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Chapter 8
Digestive System
Learning Outcomes
1.Describe the digestive system.
2.Explain the primary functions of the organs of
the digestive system.
3.Describe the two sets of teeth found in
humans.
4.Identify the three main portions of a tooth.
Learning Outcomes
5.Discuss the accessory organs of the digestive
system and state their functions.
6.Analyze, build, spell, and pronounce medical
words.
7.Describe diagnostic and laboratory tests
related to the digestive system.
Key words/Combo Forms
 Difference b/w exocrine and endocrine
 Know the combining forms on page 219
 Prand/i = meal
 Proct/o = anus and rectum
 Hepat/o = liver
 Ondot/o = tooth
 Knowing these will help you break down medical
words listed in 219-236
Bolus Journey Path
Mouth/Teeth/
Liver
Salivary Glands
Gallbladder
Pharynx/Esophagus Pancreas
Stomach
Small Intestine
Large Intestine
Highlight
procedures and
drugs
Group Work/Individual Work
 Visuals/Overviews for parts of the
digestive system
 List functions according to selected
region or area
 List key combining forms for specific area
(e.g., liver is hepat/o, or labi/o is lip)
 Create One Multiple Choice Question
Figure 8.1
Digestive system.
TABLE 8.1 Digestive System
at-a-Glance
YouTube- An Overview
 http://www.dnatube.com/video/8362/Animatio
n-of-the-digestive-system
Resources
 https://www.nlm.nih.gov/medlineplus/digestivesy
stem.html
Anatomy and Physiology
Overview
 General description of the digestive or
gastrointestinal system: a continuous tube
beginning with the mouth and ending at the
anus.
 This tube is known as the alimentary canal
and/or gastrointestinal tract and is about 30
feet long in adults.
Anatomy and Physiology
Overview
 Digestive system contains both primary and
accessory organs for the conversion of food
and fluids into a semiliquid that can be
absorbed for the body to use.
 Three main functions:
 Digestion
 Absorption
 Elimination
https://youtu.be/5_BiPdWRVCw
TABLE 8.2 Components of
Chemical Digestion
Mouth
 Tongue = Lingu/o:
 Made of skeletal muscle and covered
with mucous membrane
 Can be divided into:
 Root
 Pointed tip
 Central body
 Papilla(e) (elevations) and taste
buds (sweet, salt, sour, and bitter)
are located on the tongue's surface.
Figure 8.2 (continued)
Oral cavity: (B) anterior view as seen through the open mouth.
Teeth
 Two Sets
 20 deciduous teeth, also referred to as milk teeth
or baby teeth
 32 permanent teeth
 8 incisors
 4 canines
 8 premolars
 12 molars
Teeth
 Each tooth consists of three main portions:
 Crown
 Neck
 Root
Figure 8.4
Teeth. (A) Diagrammatic section through a typical adult tooth.
Figure 8.4 (continued)
Teeth. (B) The adult teeth.
Epiglottis – break it down
Figure 8.3
Movement of a bolus of food from the mouth to the esophagus. The bolus
then travels to the stomach.
Pharynx
 Pharynx
 A chamber that extends between the internal
nares and the entrance to the larynx and
esophagus
Pharynx (Pharynge/o)
 The pharynx is a
common passageway for
both respiration and
digestion.
 Both the larynx, or voice
box, and the esophagus
begin in the pharynx.
 The epiglottis (a flap of
tissue) blocks the
opening of the larynx,
preventing food from
entering the airway
leading to the trachea
(windpipe).
Esophagus
 A muscular tube about 10 inches long that
leads from the pharynx to the stomach.
 The lower esophageal or cardiac sphincter is at
the junction with the stomach.
 This esophageal sphincter:
 relaxes to permit passage of food.
 contracts to prevent the backup of stomach
contents.
Esophagus = Esophag/o
 Food is carried along the esophagus by a series
of wavelike muscular contractions called
peristalsis.
 https://youtu.be/KJaM34vmMhs
Stomach = Gastr/o
 A muscular, distensible saclike portion of the
alimentary canal between the esophagus and
duodenum.
