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20 Cards in this Set

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What are the functions of the muscularis mucosae layer and the muscularis externa layer?
Muscularis mucosae: this thin layer of muscle is the outermost layer of the mucosa. It is responsible for agitating the epithelial folds and preventing food from getting stuck in them.
Muscularis Externa - contractions here produce peristalsis
what is the difference between a serosa and an adventitia?
Serosa: outermost layer of connected tissue that is covered by visceral peritoneum.
Adventitia: NOT covered by visceral peritoneum!
** the vagus nerve makes a plexus in the adventitia and rides the esophagus train into the abdomen!
What 2 things are found in the submucosa of the GI tract?
exocrine glands (glands which secrete onto a body surface), and post-ganglionic autonomic nerves
Does the esophagus have a serosa or an adventitia?
BOTH! There is an adventitia in the thorax, but it gets covered in peritoneum and becomes a serosa once it passes the diaphragm! Tricky!
The muscularis layer of the esophagus has 3 regions.... what are they? What creates them?
The constrictor muscles are skeletal, voluntary muscle that transition gradually into esophageal smooth muscle, Thus the esophagus has skeletal muscle at the proximal1/3 , a mixture in the middle and smooth muscle at the distal 1/3.
What 2 things are found in the submucosa of the esophagus? What is the function of one of them?
1. The submucosal vascular plexus
2. Seromucous submucosal glands: when you swallow a bolus it distends the esophagus and squeezes out secretions which lubricates the passage of food
In what way is the esophageal epithelium ideally suited to its function?
It is non-keratinized b/c it doesn't need to be water proofed, and it is stratified squamous to accommodate it's exposure to lots of wear and tear (doesn't need to be simple epithelium b/c doesn't absorb anything).
What is special about the esophageal muscularis mucosae layer?
What is a special adaptation of the CT in the lamina propria? (what are 2 benefits from this adaptation)
It contains only longitudinal muscle and no circular.
The CT of the lamina propria has papilla which extend up into the epithelium to increase the contact surface area and increase anchorage strength. The papillae also contain bvessels that carry nutrients to outermost cells.
What is Barret's Esophagus?
In response to chronic GERD, the epithelium in the distal 1/3 of the esophagus can change into gastric mucosa (ie undergoes metaplasia and becomes simple columnar cells), When this happens 5-10% of cases will go on to develop cancer.
Clusterso epithelial cells called acini empty into intercalated ducts.
What do the acinar cells look like and what do they secrete? What are they stimulated by?
What do the epith of ducts secrete? What stimulates them?
Acinar cells have a basophillic base (blue ring around outside of the acini) and an eiosinophilic apical cytoplasm (d/t stored secretory granules). THey secrete Ptic enzymes in response to cholecystikinin.
The epith of intercalated ducts secrete a watery alkaline fluid in response to secretin. This fluid neutralizes the gastric pH.
In the pancreas, intercalated ducts join progressively larger ducts and empty eventually into the main or accessory pancreatic duct. How does their epithelium change as they do this?
The epithelium of the smaller ducts is cuboidal and becomes stratified cudoidal in the larger ducts
The endocrine portion of pancreatic tissue is interspersed among the exocrine acini. What does it look like and what types of cells contribute each of it's 3 main secretions?
Spherical clusters of pale staining epithelial cells, interspersed with a rich plexus of fenestrated capillaries and surrounded by reticular fibers = endocrine bits of the pancrease.
α-cells = glucagon (tend to occupy the periphery of the islet)
β-cells = insulin (tend to be larger and at the centre of the islet)
δ-cells = somatostatin
** don't have to differentiate these
*** careful that you don't confuse islets with ganglia! ***
Does the stomach have a serosa or an adventitia?
what and where is it's extra layer of muscle?
what forms the rugae in the empty (non-distended) stomach?
The stomach has a serosa b/c mostly covered in peritoneum
There is an oblique layer of muscle in the body of the stomach. It is the innermost part of the muscularis (borders the submucosa)
The Rugae of the stomach are formed by the submucosa
What type of epithelium is in the mucosa of the stomach?
There are gastric pits and glands in the mucosa. What is the difference between the glands of the body & fundus, vs the glans of the carida and pylorus
simple columnar epithelium on a CT lamina propria and muscularis mucosa.
Body & fundus = straight glands
Pylorus & cardia = shorter and coiled glands, with mucous cells predominating
What does the parietal cell look like and what does (2) it secrete?
What does the chief cell look like and what does it make?
What does the enteroendocrine cell look like and what does it make?
Parietal: Very eiosinophilic (pink); secretes HCl and intrinsic factor
Chief: basophilic b/c of all it's RER's; makes digestive enzymes.
Enteroendocrine: difficult to id in the stomach - look for granules at apical end b/c that's where they secrete (onto CT). Make hormones for local coordination of tissue
The small intestine has a typical serosa and muscularis layer. What 2 things are special about the submucosa?
What type of epithelium makes up the mucosa layer?
SI submucosa:
1. Plicae circulares - semicircular folds the get smaller and less frequent as you go towards ileum
2. Brunner's glands - mucous glands that make a an alkaline mucuous to neutralize stuff coming out of duodenum
Mucosa: simple columnar epithelium that project as villi and invaginates as crypts (of Liberkuhn) ** brush border! **
In the small intestine, what does an M cell do?
What does a paneth cell do?
Looks like upside-down bowl. These cells will endocytose the contents of the intestinal lume and present it to the APCs of the immune system.
Paneth cell - synthesize and secrete lysozomal enzymes and a-defensins which will attack bacteria and cause them to lyse.
What 3 structures are found in the lamina propria of the small intestine?
1. bands of smooth muscle - change the shape of the villi
2. Peyer's patches - large clusters of lypmocytes that brak through into the submucosa (most prominent in the ileum)
3. Capillary plexuses to carry away the products of digestion and lacteals to carry away the fat
Large Intestine:
1. Serosa - contains what?
2. Describe the inner and the outer layers of the muscularis,
1. Serosa - has pendulous pockets of fat clled the appendices epiplocae
2. Muscularis - inner circular layer thickend to for internal anal sphincter at rectoanal junction. Outer layer is 3 ribbons (taenia coli) - complete lay in appen/rectum
The large intestine has a typical submucosa. Describe how the mucosa is different:
- type of epithelium? (the crypts are tightly packed & there's no villi)
- What cell predominates? 6 others?
* the muscularis mucosa disappears abover the rectoanal junction - submucosa & LP blend
LI mucosa = simple columnar epithelium with abrupt transition to stratified squamous epithelium at recto-anal junction.
- Goblet cells predominate; also have enterocytes, M-cells, enteroendocrine, Paneth (few), and intraepithelial lymphocytes
** Vascular plexus drains to both systemic and portal veins. If either get blocked --> hemorrhoids