CHAPTER 12
Digestive System
Digestive System Overview
• Digestive System
– Known as gastrointestinal tract
• Also known as digestive tract or alimentary canal
– Approximately 30 feet long
• Begins with mouth (oral cavity), ends with anus
– Functions
• Prepare foods for absorption into the bloodstream
• Prepare foods for use by the body cells
• Responsible for elimination of solid wastes from
the body
2
Digestive System Structures
• Oral cavity (Buccal cavity)
– Lips
– Cheeks
– Hard palate
• Rugae
– Soft palate
– Uvula
– Tongue
• Principle organ of the sense of taste
• Also assists in process of chewing (mastication)
and swallowing (deglutition)
3
Digestive System Structures
• Salivary glands
– Three pairs
• Parotids
• Submandibulars
• Sublinguals
– Secrete saliva
• Mostly water, but contains mucus and digestive
enzymes that aid in digestive process
– Digestive enzymes contained in saliva
• Amylase – aids in digestion of carbohydrates
• Lipase – aids in digestion of fats
4
Digestive System Structures
• Pharynx
– Known as the throat
– Serves as passageway for both respiratory
and digestive systems
– Oropharynx
• Section leading away from oral cavity
– Nasopharynx
• Behind nasal cavity
– Laryngopharynx
• Lower portion – opens into esophagus and larynx
5
Digestive System Structures
• Esophagus
– Receives food from pharynx and propels it
to stomach
– Cardiac sphincter (lower esophageal
sphincter) controls passage of food from
esophagus into the stomach
• Relaxes = food enters stomach
• Contracts = stomach contents prevented from
reentering the esophagus
6
Digestive System Structures
• Stomach
– Fundus
• Upper rounded portion
– Body
• Central part
7
Digestive System Structures
• Stomach
– Pylorus
• Lower tubular part (also called the gastric antrum)
• Pyloric sphincter regulates passage of food from
stomach into the duodenum
– Folds in mucous membranes of stomach =
Rugae
8
Digestive System Structures
• Stomach
– Gastric juices breakdown food in stomach
– Muscular action of stomach causes churning
of food
• Mixes food with the secretions
• Chyme = liquidlike mixture of partially digested
food and digestive secretions
9
Digestive System Structures
• Small intestine
– Approximately 20 feet long
– Also known as the small bowel
– Divided into three parts
• Duodenum
• Jejunum
• Ileum
10
Digestive System Structures
• Large intestine
– Cecum
• Appendix hangs from lower portion of cecum
– Ascending colon
• Hepatic flexure
– Transverse colon
• Splenic flexure
–
–
–
–
Descending colon
Sigmoid colon
Rectum
Anus
11
Accessory Organs of Digestion
• Liver
– Located immediately under diaphragm,
slightly to the right
– Only digestive function
• Production of bile for emulsification of fats in
small intestine
12
Accessory Organs of Digestion
• Liver
– Additional functions of liver
• Excretion of bile pigments into bile
• Synthesis of vitamin K-dependent plasma proteins
• Amino acid metabolism
• Carbohydrate metabolism
• Fat metabolism
• Phagocytosis
• Detoxification
• Storage of vital nutrients
13
Accessory Organs of Digestion
• Gallbladder
– Pear-shaped sac, located under surface of
liver
– Main function:
• To store and concentrate bile produced by the liver
• Releases bile in response to presence of fatty
content of food present in duodenum
• Emulsifies fats
14
Accessory Organs of Digestion
• Pancreas
– Located in upper left quadrant of abdomen, behind
stomach
– Functions as exocrine gland to manufacture digestive
juices
• Trypsin – breaks down proteins
• Pancreatic lipase – breaks down fats
• Pancreatic amylase – breaks down carbohydrates
• Sodium bicarbonate – neutralizes acidic stomach
contents
15
Accessory Organs of Digestion
• Pancreas
– Functions as endocrine gland to manufacture
insulin and glucagon
• Insulin – hormone that makes it possible for
glucose to pass from blood through cell
membranes to be used for energy
• Insulin also promotes conversion of excess glucose
into glycogen
• Glucagon – hormone that stimulates the liver to
convert glycogen into glucose in time of need
16
Accessory Organs of Digestion
