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118 Cards in this Set
- Front
- Back
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What are the six major subdivisions of the digestive tract?
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-oral cavity, teeth, tongue
-pharynx -esophagus -stomach -small intestine -large intestine |
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Which subdivision is responsible for mechanical processing, moistening, and mixing with salivary secretions?
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oral cavity, teeth, tongue
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What does the pharynx do?
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propes materials into the esophagus
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What does the esophagus do?
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transports materials to the stomach
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Where does chemical breakdown of materials and mechanical processing occur?
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stomach
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What does the small intestine do?
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enzyme digestion, water, organic substrates vitamins, ions
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What does the large intestine do?
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enzyme digesion and absorption of water, organic substrates, vitamins, ions
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What type of tissue is the oral cavity composed of?
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stratified squamous epithelium
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What does the mouth begin digestion of?
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carbs and lipids
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What prevents food from entering the pharynx prematurely?
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uvula
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What allows for expansion durng the passage of a large bolus?
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musosa and submucoas folds
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What keeps the lumen closed?
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muscle tone
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What are the three phases of swallowing?
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1. buccal phase (voluntary)
2. pharyngeal phase (both 3. esophageal phase (involuntary |
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Where does the esophagus begin?
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posterior to the cricoid cartilage
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Describe the buccal phase.
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begins with bolus against hard palate, tongue forces blus into oropharynx and elevates the soft palate.
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Describe the pharyngeal phase.
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begins when tactile receptors on the palatal arches and uvula are stimulated. Motor commands sent form medulla oblongat and contractions of muscle in pharynx occur
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Describe esophageal phase.
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begins as conteraction of pharngeal muscles forces the bolus through the esophagus. Bolus is pushed thorugh stomach by waves.
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What occurs if a dry bolus travels slowly?
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secondary peristaltic waves
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What is the peritoneal cavity lined by?
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peritoneum
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What can the peritoneum be divided into?
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visceral peritoneum-covers the organs in the peritoneal
parietal peritoneum-lines inner surface of body wall |
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The serous membrane lining the peritoneal cavity produces..
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peritoneal fluid
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What is the purpose of peritoneal fluid?
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essential lubrication
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What happens if there is no peritoneal fluid?
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friction and irritation
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What diseases accelerate the rate of fluids moving into the peritoneal cavity?
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liver disease, kidney disease, heart failure
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What does the accumulation of peritoneal fluid result in?
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ascites
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What are the three layers of the muscularis externa?
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-longitudinal muscle layers
-circular muscle layer -oblique muscle layer |
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What is the function of rugae?
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allow the gastric lumen to expand
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What are the four main regions of the stomach?
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-fundus
-cardia -body -pylorus |
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What lines the rugae?
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mucous cells for protection from secretions of exocrine cells
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Whath do the rugae folds have?
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gastric pits for th eoxocrine glands to drop their contents into
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What is the pyloric sphincter?
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regulates the release of chyme into the duodenum
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What are the complete layers of the stomach wall?
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1. Mucosa (gastric pits, lamina propria, muscularis mucosae
2. submucosa (artery and vein) 3. muscularis externa (oblique, circular, longitudinal ) 4. serosa |
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Is the mucous produced by the stomach epithelium alkaline or acidic?
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alkaline to defent against adic and enzymes in the gastric lumen
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What secretes most of the acid and enzymes involved in gastric digestion?
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gastric glands in the fundus
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What types of cells are the gastric glands dominated by?
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parietal cells and chief cells
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how many mL of gastric juice does the gastric glands produce a day?
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1500
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What do exocrine glands form?
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secretions form gastric juice
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What is the function of mucous neck cells?
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secrete mucus to protect our cells so we dont digest our stomach
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What do parietal cells secrete?
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-intrinsic factor
-hydrochloric acid |
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What is the purpose of intrinsic factor?
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abscorb vitamin B12
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What does parietal cells keep the pH of the stomach at?
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1.5-2.0
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Why doesnt parietal cells produce HCl into the cytoplasm?
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it is too acidic and would erode secretory vesicles
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What type of cells are G cells?
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enteroendocrine cells
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What doo G cells secrete?
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gastrin
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What is the function of gastrin?
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-stimulates secretion by parietal and chief cells
-stimulates gastric wall contractions |
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What do D cells secrete?
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somatostatin
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What is the purpose of somatostatin?
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-released adjacent to G cells
-inhibits the release of gastrin |
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What is the function of mucous neck cells?
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secrete mucus to protect our cells so we dont digest our stomach
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What do parietal cells secrete?
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-intrinsic factor
-hydrochloric acid |
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What is the purpose of intrinsic factor?
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abscorb vitamin B12
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What does parietal cells keep the pH of the stomach at?
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1.5-2.0
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Why doesnt parietal cells produce HCl into the cytoplasm?
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it is too acidic and would erode secretory vesicles
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What type of cells are G cells?
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enteroendocrine cells
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What doo G cells secrete?
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gastrin
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What is the function of gastrin?
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-stimulates secretion by parietal and chief cells
-stimulates gastric wall contractions |
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What do D cells secrete?
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somatostatin
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What is the purpose of somatostatin?
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-released adjacent to G cells
-inhibits the release of gastrin |
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What is D cell release controlled by?
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sympathetic nervous system
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What happens to the D cell release when the parasympathetic nervous system increases?
