbohydrates (e.g., bread, pasta, fruit). (Refer to PowerPoint Slide
42.)
•
Ask a volunteer to define lipids. (Fats). Tell students that lipids are
used by the body to make energy when sugar is low, and that a certain amount of
fat is also needed to absorb fat-soluble vitamins (A, D, E, and K). Be sure to draw
their attention to Table 33-1: Common Vitamins and Their Importance in the Body,
which summarizes some common vitamins and their functions. (Refer to
PowerPoint Slide 43.)
•
Have your students explain why the body needs protein (growth
and repair of tissues). Ask them to name foods that are high in protein. (e.g., meat,
eggs, milk, fish, poultry, nuts, cheese, and legumes) (Refer to PowerPoint Slide
44.)
•
Ask your students: What minerals are important to our bodies?
(Calcium, phosphorus, sulfur, sodium, chlorine, and magnesium.) Point out that
the minerals iron, manganese, copper, iodine, and zinc are also needed, but only in
trace amounts.
Learning Activities
Have your students research how aging affects the digestive system and write a brief
report to share with the class. (Refer to PowerPoint Slide 46.)
•
Invite a registered dietician or nutritionist to the class. In preparation for
the visit, ask class members to keep a food diary of everything they've eaten or drunk for
at least two weeks. Ask some volunteers to share their diary as a way to initiate a
discussion about good eating habits, especially in our "fast food" type of world. Be sure
students prepare questions for the speaker.
Learning Outcome 33.4: Describe the causes, signs and symptoms, and treatments of various
common diseases and disorders of the digestive system.
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•
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Lecture Topics
Review each disease discussed in the textbook. Stress to students that their understanding of the
causes, signs and symptoms, and treatment of these disorders will assist them in their role as
medical assistants. (Refer to PowerPoint Slides 47 – 52.)
Discussion Points
Be sure your students understand the diagnostic and therapeutic procedures used to diagnose and
treat digestive diseases (sigmoidoscopy, colonoscopy, endoscopy, colectomy, colostomy,
gastrectomy, gastrostomy, jejunostomy).
•
Encourage questions and discussions on the common diseases and
procedures discussed in the textbook. Many students will have had experience with, or
know someone who has had experience with, at least one of these conditions. Encourage
open discussion within the class.
Learning Activities
Have each student choose a digestive disease or disorder and complete additional research
on the background of the disease, its causes or contributing factors, preventive measures
(if any), treatment, and the prognosis for patients. This project may be an oral or written
presentation.
Case Studies
•
The following case studies can be presented to students so that you can assess their
responses to situations they may encounter in the workplace setting.
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James Cho is a new patient who arrives at your clinic with a chief complaint of
abdominal pain and vomiting, fatigue, and weight loss. He notes that although he has
experienced overall weight loss, his stomach "looks huge." As his history is taken, he notes
no alcohol use. In speaking with him, you notice a yellow tinge to the whites of his eyes.
During examination, the physician notes organomegaly (organ enlargement) in the RUQ.
•
What disease could James be suffering from? (Cirrhosis.) Which organ is enlarged?
(Liver.) What is the clinical name for the yellow tint of his sclera? (Jaundice, or icterus.)
If James does not drink alcohol, what are other possible causes for his condition? (Hepatitis
B or C, autoimmune disease, or a possible reaction to medication.)
•
Deanna Mathers is a 30-year-old woman with known eczema. She has been complaining
recently of intermittent abdominal pain and fever, with severe bouts of diarrhea
alternating with constipation. She does note that there has been blood in her stool, but
states that she does not have hemorrhoids. Her physician comments that her eczema may
be a clue as to her GI disturbance.
•
What do you think her diagnosis may be? (Crohn's disease.) What are some of the
treatment options? (Anti-inflammatory drugs; antibiotics; changes in diet; a partial or, in
severe cases, total colectomy to remove the diseased intestine.)
Assessment
•
Encourage students to use the various features in the Student Workbook for self-assessment.
These features include vocabulary and content reviews, applications, case studies, and
competency checklists (to assess mastery of procedures introduced in the chapter). You can
assess students' grasp of the materials through a chapter test, using the vocabulary and
content reviews. You can also refer to the activities and exercises on the Online Learning
Center (OLC) and within the medical assisting student CD packaged with the student
textbook.
Medical Assisting Media
Found on Connect Plus™
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Electronic Health Records (E.H.R.) SpringCharts® Exercises
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LearnSmart™
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BodyAnimat3d
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Administration and Clinical Administration Videos
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eBook (if you’ve adopted ConnectPlus)
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Online Learning Center™: www.mhhe.com/BoothMA5e
Resources
In addition to the publications listed on the OLC, you may find the following materials useful.
