Digestive System II Flashcards
What are the four layers of the GI tract?
1) mucosa (mucous membrane)
2) submucosa
3) Muscularis externa
4) Adventitia or Serosa
What is the thin covering or sac that holds all the intestines and organs in place in the torso of the body?
mesentaries
The inner layer of the GI tract, the mucosa, is composed of what three layers (from innermost to outermost)?
1) epithelium
2) lamina propria
3) muscularis mucosae
The third layer of the GI tract, the musculari externa, is composed of what two layers (from innermost to outermost)?
1) inner circular layer
2) outer longitudinal layer
The external layer of the GI tract, the adevntitia or serosa, is composed of what?
1) areolar tissue
2) mesothelium
Which layer of the GI tract wall is composed of smooth muscle?
muscularis externa
What are the two nerve plexi in the GI tract wall?
1) submucosal nerve plexus
2) myenteric nerve plexus
What is the nervous system the controls the gut called?
Enteric nervous system
Which nerve plexus of the ENS regulates mucosal tension and folding, and secretion of mucosal glands?
submucosal nerve plexus
Which nerve plexus regulates peristalsis of the submucosal plexus?
myenteric plexus
The esophagus extends from which two functioning points at the cardiac orifice?
From the upper esphogeal sphincter to the lower esophogeal sphincter
What kind of epithelium makes up the esophagus?
nonkeratinized stratified squamos epithelium
Which two glands are found in the esophagus?
1) mucous submucosal glands
2) esophageal glands
The muscularis externa has an inner ____ muscle layer and an outer ____ muscle layer.
circular; longitudinal
Which layer in the esophagus are esophageal glands located?
lamina propria
What is the boundary located between the submucosal glands and the esophageal glands?
gastroesophageal junction
What are folds within the stomach called that grind chunks of food?
gastric rugae
Food enters into the stomach from the ____ and exits the stomach through the ____.
esophagus; duodenum
The muscular layers of the stomach are found in what layer?
muscularis externa
What is the mucous layer of the stomach composed of?
1) epithelium
2) gastric pits
3) glands
4) lamina propria
5) muscularis mucosae
What is the submucosa layer of the stomach composed of?
1) connective tissue
2) blood vessels
3) submucosal plexus
What is the muscularis externa layer of the stomach composed of?
1) three muscle layers
2) myenteric plexus
Which special cells are associated with gastric pits (two kinds)?
parietal cells and goblet cells
Which kind of epithelium are gastric pits lined with?
simple columnar epithelium
What opens into the base of each gastric pit?
gastric glands
Which kind of glands dominate the stomach? Why is this?
mucous glands; it helps prevent corrosion
What are the three glands found in the stomach?
1) cardiac glands
2) pyloric glands
3) gastric glands
Which glands of the stomach are composed of shallow gastric pits, a long gland, and is purely mucous? Which region are they found?
cardiac glands; cardiac region
Which glands of the stomach have deep gastric pits, are shorter glands, are loosely arrayed in the lamina propria, and are purely mucous? What region are they found?
pyloric glands; pyloric region
Which glands of the stomach have a mouth, neck, body, and fundus and have five types of cells? What region are they found?
gastric glands; fundus, body, and most of the pyloric region
What are the five cells of the gastric glands?
1) stem (regenerative) cells
2) mucous neck cells
3) parietal (oxyntic) cells
4) chief (zymogenic) cells
5) enteroendocrine cells
Which two cells of the gastric glands secrete proteins?
- parietal (oxyntic) cells
- chief (zymogenic) cells
What do parietal cells secrete in the gastric glands?
- hydrochloric acid (HCl) - pH 8
- Intrisic factors
What do chief cells secrete in the gastric glands?
- pepsinogen
- gastric lipase (infants)
- chymosin (infants)
What do enteroendocrine cells secret in the gastric glands?
- hormones
- paracrines
What do mucous neck cells secrete in the gastric glands?
mucus
Purposes of hydrochloric acid:
1) activates ____ and ____ lipase
2) breaks up connective tissues and ____ fiber (collagen and cellulose)
3) converts Fe3+ to ____.
