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Chapter 23
Digestive System
270
Anatomy
Undergraduate 2
02/22/2012

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Term
Role of the alimentary canal
Definition
digest and absorbs food
Term
Structures of the alimentary canal
Definition
Mouth, pharynx, esophagus, stomach, small intestine, and large intestine
Term
Accessory digestive organs
Definition
teeth, tongue, gallbladder, salivary glands, liver, and pancreas
Term
Role of accessory digestive organs
Definition
produce secretions that help digest food
Term
Six essential activities of the digestive process
Definition
Ingestion, Mechanical digestion, Propulsion, Chemical digestion, Absorption, Defecation
Term
Ingestion
Definition
taking food into the digestive tract
Term
Mechanical digestion
Definition
chewing, mixing, and churning food
Term
Propulsion
Definition
swallowing and peristalsis
Term
Peristalsis
Definition
waves of contraction and relaxation of muscles in the organ walls
Term
segmentation
Definition
rhythmic constriction of the intestines that mixes food with digestive juices
Term
Gastrointestinal activities
Definition
Chemical digestion, absorption, defecation
Term
Chemical digestion
Definition
catabolic breakdown of food
Term
absorption
Definition
movement of nutrients from the GI tract to the blood or lymph
Term
Defecation
Definition
elimination of indigestible solid wastes
Term
GI Tract
Definition
external environment for the digestive process
Term
Regulation of digestion involves?
Definition
Mechanical and chemical stimuli, extrinsic control, intrinsic controls
Term
Regulation of digestion: Mechanical and chemical stimuli
Definition
stretch receptors, osmolarity, presence of substrate in the lumen
Term
Regulation of digestion: Extrinsic control
Definition
CNS centers
Term
Regulation of digestion: Intrinsic control
Definition
Local centers
Term
Receptors of the GI tract: What do mechano- and chemoreceptors respond to?
Definition
stretch, osmolarity, and pH. Presence of substrate, and end products of digestion
Term
Mechano and chemoreceptors initiate what reflexes?
Definition
activate or inhibit digestive glands. mix lumen contents and move them along
Term
Peritoneum
Definition
serous membrane of the abdominal cavity
Term
Visceral peritoneum
Definition
covers external surface of most digestive organs
Term
Parietal peritoneum
Definition
lines the body wall
Term
Peritoneal cavity
Definition
lubricates digestive organs. allows them to slide across one another
Term
Mesentery
Definition
double layer of peritoneum
Term
Role of the mesentery
Definition
Vascular and nerve supplies to the viscera. hold digestive organs in place and store fat
Term
Retroperitoneal organs
Definition
organs outside the peritoneum
Term
Peritoneal organs (intraperitoneal)
Definition
organs surrounded by peritoneum
Term
Splanchnic Circulation: Hepatic artery serves what organ?
Definition
Liver
Term
Splanchnic Circulation: Splenic artery serves what organ?
Definition
Spleen
Term
Splanchnic Circulation: Left gastric artery serves which organ?
Definition
Stomach
Term
Splanchnic Circulation: Inferior mesenteric artery serves which organ?
Definition
Small intestine
Term
Splanchnic Circulation: Superior mesenteric artery serves what organ?
Definition
Large intestine
Term
Hepatic portal circulation: Collection
Definition
Takes nutrient-rich venous blood from the digestive viscera
Term
Hepatic portal circulation: Delivery
Definition
Blood is delivered to the liver for metabolic processing and storage
Term
Histology of the Alimentary Canal
Definition
From esophagus to the anal canal the walls of the GI tract have the same four tunics
Term
What are the four tunics?
Definition
Lumen outward: Mucosa, submucosa, muscularis externa, and serosa
Term
Specificity of the tunics?
