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
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)
From lumen outward, what is the structural organization of the alimentary canal?
1. Mucosa made up of lining epithelium, lamina propria, and muscularis mucosae
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?
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
-protect esophageal wall, especially where connects with stomach because of low pH. This is why so much mucous at distal end
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)
-paneth cells (only in SI)
Submucosa - duodenum - Brunner's glands
-produces alkaline mucous glands
-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?
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)
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
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 RA of heart
What are structual and functional units that compose the liver called?
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
What is a thin tube that collects bile secreted by hepatocytes. They merge to form bile ducts that become common hepatic duct
Function of the gallbladder
store and concentrate bile