GI Tract (Exam III) Flashcards
What is the name of the canal that extends from the oral cavity to the anus?
alimentary canal
What are 5 phases of food breakdown?
- ingestion
- fragmentation
- digestion
- absorption
- elimination
____ occurs in the oral cavity, accompanied by _____; resulting in ____ formation
ingestion; fragmentation; bolus
The stomach completes ____ & initiates ____
fragmentation; digestion
Contractions of smooth muscles in GI system:
peristalsis
Peristalsis is under ___ control
autonomic
What do pancreatic and biliary secretions in the duodenum do?
emulsification of fat
Where does emulsification of fat occur?
duodenum
What occurs in the jejunum and ileum?
primary absorption of nutrients
What occurs in the colon?
resorption of water & elimination of waste
The muscular tube of GI tract lined by:
mucus membrane
There are a large number of ____ associated with the GI tract
glands
List 3 glands associated with GI tract
- liver glands
- pancreas glands
- intestinal glands
The liver, pancreas and intestinal glands all have what in common?
All embryological outgrowths of the GI tract
Diffuse lymphoid tissue scattered throughout GI tract:
MALT and GALT
What are the 4 distinct layers of the GI tract:
- mucosa
- submucosa
- muscularis externa
- Adventitia (serosa)
The mucosa has 3 overall functions including:
- protection
- secretion
- absorption
Different types of mucosa are modified for:
diferent functions
The mucosa of the GI tract is subdivided into 3 layers including:
- epithelium
- lamina propria
- muscularis mucosae
The layer of mucosa that has secretory & absorptive function;
epithelium
The ____ layer of the mucosa has different modifications at different levels of the GI tract
epithelium
The layer of mucosa- underlying connective tissue
lamina propria
What are some components of the lamina propria? (4)
- lymphoid nodules
- glands
- blood vessels
- lymphatics
The layer of mucosa- thin layer of smooth muscle
muscularis mucosae
The layer of mucosa that is a boundary between the mucosa and submucosa
muscularis mucosa
What does the muscularis mucosa act as a boundary between?
mucosa & submucosa
There are large numbers of ___ & ____ cells in the lamina propria:
lymphocytes and plasma cells (immune surviellence)
Layer of the gut - loose to dense irregular connective tissue layer beneath the muscularis mucosa:
submucosa
Layer of the gut responsible for supporting mucosa:
submucosa
List the components of submucosa:
Larger blood vessels, nerves and lymphatics
Inner circular and outer longitudinal smooth muscle layers of the gut:
muscularis externa
The muscularis externa may also be called:
muscularis propria
The smooth muscle fibers of the muscularis externa are oriented at:
right angles to one another
The inner circular layer of the muscularis externa (propria) contains fibers:
fibers going circumferential around the gut
The outer longitudinal layer of the muscularis externa contains:
muscle fibers orieneted at right angles to one another
The local contractions that result in mixing of food in the gut:
segmentation
Segmentation occurs both ___ & ____ in either direction
proximally and distally
____ propels food only in the distal direction
peristalsis
Overall effect is like kneading bread dough that results in mixing food with digestive secretions but NOT pushing food down the gut
segmentation
When talking peristalsis, another term we can use to describe the direction that food is pushed is ____ which means ____.
Aborally; away from mouth toward anus
Describe the contractions of peristalsis
forecful an organized
Outer loose connective tissue layer of the gut that contains major nerves, vessels, and adipose tissue
adventitia
The adventitia within the abdominal cavity is referred to as:
serosa or visceral peritoneum
The adventitia in the gut (serosa/ visceral peritoneum) is continuous with:
supporting mesentery
The adventitia of the gut (serosa/visceral peritoneum) is lined by:
simple squamous epithelium (mesothelium)
In other areas, the adventia (serosa/visceral peritoneum) merges with:
retroperitoneal tissue
The smooth and shiny surface of the gut
adventitia (serosa/visceral peritoneum)
The smooth muscle of the gut is controlled by:
autonomic nervous system
The parasympathetic stimulation of the smooth muscle of the gut results in:
excitatory
The sympathetic stimulation of smooth muscle of the gut results in”
inhibitor
The parasympathetic motor nerves synapse with:
ganglia located near the effector organ
In the GI tract, ganglia are located:
within wall of gut (within submucosa and muscularis externa)
Clusters of parasympathetic ganglia within the submucosa:
meissner’s plexus (submucosal plexus)
What type of ganglia comprise meissners plexus?