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they turn off
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Where are hydrogen ions generated?
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parietal cell
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How are hydrogen ions generated in a parietal cell?
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the enzyme carbonic anhydrase converts CO2 and H20 to carbonic acid
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What is the release of somatostatin overriden by?
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neural and hormonal stimuli
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Where does the small intestin start and end?
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starts at the pyloric sphincter, ends at the ileocecal valve
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What are the three divisions of the small intestine?
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-duodenum
-jejunum -ileum |
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What is the purpose of plicae circulares?
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-causes a turbulent flow through the intestines
-permanent folding of mucosa and submucosa |
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Do plicae circulares expand?
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No
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What are villi?
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projections of absorptive epithelial layer
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What is D cell release controlled by?
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sympathetic nervous system
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What happens to the D cell release when the parasympathetic nervous system increases?
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they turn off
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Where are hydrogen ions generated?
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parietal cell
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How are hydrogen ions generated in a parietal cell?
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the enzyme carbonic anhydrase converts CO2 and H20 to carbonic acid
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What is the release of somatostatin overriden by?
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neural and hormonal stimuli
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Where does the small intestin start and end?
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starts at the pyloric sphincter, ends at the ileocecal valve
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What are the three divisions of the small intestine?
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-duodenum
-jejunum -ileum |
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What is the purpose of plicae circulares?
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-causes a turbulent flow through the intestines
-permanent folding of mucosa and submucosa |
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Do plicae circulares expand?
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No
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What are villi?
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projections of absorptive epithelial layer
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Where are villi largest?
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duodenum, gradually narrow and shorten
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What is the structure of the villi
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epithelial columnar cells
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What does each villus contain?
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capillary bed and lacteal
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What does a lacteal to?
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transports materials that cant enter blood capillaries
-lymph vessels that absorb lipids |
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What gets fluid moving in the lacteals?
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contractions of the muscularis mucosae
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What are the layers of the small intestine?
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1. mucosa
2. submucosa 3. muscularis externa. 4. serosa |
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What percentage of nutrient absorption occurs in the small intestine?
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ninety
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What segment of the small intestine is closest to the stomach?
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duodenum
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Where does the bulk of chemical digestion and nutrient absorption occur?
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jejunum
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What is the small intestine supported by?
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mesentry
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Which segment of the small intestine is the longest?
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ileum
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What does the ileum end with?
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the ileocecal vavle
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What is the purpose of the ileocecal valve?
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controls the flow of material from the ileum into the cecum
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What is the primary function of the duodenum?
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recieve chyme from the stomach and neutralize its acids before they damage the absorptive surfaces
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What is the submucosa of the duodenum dominated by?
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duodenal glands that produce mucous secretions
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Where is gastrin released and what is its function
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in the stomach
-stimulates acid production by parietal cell san dstimualtion fo gastric motility; mixing waves increase in intensity |
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What hromones are secreted when chyme is in the duodenum?
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-GIP
-secretin -CCK -VIP |
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What is the function of Gastric Inhibitory Peptide?
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release of insulin from the pancreas
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What is the function of secretin and CCK
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stimulates release of pancreatic enzymes and buffers
-stimulates bile secretion and ejection of bile from gallbladder |
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What is the function of Vasoactive Intestinal Peptide (VIP)
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dilation of intestinal capillaries
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What does dilation of intestinal capillaries facililtate?
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nutrient absorption
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What does release of insulin from the pancreas facilitate?
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nutrient utilization by all tissues
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What happens when materials arrive in the jejunum?
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nutrient absorption
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What are the three phases of gastric secretion?
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1. cephalic phase
2. gastric phase 3. intestinal phase |
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What are the three major function sof the large intestine?
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1. reabsorption of water and compaction of intestinal contents into feces
2. absorption of important vitamins liberated by bacterial action 3. storage of fecal material |
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What are the three segments of the large intestine?
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-cecum
-colon -rectum |
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What is the function of the cecum?
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collects and stores materials from the ileum and begins process of compatction
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Compare the diameter and wall thickness of the large intestine vs. the small intestine.
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the large intestine is larger in diameter and has thinner walls
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What are the four regions we can divdide the coon into?
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1. ascending colon
2. transverse colon 3. descending colon 4. sigmoid colon |
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What are the taeniae coli?
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three longitudinal bands of muscle that run along the outside of the colon and corresopnt to the muscularis externa of other regions
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What is the purpose of haustra?
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permit the expansion and elongation of the colon
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What are mass movements?
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powerful peristaltic contractions that occur a few times a day
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What is the rectum?
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expandable organ for the temporary storage of feces
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What triggers the urge to defecate?
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movement of th efecal material into the rectum
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What percentage of nutrient absorption occurs in the large intestine?
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less than ten percent
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What three vitamins does the large intestine absorbe?
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k, b5 and biotin
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How many mL of material enters the colon each day?
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1500
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How many mL of fecesis ejected?
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200 mL
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What does bacterial action produce that contribute to the odor of feces?
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-ammonia
-indole -skatole -hydrogen sulfide |
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What are the major characteristics of the large intestine?
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-lack of villi
-abundance of mucous cells -presence of distinctive intestinal glands |
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What is the purpose of the mucus in the large intestine?
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lubrication as fecal material becomes drier
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