Transcript Digestive System

PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
The Digestive
System
14
PART A
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The Digestive System Functions
 Ingestion—taking in food
 Digestion—breaking food down both physically
and chemically
 Absorption—movement of nutrients into the
bloodstream
 Defecation—rids the body of indigestible waste
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Organs of the Digestive System
 Two main groups
 Alimentary canal (gastrointestinal or GI
tract)—continuous coiled hollow tube
 Accessory digestive organs
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Organs of the Digestive System
Figure 14.1
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Organs of the Alimentary Canal
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
 Anus
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Mouth (Oral Cavity) Anatomy
 Lips (labia)—protect the anterior opening
 Cheeks—form the lateral walls
 Hard palate—forms the anterior roof
 Soft palate—forms the posterior roof
 Uvula—fleshy projection of the soft palate
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Mouth (Oral Cavity) Anatomy
 Vestibule—space between lips and teeth and
gums
 Oral cavity—area contained by the teeth
 Tongue
 Tonsils
 Palatine
 Lingual
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Mouth (Oral Cavity) Anatomy
Figure 14.2a
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Mouth (Oral Cavity) Anatomy
Figure 14.2b
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Mouth Physiology
 Chewing of food
 Mixing food with saliva
 Initiation of swallowing by the tongue
 Sense of taste
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Teeth
 Function is to cut and chew food
 Humans have two sets of teeth
 Deciduous (baby or “milk”) teeth
 20 teeth are fully formed by age two
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Teeth
 Permanent teeth
 Between the ages of 6 and 12
 A full set is 32 teeth, but some people do not
have wisdom teeth (third molars)
 If they do emerge, the wisdom teeth appear
between ages of 17 and 25
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Numbering of Teeth
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Classification of Teeth
 Incisors—cutting
 Canines—tearing or piercing
 Premolars—grinding
 Molars—grinding
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Human Deciduous and Permanent Teeth
Figure 14.9
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Regions of a Tooth
Figure 14.10
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Salivary Glands
 Three pairs of salivary glands empty secretions
into the mouth
 Parotid glands
 Submandibular glands
 Sublingual glands
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Salivary Glands
Figure 14.1
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Saliva
 Mixture of mucus and serous fluids
 Helps to form a food bolus
 Contains salivary amylase to begin starch
digestion
 Dissolves chemicals so they can be tasted
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Pharynx Physiology
 Serves as a passageway for air and food
 Food is propelled to the esophagus
 Epiglottis - large flap of muscle that closes off the
trachea
 Choking - food accidentally goes into the trachea
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Pharynx Anatomy
Figure 14.2a
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Esophagus Anatomy and Physiology
 Anatomy
 About 10 inches long
 Runs from pharynx to stomach through the
diaphragm
 Physiology
 Conducts food by peristalsis (slow rhythmic
squeezing)
 Passageway for food only
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Layers of Alimentary Canal Organs
 Four layers
 Mucosa
 Submucosa
 Muscularis externa
 Serosa
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Layers of Alimentary Canal Organs
Figure 14.3
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PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
Stomach and
Accessory
Organs
14
PART A
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Digestive System Med Terms
 Aliment – Food
 Peri – Around
 Chyme – Juice
 Pyl – gatekeeper
 Gastro – Stomach
 Vill – hairy
 Hepat – Liver
 -ase – enzyme
 Lingu – Tongue
 Flora – bacteria
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Stomach Anatomy
 Located on the left side of the abdominal cavity
 Food enters at the cardioesophageal sphincter
 Food empties into the small intestine at the
pyloric sphincter (valve)
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Stomach Anatomy
 Regions of the stomach
 Cardiac region—near the heart
 Fundus—expanded portion lateral to the
cardiac region
 Body—midportion
 Pylorus—funnel-shaped terminal end
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Stomach Internal Anatomy
 Rugae—internal folds of the mucosa
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Stomach Anatomy
Figure 14.4b
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Stomach Anatomy
Figure 14.5a
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Stomach Physiology
 Storage tank for food and site for large breakdown
 Delivers chyme (processed food) to the small intestine
 Alcohol and aspirin are the only items absorbed in the
stomach
 Gas is trapped in the fundus and contracts to burp
Food (Mouth) --> Bolus (Swallowed) --> Chyme (Processed)
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Structure of the Stomach Mucosa (Lining)
 Mucosa is simple columnar epithelium
 Mucous neck cells—make sticky mucus
 Gastric glands—secrete gastric juice
 Chief cells—produce enzymes (pepsinogens)
 Parietal cells—produce hydrochloric acid
 Enteroendocrine cells—produce gastrin
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Structure of the Stomach Mucosa
Figure 14.4c
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Structure of the Stomach Mucosa
Figure 14.4d
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Propulsion in the Stomach
Figure 14.15a–c
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Small Intestine
 The body’s major digestive organ
 Nutrients are absorbed into the blood
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Subdivisions of the Small Intestine
 Duodenum
 Attached to the stomach
 Jejunum
 Middle segment
 Ileum
 Posterior segment, connects to large intestine
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Small Intestine Anatomy
 Three structural modifications that increase
surface area
 Microvilli—tiny fingers on villi
 Villi—fingerlike structures formed by the
mucosa
 Circular folds - deep folds of mucosa and
submucosa
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Small Intestine Anatomy
Figure 14.7a
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Small Intestine Anatomy
Figure 14.7b
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Small Intestine Anatomy
Figure 14.7c
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Chemical Digestion in the Small Intestine
 Enzymes are produced by
 Intestinal cells
 Pancreas (enters through pancreatic duct)
 Bile, formed by the liver, enters via the bile
duct
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Pancreas
 Produces a wide spectrum of digestive enzymes
that break down all categories of food
 Alkaline fluid neutralizes acidic chyme from
stomach
 Insulin controls blood sugar levels: diabetes
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Bile
 Function—physically breaking large fat globules
into smaller ones
 Produced by cells in the liver
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Gallbladder
 Sac found below liver
 When no digestion is occurring, bile backs up for
storage in the gallbladder
 When digestion of fatty food is occurring, bile
enters the duodenum through cystic duct
 Gallstones are crystallized cholesterol which can
cause blockages
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Digestive Enzyme Ducts
Figure 14.6
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Large Intestine
 Larger in diameter, but shorter in length, than the
small intestine
 Frames the internal abdomen
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Large Intestine Anatomy
 Cecum—saclike first part of the large intestine
 Appendix
 Accumulation of lymphatic tissue that
sometimes becomes inflamed (appendicitis)
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Large Intestine Anatomy
 Colon
 Ascending—travels up
 Transverse—travels across
 Descending—travels down
 Sigmoid—enters the pelvis
 Rectum
 Anal canal
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Large Intestine Anatomy
 No villi present
 Goblet cells produce alkaline mucus which
lubricates the passage of feces
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Large Intestine
Figure 14.8
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Functions of the Digestive System
Figure 14.11
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