parasympathetic
Larger clusters of ganglia located between inner circular and outer longitudinal muscular layers:
myenteric or Auerbachs plexus
Short, muscular tube lined by stratified squamous nonkeratinized epithelium
Esophagus
What type of cells line the esophagus?
stratified squamous nonkeratinized epithelium
In the upper third of the esophagus the muscularis externa is composed of:
The middle third of esophagus is composed of:
The lower third of the esophagus is composed of:
voluntary skeletal muscle
Skeletal & smooth muscle
Smooth muscle only
Due to the muscle make up of the esophagus, swallowing occurs in the upper 1/3 made of _____ so it is _____
Vomiting occurs in the Lower 1/3 of the esophagus made of _____ so it is ____
- skeletal muscle; voluntary
- smooth muscle; involuntary
Where is the gastroesophageal sphinctor located?
Gastroesophageal junction between stomach and esophagus
Heart burn:
pyrosis
Pyrosis is due to regurgitation of ____ into the _____ from the ____ of the stomach
stomach acid; distal esophagus; cardia
Regions of the stomach: (3)
cardia; fundus; pyrorus
The carida is surrounded by:
smooth muscle cardiac sphinctor
The smooth muscle cardiac sphinctor that surrounds the cardia is known as the:
gastroesophageal sphinctor
Adjacent to the esophagus; contains predominantly mucus-secreting glands:
cardiac sphincter (gastroesophageal sphinctor)
The glandular portion of the stomach:
fundus
The fundus secretes (3)
acid, pepsin, some mucus
Somes texts differentiate the fundus from the ____. Both are glandular but the fundus is closest to the _____ and the _____ is closest to the ____.
-corups
-cardia
- corpus; pyrloris
Portion of the stomach containing primarily mucus (&gastrin) secreting glands
pylorus
The smooth muscle ____ control outflow from the stomach into duodenum
pylroric sphinctor
The loss of stomach/duodenal epithelium/ mucosa:
peptic/gastric ulcer
An ulcer occurs when damage extends below the level of the _____ leading to bleeding.
basement membrane and lamina propria
Partial loss of the epithelium of the stomach leading to no bleeding
erosion
What is the treatment for peptic/gastric ulcers?
antacids (tagamet, cimetidine)
The term peptic ulcers house:
stomach and duodenal ulcers
Ulcers are frequently assoicated with:
chronic infection w/ helicobacter pylori
Helicobacter pylori produce ____ resulting in _____ and secondarily leading to____
urease; increased gastric pH; increased acid production
Treatment of helicobacter pylori includes:
triple therapy
The triple therapy used to treat helicobacter pylori includes:
2 long term antibiotics & proton pump inhibitor
Distensible organ used for food storage:
stomach
How many chambers does the stomach have in most animals?
one
In the stomach food undergoes mechanical breakdown via ____ and chemical breakdown via ____ to form ____
muscular activity; gastric secretions; chyme
In addition to the inner circular and outer longitudinal layers of the stomach, there is also:
3rd inner oblique layer in muscularis externa
Little _____ occurs in the stomach
What are the exceptions?
absorption
exceptions: water, alcohol, & some drugs
The stomach lining contains prominent longitudinal folds called:
ruggae
In the glandular body of the stomach (fundus), muscosa contains prominent:
gastric pits called foveolae
The gastric pits (foveolae) of the fundus forms the entrance to ____
gastric glands
The gastric glands of the fundus are:
straight tubular glands
The gastric glands of the stomach secrete:
~2 liters of watery gastric juice/ day
The watery gastric juice secreted by the gastric glands of the stomac contains: (what makes up the gastric juice and at what PH)
- HCL (pH~1)
- pepsinogen
Pepsinogen is an _____ of ____.
inactive precurser of pepsin
Pepsinogen is converted to pepsin by the action of:
HCL
In addition to the pepsinogen and HCL, what other components are found in the gastric juices of the stomach?
gastrin, renin, & lipase
How does the mucosa of the stomach protect itself from the harsh environment?
thick layer of mucus
Gastric glands contain how many types of cells? name them
5 classes
- mucus secreting cells
-acid secreting cells
- pepsin secreting cells
- enteroendocrine cells
- undifferentiated stem cells
The mucus secreting cells of the gastric glands look ___ on H& E
clear
The mucus secreting cells of the gastric glands cover the:
luminal surface and upper third of pit
How often are the mucus secreting cells renewed?
