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122 Cards in this Set

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  • Back
What is the major function of the esophagus?
Transport
What is the major functions of the stomach?
Mechanical disruption, absorption of water and alcohol
What are the major functions of the small intestine?
chemical and mechanical digestion, absorption
What are the major functions of the large intestine?
Absorb electrolytes and vitamins, begin generation of feces.
What are the major functions of the rectum and anus?
defecation
What are the 4 major layers of the GI tract from the lumen outwards?
Mucosa, Submucosa, Muscularis, Serosa (adventitia).
What two plexuses are associated with the GI tract? Which one is found everywhere in the GI tract?
The submucosa plexus (plexus of Meissner) is found throughout most of the GI tract. THe Myenteric plexus, (plexus of auerbach) is found everywhere in the GI tract.
What are the 3 layers of the mucosa from the lumen outwards?
Epithelium, lamina propria, muscularis mucosae.
Where are most of the glands and neurons found?
In the submucosa.
What tissue type is the submucosa?
Fibroelastic CT.
What are the 2 layers of the muscularis layer? Which one is more internal?
The circular muscle layer is internal to the longitudinal muslce layer.
What are the two layers of the serosa from most internal to external?
The connective tissue and the epithelium
What layer is sometimes continuous with the peritoneom in the GI tract?
The Epithlium layer of the serosa.
What type of epithelium is the mucosa in the esophagus and anus? What purpose does this serve?
Stratified squamous, is protective.
What type of epithelium is the mucosa in the GI tract in everywhere but the esophagus and anus? What is its purpose?
Simple Columnar, secretes enzymes and absorbs nutrients.
What do goblet cells do?
Secrete mucous onto cell surfaces.
What do enteroendocrine cells do?
Secrete hormones.
Where are Goblet cells and enteroendocrine cells found?
In the mucosa.
What is the lamina propria?
A thin layer of loose CT.
What is the muscularis mucosae? How many layers is it usually made up of? Where is it made up of a different number?
A thin layer of smooth muscle. Usually made up of 2 layers. 1 discontinuous layer in the esophagus.
What type of tissue is the submucosa?
Loose fibroelastic CT>
What does the submucosa contain?
BV, glands, lymphatic tissue, Meissner's plexus.
Where is the only places the submucosa containes glands?
esophagus and duodenum.
Where is skeletal muscle found in the GI tract? What is the purpose of this muscle?
The skeletal muscle is found in the mouth, pharynx, upper esophagus and anus. It allows for control over swallowing and defecation.
What two layers make up the smooth muscle of the GI tract? What do they do?
The inner circular fibers and outer longitudinal fibers. They mix, crush and propel food along by peristalsis.
What innervates the circular and longitudinal smooth muscle layers?
Auerbach's plexus (myenteric)
Embryologically, where all are the neurons and support cells of the gut derived from?
Neural crest.
What is the function of the myenteric plexus (auerbach's plexus) and where is it located?
IT is mostly motor and it regulates peristalsis. It is located between muslce layers in the muscularis externa.
Is the enteric system part of parasympathetic and sympathetic ganglia?
NO
What is the function of the submucosal plexus (Meissner's plexus) Where is it located?
Mainly secretory-motor, it releases hormones and peptides and innervats the mucosa. IT is located in the submucosa.
What signalling molecule does the parasympathetic autonomic inputs to the GI tract have and what do they do?
ACh increasees motility.
Where does most of the parasympathetic input to the gut come from?
The vagus nerve.
What signalling molecule does the sympathetic autonomic inputs to the GI tract have and what do they do?
NE relaxes the gut.
What external signal tells myenteric cells to activate?
Activation of EC cells via a bolus of food deforming the villous surface of the gut.
Which is more internal the myenteric plexus or the submucosal plexus?
The myenteric plexus is outside of the submucosal plexus.
Do the myenteric plexus and submucosal plexus communicate?
YES
Together what do the submucosal plexus and the myenteric plexus make up?
The enteric plexus.
What is the funciton of the esophagus?
Move masticated food.
Describe the epithelium of the esophagus.
Stratified squamous epithelium.
Describe the muscularis mucosae of the esophagus.
Single layer of smooth muscle irregularly distrubuted and discontinuous.
Describe the lamina propria of the esphagus. What is found in it?
