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Chapter 25
Digestive System
93
Anatomy
Undergraduate 1
04/24/2012

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Term
functions of digestive system
Definition
Ingestion via the mouth
• Mechanical processing via the tongue, teeth and digestive tract
• Digestion by chemical and enzymatic breakdown
• Secretion by the pancreas, small intestine, gallbladder and
stomach
• Absorption of organic molecules, electrolytes, vitamins and
water by the digestive epithelium
• Excretion by the liver and gastrointestinal tube
• Compaction-
Defense
Term
compaction
Definition
progressive dehydration of indigestible materials
and organic wastes prior to elimination
Term
what are the components and functions of the mucosa of the digestive tract
Definition
the components of the mucosa are 1. the mucosal epithelium 2. the lamina propria, aeolar tissue underlying epithelium 3. the muscularis mucosae, bands of smooth muscle fibers arranged in concentic layers. the mucosa of the digestive tract is an example of a mucous membrane, serving both absorptive and secretory functions
Term
what is the functions of mesenteries
Definition
mesenteries provide an access route for the passage of blood vessels, nerves, and lymphatics to and from digestive tract. they also stabilize the relative positions of the attached organs
Term
what are the functional differences between peristalsis and segmentation
Definition
peristalsis is waves of muscular contractions that move substances the length of the digestive tube. segmentation activities churn and mix the contents of the small and large intestines but do not produce net movement in a particular direction
Term
what is important about the lack of organization in the contractile filaments of smooth muscle cells
Definition
this allows the stretched smooth muscle to adapt to its new shape and still have the ability to contract when needed
Term
what type of epithelium lines the oral cavity?
Definition
the oral cavity is lined by the oral mucosa, which is composed of nonkertantinized stratified squamous epithelium
Term
What are the functions of saliva?
Definition
at mealtime, salvia lubericates the mouth and dissolves chemicals that stimulate the taste buds. Saliva contains the digestive enzyme salivary amylase which begins the chemical breakdown of carbohydrates
Term
What nutrient begins its chemical breakdown in the mouth?
Definition
carbohydrates are broken down by the salivary amylase in the mouth
Term
pretend you are eating a apple. summarize the action of the teeth?
Definition
the incisors cut away a section of a apple, which then enters the mouth. The cuspids tear at the rough skin and pulp of the apple. The apple then moves to the biscupid and molars through mashing and grinding before being swallowed.
Term
Mesenteries
Definition
Mesenteries- fused, double sheets of peritoneal membrane
Term
Location of falciform
Definition
Falciform ligament- between the liver and diaphragm
Term
Greater omentum location and function
Definition
Greater omentum- hangs from the greater curvature of
the stomach
• Stores fat, cushions the organ
Term
Lesser omentum location
Definition
lesser omentum- between the lesser curvature of the
stomach and liver
Term
Peritoneum location and function?
Definition
All but the first 25 cm of the small intestine is suspended by a
thick mesenterial sheet named the mesentery proper
• Provides stability but permits independent movement
Term
Mesocolon?
Definition
Mesocolon- mesentery attached to the large intestine
Term
submucosa -describe
Definition
• Submucosa
• Layer of dense, irregular connective tissue
• Contains larger blood vessels- absorbed molecules the pass
through the columnar epithelial cells of the mucosa enter
the vessels in the submucosa
Term
Submucosal plexus
Definition
Submucosal plexus- network of nerve fibers located along
the out margin of the submucosa
Term
Describe the oral cavity
Definition
Lined by the oral mucosa
• Stratified squamous epithelium
Term
Tongue function
Definition
• Functions
• Mechanical processing of food
• Manipulation to assist in chewing and prepare material for
swallowing
• Sensory analysis (touch, temperature, taste receptors)
• Secretion of mucins and enzymes
Term
How much salvia is produced daily?
Definition
1.5 liters
Term
Desribe what saliva is made up with?
Definition
99.4% of saliva is water plus ions, buffers, metabolites and enzymes
Term
How is salvia transported?