every 3-5/4-7 days
Type of cells that secretes thick, INSOLUBLE mucus and bicarbonate ions- where are they located?
surface mucus cells- located on surface
Type of cell that secretes SOLUBLE mucus- where are they located?
mucus neck cell- located in upper third of pit, at neck of gastric gland
Which mucus secreting cells of the gastric glands have direct contact with stomach acid?
surface mucus cells
Acid secreting cells (a type of gastric gland cell) also can be called:
parietal cells or oxyntic cells
Acid secreting cells (parietal cells/oxyntic cells), secrete ____ & _____
HCl and intrinsic factor
The HCL and intrinsic factor secreted by acid secreting cells of the gastric gland is necessary for:
absorption of vitamin B12 from the ileum
The acid secreting cells (parietal/oxyntic cells) are most numerous in the:
middle third of gastric gland
How do the acid secreting cells (parietal/oxyntic) stain?
pink to purple
Pepsin secreting cells can also be called:
chief cells, peptic cells or zymogenic cells
Pepsin secreting cells (chief/peptic/zymogenic cells) secretes:
inactive pepsinogen
Pepsin secreting cells (chief/peptic/zymogenic) cells are located at:
base of gastric gland (bottom third)
Pepsin secreting cells (chief/peptic/zymogenic) cells stain ____ due to ____
purple due to large numbers ribosomes
Describe the lifespan of parietal and chief cells:
long lifespans, replaced every 1 year
Parietal and chief cells are controlled by:
autonomic nervous system and hormones from endocrine cells in region of pylorus
Enteroendocrine cells can also be called ____, what does this stand for?
APUD cells; Amine Precurser Uptake and Decarboxylation
What are target cells with local vicinity
paracrine cells
Secrete variety of peptide hormones in response to local factors:
paracrine cells
Cells that respond to local factors to accomplish control of GI motility and gastric secretion:
paracrine cells
Gastrin is secreted by ____ cells:
G-cells
Gastrin stimulates the secretion of ___ & ____
HCL and pepsin
D cells secrete:
somatostatin
Somatostatin secreted by D cells inhibits:
gastrin secretion
Secretin is secreted by :
S cells
What is the functions of secretin (secreted by S cells)
inhibits gastric secretion, and stimulates smooth muscle contraction
Gastric glands contain ____ mainly in the neck of the gland:
undifferentiated stem cells
Cells that continuously divide to replace lost or damaged epithelial cells
undifferentiated stem cells
As the undifferentiated stem cells of the gastric gland mature, they:
migrate up or down gland
Describe the size of the small intestine in humans:
4-6 meters long
The small intestine is the primary site of:
absorption and digestion
What are the 3 parts of the small intestine (in order)
duodenum, jejunum, ileum
The mucosa and submucosa throughout the small intestine is arranged in valve-like folds/rings called:
plica-circulares
The plica circulares are also called ___ and contain a _____ core.
valves of kerkring; submucosal core
The purpose of the plica circulares in the small intestine is to:
increase surface area
The mucosal surface is made up of the small intestine is made up of:
villi
The core of the villi that line the mucosal surface of the small intestine is:
lamina propria
Between the vili that line the mucosal surface of the small intestine are:
crypts of lieberkuhn
gluten enterophathy=
coeliac disease
Coeliac disease has what effect on villi leading to what downstream effect?
causes villus blunting and atrophy leading to malabsorption and weightloss
The epthelium of the small intestine is supported by:
connective tissue lamina propria
The connective tissue lamina propria of the epithelium located in the small intestine contains ______ for absorption of nutrients:
capillaries and lymphatics
Intestinal villi are lined by:
simple columnar epithelium
Mucosal cells of the small intestine are called ____ and cover the surface of ____.
enterocytes ; villi
The apical/luminal surface of the small intestine is ____ and modified into ___
highly folded; microvilli
The microvilli of the small intestine = _____ or _____
striated or brushed border
The microvilli of the luminal surface of the small intestine serve to:
increase surface area for absorption
The microvilli of the small intestine are coated with:
glyocalyx of disaccharrides (site of membrane digestion)
Plicae, Villi and microvilli all:
increase surface area
Interspersed among enterocytes are:
mucous-secreting goblet cells
The mucous secreting goblet cells synthesize ____ which later forms into ____
mucinogen to mucus
The mucinogen synthesized by goblet cells is stored in _____ to function to ____
membrane bound granules that lubricate and protect epithelium
At the base of the crypts of the small intestine are:
stem cells
The stem cells located at the base of the crypts of the small intestine primarly replace:
enterocytes
The entire epithelial lining of the small intestine is replaced every:
3-5 days
In addition to stem cells, what else is found at the base of the crypts?