Definition
Each tunic has a predominant tissue type, specific digestive function
Term
Mucosa: Anatomy
Definition
Inner most layer
Term
Muscoa: Secretions
Definition
Mucus, digestive enzymes, and hormones
Term
Mucosa: Digestive functions
Definition
Absoprtion of digestion and products into blood (small intestine)
Term
Mucosa: other roles
Definition
protects against infection
Term
Epithelium of the mucosa
Definition
produces mucus
Term
Lamina propia of the mucosa
Definition
contains capillaries that nourish the epithelium and collects digested material
Term
Muscularis mucosae of the mucosa
Definition
smooth muscle layers that produce local movement of mucosa
Term
Submucosa: anatomy basics
Definition
connective tissue pouch that helps organs, especially the stomach expand. sheath that "holds" inner layers intact
Term
Muscularis externa: Basic anatomy
Definition
Layer of smooth muscle cells that perform segmentation or peristalsis
Term
Muscularis externa: "Blocker"
Definition
Thickened areas, called sphincters, prevent backflow
Term
Muscularis externa: Inner layer
Definition
runs with the circumference of tube, pushes forward, circular muscle
Term
Muscularis Externa: Outer layer
Definition
Longitudinal muscle. Runs the length of the tube. Pushes forward
Term
Serosa - role
Definition
"Sausage Casing" Visceral peritoneum that holds everything together
Term
Muscles of mastication
Definition
Masseter and platysma
Term
Muscles of the lips
Definition
Orbicularis oris
Term
Muscles of the cheeks
Definition
buccinators
Term
Vestibule
Definition
bounded by the lips and cheeks externally, and teeth and gums internally
Term
Oral cavity proper
Definition
area that lies within the teeth and gums
Term
Labial frenulum
Definition
median fold that joins the internal aspect of each lip to the gum
Term
Hard palate
Definition
underlain by palatine bones and palatine processes of maxillae
Term
Role of the hard palate
Definition
assists the tongue in chewing
Term
Anatomy of the hard palate
Definition
Slightly corrugated on either side of the raphe (midline ridge)
Term
Soft palate
Definition
mobile fold formed mostly of skeletal muscle
Term
Role of the soft palate
Definition
Closes off the nasopharynx during swallowing
Term
Soft palate - projections
Definition
Uvula projects downward from its free edge
Term
Tongue - attachment
Definition
Lingual frenulum secures the tongue to the floor of the mouth
Term
Salivary glands: Role
Definition
Produce and secrete saliva
Term
Role of saliva
Definition
Cleanses the mouth, moistens and dissolves food chemicals, aids in bolus formation, contains enzymes that break down starch
Term
Three pairs of extrinsic salivary glands
Definition
Parotid, submandibular, sublingual
Term
Parotid gland: Opens into...
Definition
The vestibule next to second upper molar
Term
Submandibular gland opens into...
Definition
the base of the lingual frenulum
Term
Sublingual gland opens...
Definition
via 10-12 ducts into the floor of the mouth
Term
Saliva: Source
Definition
secreted from serous and mucous cells of salivary glands
Term
hypo-osmotic
Definition
Containing a lower concentration of osmotically active components than a standard solution.
Term
Saliva composition
Definition
97-99.5% water, hypo-osmotic, slightly acidic solution
Term
What does saliva contain?
Definition
Electrolytes, digestive enzyme, proteins, metabolic wastes
Term
Electrolytes of saliva
Definition
Na+, K+, Cl-, PO4 2-, HCO3-
Term
Digestive enzyme of saliva
Definition
salivary amylase
Term
Proteins of saliva
Definition
mucin, lysozyme, defensins, and IgA
Term
Role of defensins
Definition
bind to foreign proteins
Term
IgA
Definition
Immunogoblin A, Antibody A
Term
Metabolic wastes of saliva
Definition
urea and uric acid
Term
What do salivary glands secrete serous, enzyme-rich saliva in response to?
Definition
Ingested food wich stimulates chemoreceptors and pressoreceptors, and the thought of food
Term
What system inhibits salivation and results in dry mouth?
Definition
Strong sympathetic stimulation
Term
The mouth, the oro- and laryngopharanx allow passage of what?
Definition
Food and fluids to the esophagus. air to the trachea
Term
What is the pharynx lined with?
Definition
Stratified squamous epithelium and mucus glands
Term
What are the two skeletal muscle layers of the Pharynx?
Definition
Inner longitudinal, Outer pharyngeal constrictors
Term
What is the esophagus?
Definition
Muscular tube going from the laryngopharynx to the stomach
Term
What does the esophagus travel through?
Definition
The mediastinum and pierces the diaphragm
Term
Where do the esophagus join the stomach?
Definition
The cardiac orifice
Term
Esophageal Mucosa
Definition
nonkeratinized stratified squamous epithelium
Term
What is the shape of the esophagus when it is empty?
Definition
Folded longitudinally
Term
What is the shape of the esophagus when food is present?
Definition
Flattened from resting position
Term
What are the changes in the muscularis as the bolus moves from superior to inferior portions?