• Teeth
– Primary responsibility
• Chewing (mastication)
• Food is ground by teeth and softened by saliva
– Primary teeth = deciduous teeth
• Set of 20 teeth – appears around age 6 months
– Secondary teeth = permanent teeth
• Begin to appear around age 6
17
Accessory Organs of Digestion
• Teeth
– Incisors
• Chisel shape with sharp edges for biting food
– Canine or cuspid teeth
• Useful for grasping and tearing food
– Bicuspids (premolars) and molars
• Flat surfaces, multiple projections for crushing and
grinding food
18
Accessory Organs of Digestion
• Teeth
– Crown
• Visible part of the tooth
• Covered with enamel – hardest substance in body
– Neck
• Lies just beneath the gum line
– Root
• Embedded in bony socket of the jaw bone
– Root canal = pulp cavity
• Central core of the tooth
19
Accessory Organs of Digestion
Layers of Teeth
20
Common Signs and Symptoms
• Achlorhydria
– Abnormal condition characterized by the
absence of hydrochloric acid in the gastric
juice
• Anorexia
– Lack or loss of appetite, resulting in the
inability to eat
21
Common Signs and Symptoms
• Aphagia
– Condition characterized by the loss of the
ability to swallow as a result of organic or
psychologic causes
• Ascites
– Abnormal accumulation of fluid within the
peritoneal cavity
• Fluid contains large amounts of protein and
electrolytes
22
Common Signs and Symptoms
• Borborygmus
– An audible abdominal sound produced by
hyperactive intestinal peristalsis
• Borborygmi are rumbling, gurgling, and tinkling
noises heard when listening with a stethoscope
23
Common Signs and Symptoms
• Constipation
– Difficulty in passing stools, or an
incomplete or infrequent passage of hard
stools
• Diarrhea
– Frequent passage of loose, watery stools
24
Common Signs and Symptoms
• Dyspepsia
– Vague feeling of epigastric discomfort after
eating
– Involves an uncomfortable feeling of fullness,
heartburn, bloating, and nausea
• Dysphagia
– Difficulty in swallowing, commonly associated
with obstructive or motor disorders of the
esophagus
25
Common Signs and Symptoms
• Emaciation
– Excessive leanness caused by disease or
lack of nutrition
• Emesis
– Material expelled from the stomach during
vomiting
– Vomitus
26
Common Signs and Symptoms
• Eructation
– Act of bringing up air from the stomach with a
characteristic sound through the mouth
– Belching
• Flatus; Flatulence
– Air or gas in the intestine that is passed
through the rectum
27
Common Signs and Symptoms
• Gastroesophageal Reflux
– Backflow of contents of stomach into esophagus
– Often result of incompetence of the lower esophageal
sphincter
• Icterus
– A yellowish discoloration of the skin, mucous
membranes, and sclera of the eyes, caused by
greater than normal amounts of bilirubin in the blood
– Also called jaundice
28
Common Signs and Symptoms
• Melena
– An abnormal, black, tarry stool containing
digested blood
• Nausea
– Unpleasant sensation often leading to the
urge to vomit
• Pruritus ani
– A common chronic condition of itching of the
skin around the anus
29
Common Signs and Symptoms
• Steatorrhea
– Greater than normal amounts of fat in the
feces
• Characterized by frothy, foul-smelling fecal matter
that floats
• Vomit
– To expel the contents of the stomach through
the esophagus and out of the mouth
30
PATHOLOGICAL CONDITIONS
Digestive System
Achalasia
• Pronounced
– (ak-al-LAY-zee-ah)
• Defined
– Decreased mobility of the lower two-thirds of
the esophagus along with constriction of the
lower esophageal sphincter
32
Anal Fistula
• Pronounced
– (AY-nal FISS-too-lah)
• Defined
– Abnormal passageway in the skin surface
near the anus usually connecting with the
rectum
• May occur as the result of a draining abscess
33
Aphthous Stomatitis
• Pronounced
– (AFF-thus stoh-mah-TYE-tis)
• Defined
– Small inflammatory noninfectious ulcerated
lesions occurring in the lips, tongue, and
inside the cheeks of the mouth
– Also called canker sores
34
Appendicitis
• Pronounced
– (ap-pen-dih-SIGH-tis)
• Defined
– Inflammation of the vermiform appendix
• Usually an acute condition that can lead to rupture