paneth cells
What type of granules do paneth cells contain?
large eosinophilic granules
The large eosinophilic granules of paneth cells produce antibacterial proteins called _____ and enzymes including ____.
defensins and lysozyme
In the small intestine, scattered throughout are small numbers of ___ cells:
eneroendocrine (APUD) cells
The enteroendocrine cells located in the small intestine function to:
regulate GI motility and secretion
In the small intestine:
- S cells secrete ___ which stimulates the release of ____ from the ___
- I cells secrete ____ which stimulates ____ and contraction of the ____.
- A cells secrete _____ which serves to ____.
- K cells secrete ____, which is ____.
- secretin; bicarb; pancreas
- CCK; pancreatic secretion; gallbladder
- glucagon; raise blood sugar
- GIP; gastric inhibitory peptide
MALT is located in ____ & ______ of the small intestine
lamina propria & submucosa
MALT contains ___ cells that secrete ___
plasma cells; IgA
The epithelium of MALT contains enlarges ____
M-Cells (microfold)
squamoid enterocytes modified for Ag sampling, and uptake of macromolecules:
M- cells (of MALT)
Dome-shaped areas grossly visible on the surface of mucosa that project into the lumen (in MALT)
Peyer’s Patches
Peyers Patches contain what type of Loci?
B and T cell loci
The duodenum is characterized by the presence of ____ in the submucosa:
Brunner’s gland
Where are brunners glands located?
submucosa of duodenum
In the duodenum, there is a large # of highly convoluted, branched:
tubuloalveolar submucosal glands
The tubuloalveolar submucosal glands of the duodenum are: (in appearance)
highly convoluted and branched, large #s
In the duodenum there is a large # of highly convuluted branched tubuloalveolar submucosal glands called:
brunners glands
The brunner’s glands secrete ___ & ____ which is unique to the duodenum
mucus and zymogens
The main function duodenum is to: (who helps)
neutralize gastric acid and pepsin (assisted by pancreas and gallbladder)
What empties into the duodenum at the major duodenal papilla?
pancreatic duct & bile duct
The pancreatic duct and bile duct empty into the duodenum at the:
major duodenal papilla
Chyme from the stomach stimulates the release of 2 hormones from ___ cells. What are the hormones?
APUD Cells
secretin & CCK
Both secretin and CCK released from APUD cells promote
highly alkaline pancreatic secretion:
Pancreatic secretions are highly alkaline due to ____ for the purpose of ___
bicarbonate; neutralize stomach acid
CCK also stimulates the contraction of ____ and the release of ____.
gallbladder; bile acids
act as emulsifying agents for digestion of lipids, to form micelles:
bile acids
Pancreatic secretions also contain proteolytic enzymes ____ & ____ for digestion of proteins:
trypsin and chymotrypsin
Tyrpsin and chymotrypsin are ____ enzymes
proteolytic
the pancreas secretes ____ & ____ for the digestion of proteins, ____ for the digestion of carbs, and _____ for the digestion of lipids
trypsin and chymotrypsin
amylase
lipase
Trypsin and chymotrypsin are secreted as _____ & _____ which are _____ to prevent autolysis.
trypsinogen & chymotrypsinogen ; zymogens
Tyrpsin is activated by _____; trypsins then activates _____.
enterokinase; chymotrypsin
Digestion is a two step process including:
luminal digestion and membrane digestion
Involves the mixing of chyme and pancreatinc enzymes to result in molecular breakdown:
luminal digestion
Involves enzymes of glycocalyx on plasma membrane of enterocytes:
membrane digestion
Enterocytes synthesize various enzymes including: (3)
peptidases, peptide hydrolases, disaccharidases
Enterocytes synthesize various enzymes but also produces various ____ for absorption of carbs and amino acids
carrier proteins
During digestion and absorption, ____ are initially denatured by HCL from _____ cells.