Definition
Skeletal and smooth muscle respectively
Term
Digestive Processes in the Mouth: Step 1
Definition
Food is Ingested
Term
Digestive Processes in the Mouth: Step 2
Definition
Mechanical digestion begins, mastication
Term
Digestive Processes in the Mouth: Step 3
Definition
Propulsion is initiated by swallowing
Term
Digestive Processes in the Mouth: Step 4
Definition
Salivary amylase begins breakdown of starch and simple sugars
Term
Digestive Processes in the Mouth: Step 5
Definition
Pharynx and esophagus serve as conduits to pass food from the mouth to the stomach
Term
Digestive Processes in the Mouth: Step 5
Definition
Oral cavity shapes the broken down mass into a bolus that is swallowed
Term
Deglutition
Definition
Swallowing
Term
What is swallowing (deglutition)?
Definition
Coordinated activity of the tongue, soft palate, pharynx, esophagus, and 22 separate muscle groups
Term
Buccal phase: Step 1
Definition
Voluntary swallowing
Term
Buccal Phase: Step 2
Definition
Tip of tongue must press against roof of mouth
Term
Buccal Phase: Step 3
Definition
Bolus is forced into the oropharynx
Term
Buccal Phase: Step 4
Definition
Once bolus is past the uvula swalling is out of our control
Term
Block #1
Definition
Uvula and soft palette ascend and close off nasopharynx
Term
Pharyngeal-esophygeal phase
Definition
controlled by the medulla and lower pons
Term
Block #2
Definition
Epiglottis descends blocking off trachea
Term
Pharyngeal-esophygeal phase: Step 1
Definition
All routes except into the digestive tract are sealed off
Term
Pharyngeal-esophygeal phase: Step 2
Definition
Peristalis moves food through the pharynx to the esophagus
Term
Pharyngeal-esophygeal phase: Solids
Definition
Food travels to the stomach in 8-10 seconds
Term
Pharyngeal-esophygeal phase: Liquids
Definition
Water, saliva, liquds reach stomach in 1-2 seconds
Term
GERD
Definition
Gastroesophageal reflux disease: Characterized by gastroesophageal sphincter not working properly
Term
Block #3
Definition
Upper esophageal sphincter
Term
Black #4
Definition
Gastroesophageal Sphincter
Term
Chyme
Definition
creamy paste
Term
What chemical breakdown occurs in the stomach?
Definition
Protein
Term
Stomach: Trivia
Definition
15 to 25 cm long. 50 ml volume. Can hold up to 4L when full.
Term
What happens when the stomach is empty?
Definition
Collapses into folds called rugae - the sound of stomach growling
Term
Cardiac region
Definition
surrounds the cardiac orifice
Term
Fundus
Definition
Dome-shaped region beneath the diaphragm
Term
Body
Definition
midportion of the stomach
Term
Pyloric region
Definition
made up of the antrum and canal which terminates at the pylorus
Term
What is the pylorus continuous with?
Definition
The duodenum through the pyloric sphincter
Term
Block #5
Definition
Pyloric Sphincter, active sphincter
Term
Greater curvature of the stomach
Definition
entire extent of the convex lateral surface
Term
Lesser curvature of the stomach
Definition
concave medial surface
Term
What is the stomach held in place by?
Definition
Two omenta (mesentaries)
Term
Two mesentearies of the stomach
Definition
Lesser omentum, greature omentum
Term
Lesser omentum
Definition
Runs from the liver to the lesser curvature
Term
Greater omentum
Definition
drapes inferiorly from the greater curvature to the small intestine
Term
Microscopic modifications of the anatomy of the stomach
Definition
Muscularis - has an additional oblique layer
Term
Role of the oblique layer of the muscularis
Definition
Allows the stomach to churn, mix, and pummel food physically. Breaks down food into smaller fragments
Term
What is the epithelial lining of the stomach composed of?
Definition
Goblet cells that produce a coat of alkaline mucus
Term
What is the role of the alkaline mucus produced by the goblet cells?
Definition
Traps a bicarbonate-rich fluid beneath it
Term
What do gastric pits contain?
Definition
Gastric glands
Term
What do gastric glands secrete?
Definition
gastric juice
Term
What does gastric juice contain?
Definition
mucus, gastrin
Term
What is gastrin?
Definition
hormone that stimulates secretion of gastric acid
Term
Gastric glands of the fundus and body have what secretory cells?
Definition
mucous neck cells, parietal cells
Term
Mucous neck cells
Definition
secrete acid mucus
Term
parietal cells
Definition
secrete HCL and intrinsic factor
Term
What do Chief cells produce?
Definition
pepsinogen
Term
What is pepsinogen?
Definition
inactive form of pepsin
Term
How is pepsinogen activated by?