(perforation) with resultant inflammation of the
peritoneum (peritonitis)
35
Celiac Disease
• Pronounced
– (SEE-lee-ak disease)
• Defined
– Nutrient malabsorption due to damaged small
bowel mucosa
36
Cirrhosis
• Pronounced
– (sih-ROH-sis)
• Defined
– Disease of the liver that is chronic and
degenerative causing injury to the
hepatocytes (functional cells of the liver)
• Fat infiltrates lobules of the liver, causing tissue
covering the lobes to become fibrous
• Functions of liver eventually deteriorate
37
Colorectal Cancer
• Pronounced
– (koh-loh-REK-tal CAN-sir)
• Defined
– Presence of a malignant neoplasm in the
large intestine
38
Constipation
• Pronounced
– (kon-stih-PAY-shun)
• Defined
– A state in which the individual’s pattern of
bowel elimination is characterized by a
decrease in the frequency of bowel
movements and the passage of hard, dry
stools
• Individual experiences difficult defecation
39
Crohn’s Disease
• Pronounced
– (KROHNZ dih-ZEEZ)
• Defined
– Digestive tract inflammation of a chronic
nature causing fever, cramping, diarrhea,
weight loss, and anorexia
40
Dental Caries
• Pronounced
– (DEN-tal KAIR-eez)
• Defined
– Tooth decay caused by acid-forming
microorganisms
41
Dysentery
• Pronounced
– (DISS-en-ter-ee)
• Defined
– A term used to describe painful intestinal
inflammation typically caused by ingesting
water or food containing bacteria, protozoa,
parasites, or chemical irritants
• Person has frequent stools that often contain blood
42
Diverticular Disease
• Pronounced
– (dye-ver-TIK-yoo-lar dih-ZEEZ)
• Defined
– Expression used to characterize both
diverticulosis and diverticulitis
• Diverticulosis = non-inflamed outpouchings or
herniations of the muscular layer of the intestines,
typically the sigmoid colon
• Diverticulitis = inflammation of these outpouchings
43
Esophageal Varices
• Pronounced
– (eh-soff-ah-JEE-al VAIR-ih-seez)
• Defined
– Swollen, twisted (tortuous) veins located in
the distal end of the esophagus
44
Gallstones (Cholelithiasis)
• Pronounced
– (koh-lee-lih-THIGH-ah-sis)
• Defined
– Pigmented or hardened cholesterol stones
formed as a result of bile crystallization
45
Hemorrhoids
• Pronounced
– (HEM-oh-roydz)
• Defined
– Hemorrhoid is an unnaturally distended or
swollen vein (varicosity) in distal rectum or
anus
46
Hepatitis
• Pronounced
– (hep-ah-TYE-tis)
• Defined
– Acute or chronic inflammation of the liver due
to a viral or bacterial infection, drugs, alcohol,
toxins, or parasites
47
Hernia
• Pronounced
– (HER-nee-ah)
• Defined
– Irregular protrusion of tissue, organ, or a
portion of an organ through an abnormal
break in the surrounding cavity’s muscular
wall
48
Herpetic Stomatitis
• Pronounced
– (her-PEH-tic stoh-mah-TYE-tis)
• Defined
– Inflammatory infectious lesions in or on the
oral cavity occurring as a primary or a
secondary viral infection caused by herpes
simplex
49
Hirschsprung’s Disease
(Congenital Megacolon)
• Pronounced
– (HIRSH-sprungz dih-ZEEZ)
– (kon-JEN-ih-tal meg-ah-KOH-lon)
• Defined
– Absence at birth of the autonomic ganglia in a
segment of the intestinal smooth muscle wall
that normally stimulates peristalsis
50
Ileus
• Pronounced
– (ILL-ee-us)
• Defined
– Obstruction of the intestine
• May occur due to twisting of the bowel, absence of
peristalsis, or presence of adhesions or tumor
51
Intestinal Obstruction
• Pronounced
– (in-TESS-tin-al ob-STRUCK-shun)
• Defined
– Complete or partial alteration in the forward
flow of the contents in the small or large
intestines
52
Intussusception
• Pronounced
– (in-tuh-suh-SEP-shun)
• Defined
– Telescoping of a portion of proximal intestine
into distal intestine usually in the ileocecal
region causing an obstruction
• Typically occurs in infants and young children
53
Irritable Bowel
Syndrome Spastic Colon
• Pronounced
– (EAR-it-ah-b’l BOW-el SIN-drom)
– (SPAS-tik COH-lon)
• Defined
– Increased motility of the small or large
intestinal wall resulting in abdominal pain,
flatulence, nausea, anorexia, and the trapping
of gas throughout the intestines
54
Oral Leukoplakia
• Pronounced