proteins ; parietal cells
After proteins are denatured by HCL from parietal cells, they then get hydrolyzed by ____ into ____
pepsin into polypeptide fragments
After proteins are denatured by HCL from parietal cells, and then are hydrolyzed by pepsin into polypeptide fragments, they are further worked on by ____ enzymes: to form ___
pancreatic enzymes - trypsin, chymotrypsin, elastase, and carboxypeptidase ; small peptide fragments
After the digestion of proteins, ____ get absorbed by enterocytes via active transport by carrier proteins
Amino acids
Carbohydrates include:
primarily starches- poly, oligo, & disaccharides
______ hydrolyze starch into disaccharides (sucrose, lactose, maltose, isomaltose)
salivary & pancreatic amylase
During digestion, once the carbs have been broken down into disaccharides, they are further broken down into monosachrarides and then absorbed by:
enterocytes using facillitated diffusion
AAs and monoscacharides are absorbed by ____ lining villi, transported across the epithelium, enter capillaries with lamina propria and make their way into _____ for ____
enterocytes; portal vein for liver storage
Lipids come in the form of primarily _____ from the diet and then are emulsified by the action of ____.
triglycerides; bile acids
After triglycerides are emulsified by biles acids, they are further broke down into ___ & ____ by ____.
monoglycerides and fatty acids by pacnreatic lipase
When the monglycerides and fatty acids are formed from panacreatic lipase, this forms:
extracellular micelles
Micelles are absorbed by ____, then ___ into triglycerides within the enterocyte & coated with proteins & phospholipids to form _____
enterocytes; resynthesized; intraellular chylomicrons
Initially triglycerides from diet, that are now intracellular chylomicrons are transported across the enterocytes to ___
lacteals
blind-ended lymph vessels within lamina propria of villi:
lacteals
What is the lass step of digestion and absorption of lipids:
carried to thoracic duct & general circulation
Includes cecum, appendix, ascending, transverse descending and sigmoid colon an drevtum
large intestine
What does large intestine lack?
villi & plicae circulares
Small, blind-ended sack, distal to the ileocecal junction:
appendix
Used for bacterial digestion in herbivores: vestigeal cecum
appendix
The appendix contains large amounts of:
submucosal MALT
The appendix is active in:
children
Inflamed appendix; treatment
appendicits; appendectomy
The primary function of the colon is:
H2O and electrolyte resorption
The colon produces ____ for elimination of undigested food and waste
mucus
In the colon we have large #’s of _____ in the epithelium and ____ glands in the submucosa
goblet cells; colonic glands
What glands are NOT present in the colon?
Brunners
The colon lacks ____ & _____
villi & plicae firculares
The mucosal epithelium of the colon is similar to the _____ but in adults what cells are absent?
small intestine; paneth cells
MALT in the large intestine does NOT form:
domed peyer’s patches
No ____ are present in lamina propria of the colon:
lacteals
In the colon, epithelial cell replacement occurs every 5 days from ____ located at the base of ____
stem cells ; grandular crypts
In the colon, there are large numbers of commensal bacterial called ____ .
coliforms
The outer longitudinal layer in the muscularis external of the colon is is reduced or incomplete- forming
3 longitudinal strips- taenia coli
The taenia coli in the colon are responsible for formation of
haustra
sacculations of large intestine:
Haustra
GI polyps indicate:
adenoma
Any mass arising from the wall of the colon that protrudes into the lumem; generally asymptomatic, and the most common sign is rectal bleeding. Treatment is surgical removal:
polyps- adenoma
colon cancer=
adenocarcinoma
______ roughage & fiber in diet, can ____ colon cancer by ____ transit time & ____ GI motility
increased; decrease; decreasing; increasing
Treatment of adenocarcinoma (colon cancer) involves:
surgical removal; maybe even colon resction
There are new test kits for early detection of colon cancer, that detect ____
tumor antibodies
Short dilated terminal portion of the large intestine:
rectum
the rectum contains _____ folds and large #’s of _____ glands
transverse rectal folds; mucus glands
In the rectum, there is a transition of mucosa from ______ to ______ at the anal canal.
simple columnar epithelium to stratified squamous epithelium
Anal canal contains longitudinal folds called:
anal columns
The anal columns may also be called:
columns of margani
Within the anal canal, ____ extend into the submucosa and muscularis externa
anal glands
In the rectum, branched, straight, tubular glands that secrete mucus:
anal glands
Surrounding musculature of the forms:
internal and external sphinctors
The external sphincter of the rectum is ______ while the internal sphincter of the rectum is ____.
voluntary (skeletal muscle)
involuntary (smooth muscle)
Occasional enalrgement and irriation of the submucosal veins around the anal canal:
hermorrhoids
The external opening; exit of the GI tract:
anus
