Digestive System 1A Flashcards
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what are the 6 functions of the digestive system
1.) ingestion
2.) motility
3.) secretion
4.) digestion
5.) absorption
6.) elimination
what are the four layers of the GI tract from superficial to deep
adventitia (serosa)
muscularis
submucosa
mucosa
what is the mucosa of the GI tract and what are its layers
innermost lining of GI tract
layers deep to superficial: epithelium, lamina propria, and muscularis mucosae
what is the epithelial layer of the mucosa and what’s its function
innermost layer directly in contact with lumen contents
made of simple columnar cells that secrete and absorb
what is the lamina propria of the mucosa and what’s its function
middle layer of the mucosa
made of areolar tissue
contains blood vessels, lymph vessels, and nerves
absorbs substances from the epithelium through it vessels
what is the muscularis mucosae of the mucosa and what’s its function
outer layer of the mucosa
contracts to help the release of secretions and increase contact of matierals with mucosa
both allow more efficient absorption
what is the submucosal layer of the GI tract
layer above the mucosa
has lots of blood vessels, lymph vessels, and nerves
innervated by the submucosal nerve plexus
houses mucosa-associated lymphatic tissue (MALT) and peyer patches
what is the submucosal nerve plexus of the submucosal layer and what is its function
bundles of nerves and ganglia
innervates smooth muscle and glands of the mucosa and submucosa
what is mucosa-associated lymphatic tissue (MALT) of the submucosal layer and what is its function
clusters of lymphocytes
prevents ingested microbes from crossing GI tract and causing food born illnesses in the body
what are peyer patches of the submucosal layer and what are their function
larger aggregates of lymphatic nodules
found in the distal small intestine
have immune cells which protect against pathogens
what is the muscularis layer of the GI tract and what’s its function
layer above the submucosal layer
made of inner circular layer, outer longitudinal layer, and myenteric nerve plexus
function is motility - mixing and propulsion
what is the inner circular layer of the muscularis and what’s its function
made of smooth muscle cells oriented circumferentially contracts to constrict lumen
thickened in certain areas to form sphincters
sphincters control movement of materials and prevents backflow
what is the outer longitudinal layer of the muscularis and what’s its function
smooth muscle cells oriented vertically
contracts to shorten tube
what is the myenteric nerve plexus of the muscularis and what does it do
clumps of nerves with their autonomic ganglia
found between the outer and inner muscular layers
control the contraction of the muscularis
what are some features of the myenteric nerve plexus of the muscularis
axons with their ganglia
found between the outer and inner muscular layers control the contraction
define mixing
backwards and forwards motion of GI tract to blend ingested material with secretions
define propulsion
directional movements of materials through GI tract
peristalsis
what is the adventitia or serosa of the GI tract
outermost layer that is either adventitia or serosa depending where we are in the organ
what is the adventitia of GI tract
outermost layer of GI tract
considered adventitia when we are outside the peritoneal cavity
what is the serosa of the GI tract
outermost layer of the GI tract
adventitia + outer covering of serous membrane (visceral peritoneum)
only found on organs within the peritoneal cavity
which area of the GI tract absorbs the most water
small intestine
what is the enteric nervous system (ENS) and how does it regulate the digestive system
sensory and motor neurons in the submucosal plexus and myenteric plexus
innervates smooth muscle and glands of GI tract (submucosal plexus)
coordinates mixing and propulsion reflexes (myenteric plexus)
how does the autonomic nervous system (ANS) regulate the digestive system
parasympathetic: stimulates GI motility, release of secretions, and relaxes GI sphincters
sympathetic: inhibit GI motility, release of secretions, constricts GI sphincters, and vasoconstricts GI tract blood vessels
how does the facial nerve regulate the digestive system
parasympathetic nerve
stimulate salivary secretions from sublingual and submandibular glands
how does the glossopharyngeal nerve regulate the digestive system
parasympathetic gland
stimulate salivary secretions from the parotid gland
how does the vagus nerve regulate the digestive system
parasympathetic nerve
stimulates the digestive activities of most of the digestive system organs
what type of reflex is the enteric nervous system (ENS) and what does it coordinate
short, local reflex
coordinates small segments of GI tract
what type of reflex is the autonomic nervous system (ANS) and what does it coordinate
long reflex
sensory input goes to central nervous system
output goes through autonomic nervous system
coordinates GI motility, secretions, and accessory digestive organs
where are circulating hormones released
into the blood
where are local hormones released
from adjacent cells
what type of hormone is gastrin and what is its function
circulating hormone
stimulates stomach motility and release of gastric secretions from parietal and chief cells
what is the function of somatostatin
regulates the function of nearby enteroendocrine and exocrine cells
inhibits release of acidic secretions in response to increased acid
what type of hormone is cholecystokinin and what is its function in the stomach
circulating hormone
inhibits motility and gastric secretions
what type of hormone is cholecystokinin and what does it do in the gallbladder
circulating hormone
stimulates release of bile
what type of hormone is cholecystokinin and what does it do in the pancreas
circulating hormone
stimulates release of enzyme-rich pancreatic juice
what type of hormone is cholecystokinin and what does it do to the hepatopancreatic sphincter
circulating hormone
causes relaxation of the sphincter
what type of hormone is cholecystokinin and what does it do to the iliocecal valve
