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35 Cards in this Set

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Describe the basic arrangement of tissues that forms the wall of the GI tract from the lower esophagus to the anal canal.
From the lower esophagus to the anal canal the GI tract wall is composed of 4 tissue layers: the mucosa, submucosa, muscularis, and serosa.
Name the 4 tissue layers of the GI tract wall from deep to superficial.
Mucosa
Submucosa
Muscularis
Serosa
Describe the composition of the mucosal layer of the GI tract wall.
The mucosa is the inner lining of the GI tract. It is a mucous membrane that is itself further subdivided into three layers.

The three layers of the mucosa are the epithelium, the lamina propria, and the muscularis mucosae
To which layer of the GI tract wall does the muscularis mucosae belong to?
The muscularis mucosae is part of the mucosal layer.
What is the etymology of mucosa?
Latin

mūcōsus

"slimy"
What is the rate at which epithelial cells of the GI tract are replaced?
Every 5-7 days the epithelial cells of the mucosa slough off and are replaced by
How many tissue layers is the GI tract wall composed of?
The GI tract wall has four principle tissue layers:

Mucosa
Submucosa
Muscularis
Serosa
What type of epithelial tissue lines the mucosal layer of the mouth, pharynx, esophagus, and anal canal?
Nonkeratinized stratified squamous epithelium

This type of epithelial tissue provides a protective function.
In which sections of the GI tract is the mucosa lined with stratified squamous epithelium?
Mouth, pharynx, esophagus, and anal canal.
What type of tissue is the lamina propria made of?
Areolar connective tissue
Where in the GI tract wall are the majority of cells of the mucosa-associate lymphatic tissue (MALT) located?
The majority of cells that comprise MALT tissue are found in the lamina propria of the mucosal tissue layer.
What is the function of the muscularis mucosae?
The muscularis mucosae causes the mucosal layer to form many small folds, thereby increasing the area available for digestion and absorption.
What causes the mucous layer of the GI tract to form many small folds, thereby increasing the area available for digestion and absorption?
This is caused by contraction of the muscularis mucosae, a thin muscle layer within the mucosa.
Is the mucosal layer vascular?
Yes

The lamina propria contains fine blood vessels and lymphatic vessels.
What can be found within the lamina propria (other than the areolar connective tissue that it's actually made of)?
Fine blood vessels
Lymph vessels
MALT tissue
What can be found in the submucosal tissue layer (other than the areolar connective tissue from which it's made)?
Numerous blood and lymphatic vessels

Submucosal plexus
Is the inner sheet of smooth muscle in the muscularis arranged circularly or longitudinally?
Circularly
Is the outer sheet of smooth muscle in the muscularis arranged circularly or longitudinally?
Longitudinally
Describe the arrangement of muscle sheets in the muscularis layer of the GI tract wall.
There are two sheets of smooth muscle in the muscularis: an inner sheet of circular muscle fibers and an outer sheet of longitudinal muscle fibers.
Where is the myenteric plexus located in the GI tract wall?
The myenteric plexus is located between the circular and longitudinal sheets of smooth muscle in the muscularis layer of the GI tract wall.
By which other name is the serosal layer of the GI tract wall known?
Visceral peritoneum
What is the serosa comprised of?
Areolar connective tissue
Which neuronal system is known as "the brain of the gut"?
Enteric nervous system
The enteric nervous system is arranged into two plexuses. What are they?
1) Submucosal plexus (submucosal layer of GI tract wall)

2) Myenteric plexus (muscularis layer of GI tract wall, between circular and longitudinal sheets)
Which plexus of the enteric nervous system (ENS) is responsible for GI tract motility?
Myenteric plexus
What is the ENS?
The ENS is the enteric nervous system, also known as the "brain of the gut."

The ENS is arranged in two plexuses: the MYENTERIC PLEXUS, located between the circular and longitudinal smooth muscle sheets of the muscularis, and the SUBMUCOSAL PLEXUS, located in the submucosal layer of the GI tract wall.

Motor neurons of the myenteric plexus control the smooth muscle of the muscularis and are thus responsible for GI tract motility.

Motor neurons of the submucosal plexus control secretory cells of the mucosal epithelium and are thus responsible for GI tract secretions.

Although the ENS can operate independently, the ANS connects to the ENS and can override it through sympathetic or parasympathetic stimulation.
What do the motor neurons of the submucosal plexus control?
The motor neurons of the submucosal plexus control the secretory cells of the mucosal epithelium, thereby controlling the secretions of the organs of the GI tract.
Motor neurons of which plexus of the ENS control secretory cells in the mucosal epithelium?
Secretory cells of the mucosal epithelium, and therefore the secretions of the organs of the GI tract, are controlled by the motor neurons of the SUBMUCOSAL plexus.
Motor neurons of which plexus of the ENS are responsible for GI tract motility?
Motor neurons of the MYENTERIC plexus control the contractions of the smooth muscle that comprises the muscularis layer of the GI tract wall.
What general effect does parasympathetic stimulation have on the GI tract wall?
In general, parasympathetic stimulation of the GI tract results in increased GI motility and increased GI secretions by stimulating motor neurons of the ENS.
What general effect does sympathetic stimulation have on the GI tract wall?
In general, sympathetic stimulation of the GI tract results in decreased GI motility and decreased GI secretions via inhibition of ENS motor neurons.
Which cranial nerve provides parasympathetic innervation to the GI tract?
Vagus nerve (CN X)
Which structures are supplied by branches of the celiac trunk?
1) Liver (hepatic artery)
2) Stomach (gastric artery)
3) Spleen (splenic artery)
From superior to inferior list the major arteries branching from the abdominal aorta and the respective structures that they supply.
1) Celiac trunk
-liver
-stomach
-speen

2) Superior mesenteric artery
-small bowel (duodenum, jejunum, ileum)
-ascending colon

3) Renal arteries
-kidneys

4) Inferior mesenteric artery
-descending colon
What is the splanchnic circulation?
The adjective visceral, also splanchnic, is used for anything pertaining to the internal organs, or viscera.

The singluar form of viscera, by the way, is viscus.

The splanchnic circulation, then, is the circulation that supplies and drains the viscera: the liver, gallbladder, pancreas, spleen, stomach, small bowel, and colon.