Definition
HCl in the stomach. Pepsin itself via a positive feedback mechanism
Term
What is pepsin?
Definition
enzyme that digests proteins into peptides
Term
Enteroendocrine cells
Definition
secrete digestive hormones into the lamina propia
Term
What is the role of Cholecystokinin?
Definition
A stimulating hormone which turns on enzymes that stimulate intestinal digestion of fats and proteins
Term
What is the role of Somatostatin?
Definition
Inhibitory hormone that suppresses gastrin release
Term
What protective systems does the mucosal barrier contain?
Definition
Thick coat of bicarbonate-rich mucus on the stomach wall. Epithelial cells that are joined by tight junctions. Gastric glands that have cells impermeable to HCl
Term
Digestion in the stomach: Physical
Definition
Holds ingested food. Degrades the food, deliver chyme to the small intestine, rolls and churns food
Term
Digestion in the Stomach: Chemical
Definition
Enzymatically digest proteins with pepsin, secretes intrinsic factor required for absorption of vitamin B12
Term
Three phases of digestion
Definition
Cephalic control, gastric phase, intestinal phase
Term
Cephalic Phase: Excitatory Events
Definition
Triggers: sight smell, taste, thought of food
Vagus nerve transmits signals to stomach glands
Term
Cephalic Phase: Inhibitory Events
Definition
Loss of appetite, Depressions, Decrease in in stimulation of the parasympathetic division
Term
Gastric phase: Excitatory events
Definition
Stomach distension, 3-4 hours long, 2/3 of gastric juices released during this time, activation of chemoreceptors by peptides caffeine, and rising pH, release of gastrin into blood
Term
Gastric Phase: Inhibitory events
Definition
a pH lower than 2, emotional upset that overrides the parasympathetic division
Term
Intestinal Phase: Excitatory Phase
Definition
low pH; partially digested food enters the duodenum and encourages gastric gland activity
Term
Intestinal Phase: Inhibitory Phase
Definition
distension of duodenum, presence of fatty, acidic, or hypertonic chyme, and /or irritants in the duodenum
Term
Intestinal Phase: Inhibitory Action
Definition
Initiates inhibition of local reflexes and vagal nuclei. Closes the pyloric sphincter. Releases enterogastrone that inhibits gastric secretion
Term
Regulation and Mechanism of HCl secretion: What is HCl secretion stimulated by?
Definition
Acetycholine, histamine, gastrin through second-messenger systems
Term
When is release of HCl acid low?
Definition
If only one ligand binds to parietal cells
Term
When is release of HCl acid high?
Definition
If all three ligands bind to parietal cells.
Term
What role do antihistamines play in HCl release?
Definition
Decreasing release
Term
How quick is muscle adaptation in stomach?
Definition
Slow
Term
At what point does stomach pressure cease to be constant?
Definition
Until about 1L of food is ingested
Term
How is the unchanging pressure of the stomach maintained?
Definition
Reflex-mediated relaxation and plasticity
Term
What are the reflex-mediate events?
Definition
Receptive relaxation, adaptive releaxation
Term
Receptive relaxation
Definition
as food travels in the esophagus, stomach muscles relax
Term
adaptive releaxation
Definition
the stomach dilates in response to gastric filling
Term
What is the basic electrical rhythm (BER) of gastric contractile activity initiated by?
Definition
Pacemaker cells (Cells of Cajal)
Term
Where does the most vigorous peristalsis and mixing occur?
Definition
Near the pylorus
Term
What happens with chyme in the stomach?
Definition
Delivered in small amounts to the duodenum. Forced backward into stomach for further mixing.
Term
How is gastric emptying regulated?
Definition
The neural enterogastric reflex. Hormonal (enterogastrone) mechanisms
Term
What type of chyme moves faster through the duodenum?
Definition
Carbohydrate-rich
Term
What
Definition
Term
type of chyme is digested more slowly? What does this cause?
Definition
Fat-laden. Food remains in the stomach longer
Term
Small Intestine: Gross anatomy
Definition
Runs from pyloric sphincter to the ileocecal valve. 20 ft long by 1-1.5" in diameter.
Term
What are the three subdivisions of the small intestine?
Definition
Duodenum, jejunum, and ileum
Term
Duodenum: Trivia
Definition
10 inches long. Immobile
Term
Duodenum: Physical role in digestion
Definition
Site where food transfers from the stomach, along with bile and pancreatic juice
Term
How is the Sphincter of Oddi regulated?