4) nonspecific disease resistance aka ____ properties
1) pepsin; lingual
2) plant
3) Fe2+
4) antibacterial
Which region of the stomach have the deepest gastric pits?
pyloric stomach
The gastric pits in the pyloric region of the stomach are somewhat ____, giving a sawtooth appearnce.
coiled
What do G cells in the stomach secrete?
gastrin
What do ECL cells in the stomach secrete?
histamine
What do D cells in the stomach secrete?
somatostatin
What is the function of the parietal cells secretion?
- Kills microbes and activates pepsinogen
- Bind Vitamin B12 to allow its absorption
What is the function of the chief cells secretion?
- protein digestion
- fat digestion
What is the function of the G cells secretion?
stimulates gastric acid secretion
What is the function of the ECL cells secretion?
stimulates gastric acid secretion
What is the function of the mucus-neck cells secretion?
protects stomach epithelium from acid
What is the function of the D cells secretion?
inhibits gastric acid secretion
Even though HCl kills most bacteria in the stomach, which bacteria sits deep within the stomach and can cause ulcers?
H. pylori
At what point does the small intestine start, and where does it end?
starts - pyloric sphincter
ends - ileocecal valve
What is the order of the regions of the small intestine called starting from where food travels through first to where it ends?
1) duodenum
2) jejunum
3) ileum
Which portion of the small intestine includes chyme, bile, and pancreatic juice?
duodenum
Which portion of the small intestine is the site of most digestion and absorption?
jejunum
Which portion of the small intestine has a thinner wall, and is the site of the rest of digestive and absorption properties?
ileum
What is the upper region of the small intestine called (duodenum region)?
epigastric region
What is the middle region of the small intestine called (jejunum)?
umbilical region
What is the lower region of the small intestine called (ileum)?
hypogastric region
What are the four things that increases intestinal surface area?
1) length
2) circular folds
3) villi
4) microvilli
What is the total surface area of the small intestine?
~2150 square feet
What is the main factor which increases surface area in the small intestine which is mainly prevalent in the jejunum?
circular folds (pilcae circulares, valves of Kerckring)
Why is a large surface area important in the small intestine?
- slows the progression of chyme
- makes chyme spiral down the intestine
- increases epithelial contact for digestion and absorption
Which type of villi has a ridge-like appearance?
foliate villi
Which type of villi has a tounge-shaped appearance?
linguiform villi
Which component of villi helps transport lipid molecules?
lacteal
What are the absorption cells called in villi?
enterocytes
What type of cells are located on villi and aid in secretions (different from absorption cells?
goblet cells
What is a dense cytoskeleton aggregation at the apical pole of the cell? What filament is anchored here?
terminal web; actin filaments
Which intestinal cells secrete antibacterial lysozyme?
Paneth cells
What glands within the duodenum are located in the submucosa?
Duodenal glands
What is another name for duodenal glands?
Glands of Brunner
Which portion of the small intestine has Peyer’s patches?
ileum
Which portion of the small intestine have the shortest villi and more lymphocytes than anywhere else?
ileum
What are all the parts of the large intestine?
1) cecum
2) appendix
3) colon
4) rectum
5) anal canal
What are the different regions of the colon?
1) ascending
2) transverse
3) descending
4) sigmoid
What is the main functions of the large intestine?
- absorption of water and electrolytes
- water conservation
- consolidation of residue into feces
- defaction
What tissue is the appendix mainly composed of?
GALT
What surface area enhancer does the colon have? What does it not have?
have - intestinal crypts
doesn’t have - villi, circular folds
In the intestinal crypts of the colon, which cells give rise to neutrophils which help with anibacterial defense?
STEM cells
What are the two sphincters of the anal canal?
- internal anal sphincter
- external anal sphincter
Which sphincter in the anal canal is involuntary?
internal anal sphincter
Which sphincter in the anal canal is voluntary?
external anal sphincter
Which kind of muscle controls the external anal sphincter?
skeletal muscle