Dense irregular CT, diffuse lymphoid tissue, arterioles and venules. Also esophageal -cardiac glands, pharynx and gastric junction and sero-mucous glands.
What type of secretion do esophageal cardiac glands secrete?
mucous.
Describe the submucosa of the esophagus. WHat is found in it?
Dense fibroelastic CT. Also has esophageal glands.
What do esophageal glands secrete?
Seromucus, pepsinogen, lysozyme. (beginning of digestion).
Describe the transition of muscle from upper to lower region of the esophagus.
Upper region-All skeletal
Middle - skeletal and smooth
Lower - All Smooth
What is the adventitia or serosa of the esophagus continuous with?
The adventition of the diaphragm.
What are the four parts of the stomach?
Cardia, fundus, body, pylorus
Which part of the stomach is continuous with the esophagus?
The cardia.
What is the main function of the stomach?
Mechanical and chemical digestion.
What 4 chemicals does the stomach release? What do each of them do?
Hydrochloric acid - activates pepsinogen
Pepsin
Renin-milk/calcium metabolism
Gastric lipase
How many layers of smooth muscle does the stomach have? Give them in order from deepest to most superficial.
Oblique, Circular, longitudinal
What is the purpose of the oblique muscular layer?
Adds strength.
What do the dips in the epithelial lining form?
Gastric pits.
What are at the bottom of gastric pits?
Gastric glands.
What is found in the submucosa of the stomach?
Arteries, veins
What are rugae and where are they found?
Folds of mucosa and submucosa of the stomach.
What forms gastric pits?
Invaginations of the epithelium
Where are gastric glands found?
IN the lamina propria and they open into gastric pits.
Which layer of the muscularis externa forms the pyloric sphincter?
The middle circular layer.
What 6 cell types are found in the stomach? Give them in order from most superficial to deepest (going from the lumen in).
Surface lining cell, regenerative cell, mucous neck cell, parietal cell, chief cell, enteroendocrine cell.
Describe the action of regenerative cells in the stomach epithelium.
The migrate up and down and replace all cell types in gland and pit.
Where are regernation cells found only at the base of the glands?
Small intestine.
What are the 3 regions of glands from most superior to inferior (lumen inwards)?
Isthmus, neck, base.
What do parietal cells secrete?
Hydrochloric acid and gastric intrinsic factor.
What do Chief cells secrete?
Pepsinogen, gastric lipase, renin.
What do enteroendocrine cells secrete?
Glucagon and gastric inhibitory peptide (prevent further HCl production from parietal cells).
What does HCl do in the gut?
Converts pepsinogen from chief cell pepsin.
What is gastric intrinsic factor for? What secretes it?
Parietal cells secrete it to absorb Vitamin B12.
What does gastric hormone do?
Release more gastric juice, increase gastric motility, relax pyloric sphincter, constrict esophageal sphincter.
What is the primary cell type in the cardiac mucosa of the stomach? What cell do they lack?
Mostly surface lining cells. NO chief cells.
What cell types are present in the fundic mucosa?
All cell types present, regenerative cells replace most of them.
What type of cells are found in the pyloric mucosa?
Mainly mucous neck cells, only a few chief cells.
Destinguich the glands between the cardiac mucosa, fundic and body mucosa, and the pyloric mucosa.
Cardiac - glands highly coiled, gastric pits shallow
Fundic and body - glands long and straight, gastric pits short
Pyloric mucosa - glands branched and deep, gastric pits deep.
Which section of the stomach mucosal glands has the shortest isthmus?
Fundic and body mucosa
Which section of the stomach mucosal glands has the longest isthmus?
Pyloric mucosa.
Describe the changes that Parietal cells undergo to secrete HCl.
They change structure to secrete.
What are the 3 ways HCl is produced from parietal cells? What is the signalling molecule associated with each?
Gastrin (stretch on EC cells)
Histamine (stretch on EC cells)
Acetylcholine (vagus nerve, psychological)
What is the major stimulus for HCl release in the stomach?
Stretch of stomach.
What is the #1 major purpose of the small intestine?
Absorption.
Which is longer the duodenum, jejunum, or ilieum?
The ileum is longest followed by the jejunum and finally the duodenum is only 10 inches long.
What is the purpose of villi in the small intestine?
Increase surface area
Where are regenerative cells found in the small intestine?
At the base of the crypt of lieberkuhn.
