digestive system Flashcards
what structures are considered accessory organs in the GI tract and what is their overall function
teeth, tongue, salivary glands, pancreas, liver, and gallbladder
job: digestion only
what structures are the main organs of the GI tract and what is their overall function
mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus and rectum
job: to digest and absorb
what is the cephalic phase, what activates it, and what organs are involved
it was prepares the mouth and stomach for food
-sight, smell, taste, and the thought of food activates neural centers
-nerves in the head will stimulate salvation
-the vagus nerve stimulates salvation and gastric juices in the stomach
-mouth, pharynx, and esophagus are here
what is deglutition in the pharynx and esophagus and what happens in each stage
buccal: bolus goes into pharynx and the tongue moves the bolus against its palate
pharyngeal: bolus goes into the esophagus and pharyngeal receptors send action potentials to the deglutition center
esophageal: bolus goes into the stomach passing through the lower esophagus sphincter
what are the 4 functional layers of the gi tract from deepest to superficial
mucosa (inner), submucosa, muscularis, serosa (outer)
what is the composition of the mucosa layer
it is made of various epithelial cells
it contains blood and lymphatic vessels
it also contains a thin layer of muscle
what is the composition of submucosa layer
it is made of areolar and elastic connective tissue
it contains blood and lymphatic vessels
it also contains a plexus (submucosal) that allows GI secretion
what is the composition of the muscularis layer
it is the main muscle layer containing voluntary and involuntary portions
it also contains a plexus (myenteric) that allows GI motility
what is the composition of the serosa layer
contains areolar and dense connective tissue
it folds into mesenteries that stabilizes organs, blood vessels, and provides attachments for blood vessels going to small intestine
what is the location, stimuli, and responses of the enteric nervous system
-the nervous system is located in two nerve plexus, the myenteric and submucosal
-the stimuli consists of interneurons, motor neurons, and sensory neurons
-the myenteric plexus will do motility responses and the submucosal will do secretion
what is the gastric phase, what activates it, and what organs are involved
-the gastric phase promotes gastric juice secretion and motility and leads to stomach distention and ph increases
-enteric and parasympathetic nervous systems activate this phase stimulating smooth muscle contraction and gastric juice secretion
-the stomach, liver, gall bladder, and pancreas are here
what is the intestinal phase, what activates it, and what organs are involved
-the intestinal phase promotes digestion in the small intestine and slows it down in the stomach, it also deals with the contents of chyme and how much can be held
-digested proteins, lipids, and low ph from chyme stimulates the secretion of CCK and secretin
-the small intestine, large intestine, and anus are here
what are the 4 cell types of the stomach and what are their functions
-g cells create gastrin , parietal cells create HCI, and chief cells create pepsinogen and gastric lipase
-gastrin will stimulate the release of HCI and pepsinogen which will then form pepsin
-pepsin is responsible for breaking down proteins and triglycerides
what is the chemical digestion process of the stomach
chemical digestion is done through the use of the stomach cells that use enzymes to break down proteins and triglycerides
what is the mechanical digestion process of the stomach
propulsion, grinding, and retropulsion breaks down food particles into chyme through repeated mixing
-propulsion: peristalic waves are initiated are starting moving
-grinding: very strong peristalic waves here and heavy mixing
-retropulsion: peristalic waves close a sphincter holding chyme in
