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Where does the alimentary canal begin?
Oral cavity
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What bone does the tongue attach to?
Hyoid bone
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What is the space between the lips and gums called?
Vestibule
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What event do the teeth help with?
Mastication
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What parts if digestion begin in the oral cavity?
Chemical and mechanical digestion
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What covers the tongue and may contain taste buds?
Papillae
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How does the tongue help with mastication?
Manipulates food, initiates swallowing, and permits enjoyment
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Identify locations of the parotid, sublingual, and submandibular glands
See book
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What composes the alimentary canal?
Mouth, pharynx, esophagus, stomach, small and large intestines
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What composes the mucosa?
Epithelium, lamina propia, and muscularis mucosae
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What is the epithelium composed of?
Simple columnar
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What is the lamina propia composed of?
Areolar connective tissue
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What is the muscularis mucosae composed of?
Smooth muscle
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What are the main functions of the mucosa?
Secretion of enzymes, mucus, hormones, etc.; absorption if digested foodstuffs; and protection against bacterial invasion
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What is the submucosa composed if?
Moderately dense connective tissue containing blood and lymph vessels, lymphoid follicles, and nerve fibers
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What is the function of the submicosa?
Protection and nutrition
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What is the muscularis composed of?
2 layers of smooth muscle. The inner layer runs circular and the outer longitudinal
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What does the muscularis do?
Regulates motility of the GI tract
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What composes the serosa?
Epithelium and connective tissue
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What is the outermost layer of the alimentary canal?
Serosa
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What is the innermost layer of the alimentary canal?
Mucosa
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What is the second innermost layer of the alimentary canal?
Submucosa
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What is the 2nd outermost layer of the alimentary canal?
Muscularis
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What does the serosa become outside the abdominopelvic cavity?
Adventiva
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What is another name for the esophagus?
Gullet
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Does the esophagus have any digestive or absorptive function?
No
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What type of muscle exists at the superior and inferior ends of the esophagus?
Skeletal muscle at the superior end and smooth muscle at the inferior end
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What controls food passage into the stomach?
Gastroesophageal sphincter
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What is the role of the fivefold adventiva?
It anchors organs to surrounding tissues
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Is the gastroesophageal sphincter a true sphincter?
No
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What is the site of temporary storage along with chemical and mechanical breakdown of food?
Stomach
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How many layers of muscle are in the stomach?
3 (oblique, circular, and longitudinal)
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What is the area of the stomach that surrounds the office that food enters the stomach?
Cardiac region
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What is the region of the stomach superolateral to the cardiac region?
Fundus
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What is the midportion of the stomach?
Body
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What is the funnel shaped region of the stomach continuous with the small intestines?
Pyloric region
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What is the concave medial surface of the stomach called?
Lesser curvature
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What is the convex lateral surface of the stomach called?
Greater curvature
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What extends from the lesser curvature?
Lesser omentum (from liver to curvature)
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What extends from the greater curvature?
Greater omentum (which reflects down like an apron over the abdominal contents and attaches to the transverse colon)
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What are the folds in the stomach lining?
Rugae
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What does the oblique layer of muscle allow?
Churning
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What do the gastric glands secrete?
HCl and hydrolytic enzymes
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What is the primary enzyme secreted by the stomach?
Pepsinogen
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Where are proteins first broken down and what is responsible?
The stomach and pepsinogen
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Where does most digestive activity occur in the stomach?
Pyloric region
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How does chyme enter the intestines?
Via the pyloric sphincter (a true sphincter)
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What cells are located in gastric glands?
Chief and parietal cells
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What do chief cells secrete?
Pepsinogen
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What do parietal cells secrete?
HCl and intrinsic factor
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What type of epithelium is in the stomach?
Simple columnar
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What are the 3 subdivisions of the small intestines?
Duodenum, jejunum, and ileum
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Location of nearly all nutrient absorption
Small intestines
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What are the hydrolytic enzymes bound to the microvilli of columnar epithelial cells?
Brush border enzyme
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The orifice controlled by the sphincter of Oddi
Duodenal papilla
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The sphincter that allows pancreatic enzymes and bile to enter the duodenum
Sphincter of Oddi
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What are the areas between villi of the intestines?
Intestinal crypts
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Minute projections if the surface plasma membrane of lining cells.
Microvilli
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Finger Ike projections of the mucosa
Villi
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Deep, permanent folds of the mucosa and submucosa they force chyme to spiral throughout the intestines
Circular folds (plicae circulares)
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Scattered mucus producing glands in duodenum
Brunner's glands
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Where does any undigested residue enter the large intestines?
The ileoceal sphincter
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Aggregated lymphoid follicles on small intestines (especially the ileum)
Peyer's patches
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Where is the higher concentration of goblet cells?
Colon
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What are the subdivisions of the large intestines?