Definition
• Transported by a network of fine ducts to a single large duct
• Opens into the surface of the oral mucosa
Term
Functions of salvia
Definition
• Functions
• At mealtimes- lubricate the mouth, moisten food and
dissolve chemicals
• At other times- flushes oral surfaces and helps to control oral bacteria
Term
Describe Partoid salivary gland and function
Definition
Parotid
• Largest salivary glands (25% of secretions)
• Between the zygomatic arch and the sternocleidomastoid
• Duct pierces the buccinator between the skin and masseter
Term
Describe location of sublinguial salivary glands location and % of saliva secretions
Definition
• Sublingual
• Ducts found under the tongue
• 5% of secretions
Term
Describe submandibular saliva glands location and % of salvia secretions
Definition
Submandiublar
• Along the medial surfaces of the mandible
• 70% of secretions
Term
Mastication
Definition
Mastication- breaks down tough
connective tissues and plant fibers
Term
Incisor teeth function
Definition
Incisors- clipping or cutting
Term
Cuspids teeth function
Definition
Cuspids (canines)- tearing or slashing
Term
bicuspids teeth function
Definition
Bicuspids- crushing, mashing and grinding
Term
molar teeth function
Definition
Molars- crushing and grinding
Term
Deciduous teeth decribe and #
Definition
Deciduous teeth- baby teeth, usually
there are 20
Term
Permanent teeth- # what extra teeth appear
Definition
Permanent teeth- usually have 32
• 3 additional molar appear on each
side of the upper and lower jaw
Term
Pharyngeal function
Definition
Common passageway for food, liquids and air
• Pharyngeal muscle cooperate with the muscle of the oral
cavity and esophagus to initiate the swallowing process also
known as deglutition
Term
Deglutition
Definition
swallowing process also
known as deglutition
Term
Pharyngeal constrictors
Definition
Pharyngeal constrictors- push the bolus toward the
esophagus
Term
Palatopharyngeus function
Definition
Palatopharyngeus- elevates the larynx
Term
function of Palatal muscles
Definition
Palatal muscles- raise the soft palate
Term
Esophagus -decribe; location; passes through; and length
Definition
Hollow muscular tube that
transports foods and liquids to
the stomach
• Posterior to the trachea in the
mediastinum
• Passes through the esophageal
hiatus in the diaphragm to
reach the stomach
• Approximately 25 cm long and
2 cm in diameter
Term
ESOPHAGUS- HISTOLOGY
Definition
Mucosa- contains stratified
squamous epithelium
• Mucosa and submucosaform
large folds that permit
expansion during the
passage of a large bolus
• Smooth muscle of the
muscularis mucosae
gradually thickens as it
approaches the stomach
• No serosa
Term
Functions of stomach
Definition
• Functions
• Bulk storage of ingested food
• Mechanical breakdown of ingested food
• Chemical digestion of ingested food by acids and enzymes
Term
Stomach divided into 4 sections
Definition
• Divided into 4 regions
• Cardia
• Fundus
• Body- largest region
• Pylorus
• Pyloric sphincter regulates release into the duodenum
Term
Stomach-
Lesser curvature
Greater curveature
Definition
Anatomy
• Lesser curvature- medial surface
• Greater curvature- lateral surface
Term
small interstine primary role?
Definition
Primary role in the
digesting and absorption
of nutrients
Term
Small intestine (3 parts) and average length
Definition
Averages 20 feet in
length
• Duodenum
• Jejunum
• Ileum
Term
SMALL INTESTINEDUODENUM
Describe
Definition
• First segment of the small intestine
• Shortest (10 inches) and widest
• Connected to the pylorus of the stomach
• Receives chyme from the stomach and digestive juices from
the liver and pancreas
Term
SMALL INTESTINE- JEJUNUM
Describe /function and length
Definition
• Jejunum
• Second portion of the small intestine
• Approximately 8 feet long
• Bulk of chemical digestion and nutrient absorption occurs
here
Term
Ileum- location/length/ends?
Definition
• Ileum
• Third portion
• Averages 12 feet in length
• Ends at the ileocecal valve which controls the flow of
materials from the ileum to the cecum
Term
SMALL INTESTINE HISTOLOGY
Describe villi, micro villi and purpose
Definition
• Intestinal villi
• Fingerlike macroscopic folds of the mucosa that project into
the lumen
• Covered by simple columnar epithelium
• Microvilli- microscopic projections formed by the folding
of each epithelial membrane
• Increases the surface area for absorption
Term
SMALL INTESTINE HISTOLOGY
Definition
• Intestinal crypts
• Extend deep into the lamina propria
• Near the base of each crypt stem cell division continually
produce new generations of epithelial cells
• Inner lining of the intestine is replaced every 3-6 days
Term
SMALL INTESTINE HISTOLOGY
Definition
Lamia propria
• Forms the connective tissue
core of each villus
• Contain an extensive network of
capillaries and lymphatic vessels
Term
In the Small intestine what does the capillaries absorb
Definition
Capillaries- absorbs sugar and
amino acids (carries nutrients
to the hepatic portal
circulation
Term
What does lymphatic vessels absorb
Definition
• Lymphatic vessels (lacteal)-
absorb fatty acids
Term
SMALL INTESTINE HISTOLOGY
• Regional specializations
Duodenum
Definition
Duodenum- numerous mucous
glands, prominent plica
Term
SMALL INTESTINE HISTOLOGY
• Regional specializations
Jejunum
Definition
Jejunum- prominent plica over
the first half, plica diminish in size
and number to the end of the
ileum
Term
SMALL INTESTINE HISTOLOGY
• Regional specializations
Ileum
Definition
• Ileum- masses of lymph tissue
(protect the ileum from large
numbers of potentially harmful
bacteria)
Term
LARGE INTESTINE
Begins at ?
How long?
Definition
• Begins at the ileum and ends at the anus
• About 5 feet in length
Term
Function Cecum
Definition
Cecum- collects and stores arriving material, begins
compaction
Term
Appendix
(made up of?)
Function?
Definition
Appendix- abundance of lymphatic tissue that may serve to
resist infection
Term
Ascending colon (location)
Definition
Ascending colon- along the right abdominal wall
Term
Transverse colon (location)
Definition
Transverse colon- crosses the abdomen from right to left
Term
Descending Colon- location
Definition
Descending colon- along the left abdominal wall
Term
Sigmoid colon- location
Definition
Sigmoid colon- begins at the iliac fossa, s-shaped
Term
Rectum
Forms?
