Small and Large intestines Flashcards
the first part of the small intestines and the part that is retro-peritoneal
duodenum
the second part of the small intestines is the
jejunum
the third and final part of the small intestines is the
ileum
the longest part of the small intestines
ileum
the macroscopic folds of the small intestines are termed
plica circularis
what type of cells line the mucosal layer of the small intestines
simple columnar
the microscopic folds in the small intestines are made up of “finger like” structures termed
villi
the bottom regions of the villi are termed
the crypts of liberkuhn
the lamina propria connective tissue layer on the mucosa contains capillaries and the unique lymphatic vessels termed a
lacteal
what is a lacteal lymph vessel used for?
absorption of lipids (triglycerides)
the enteroendocine cells in the mucosa of the small intestines synthesize the hormones :
secretin and cholecytokinin
the cells in the mucosa of the small intestines that secrete lysozyme are called
paneth cells
the lymphoid aggregates that are large and located in the ileum are called
Peyer’s patches
the submucosa of the small intestine contained what type of gland; and what do they secrete
Brunner’s glands, alkaline fluid
the muscularis layer of the small intestines contains what type of muscle groups?
inner circular and outer longitudinal muscle groups
what is contained on the apical surface of the simple columnar cells (also called the brush border) in the small intestines
microvilli
microvilli in the small intestines secrete what enzymes for chemical digestion of carbs? (4)
alpha dextrinase, sucrase, lactase, maltase
microvilli in the small intestines secrete what enzyme for chemical digestion of proteins?
peptidases
microvilli in the small intestines secrete what enzymes for chemical digestion of nucleic acids? (2)
nucleosidases, phosphatases
what is the peristalsis called that starts as a slow wave that moves food from the stomach through the small intestines
migrating motility complexes
how long does it take for food to get from the stomach to the end of the ileum?
two hours
carb digestion begin in the … (where, with what enzyme?)
mouth with salivary amylases
what happens to the salivary amylases when they reach the stomach?
they are innactivated
what enzyme digest carbs in the small intestines (and where is it produced?)
pancreatic amylases, produced by pancreas
the final step in digestion involves the brush boarder enzymes, in which carbs are broken down into the monosaccharide:
glucose, fructose and galactose
how are monosaccharides absorbed?
across the epithelial cell into the capilaries
the two major transport mechanisms for carb absorption
facilitiated diffusion ad secondary active transport (d/t concentration gradient created by Na-K ATPase pump)
where does protein digestion begin? And with what enzyme
in the stomach, pepsin
what enzymes digest proteins in the small intestines?
trypsin, chymotrypsin, carboxypeptidase and elastase (made by pancreas)
what’s the final step in protein digestion?
brush border enzymes break the proteins into amino acids, and they are are absorbed across the epithelial cell and enter the capillaries
transport mechanisms for absorption of amino acids are:
secondary active transport (symport with Na and H)
where does most of the lipid digestion happen?
small intestines
what do most fats require to break down?
bile salts (some lingual and gastric lipase can break down short chain fats)
where are bile salts produced and what do they do
liver, they emulsify triglycerides prior to enzyme degradation by lipases
where are lipases made
pancreas
describe the process of emulsification
breaking down large lipid droplets into smaller droplets that the pancreatic lipases can act on
after triglycerides are broken down into glycerol and fatty acidsa what do they form with bile? (and where)
micelles in the lumen of the small intestine
micelles can dissociate back into fatty acids and glycerol and enter simple columnar cells where _____ are reformed
triglycerides
triglycerides are packaged as ______ which exits the epithelial cell and enters the ____.
chylomicron, lacteal
Trace the pathway of the triglyceride from the small intestine until it reaches the bloodstream:
lacteal to larger lymphatic channels….. intestinal trunk…. thoracic duct…… left subclavian vein.
At tissue level the triglyceride is broken down for the final time by the enzyme :
lipoprotein lipase
The two most common storage sites for triglycerides is in :
adipose tissue and in the liver
Bile salts used in the breakdown of lipids can be reabsorbed in the
ileum and then return to the liver
the majority of water absorption occurs in the….
small intestines
the first part of the large intestines
cecum
the valve that separates the small from the large intestines is the
ileocecal valve
the structure that hangs from the large intestine, close to the ileocecal valve is
the veriform apendix
retroperitoneal sections of large intestines
ascending and descending colon
what is the flexure on the right side of the upper abdomen, on the left?
right colic (or hepatic) flexure left colic (or splenic) flexure
what three structures come after the descending colon?
sigmoid colon, ectum, anus
the internal anal spincter is made of what type of tissue?
smooth muscle
what type of tissue is the external anal spincter?
skeletal muscle
what type of cells are in the mucosal layer of the large intestines
simple columnar and goblet cells
T/F a significant amount of nutrients continue to be absorbed in the large intestines
False
The modification of the muscularis layer in the colon results in three longitudinal muscle bands termed the
tenia coli
longitudinal bands of the colon result in pouches called
haustras
the fat attached to the muscle layer of the colon
epiploic appendages
the hormone gastrin results in ileocecal valve……
relaxation
the large intestine has a large number of bacteria that ferment carbs, what are the byproducts?
H, CO2, methane gas
. Bacteria can convert any remaining proteins to amino acids, convert bilirubin to
stercolbilin
normal feces contain:
water, inorganic salts, sloughed epithelial cells, products of bacterial decomposition, unabsorbed digested material and indigestable substances
defication is d/t the action of what system?
parasympathetic NS from spinal cord levels of S2,3,4
. The superior mesenteric artery comes off the aorta, travels deep to the _________and enters the mesentery.
pancreas
the superior mesenteric artery supplies: (5)
all of the small intestines, cecum, appendix, ascending colon and the first half of the transverse colon
the named branches of the superior mesenteric artery (5)
inferior pancreodoudenal, intestinal arteries, ileocolic, right colic and middle colic arteries
the inferior mesenteric artery comes off the lower abdominal aorta, what are it’s three main branches
left colic, sigmoidal and superior rectal
the inferior mesenteric artery supplies
the last half of the transverse colon, descending colon, sigmoid, rectum
the venous drainage for the GI tract ultimately enters the:
inferior vena cava, which then enters the liver
