list the organs in the gi tract Flashcards
list the organs that make up the gi tract
oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine
List the accessory digestive organs and structures involved in the digestive process.
teeth, tongue, and gallbaldder
List the six general functions of the digestive system
ingestion, motility, secretion, digestion, absorption, and elimination
ingestion
its the introduction of solid and liquid nutrients into the oral cavity
motility
it describes both voluntary and involuntary muscular conractions for moving materials thru the GI tract
secretion
the process of producing and releasing substances that facilitate both digestion and the movement of contents within the GI tract
digestion
the breakdown of ingested food into smaller components that may be absorbed from the GI tract
absorption
involves membrane transport of digested molecules across the epithelial lining of the GI tract into the blood and lymph
elimination
expulsion of indigestible components thru the anal canal
List the four tunics (layers) that make up the gastrointestinal wall.
mucosa, submucosa, muscularis, and serosa
Briefly explain the process of absorption
it occurs when substances are moved thru the simple columnar epithelial cells that line the GI tract wall and are absorbed into the blood or lymphatic capillaries located within the lamina propria
distinguish the action of the muscularis mucosae of the mucosal tunic from the muscularis tunic
muscularis mucosae is composed ofa thin layer of smooth muscle and it “shake things up” and the muscularis tunic is the inner circular layer
enteric nervous system
it consists of both sensory and motor neurons that extends from the esophagus to the anus
autonomic nervous system
it has the parasympathetic and the sympathetic nervous systems of the digestive system
short reflexes
its a local reflex and it only involes the enteric nervous system
long reflexes
it involves a sensory input from the central nervous system and serves as the integration center
the hormones that regulate the process of digestion
gastrin, somatosatin, cck, and secretin
what is the stimulus for release of gastrin
a bolus in stomach
what is the stimulus for release of somatosatin
if there is an increase in stomach acidity
what is the stimulus for release of cck
chyme entering duodenum, especially if chyme has a lot of fat
what is the stimulus for the release of secretin
chyme entering duodenum, especially if chyme has a lot of acid
the serous membrane is associated with the abdominopelvic cavity called what
the periotoneum.
the peritoneum is consisted of 2 serous membrane layers that are continuous with one another along what
the posterior abdominal wall
intraperiotneal organs
organs within the abdomin that are completely surrounded by visceral periotneum
retroperiotneal organs
they lie outside of the partial peritoneum directly against the posterior abdominal wall
Explain the function of the mesentery
it supports, suspends, and stabilizes the intraperitoneal organs
what are the five individual mesenteries of the abdominopelvic cavity
greater omentum, lesser omentum, falciform, mesentary proper, and mesocolon
greater omentum
extends inferiorly from the greater curvature and covers most of the abdominal organs
lesser omentum
connects the lesser curvature and the end of the duodenum to the liver
falciform
it attatches the liver to the to the internal surface of the anterior abdominal wall
mesentery proper
periotoneum that suspends most of the small intestine from the internal surface of the posterior abdominal wall
mesocolon
fold of the peritoneum that attaches the large intestine to the posterior abdominal wall (transverse/sigmoid)
what are the components of the upper gastrointestinal tract
oral cavity and salivary glands, pharynx, esophagus, and stomach
explain how the release of saliva is regulated
the salivary nuclei within the pons regulate salivation in response to parasympathic stimulation. viscous saliva is a result of sympathetic stimulation
describe the process of mastication
mechanical digestion in the oral cavity or chewing
Describe the anatomy of the pharynx and esophagus and their complementary activities in
the process of swallowing.
- entry of the bolus into the oropharynx
- elevation of the soft palate and the uvula to block the passageway between the oropharynx and the nasopharynx
- elevation of the larynx results in the epiglottis covering the trachea
what does the stomach do
the stomach secress highly aciditc gastric juices that facilitate the breakdown of food
Describe the three components of the lower gastrointestinal tract
small intestine, large intestine, and accessory digestive organs
what are the associated accessory digestive organs in the lower GI tract
liver, gallbladder, and pancreas
Identify and describe the anatomy of the small intestine
a long tube that extends between the stomach and the large intestine
List the glands found in the small intestine
goblet cells, enteroendocrine cells, and paneth cells, and duodenal submucosal glands
goblet cells
they produce mucin which lubricates and protects the intestinal lining
enteroendocrine cells
release hormones such as cck and secretin into the blood
paneth cells
assist with the functioning of the innate immune system
duodenal submucosal gland (brunner gland)
produces a viscous alkaline mucous secretion that protects the duodenum from the acidic chyme that enters from the stomach
when chyme first enters the small intestine ________ is more prevalent than peristalsis
segmentation
segmentation
mixes chyme with secretions from the accessory digestive organs thru a backward forward motion
________ propels material by alternating contraction of the muscle layers in the small intestine
peristalsis
List the accessory digestive organs associated with releasing secretions into the duodenum,
and describe the ducts that deliver these secretions
liver, gallbladder, and the pancreas biliary apparatus (liver and gallbladder) pancreatic ducts (pancreas)
oxygenated blood to the liver is delievered from ______
the hepatic artery
and deoxygenated blood ito the liver is delivered thru the _______
hepatic portal vein
how do blood and bile flow thru the liver
they enter into a sinusoid where blood is processed and then drained into the central vein of the lobule
Identify and describe the pancreas, and explain its general function in digestion.
it has endocrine and exocrine functions. exocrine cells produce pancreatic juice to assist with chemical digestion
Identify and describe the three major regions of the large intestine
the cecum, colon, and the rectum
four segments of the colon of the large intestine.
ascending, descending, transverse, and sigmoid
Explain the distinguishing histologic features of the large intestine.
lined by simple columnar epi with numorous goblet cells. it lacks intestinal villi. has intestinal crypts
Name the three classes of carbohydrates
monosaccharides, disaccharides, and polysaccharides
Explain the processing in the oral cavity that initiates carbohydrate digestion and how it is
completed in the small intestine.
digestion of starch begins in the oral cavity and is broken down by salivary amylase. starch digestion continues wothin the small intestine and is further broken down by pancreatic amylase
Explain why the proteolytic enzymes of the stomach and pancreas are synthesized in
inactive forms.
becasue they would destroy the proteins within the cells that produce them
Describe the activation of pepsin in the initiation of protein digestion in the stomach
HCl activates the formation of pepsin from pepsinogen
describe the role of pepsin in the initiation of protein digestion in the stomach
pepsin chemically digests proteins into shorter strands of amino acids
Describe the activation of proteolytic enzymes and the chemical digestion of proteins that
occurs in the small intestine.
tripsinogen, chymotripsinogen, procarboxypeptidase enter the small intestine and are activated by the enzyme enteropeptidase.
Explain the role of bile salts in mechanical digestion of lipids and the role of pancreatic lipase
in the chemical digestion of triglycerides.
bile salts emulsify lipids so that pancreatic lipase has greater access to triglyceride molecules and may more affectivly chemically digest the triglyceride molecules