Definition
Hormonally
Term
What part of the small intestine is the hepatopancratic ampulla?
Definition
Duodenum
Term
What is the hepatopancratic ampulla?
Definition
Site where the bile duct and main pancreatic duct enter the small intestine. Controlled by the hepatopancreatic sphincter
Term
Other name for the hepatopancreactic sphincter
Definition
Sphincter of Oddi
Term
What part of the small intestine joins the large intestine?
Definition
Ileum
Term
Where do the small intestine and large intestine meet?
Definition
Ileocecal valve
Term
How are the jejunum and ileum organized?
Definition
Hang like sausage links in the central and lower abdominal cavity
Term
What are the jejunum and ileum suspended by?
Definition
A thick fan-like mesentary
Term
What do the structural modifications of the small intestine wall do?
Definition
Increase surface area
Term
What are the plicae circulares?
Definition
Deep circular folds of the mucosa and submucosa
Term
What are the villi of the small intestine?
Definition
finger like extensions of the mucosa
Term
What are the microvilli of the small intestine?
Definition
Tiny projections of absorptive mucosal cells plasma membranes
Term
What are the 4 modifications of the small intestine? Their role?
Definition
Length, plicae circularis, Villi, Microvilli. To increase Surface area
Term
What is the epithelium of the mucosa made up of?
Definition
Absorptive cells and goblet cells. Enteroendocrine cells. Interspersed T-cells called intraepithelia lymphocytes
Term
What is the role of intraepithelial lymphocytes (IELs)?
Definition
Immediately release cytokines upon encountering a foreign protein (antogen)
Term
What cells secrete intestinal juice?
Definition
Cells of intestinal crypts (Crypts of Kieberkuhn)
Term
What do the intestinal crypts (of Lieberkuhn) secrete intestinal juice in response to?
Definition
Distension or irritation of the mucosa
Term
What is intestinal juice made up of?
Definition
Slighty alkaline, isotonic with blood plasma, largely water, enzyme poor, contains mucus
Term
What is the largest gland in the body?
Definition
The liver
Term
What are the four lobes of the liver?
Definition
right, left, caudate, and quadrate
Term
What separates the right and left lobes anteriorly?
Definition
The falciform ligament
Term
What does the falciform ligament do?
Definition
Suspends the liver from the diaphragm and anterior abdominal wall.
Term
What is the ligamentum teres?
Definition
A remnant of the fetal umbilical vein
Term
What runs along the free edge of the falciform ligament?
Definition
ligamentum teres
Term
What role does the lesser omentum play with the liver?
Definition
Anchors it to the stomach
Term
Where do the hepatic blood vessels enter the liver at?
Definition
The porta hepatis - gateway to the liver
Term
Where does the gallbladder rest?
Definition
in a recess on the inferior surface of the right lobe
Term
What two ducts form the bile duct?
Definition
cystic duct and hepatic duct
Term
What two ducts fuse to become the common hepatic duct?
Definition
Right and Left Hepatic duct
Term
How does bileve leave the liver?
Definition
Via the hepatic duct and cystic duct
Term
Composition of Bile
Definition
yellow-green, alkaline solution containing bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolyes
Term
What are the bile slats derivatives of?
Definition
cholesterol
Term
What are the roles of bile salts?
Definition
Emulsify fat, facilitate fat and cholesterol absorption, help solubilize cholesterol
Term
What happens with bile after being used?
Definition
It is recylced
Term
What is the chief bile pigment
Definition
bilirubin
Term
What is bilirubin a waste product of?
Definition
Heme
Term
Gallbladder: Physical anatomy
Definition
thin-walled green muscular (smooth muscle) sac on the ventral surface of the liver
Term
What does the gallbladder store and concentrate?
Definition
bile by absorbing its water and ions
Term
How does the gallbladder release bile?
Definition
Via the cystic duct, which flows into the bile duct
Term
Regulation of Bile release: Step 1
Definition
Acidic, fatty chyme causes the duodenum to release CCK and secretin into the bloodstream
Term
Regulation of Bile Release: Step 2
Definition
Bile salts and secretin transported in blood stimulate the liver to produce bile
Term
Regulation of Bile Release: Step 3
Definition
CCK causes the gallbaldder to contract, the hepatopancreatic sphincter to relax
Term
Regulation of Bile: Step 4
Definition
Result: bile enters the duodenum
Term
Pancreas: Location
Definition
Lies deep to the greater curvature of the stomach. The head is encircled by the duodenum and the tail abuts the spleen
Term
Pancreas: Exocrine Function
Definition
Secretes pancreatic juice which breaks down all categories of foodstuff. Acini (clusters of secretory cells) contain zymogen granules with digestive enyzmes
Term
Pancreas: Endocrine function
Definition
release of insulin and glucagon
Term
Composition of Pancreatic Juice
Definition
Water soluition of enzymes and electrolytes (primarily bicarbonate HCO3-)
Term
Function of pancreatic juice
Definition
Neutralizes acidic chyme, provides optimal environment for pancreatic enzymes
Term
What form are the enzymes when they are released from the pancreas?