– (OR-al loo-koh-PLAY-kee-ah)
• Defined
– Precancerous lesion occurring anywhere in
the mouth
55
Pancreatitis
• Pronounced
– (pan-kree-ah-TYE-tis)
• Defined
– Acute or chronic destructive inflammatory
condition of the pancreas
• May be acute or chronic
56
Peptic Ulcers
(Gastric, Duodenal, Perforated)
• Pronounced
– (PEP-tik ULL-sir)
– (GAS-tric, doo-oh-DEE-nal, PER-foh-ray-ted)
• Defined
– Break in the continuity of the mucous
membrane lining of the gastrointestinal tract
as a result of hyperacidity or the bacterium,
Helicobacter pylori
57
Peptic Ulcers
• Peptic ulcer descriptions
– Acute or chronic
– Singular or clustered
– Shallow or deep
• Symptoms of an ulcer
– Gnawing epigastric pain
– Heartburn or indigestion
– Nausea and vomiting
– Bloated feeling after eating
58
Periodontal Disease
• Pronounced
– (pair-ee-oh-DON-tal dih-ZEEZ)
• Defined
– Group of inflammatory gum disorders
– May lead to degeneration of teeth, gums, and
sometimes surrounding bones
59
Polyps, Colorectal
• Pronounced
– (PALL-ips koh-loh-REK-tal)
• Defined
– Small growths projecting from the mucous
membrane of the colon or rectum
• May be sessile (attached by a base) or
pedunculated (attached by a stalk)
• May vary in size and may be benign or precancerous
60
Thrush
• Pronounced
– (THRUSH)
• Defined
– Fungal infection in the mouth and throat
producing sore, creamy white, slightly
raised curdlike patches on the tongue and
other oral mucosal surfaces
• Caused by Candida albicans
61
Ulcerative Colitis
• Pronounced
– (ULL-sir-ah-tiv koh-LYE-tis)
• Defined
– Chronic inflammatory condition resulting in a
break in the continuity of the mucous
membrane lining of the colon in the form of
ulcers
• Characterized by large watery diarrheal stools
containing mucus, pus, or blood
62
Volvulus
• Pronounced
– (VOL-vyoo-lus)
• Defined
– Rotation of loops of bowel causing a twisting
on itself that results in an intestinal obstruction
63
DIAGNOSTIC
TECHNIQUES, TREATMENTS
AND PROCEDURES
Digestive System
Diagnostic Techniques,
Treatments, and Procedures
• Abdominal ultrasound
– High-frequency sound waves to provide visualization of
the internal organs of the abdomen (liver, gallbladder,
bile ducts, pancreas, kidneys, bladder, and ureters)
• Abdominocentesis (Paracentesis)
– Insertion of a needle or trochar into abdominal cavity to
remove excess fluid
• Person is in a sitting position
65
Diagnostic Techniques,
Treatments, and Procedures
• Alanine Aminotransferase (ALT)
– Hepatocellular enzyme released in elevated
amounts due to liver dysfunction
– Also known as serum glutamic pyruvic
transaminase (SGPT)
66
Diagnostic Techniques,
Treatments, and Procedures
• Alkaline Phosphatase (ALP)
– Enzyme found in highest concentrations in
liver, biliary tract, and bone
• Amylase
– Enzyme secreted normally from pancreatic
cells that travels to the duodenum by way of
pancreatic duct
– Aids in digestion
67
Diagnostic Techniques,
Treatments, and Procedures
• Appendectomy
– Surgical removal of an inflamed appendix
– May be removed via laparoscope if no rupture
has occurred
68
Diagnostic Techniques,
Treatments, and Procedures
• Barium Enema (BE)
– Infusion of a radiopaque contrast medium,
barium sulfate, into the rectum and held in
the lower intestinal tract while x-ray films
are obtained of the lower GI tract
69
Diagnostic Techniques,
Treatments, and Procedures
• Barium Swallow (Upper GI Series)
– Involves oral administration of a radiopaque
contrast medium, barium sulfate, which
flows into the esophagus as the person
swallows
70
Diagnostic Techniques,
Treatments, and Procedures
• Cheiloplasty
– Surgically correcting a defect of the lip
• Cholecystectomy
– Surgical removal of the gallbladder
• Cholecystography (Oral)
– Visualization of the gallbladder through x-ray
following the oral ingestion of pills containing a
radiopaque iodinated dye
71
Diagnostic Techniques,
Treatments, and Procedures
• Colonoscopy
– Visualization of the lining of the large intestine
using a fiberoptic colonoscope
• Colostomy
– Surgical creation of a new opening on the
