Chapter 26 Flashcards
What is part of the accessory organs?
teeth, tongue, salivary glands, liver, pancreas, gallbladder
what is part of the GI tract?
oral cavity, pharynx, esophagus, stomach, small and large intestine, anal canal
Introduction of solid and liquid nutrients into the oral cavity; 1st step of digesting and absorbing nutrients
Ingestion
Voluntary and involuntary muscular contractions for mixing and moving materials through the GI tract
Motility
Process of producing and releasing substances such as enzymes, acids, and bile into the GI tract
Secretion
Break down of ingested food into smaller pieces
Digestion
Activity of specific enzymes to break down chemical bonds to change larger molecules into smaller molecules
Chemical digestion
Ingested material is physically broken down into smaller units by chewing and mixing without chemicals
Mechanical digestion
Membrane transport of digested molecules, electrolytes,vitamins, and water from GI tract into blood or lymph
Absorption
Expulsion of digested indigestible components that are not absorbed
Elimination
Contains simple columnar epithelia, lamina propria, connective tissues with blood and lymph capillaries
Mucosa
What is the function of mucosa?
Absorption and secretion
contains connective tissue with blood and lymph vessels, MALT
Submucosa
Contains circular and longitudinal smooth muscle, myenteric nerve plexus
Muscularis
What is the function of the muscularis layer?
Allow peristalsis and mixing, stretching of the wall
Connective tissue covered by visceral peritoneum
Serosa
How is the digestive system regulated?
AP sent to CNS, affects nerves VII, IX, X; go to salivary glands, muscularis layer of GI tract, pancreas
Detect pressure in particular region of GI tract
Stretch Baroreceptors
Detect specific substances within the lumen
Chemical baroreceptors
Ap sent to CNS, autonomic response to cranial nerves VII, IX, X; causes secretion and smooth muscle contraction
Long reflex
Ap sent to nerves of myenteric nerve plexus, smooth muscle contraction
Short reflex
Chewing involving teeth and tongue
Mastication
Moisten food to break down starch, dissolve food molecules, clean/inhibit bacteria
Chemical breakdown of food
Made of stratified squamous epithelium; protection from abrasion of food
Wall of esophagus
Closes off all the time unless food comes in
Superior esophageal sphincter
Closes off area right before stomach unless food comes in; prevents acid in stomach from damaging esophagus
inferior esophageal sphincter
Phase in swallowing when mastication forms bolus, tongue pushes food back to oropharynx
Voluntary phase
Phase in swallowing when sensory receptors are stimulated, AP sent to swallowing center, causes the elevation of soft palate and uvula, movement of larynx
Pharyngeal phase
Phase in swallowing when movement through the esophagus
Esophageal phase
What is the function of the stomach?
Mechanical and chemical digestion
Depressions within mucosal layer, ends to gastric gland
Gastric pit
Digested food in stomach
Chyme
Cells that line the lumen and gastric pit, secretes alkaline mucin protection; prevents stomach acid from damaging stomach
Surface mucous cells
Cells that are below the base of the gastric pit and gland; secretes acidic mucin to create acidic environment
Mucous neck cells
Cells that secrete intrinsic factor to absorb vitamin B12 and HCl to drop pH and convert pepsinogen to pepsin
Parietal cells
Cells that secrete pepsinogen which eventually converts to pepsin
Chief cells
Cells that secrete gastrin that stimulates stomach secretions and motility
G-Cells
What is the stimulus of the cephalic phase?
Thinking, smelling, tasting food
AP is sent to medulla oblongata, AP sent to stomach via vagus nerve, results in an increase in contractile force and increase in secretion by gastric glands
Cephalic phase
Bolus enters stomach, baroreceptors and chemoreceptors stimulate, AP sent to medulla oblongata and stomach via vagus nerve, results in an increase in gastric gland secretion and contractile force
Gastric phase
Chyme enters duodenum, inhibitory AP sent to medulla oblongata, results in decrease in contractile force and gastric gland secretions
Intestinal phase
___ is released during the intestinal phase. Causes a decrease in contractile force and secretion
CCK
Spontaneously depolarize, AP sent to muscularis layer, results in establishing rhythm in muscular contractions
Pacemaker cells
Increases surface area, slows down food particles in the small intestine
Mucosa
Absorb a majority of chyme’s lipids, contains lymph capillaries and made up of simple columnar epithelium
Microvilli
Includes peyer patches, lymph and blood capillaries, and nerves in small intestine
Submucosa
Contains longitudinal and circular muscles in small intestine
muscularis
What 3 cells are in the intestinal glands?
goblet, unicellular gland, enteroendocrine
Chyme mixes with digestive secretions
Segmentation
Movement of materials down GI tract
Peristalsis
Short reflex; stimulus is food entering stomach, AP sent to ileocecal sphincter, relaxation, contents move to large intestine
Gastroileal reflex
Ring of smooth muscle, closed until stimulus happens
Ileocecal sphincter
Ribbon of muscle, longitudinal muscle of muscularis layer, help bunch up large intestine
Teniae coli
What is peristalsis like in the large intestine?
weak and sluggish
Distention stimulates muscle contraction
Haustral churning
Moves fecal matter from transverse colon to cecum
Mass movements
Oxygenated blood to liver
Hepatic artery
Deoxygenated blood with nutrients, collects nutrients from small intestine
Hepatic portal vein
Breakdown, balance, create nutrients; store glucose, minerals, vitamins, synthesize bile and cholesterol, remove harmful substances, regulate amino acids
Hepatocytes
Allows liver to have dual blood supply
Hepatic portal system
Acinar cells form pancreatic juices
Exocrine pancreas
Pancreatic islets release hormones
Endocrine pancreas
Increase blood sugar
Glucagon (alpha cells)
Decrease blood sugar
Insulin (beta cells)