Definition
Inactive
Term
Where do the inactive enzymes released from the pancreas become activated?
Definition
In the duodenum
Term
How are the inactive enzymes of the pancreas activated in the duodenum?
Definition
Via membrane-bound enteropeptidase
Term
Wjat is trypsinogen activated to?
Definition
Trypsin
Term
What is chymo-tripsinogen activated into?
Definition
chymotripsin
Term
What is procarboxypeptidase activated to?
Definition
carboxypeptidase
Term
What are the active enzymes secreted by the pancreas?
Definition
Amylase (sugar) and lipases (fats)
Term
What do amylase and lipases require for optimal activity?
Definition
Ions or bile
Term
Regulation of Pancreatic Secretion: Step 1
Definition
Secretin and CCK are released when fatty or acidic chyme enters the duodenum
Term
Regulation of Pancreatic Secretion: Step 2
Definition
CCK and secretin enter the bloodstream
Term
Regulation of Pancreatic Secretion: Step 3
Definition
CCK and secretin reach the pancreas via bloodstream
Term
Regulation of Pancreatic Secretion: Step 3
Definition
CCK and secretin reach the pancreas via bloodstream
Term
Regulation of Pancreatic Secretion: Step 4
Definition
CCK induces teh secretion of enzyme-rich pancreatic juice. Secretin causes secretion of bicarbonate-rich pancreatic juice
Term
As chyme enters the duodenum: How digested are carbohydrates?
Definition
partially
Term
As chyme enters the duodenum: How digested are proteins?
Definition
partially
Term
As chyme enters the duodenum: How digested are fats?
Definition
No digestion has taken place
Term
What is the main function of the colon?
Definition
Reabsorb water
Term
What is the large intestine dividied into?
Definition
the cecum, appendix, colon, rectum, and anal canal
Term
Where does the saclike cecum lay?
Definition
below the ileocecal valve in the right iliac fossa
Term
What does the cecum contain?
Definition
A wormlike vermiform appendix
Term
Features of the large intestine
Definition
Tenia coli, haustra, epiploic appendages
Term
Teniae coli
Definition
three bands of longitudinal smooth muscle in its muscularis
Term
haustra
Definition
pocketlike sacs caused by the tone of the teniae coli
Term
epiploic appendages
Definition
fat-filled pouches of visceral peritoneum
Term
REgions of the colon
Definition
ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, and sigmoid colon
Term
What does the sigmoid colonjoin?
Definition
The rectum
Term
What segment opens to the exterior at the anus?
Definition
Anal canal
Term
Function of the rectal valves
Definition
stop feces from being passed with gas
Term
Two sphincters of the anus
Definition
Internal and external
Term
Internal sphincter composed of what?
Definition
Smooth muscle
Term
Role of the internal sphincter
Definition
Keeps stuff in
Term
Role of the external sphincter
Definition
Helps push stuff out
Term
External anal sphincter composed of what?
Definition
Skeletal muscle
Term
When are the anal sphincters not closed?
Definition
During defecation
Term
What do the bacterial flora of the large intestine consist of?
Definition
Bacteria surviving the small intestine that enter the cecum and those entering via the anus
Term
What do bacterial flora do?
Definition
Colonize the colon. Ferment indigestible carbohydrates. Release irritating acids and gases (flatus) synthesize B complex vitamins and vitamin K
Term
Functions of the large intestine: Digestion
Definition
Digestion of enteric bacteria, no further digestion takes place
Term
Functions of the large intestine: Vitamins, minerals, and electrolytes
Definition
Are reclaimed
Term
Large intestine: Major function
Definition
Propulsion of fecal material toward teh anus
Term
Motility of the Large Intestine: Haustral Contractions
Definition
Slow segmenting movements that move the contents of the colon. Haustra sequentially contract as they are stimulated by distension
Term
Motility of the Large Intestine: Presence of food in the stomach
Definition
Activates the gastrocolic reflex. Initiates peristalsis that forces contents toward the rectum
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