Books
Ballard, Carol. 2009. The Digestive System 2nd edition. Chicago, IL. Heinemann.
Hassett, Sue. 2009. Living with Celiac Disease. Philadelphia, PA. Xlibris Publishing.
Merrill, Gary. 2008. Our Marvelous Bodies: An Introduction to the Physiology of Human
Health. Chapel Hill, NC. Longleaf Services.
Steinhardt, A. Hillary, Cepo, Julie. 2008. Crohn's and Colitis Diet Guide: Includes 150 Recipes.
Ontario, Canada. Rose, Robert, Incorporated.
Articles
Brown, L.A. 2006. The fiber factor. Better Nutrition 68:30-31.
Drugs for the treatment of gastroesophageal reflux. 2006. Digestive Disorders:10-17.
Johns Hopkins Kimmel Cancer Center. 2006. Genome code cracked for breast and colon cancers.
AScribe Health News Service, September 7.
What you might not know about digestive disorders. 2006. Digestive Disorders:10-11.
Audiovisuals
Cancer and Diet: Using Food to Eliminate Cancer. 2006. Bayview Films. DVD.
Computer Software
My Body, Myself. CD-ROM. Fogware Publishing. Windows 98/ME/XP Platforms.
Chapter 33 Textbook Answers
Case Study Critical Thinking
•
The gallbladder stores bile for the body and releases it when prompted by the hormone
cholecystokinin.
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She could have a lithotripsy procedure or medications to dissolve or break up the
gallstones.
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If gallstones are not removed, inflammation of the cystic duct can spread to the
common hepatic duct, and liver damage can result. Inflammation can also spread to the pancreatic
duct, because it opens into the common bile duct, and serious pancreatic damage can occur.
•
Most likely, Sylvia will not have to alter her diet because the liver will still
produce bile. Because bile can no longer be stored, more of it will be emptied into the small
intestine, possibly causing diarrhea.
Exam Preparation Questions
1.
a
Mucosa
2.
c
Liver
3.
b
uvula
4.
d
hernia
5.
b
Crohn’s disease
6.
e
Bile
7.
e
Triglycerides
8.
a
To help the large intestine empty more regularly.
9.
b
Constipation
10.
c
Gastritis
Medical Terminology Practice
1. bi/cusp/id = bi means “two” + cusp means “projection” + id means “having the characteristic of”;
bicuspid is a tooth that has two prominences or projections.
2. carboxy/peptid/ase = carboxy refers to carboxyl chemical groups + peptid refers to peptides
(chemicals made of amino acids) + ase means “enzyme”; carboxypeptidase is an enzyme that breaks
up peptides by removing carboxyl groups. This is one of the mechanisms by which proteins are
digested.
3. diverticul/osis = diverticula are abnormal dilations or pouches in the intestinal wall + osis means
“condition or disease”; diverticulosis is a condition in which diverticula are present in the intestine,
but are not inflamed.
4. hepato/cyte = hepato refers to the liver + cyte means “cell”; hepatocytes are cells in the liver that
process nutrients in blood and make bile.
5. idio/path/ic = idio means “self” or “from within” + path means “disease” + ic means “pertaining
to”; idiopathic diseases are those with no known cause.
6. laryngo/pharynx = laryngeo refers to the larynx + pharynx is the throat; laryngopharynx is the
part of the pharynx that lies behind the larynx.
7. nucle/ase = nucle refers to nucleic acids + ase means “enzyme”; a nuclease is an enzyme that
digests nucleic acids.
8. poly/saccharide = poly means “many” + saccharide means “sugar”; polysaccharide is a type of
carbohydrate that has many sugar molecules bonded together.
9. pylor/ic = pylor refers to the pylorus, or part of the stomach that connects to the small intestine +
ic means “pertaining to”; pyloric means “pertaining to the pylorus.”
10. sub/lingual = sub means “under” + lingual refers to the tongue; sublingual means “under the
tongue.”
Chapter 33 Student Workbook Answers
Vocabulary Review
Matching
1.
i
2.
t
3.
c
4.
y
5.
a
6.
l
7.
v
8.
d
9.
o
10.
f
11.
s
12.
x
13.
b
14.
p
15.
j
16.
q
17.
g
18.
w
19.
e
20.
h
21.
k
22.
m
23.
u
24.
n
25.
r
True or False
(These are possible answers. Accept all reasonable responses.)
26.
F: The parietal peritoneum is the lining of the abdominal cavity.
27.
F: The mucosa is the innermost layer of the alimentary canal and is responsible for absorbing
nutrients.
28.
T
29.
F: Amylase begins the digestion of carbohydrates.
30.
T
31.
F: The pharyngeal tonsils are also known as the adenoids.
32.
F: The epiglottis covers the opening of the larynx.
33.
F: The main part of the stomach is called the body.