Expands?
Definition
• Rectum
• Forms the last 15cm of the digestive tract
• Expandable organ for the temporary storage of fecal
material
Term
Anal canal- Internal anal sphincter
Definition
Anal canal
• Internal anal sphincter- smooth muscle of the muscularis
externa
Term
External anal sphincter
Definition
External anal sphincter- ring of skeletal muscle fibers,
voluntary control
Term
Anus
Definition
Anus- external opening of the anal canal
Term
Special features of Large intesitine
Taeniane coli
Definition
Taeniae coli- three separate longitudinal ribbons of smooth
muscle on the outer surface
Term
Special features of Large intesitine
Haustra
Definition
Tone in this muscle creates haustra
• Haustra- pouches that permit considerable distention and
elongation
Term
Stomach histology
Definition
Lined by a simple columnar epithelium
Term
Mucous layer stomach-
Definition
Mucous layer- protects the epithelium against the acids and
enzymes in the lumen
Term
Gastric pits
Definition
Gastric pits- shallow depressions that open onto the gastric
surface of the lumen
Term
gastric glands
Definition
Gastric glands- tubular glands dominated by secretory cells
Term
Cells of the gastric glands

Parietal
Definition
Parietal
• Secrete intrinsic factor and
hydrochloric acid
Term
Cells of the gastric glands

Chief
Definition
Chief
• Secrete pepsinogen
• Infants- rennin and gastric lipase
Term
G cells
Definition
G-cells
• Secrete gastrin (hormone)
Term
Where is the fauces
Definition
The fauces is the opening between the oral cavity and the pharynx
Term
What is occuring when the soft palate and larynx are elevated and the glottis closes
Definition
the process that is being described is deglutition or swallowing
Term
What stage of swallowing is voluntary
Definition
the buccal phase is the only voluntary phase of swallowing
Term
When someone experiences heartburn what is happening in the espophagus?
Definition
when someone experiences heartburn their lower esophagealsphincter may not have closed completely and powerful stomach acids are entering the lower esophagus causing uncomfortable acid reflux
Term
What are the function of the greater omentum
Definition
the greater omentum provides support to the surrounding organs, pads the organs from the surface of the abdomen, provides an important energy reserve, and provides insulation
Term
How do cells that line the stomach keep from becoming damagaed in such an acidic enviroment
Definition
the epithelium produces a carpet of mucus that covers the interior surfaces of the stomach, provideing protection against the powerful acids and enzymes. any cells that do become damaged are quickly replaced
Term
What do chief cells secrete?
Definition
chief cells secrete pepsinogen. In infants, they also secrete rennin and gastric lipase.
Term
What hormone stimulates the secretion of parietal and chief cells
Definition
gastrin produced by enteroendocrine cells, stimulates the secretion of parietal and chief cells
Term
Which histological features of the small intestine facilitae the digestion and absorption of nutrients?
Definition
The characterstic lining of the small intestine contain plicae circulares, which support intestinal villi. the villi are covered by a simple columnar epithelium whose apical surfaceis covered by microvilli. This arrangement increases the total area for digestion and absorption to more than 200 m
Term
What is the function of plicae?
Definition
Plicae are folds in the lining of the intestine that greatly increasethe surface area available for absorption
Term
What are the functions of intestinal crypts?
Definition
intestinnal crypts house the stem cells that produce new epitheial cells which renew the epithelial surface and add intracellular enzymes to the chyme. In addition, intestinal crypts contain cells that produce several intestinal hormones.
Term
Which secretion of the small intestine serves as a "mixing bowl"
Definition
the duodeum acts as a mixing bowl for the chyme entering from the stomach
Term
The condition of cystic fibrosis interferes with the digestion of sugars, starches, lipids, nucleic acids and protiens?
Definition
the condition of cystic fibrosis interferes with the digestion of sugars, lipids, nucleic acids and protiens
Term
The liver act as a metabolic regulator by extracting nutrients and toxins from the blood before it enters the bloodstream. It also regulates the blood, serving as a blood resevior, phagocytizing old damaged RBC's and synthesizing plasma protiens. Finally the liver synthesizes and secretes bile
Definition
the liver acts as a metabolic regulator by extracting nutrients and toxins from the blood before it enters the bloodstream. It also regulates the blood, serving as a blood reserviour, phagocytizing old or damaged RBC's and synthesizing plasma protiens. Finally, the liver synthesizes and secretes bile
Term
contraction of the hepatopancreatic sphincter seals off the passagways between the gallbladder and the small intestine and keeps bile from entering the small intestine
Definition
contraction of the hepatopancretic sphincter seals off the passageway between the gallbladder and the small intestine and keeps bile from entering the small intestine
Term
the pancreas produce digestive enzyme and buffers (exocrine functions) and hormone (endocrine functions)
Definition
the pancreas produces digestive enzymes and buffers (exocrine functions) and hormones (endocrine functions)
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