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Flashcards in Digestive System Deck (39):

T/F the structural organization of the wall of the alimentary canal is the SAME from proximal part of esophagus to distal part of anal canal



Another name for the alimentary canal

GI tract


Organs of the GI tract

mouth, pharynx, esophagus, stomach, SI, LI


Associated/Accessory Digestive organs

tongue(PB). teeth(PB), salivary gland(S), pancreas(S), liver(S), and gall bladder(S)

PB=physical breakdown


From lumen outward, what is the structural organization of the alimentary canal?

1. Mucosa made up of lining epithelium, lamina propria, and muscularis mucosae
2. Submucosa
3. Muscularis externa
4. Serosa or adventitia


2 types of epithelium that make up the lining epithelium component of mucosa

Nonkeratinized stratified squamous epithelium - lines the mouth, pro/laryngopharynx, and esophagus

Simple columnar epithelium - line stomach, SI, and LI


What type of tissue makes up lamina propria and muscularis mucosae?

Lamina propria - looser areolar CT

Muscularis mucosae - Smooth muscle tissue


What type of tissue makes up submucosa?

Dense irregular CT


What is the plexus found in submucosa?

Meissner's plexus


What type of tissue makes up musclaris externa and what are the two layers that make it up?

smooth muscle tissue

Layers are inner circular and outer longitudinal


What is the plexus found in muscularis externa?

Myenteric or Auerbach's plexus


What is the function of the inner circular and outer longitudinal layers?

Inner - can be thickened to form sphincters or valves

Outer - dilates lumen causing GI tract to shorten


What type of tissue makes up serosa and adventitia?

loose areolar CT


WHat is the difference between serosa and adventitia?

Serosa - lubrication

adventitia - bind structures together


Describe the layers of the esophagus

Mucosa - nonkeratinized stratified squamous epithelium

Muscularis externa - Proximal 1/3 is skeletal, middle 1/3 is both, and distal 1/3 is smooth (goes from voluntary to involuntary)

Serosa or adventitia


Glands of the esophagus

esophageal glands (proper) - in submucosa
esophageal cardiac glands - in lamina propria


Role of the esophagus

-produce mucous.
-protect esophageal wall, especially where connects with stomach because of low pH. This is why so much mucous at distal end
-move food


Role of stomach

-chyme produced due to partial digestion in stomach
-mixing and holding area for food
-chemical digestion begins of proteins and fats
-little bit of absorption (<10%)


Gross anatomical subdivisions of stomach

1. Cardia - surround opening to entry
2. Fundus - superior and left of cardia
3. Body - large central area inferior to fundus
4. Pylorus - funnel shaped region


Histological subdivisions of stomach

1. cardia - cardiac glands; primarily mucous
2. fundus/body - gastric glands contain cells that secrete HCl and pepsin (3 parts: isthmus, neck, and base)
3. pylorus - pyloric glands; primarily mucous b/c help mediate low pH


Describe the layers of the stomach

Mucosa - non-ciliated, simple columnar epithelium, and gastric pits that lead to glands (simple branched tubular glands)


Muscularis externa - 3 layers of smooth muscle (outer longitudinal, middle circular, and inner oblique)

Serosa - on outside, no adventitia


Role of the SI

Large SA for absorption
-long length (10ft living, 21ft cadaver)
-plicae circulares (submucosa core)
-villi (fingerlike projections of mucosa
-microvilli (projections of apical membrane of intestinal absorptive cells; striated border)


Decribe the layers of the SI

Mucosa - epithelium is simple columnar epithelium
- absorptive cells and goblet cells
-Crypts of Lieberkuhn (intestinal glands)
-tubular glands
-paneth cells (only in SI)
-enteroendocrine cells
-stem cells

Submucosa - duodenum - Brunner's glands
-produces alkaline mucous glands

Muscularis externa
-2 layers (outer longitudinal and inner circular)

Serosa or adventitia


In the ileum, groups of lymphatic nodules are present in the lamina propria and submucosa. These aggregated lymphatic follicles are referred to as what?

Peyer's patches


Specialized epithelial cells in ileum overlying Peyer's patches are called what?

M (miccrofold) cells


T/F The LI has plicae circulares and villi?

False. Only SI


Describe the layers of the LI

Epithelium - simple columnar epithelium
Crypts of Lieberkuhn (intestinal glands)
-tubular glands
-absorptive cells
-goblet cells
-enteroendocrine cells
-stem cells
Lamina propria - lymphoid cels and lymphoid nodules


Muscularis extera - 2 layers
-teniae coli is outer longitudinal

Serosa or adventitia


T/F SI have paneth cells while LI don't



Name the different parts of the pancreas

Uncinate process, head, neck, body, and tail


What percent of the pancreas functions as an exocrine gland and what are the glands called?

98-99% and compound acinar glands


What percent of the pancreas functions as an endocrine gland and what are the glands called?

1-2% and islets of langerhans


What do the exocrine glands do?

produce enzymes (bicarbonate) that are put into ducts that enter the duodenum
-this increases the pH of chyme


What percentage of the blood coming to the liver is oxygenated from the hepatic artery and what percentage is from deoxygenated blood from hepatic portal vein

25% oxygenated
75% deoxygenated


Name the pathway of blood from liver to right atrium

Hepatic artery and hepatic vein
to liver sinusoids
to central vein
to hepatic vein
to IVC
to RA of heart


What are structual and functional units that compose the liver called?

hepatic lobules


These are the largest cells lining the sinusoids. Their function is to be phagocytic or breakdown damaged or old RBCs that reach the liver from the spleen

Kupffer Cells


What is a thin tube that collects bile secreted by hepatocytes. They merge to form bile ducts that become common hepatic duct

Bile canaliculi


Function of the gallbladder

store and concentrate bile


Describe the layers of the gallbladder

Has mucosa, muscularis propria and serosa on free surface
No muscularis mucosa or submucosa is present