34.
T
35.
F: If a patient’s stomach has been removed, a J tube may be inserted for feeding.
36.
T
37.
F: The liver is located in the right upper quadrant of the abdomen.
38.
F: The descending colon becomes the sigmoid colon.
39.
F: The liver makes bile, which is then stored in the gallbladder.
40.
T
Content Review
Multiple Choice
1.
c
2.
c
3.
b
4.
d
5.
e
6.
a
7.
c
8.
b
9.
e
10.
d
Sentence Completion
11.
parotid
12.
diarrhea
13.
esophageal hiatus
14.
Nutrients
15.
Intrinsic factor
16.
K
17.
acinar cells
18.
Constipation
19.
bicarbonate ions
20.
small intestine
Short Answer
21.
A.
salivary glands
B.
liver
C.
gallbladder
D.
pancreas
E.
mouth
F.
pharynx
G.
esophagus
H.
stomach
I.
small intestine
J.
large intestine
K.
rectum
L.
anus
22.
23.
A.
esophagus
B.
cardiac region
C.
duodenum
D.
pyloric sphincter
E.
pyloric canal
F.
pylorus
G.
fundus
H.
body
I.
rugae
A.
serosa
B.
ascending colon
C.
ileocecal sphincter
D.
opening of vermiform appendix
E.
cecum
F.
vermiform appendix
G.
rectum
H.
muscular layer
I.
mucosa
J.
transverse colon
K.
descending colon
L.
sigmoid colon
M. anal canal
24.
A.
The production of visual receptors, mucus, the normal growth of bones and teeth,
the repair of epithelial tissues
B.
The metabolism of carbohydrates and fats, and cell growth
C.
The production of collagen, amino acids, and hormones; the absorption of iron
D.
the production of myelin and the metabolism of carbohydrates and nucleic acids
E.
The production of amino acids, DNA, and red blood cells
F.
The prevention of the breakdown of certain tissues
Critical Thinking
1.
During swallowing, the opening to the lower airway is covered by the epiglottis, which prevents
breathing.
2.
If ulcerations or other painful lesions are present in the mouth, eating becomes painful and is
avoided. If gums or teeth are diseased, or if teeth are lost or removed, chewing becomes difficult and/or
painful, sometimes to the point of being impossible. Nutrition lessens because patients either don’t eat or
change their diets to include only soft foods that have little fiber or nutritional value. This change in diet
also makes defecation difficult, resulting in constipation and hemorrhoids. In some cases, more serious
diseases such as colitis, polyps, or even colon cancer may subsequently occur.
3.
The esophageal or cardiac sphincter must open to allow stomach contents to enter the esophagus.
4.
Fiber increases fecal bulk, making the movement of feces easier. Water absorption makes feces
softer, which eases the process of elimination, and triggers the defecation reflex on a regular basis,
making constipation less of a problem for patients. Science and medical experts also point to roughage as
an important part of the diet to decrease incidences of colon diseases, including cancer. Fiber increases
water absorption and bulk, causing more rapid emptying of the colon, and decreasing the production of
benign growths such as adenomas or polyps, which increase the risk of cancer.
5.
A hiatal hernia occurs at the opening in the diaphragm that allows the esophagus to connect with
the stomach. In this type of hernia, a portion of the stomach is pushed through this opening. An inguinal
hernia occurs when a portion of the large intestine protrudes into the inguinal canal, which is located
where the thigh and body trunk meet. In males, the hernia can also protrude into the scrotum.
Application
1.
A.
The nasopharynx is located behind the nasal cavity. It allows air to flow between the
nasal cavity and the oropharynx.
B.
The oropharynx is located behind the oral cavity. It allows food and air to flow between
the oral cavity and the laryngopharynx.
C.
The laryngopharynx is located behind the larynx. It allows air to flow between it and the
larynx. It also allows food to flow from it to the esophagus.
2.
A.
Used primarily to make energy
B.
used primarily for the growth of tissues, the repair of tissues, and the production of
hormones and enzymes
C.
Used primarily to make cell membranes, insulate the body, provide cushioning for the
body, store energy, and make hormones
D.
Used in many functions in metabolism and cell growth
E.
Used to make enzymes, cell membranes, and various proteins such as hemoglobin
Case Studies
Case 1
He will have to eat meals more often, but with smaller proportions, because his rate of digestion and
absorption will be decreased.
Case 2
Alcohol in the bloodstream is detoxified by the liver. If the liver is diseased, detoxification cannot readily
be accomplished. Continuing to drink alcohol will make an existing problem worse, exacerbating the
illness and continuing the liver destruction, which can eventually lead to death.
Case 3
She is missing calcium and vitamin D, which may result in bone disorders.
Case 4
Polyps can become cancerous, so they should be removed.