What cells are found in the small intestine? (5)
Surface absorptive, goblet cell, enteroendocrine cell, regenerative cell, paneth cell.
What are plicae circularis? What is their function? What layers do they involve?
Plicae circularis are large folds of the mucosa and submucosa. Their purpose is to increase surface area.
Where are villi found inthe small intestine?
On top of the plicae circularis.
What lines the villi inthe small intestine?
Microvilli
What are the 4 functions of surface absorptive cells in the small intestine?
Absorb water, reesterify fatty acids, form chylomicrons, trnasport and absorb nutrients.
Describe the villi of the duodenum. What cells are theier few of? What special gland is found here?
THe villi are broad, numerous, and tall. They have few goblet cells. They also have Brunner's glands.
What are Brunner's glands and where are they found? What ist their morphology? What is their purpose?
Brunner's glands are found in the submucosa of the duodenum. They are tubular alveolar and the secrete an alkaline secretion to neutralize chyme.
Describe the villi of the jejunum. What cell type is found in large numbers here?
Their villi are narrow, shorter, and less dense than in the duodenum. They have many goblet cells.
Describe the villi of the ileum. What special cells are found here? What sort of cells to they have many of?
The villi are the shortest, narrowest, and smallest in number of the small intestine. They also have peyer's patches and microfold cells. They also have many goblet cells.
What is the only place peyer's patches are found?
Ileum.
What are microfold cells? Where are they found? What do they do?
Microfold cells are found over the peyer's patch in the ileum. They pick up and transport antigens (M cells).
What cells are found in the crypts of intestinal glands?
Stem cells and paneth cells.
What do crypt cells secrete?
IgA
What cell type is diagnostic of the small intestine? Describe them.
Paneth cells (large, full of granules, secretes lysozyme, at base of gland)
What do paneth cells do?
Secrete lysozyme (kills bacteria).
Where do glands open in the small intestine?
In between villi.
Describe enteroendocrine cells.
Triangle shapped, large nucleus, at the base of gland.
What type of glands are the crypts of lieberkuhn associated with?
Simple or branched tubular glands.
What are the crypts of lieberkuhn comprised of? (5) (cell types)
Surface absorptive cells, goblet cells, regernative cells, enteroendocrine cells, paneth cells.
What type of glands are Brunner's glands? Where are they found?
Branched tubulo alveolar glands (secrete mucous alkaline fluid to neutralize chyme). Brunner's glands are found in the submucosa of the duodenum.
How long is the large intestine?
5 ft 2 in
How long is the rectum?
8 in
How long is the anal canal?
1 in
What type of muscle and control is involved in the internal sphincter?
Internal sphincter
Smooth muscle
Involuntary control
What type of muscle and control is involved in the external sphincter?
External sphincter
Skeletal muscle
Voluntary control
What 4 cell types are found in the large intestine?
Absorptive, goblet, regenerative, enteroendocrine cell
What special feature does the large intestine have? What does it lack? What type of cells does it have many of?
Large intestine has crypts of lieberkuhn, no villi or paneth cells. Numerous surface absorptive cells and dense goblet cells.
Describe the musclular layer of the large intestine.
Normal circular layer with an unusual longitudinal musculature (Taenia coli).
What does the visceral peritoneum = in the large intestine?
Serosa
What are taenia coli and how many are there?
They are an outer longitudinal layer that forms three fascicles.
What do taenia coli form? How do they do this?
Taenia coli form Haustra coli or sacculations by maintaining constant tonus.
What are haustra coli?
Large bumps of the large intestine formed by taenia coli
How are the crypts in the rectum and anal canal different from the colon? How about goblet cells?
They are few and deeper crypts. ALso more goblet cells.
What are the most numerous cells of the rectum and anal canal?
The surface absorptive cells.
What happens to the epithelium at the rectal anal junction? what type of glands are found here?
Epithelium becomes stratifed squamous keratinized. Also branched circumanal glands are found here.
What is the point at which longitudinal smooth muscle disappears in the anus?
Puborectalis.
What happens to the epithelium at the pectineal line?
Columnar -> PCE
What forms the internal anal sphincter?
The circular muscle.
What plexus is found near the anal canal?
The external hemprroidal plexus.
What do the anal columns do?
The anal columns of margandy provide the strength and flexibility to create and hold a column of feces.