Cecum, vermiform appendix, colon, rectum, and anal canal
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What is the vermiform appendix attached to?
The cesum
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What are the divisions of the colon?
Ascending colon, right colic flexure, transverse colon, left colic flexure, descending colon, and sigmoid colon.
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What is the end of the anal canal?
The anus
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How many sphincters does the anus have?
2, external (voluntary) and internal (involuntary)
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What is the longitudinal muscle layer of the muscularis reduced to in the large intestines
Teniae coli
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What causes the formation of the haustra in the large intestines?
The shortened teniae coli
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What are the pocketlike sacs of the large intestines called?
Haustra
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What is the largest gland in the body?
Liver
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What digestive role does the liver play?
Creates bile
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What is the function of bile?
Emulsifies fats to allow for more efficient lipase activity
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Where is bile held when digestive activity is not occurring in the digestive tract?
Gall bladder
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Through what does bile enter the duodenum?
Exits the liver through the common hepatic duct and enters the duodenum through the bile duct
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How does bile get from the liver to the gallbladder?
Cystic duct
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What organ of the digestive system has endocrine and exocrine functions?
Pancreas
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What hormones does the pancreas produce?
Insulin and glucagon
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What type of enzymes does the pancreas produce?
Hydrolytic
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What function does the alkalinity of the pancreatic juice have?
It neutralizes the acidic chyme from the stomach entering the duodenum
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What is the movement that moves food along the digestive system?
Peristalsis
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Identify the arteries and veins aiding the digestive system
See book
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What fan shaped double layer of peritoneum suspends the small intestines?
Mesentery
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What is swallowing formally called?
Deglutition
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What is movement of material along the alimentary canal?
Propulsion
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What is the purpose of physical digestion?
Reduce bulk, increase surface area, and allows for chemical digestion
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What is the purpose of chemical digestion
Hydrolyze large complex molecules into subunits
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What is the transport of digestive end products into the blood or lymph?
Absorption
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What type of epithelium is the esophagus?
Non-keratinized stratified squamous epithelium
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What does the longitudinal smooth muscle of the muscularis externa aid in?
Peristalsis
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What does the circular smooth muscle of the muscularis externa aid in?
Segmentation (mixing action)
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What does saliva contain?
Segmentation (mixing action)
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What part of saliva have protective roles?
Lysozyme and IgA antibodies
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What nerves control the mouth?
facial and glossopharyngeal
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What area of the brain responds to taste and physical contact on the tongue?
Salivary center in brainstem
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What area of the brain responds to smell and anticipation?
Higher brain centers (cephalic control)
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What role does the uvula have?
Hinges upwards during swallowing to prevent food from entering the nasal cavity.
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What muscles contract to push food into the esophagus?
Pharyngeal muscles
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What is reflexive relaxation?
The upper and lower ends of the esophagus remain tonically contracted unless a bolus approaches
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What controls the esophageal and pharyngeals contractions of swallowing?
Autonomic NS
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Where are esophageal glands located?
In submucosa
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What do the esophageal glands do?
Secrete mucus for lubricaation and protection
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What allows food into the stomach?
Gastroesophageal region (cardiac sphincter)
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What is a hital hernia?
Protrusion of stomach into the thorax through weakeness in the diaphram
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What problems does a hiatal hernia propose?
Increased chance of acid to enter the esophagus and impared swallowing
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What layer of the alimentary canal is thicker in the stomach?
Submucosa (more mucus secreting cells)
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Where are extensive gastric pits located?
Body of the stomach
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What are the roles of gastric pits?
Increased surface mucosa for secretion and absorption
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What does H+ do in digestion?
Activates pespinogen to the active form pepsin
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How ar respiration and digestion related?
H+ are derrived from the same chemical reaction of CO2 and H2O producing carbonic acid which substitutes HCO3- for Cl-
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What is the role of mucous surface cells?
Produce mucous lining
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What is the role of mucoous neck cells?
Produce alkaline mucus to protect lining from acidity
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What are the hormone producing cells of the GI tract called?
Enteroendocrine cells
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Which cells compose the enteroendocrine cell group?
G-Cells, ECL cells, and D-Cells
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What hormones are produced by the enteroendocrine cells?
Gastrin, histamine, endorphines, seratonin, and somatostatin
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What do ECL cells do?
Secrete histamine
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What do G cells do?
Secrete gastrin
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What does gastrin do?
Stimulates ECL and parietal cells
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What do D cells do?
Secrete somatostatin
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What does somatostatin do?
Inhibits ECL and parietal cells
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What are ways the stomach prevents itself from its acid?
Tight junctions of mucosal lining cells, alkaline mucous secreted, and constant exfoliation of lining cells.
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What is absorbed in the stomach?