abdominal wall through which the feces will
be expelled, by bringing the incised colon out
to the abdominal surface
• Abdominal-wall anus
72
Diagnostic Techniques,
Treatments, and Procedures
• CT of the abdomen
– Painless, noninvasive x-ray procedure
– Produces an image created by the computer
representing a detailed cross section of the
tissue structure within the abdomen
– Computerized tomography (CT) of the
abdomen
73
Diagnostic Techniques,
Treatments, and Procedures
• Endoscopic Retrograde
Cholangiopancreatography
– Examines the size of and filling of the
pancreatic and biliary ducts through direct
radiographic visualization with a fiberoptic
endoscope
74
Diagnostic Techniques,
Treatments, and Procedures
• Esophagogastroduodenoscopy (EGD)
– Process of direct visualization of the
esophagus, stomach, and duodenum using a
lighted, fiberoptic endoscope
• Also known as an upper endoscopy
75
Diagnostic Techniques,
Treatments, and Procedures
• Extracorporeal Shock Wave Lithotripsy
(ESWL)
– Alternative treatment for gallstones by using
ultrasound to align the computerized
lithotripter and source of shock waves with the
stones
– To crush the gallstones and thus enable the
contraction of the gallbladder to remove stone
fragments
76
Diagnostic Techniques,
Treatments, and Procedures
• Fluoroscopy
– Radiological technique used to examine the
function of an organ or a body part using a
fluoroscope
• Gastric analysis
– Study of the stomach contents to determine
the acid content and to detect the presence of
blood, bacteria, bile, and abnormal cells
77
Diagnostic Techniques,
Treatments, and Procedures
• Gastric Lavage
– Irrigation, or washing out, of the stomach
with sterile water or a saline solution
78
Diagnostic Techniques,
Treatments, and Procedures
• Herniorrhaphy
– Surgical repair of a hernia by closing the
defect using sutures, mesh, or wire
• Liver biopsy
– Piece of liver tissue obtained for examination
by inserting a specially designed needle into
the liver through the abdominal wall
79
Diagnostic Techniques,
Treatments, and Procedures
• Liver scan
– Noninvasive scanning technique
– Enables visualization of shape, size, and
consistency of liver after IV injection of a
radioactive compound
• Magnetic Resonance Imaging (MRI)
– Noninvasive scanning procedure that provides
visualization of fluid, soft tissue, and bony
structures without the use of radiation
80
Diagnostic Techniques,
Treatments, and Procedures
• Nasogastric intubation
– Placement of a tube through the nose into the
stomach
– To relieve gastric distension by removing
gastric secretions, gas, or food
81
Diagnostic Techniques,
Treatments, and Procedures
• Percutaneous Transhepatic
Cholangiography (PTC) or (PTHC)
– Examination of bile duct structure using a
needle to pass directly into an intrahepatic
bile duct to inject a contrast medium
82
Diagnostic Techniques,
Treatments, and Procedures
• Serum Bilirubin
– Measurement of bilirubin level in serum
• Serum bilirubin levels are a result of the
breakdown of red blood cells
• Serum Glutamic-oxaloacetic
Transaminase (SGOT)
– Enzyme that has very high concentrations in
liver cells
• Also known as aspartate aminotransferase (AT)
83
Diagnostic Techniques,
Treatments, and Procedures
• Small bowel follow-through
– Oral administration of a radiopaque contrast
medium, barium sulfate
– Flows through the GI system
– X-ray films are obtained at timed intervals to
observe the progression of the barium
through the small intestine
84
Diagnostic Techniques,
Treatments, and Procedures
• Stool analysis for occult blood
– Analysis of a stool sample to determine
presence of blood not visible to naked eye
• Stool culture
– Collection of a stool specimen placed on one
or more culture mediums
– Allowed to grow colonies of microorganisms
to identify specific pathogen(s)
85
Diagnostic Techniques,
Treatments, and Procedures
• Stool Guaiac
– Test on a stool specimen using guaiac as a
reagent
– Identifies presence of blood in stool
• Urinary Bilirubin
– Tests for conjugated or direct bilirubin in a
urine specimen
86