circulating hormone
causes relaxation of the iliocecal valve
what type of hormone is secretin and what does it do in the stomach
circulating hormone
inhibits stomach motility and gastric secretions
what type of hormone is secretin and what does it do in the liver and pancreas
circulating hormone
stimulates secretion of bicarbonate
what does glucose-dependent insulinotropic peptide do in the pancreas
regulates release of insulin from beta cells
what does motilin do in the small intestine
regulates migrating motility complex to move contents from small to large intestine
what does hepcidin do in the small intestine
inhibits absorption of iron
what is the peritoneum and what are its two layers
serous membrane of abdominopelvic cavity
parietal and visceral layer
what is the mesentery and what is its function
double layer of visceral peritoneum
blood vessels, lymph vessels, and nerves between the layers
supports, suspends, and stabilizes intraperitoneal GI tract organs
what is the greater omentum
fat apron
extends inferiorly from greater curvature of the stomach and covers most abdominal organs
what is the lesser omentum
fat apron
connects the lesser curvature of the stomach to the proximal end of duodenum to the liver
what is that falciform ligament and what is its function
flat, thin crescent shaped fold that attaches the liver to internal surface of anterior abdominal wall
what is the mesentery proper layer of the mesentery and what is its function
fan-shaped fold of peritoneum
suspends most of small intestine from posterior abdominal wall
what is the mesocolon layer of the mesentery and is its function
fold of periotneum
attaches part of the large intestine to posterior abdominal wall
what is peritonitis
inflammation of the peritoneum
GI contents get into the peritoneum and cause inflammation
usually caused by GI tract perforation
where does the upper GI tract start and end
oral cavity and duodenum
where does most of the nutrient absorption occur
small intestine
what is the oral cavity proper
area from back of teeth to oropharynx
what are the transverse palatine folds and what is their function
ridges at the top of the mouth
assist tongue in manipulating materials
what does the uvula do
elevates soft palate during swallowing to close off posterior entrance into nasopharynx
what is the fauces
area between palatoglossal and palatopharyngeal arch
what type of tissue is the oral cavity made of and what is its function
stratified squamous epithelium
protects against abrasions
what are intrinsic salivary glands and what do they do
unicellular glands that are within the oral cavity
continually release secretions containing lipase
what are extrinsic salivary glands and what do they do
glands that are outside of oral cavity
produce the majority of saliva
parotid, submandibular, and sublingual
infection of what gland causes mumps (myxovirus)
parotid
what are the 5 functions of saliva
1.) moistens food to make a bolus
2.) has salivary amylase which initiates breakdown of starch
3.) stimulates taste receptors
4.) cleanses oral cavity structures
5.) has antibacterial substances that inhibit bacterial growth
would parasympathetic stimulation increase or decrease output to salivary glands
increase
would sympathetic stimulation increase or decrease output to salivary glands
decrease
what type of joint is a tooth
gomphosis joint
what is the cementum of a tooth
material surrounding root on the outside of the dentin
what are dental caries
damage to dentin, enamel, or cementum due to bateria
essentially cavities
what do the incisors do
slice food
what do canines do
puncture and tear food
what do premolars and molars do
crush and grind food
what is the esophageal hiatus
opening in the diaphragm where the esophagus passes through
what is deglutition
swallowing
explain the voluntary phase of swallowing
1st phase - voluntary
food is ingested
it is mixed with secretions to form a bolus which moves towards oropharynx
explain the pharyngeal phase of swallowing
2nd phase - involuntary
tactile sensory receptors in fauces are stimulated to send sensory input to the swallowing center in medulla
bolus moves into oropharynx and measures are taken to ensure nothing goes into trachea
explain the esophageal phase of swallowing
3rd phase - involuntary
bolus goes into esophagus and stimulates peristalsis
bolus moves goes into stomach once sphincters relax
explain reflux esophagitis
inflammation of esophagus from acid reflux
heartburn
caused by: obesity, hiatal hernias, smokers, etc.
not GERD
explain gastroesophageal reflux disease (GERD)
chronic reflux esophagitis
erosion of esophageal tissue due to acid reflux
can change stratified squamous to columnar secretory cells (Barrett’s esophagus) which may lead to cancer
treated with things like antacids and things to limit secretion into the stomach
define peristalsis
sequential contraction of the muscularis layers moves like a wave
which organs are not found within the peritoneal cavity
kidneys, pancreas, ascending + descending colon, and rectum
what does lingual lipase do
begins digestion of triglycerides
what are parotid glands and what do they do
largest gland, located near the ear
produce 25-30% of saliva through parotid duct and into the oral cavity (second molar)
what are submandibular glands and what do they do
found beneath the angle of the jaw
produce 60-70% of saliva that is transported to the underside of the tongue through the submandibular duct
what are the sublingual glands and what do they do
glands beanth the tongue
produce 3-5% of saliva that is dumped under the tongue
what are the two types of secretory cells in the salivary glands and what do they do
mucous cells: secrete mucin
serous cells: secrete watery fluid containing electrolytes and amylase
what does salivary amylase do
initiates the breakdown starch
what are the three types of antibacterial substances found in saliva
mucin
lysozyme
IgA antibodies
what regulates salivary secretions
the salivary nuclei within the brainstem
what is the function of the superior esophageal sphincter
closes during inhalation so air does not enter the esophagus