Water, electrolytes, monosaccharides, fat soluble molecules (like alcohol)
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What causes peptic ulcers?
Not protected portions of the stomach lining
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Where is the greatest porportion of ulcers?
In the duodenum
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What is associated with ulcers?
H. Pylori
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Where does positive stimulus for the stomach come from?
Parsympathetic division via vagus nerve
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When does the gastric phase begin?
With direct response to contact of food in the stomach via pressoreceptors
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What is retropulsion?
When chyme surges backwards only to be pushed forward again into the pylorus
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What happens in the gastric phase?
ACh and histamine are released, chyme surges forward, retropulsion, and release of gastrin into blood due to chyme in the pylorus
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What causes increased churning and pressure in the stomach?
Presence of chyme in the pylorus
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When does the intestinal phase start?
When chyme enters the duodenum
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What happens in the intestinal phase?
G cells secrete gastrin (start signal), gastric inhibitory peptide (GIP) secreted (stop signal)
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What inhibits gastrine secretion?
Decreased ph
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What does Gastric inhibitory peptide (GIP) do?
Inhibits stomach secretion and motility to give the duodenum more time to procede before more chyme comes in
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What is the enterogastric reflux?
Decreased motility and forcefully closes the pyloric sphincter
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Where is the site of most digestive enzyme release and the start of intensive digestion?
Duodenum
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What timulates the release of CCK into the blood?
Presence of fatty chyme in the duodenum
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What does CCK do?
Inhibits stomach, stimulates the release of enzymes by the pancreas, and stimulates contraction of the gall bladder to release bile
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What does secretin do?
Decreases acid secretion by stimulating the pancrease to release bicarbonate
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What controls passes out of the pancreas through the hepatopancreatic ampulla?
Sphincter of Oddi
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What do the pancreatic duct and common bile duct become?
Hepatopancreatic ampulla
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What makes up pancreatic juice?
Lipase, Tyyrpsin, chymotrypsin, carboxypeptidase, bicaronate, and amylase
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What does lipase do?
Splits emulsified fats into glycerol and fatty acids
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What do trypsin and chymotrypsin do?
Breaks polypeptides into dipeptides
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What does carboxypeptidase do?
Splits dipeptides into amino acids
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What does bicarbonate do?
Neutralizes acid to pH 8 (level needed for activity of protease activity)
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What does amylase do?
Cleaves polysaccharides into shorter chains and disaccharides
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What are some intestinal enzymes (Brush Border enzymes)?
Aminopeptidase, carboxypeptidase, sucrase, lactase, maltase, and enterokinase
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What do aminopeptidase and carboxypeptidase do?
Split dipeptides into amino acids
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What do sucrase, maltase, and lactase do?
Split disaccharides into monosaccharides
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What does enterokinase do?
activates trypsinogen into trypsin (which activates chymotrypsin and carboxypeptidase)
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What in the small intestines increases surface area?
Circular folds, villi, and microvilli
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What is the source of secretory cells of the mucosa in the intestines?
Intestinal crypts
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What role does the muscularis mucosae have in the small intestines?
Contracts to move villi and increase exposure to contents
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What is the function of the colon?
Absorption of remaining water and production of feces
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When does the ilececal sphincter relax?
WHen peristalsis arrives from the ileum
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What is haustral churning caused by?
Segmentation contractions
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What is mass peristalsis?
Large movements which occur at intervals
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What is mass peristalsis initiated by?
Gastrocolic reflex
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What is the gastrocolic reflex?
Stimulation of the colon due to food entering the stomach
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What vitamins are produced during mass peristalis?
Vitamin K and B
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What is the defecation reflex?
Involuntary relaxation of the internal anal sphincter due to mass movement then voluntary relaxation of the external anal sphincter
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How are monosaccharides and amino acids absorbed?
Active co-transport
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How are large molecules absorbed?
endocytosis
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How ar fatty acids and fat-soluble molecules absorbed?
Aggregated into micelles and diffuse into phospholipid matrix of mucosal lining cells
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What is the manufacturing function of the liver?
Manufature of blood proteins, urea, and bile
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What does the liver store?
Glycogen, iron, and fatu soluble vitamins A,D,E, and K
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Detoxification is carried out by what organ?
Liver
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The liver metabolizes proteins through what processes?
Transamination and deamination
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What processes does the liver control in reguards to glycogen?
Glycogenesis (glucose to glycogen), glycogenolysis (Glycogen to glucose), gluconeogenesis (non-carb source to glucose)
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What are the absorptive phases of glycemic regulation?
Glycogenesis, protein manufacture, and lipogenesis
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What are the stages of the post-absorptive phase of glycemic regulation?
Glycogenolysis, lipolysis, and gluconeogenesis
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What are some hormones important to nutrient processing?
Insulin, glucagon, epinephrine, and cortisol
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