 Fundus: upper region of the stomach.
 Body: the main portion.
 Antrum: the lower region.
 Rugae: folds in the mucous membrane lining
the stomach
 https://youtu.be/Yoo91B3aVbw
Figure 8.5
Stomach = Gastr/o
Small Intestine
 About 21 feet long and 1 inch in diameter.
 Extends from pyloric sphincter at base of
stomach to entrance of large intestine.
 Divided into three parts:
 Duodenum (doo″o-de´num)
 Jejunum (jĕ-jū'nŭm)
 Ileum (il'ē-ŭm) Do not confuse this word with ilium.
Figure 8.6
Small intestine.
Small Intestine
 Chyme is mixed with bile and pancreatic juice.
 Digestion and absorption take place chiefly in
the small intestine.
 Tiny capillaries and lymph vessels absorb
nutrients, which are transferred to body cells
by the circulatory system.
 https://youtu.be/VSATCzXqLr0
Large Intestine
 About 5 feet long and 2.5 inches in diameter.
 Divided into:
 Cecum
 Colon (colon/o)
 Rectum (rect/o)
 Anal canal (proct/o = anus and rectum)
https://youtu.be/oZgx_52vVTU
Figure 8.7
Large intestine.
Accessory Organs
 These organs are not actually part of the
digestive tube but are closely related to the
digestive process:
 Salivary glands
 Liver
 Gallbladder
 Pancreas
 https://youtu.be/0n6MJqmKFzY
Accessory Organs
 Salivary Glands (Sial/o = saliva, salivary)
 Located in or near the mouth.
 Secrete saliva in response to sight, smell, taste, or
mental image of food.
 Salivary Glands
 Parotid
 Submandibular
 Sublingual
Figure 8.8
Salivary glands, salivary ducts and the tongue.
Accessory Organs
 Liver = Hepat/o
 The largest glandular organ in the body.
 Weighs about 3 ½ lbs.
 Located in the upper right part of the abdomen.
 Plays an essential role in the normal metabolism
of carbohydrates, fats, and proteins.
Figure 8.9
Liver.
Accessory Organs
 Carbohydrate Metabolism
 Changes glucose to glycogen and stores it until
needed by body cells.
 When required, glycogen is converted back to
glucose.
 Fat Metabolism
 The liver serves as a storage place and acts to
desaturate fats before releasing them into the
bloodstream.
 Protein Metabolism
 The liver acts as a storage place and assists in
both protein anabolism and catabolism.
Accessory Organs
 The liver manufactures the following important
substances:
 Bile
 Fibrinogen and prothrombin
 Heparin
 Blood proteins
 The liver stores iron and vitamins B12, A, D, E,
and K.
 Detoxifies many harmful substances (toxins),
such as drugs and alcohol.
Figure 8.15
The liver in this photograph was from a deceased patient with an advanced
state of cirrhosis.
Accessory Organs
 Gallbladder (Chol/e = gall, bile)
 A small, pear-shaped sac attached to the liver in
which excess bile is stored and concentrated.
 Concentration is accomplished by reabsorption of
water.
 What causes gallbladder stones?
Figure 8.14
Gallbladder with gallstones. Note the stones in the hepatic duct, gallbladder,
and common bile duct. http://www.niddk.nih.gov/health-information/healthtopics/digestive-diseases/gallstones/Pages/facts.aspx
Accessory Organs
 Pancreas = Pancreat/o
 A large, elongated gland situated behind the
stomach and secreting pancreatic juice into the
small intestine.
 Contains cells that produce digestive enzymes.
 Other specialized cells secrete the hormones
insulin and glucagon directly into the bloodstream.
 Check out here for an explanation of the
endocrine and exocrine functions
Figure 8.10
Pancreas.
Group Work/Individual Work
 Visuals/Overviews for parts of the
digestive system
 List functions according to selected
region or area
 List key combining forms for specific area
(e.g., liver is hepat/o, or labi/o is lip)
 Create One Multiple Choice Question