Digestion 2 Flashcards

1
Q

what are the organs of the lower GI tract

A

small intestine to anus

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2
Q

what are the two main functions of the lower GI tract

A

digest and absorb
eliminate indigestible and unabsorbed material

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3
Q

what does the small intestine absorb

A

most nutrients
most water
electrolytes
vitamins

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4
Q

what is the function of the duodenum

A

receives chyme from stomach
chemical digestion and absorption
gets accessory gland secretions from liver, gallbladder, and pancreas

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5
Q

what are the three structures in the small intestine that increase surface area

A

circular folds, villi, and microvilli

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6
Q

what do the circular folds of the small intestine do

A

folds made of mucosa and submucosa
increase surface area to increase nutrient absorption
slow movement of chyme

most found in duodenum and jejunum, some in the ileum

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7
Q

what do the villi of the small intestine do

A

simple columnar epithelium and lamina propria projections
increase surface area for absorption and secretion
most found in jejunum
have vessels for nutrient absorption and lacteals

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8
Q

what do lacteals do

A

lymphatic capillaries that absorb lipid and lipid soluble vitamins that are too large to be absorbed by the blood capillaries

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9
Q

what do the microvilli of the small intestine do

A

extensions of simple columnar cells
make up brush boarder
increase surface area
secrete brush boarder enzymes which complete chemical digestion of most nutrients

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10
Q

what are intestinal glands and what do they secrete

A

invaginations of mucosa between villi
secrete intestinal juice

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11
Q

what are paneth cells and what do they do

A

found in the base of intestinal crypts
secrete lysozyme and other antimicrobial agents that help the innate immune system

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12
Q

what does the duodenal submucosal gland do

A

produces viscous alkaline mucus that protects the duodenum from chyme

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13
Q

what are the three functions of the smooth muscle of the small intestine

A

mixes chyme with gland secretions
segmentation (back and forward motion)
propels contents through small intestine by peristalsis

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14
Q

what are the two main functions of the small intestine

A

chemical digestion
absorption of smaller, simpler molecules

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15
Q

explain the early intestinal phase

A

segmentation (mixing)
contractions initiated by pacemaker cells
more contractions/minute in duodenum, less in the ileum
slows everything down as it goes through to allow for nutrient absorption
frequency of contractions usually won’t change but the force can depending on the enteric nervous system

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16
Q

explain the late intestinal phase

A

peristalsis (moving) initiated by motilin hormone released by the duodenum
peristalsis contractions (migrating motility complex) move everything to large intestine

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17
Q

what does the gastroileal reflex

A

causes the ileum to contract
ileocecal spinchter relaxes and cecum relaxes
contents move from ileum to cecum
this all happens in response to food entering stomach

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18
Q

what are the three accessory digestive organs that release secretions into the duodenum

A

liver
gallbladder
pancreas

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19
Q

what is bile

A

secretion produced by the liver
stored, concentrated, and released by gallbladder
contains: bicarbonate ions, salts, pigments, cholesterol, lecithin

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20
Q

what is the biliary apparatus

A

network of ducts draining left and right lobes of liver drain into hepatic ducts
hepatic ducts merge to form single common hepatic duct
common hepatic duct merges with cystic duct from gallbladder to form common bile duct

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21
Q

what does the accessory pancreatic duct do

A

penetrates duodenal wall at minor duodenal papilla to release small amounts of pancreatic juice

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22
Q

what does the hepatopancreatic ampulla do

A

swelling on posterior duodenal wall where common bile duct and main pancreatic duct pierce duodenal wall

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23
Q

what does the major duodenal papilla do

A

projection within duodenum where duct penetrates wall
bile and pancreatic juice enters here

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24
Q

what does the hepatopancreatic sphincter do

A

regulates movement of bile and pancreatic juice into duodenum

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25
Q

what does the falciform ligament do

A

separates right and left lobes of liver

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26
Q

what is the round ligament a remnant of

A

remnant of fetal umbilical vein found at the bottom of the falciform ligament

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27
Q

what is the ligament venosum a remnant of

A

remnant of ductus venous in embryo

28
Q

what is the porta hepatis

A

where blood, lymph vessels, bile ducs, and nerves enter and leave liver

29
Q

what are hepatic lobules

A

where the liver’s connective tissue capsule branches throughout the organ to form septa (walls) to partition the liver
(structural and functional units of liver)
made of hepatocytes (liver cells)

30
Q

what are portal triads

A

found at the periphery of each hepatic lobule
made of bile ductule and microscopic branches of both hepatic portal vein and hepatic artery

31
Q

what does the central (hepatic) vein do

A

found at the center of each hepatic lobule
drains the lobule’s blood flow
all central veins merge to form right and left hepatic veins which will empty into the inferior vena cava

32
Q

what does the hepatic artery do

A

transports oxygenated blood to liver
delivers 25% of the liver’s blood

33
Q

what does the hepatic portal vein do

A

transports deoxygenated and nutrient rich blood from capillary beds of GI tracts, spleen, and pancreas
delivers 75% of the liver’s blood

34
Q

what are stellate (Kupffer) cells and what do they do

A

fixed macrophages found in the liver
engage in phagocytosis of potentially harmful substances

35
Q

what is cirrhosis of the liver

A

hepatocytes are replaced by fibrous scar tissue
can compress blood vessels (hepatic portal hypertension)
causes: hepatitis B/C, alcoholism, injury

36
Q

what are gallstones

A

condensations of cholesterol or calcium and bile salts
causes cholecystitis (inflammation of gallbladder)
may need to be removed (cholecystectomy)

37
Q

what are the two main functions of the pancreas

A

produces and secretes insulin and glucagon (endocrine)
produces pancreatic juice to assist with digestive activities (exocrine)

38
Q

what do acinar cells of the pancreas do

A

arranged in saclike acini
produce and release digestive enzymes

39
Q

what is pancreatic juice

A

formed by acinar and pancreatic duct cells
alkaline fluid made of mostly water, bicarbonate, and digestive enzymes (amylase, lipase)

40
Q

what is cholecystokinin and what does it do

A

hormone released from small intestine in response to fatty chyme
causes gallbladder to contract and release bile
causes pancreas to release pancreatic juice
relaxes smooth muscle within hepatopancreatic ampulla to allow bile and pancreatic juice into small intestine
inhibits stomach motility and release of gastric secretions

41
Q

what is secretin and what does it do

A

released from small intestine if chyme gets too acidic
causes release of alkaline solution containing bicarbonate to neutralize acidic chyme
inhibits gastric sections and motility

42
Q

what are the three functions of the large intestine

A

absorbs a little amount of water, electrolytes, and some vitamins
compacts watery chyme into feces
stores feces until eliminated

43
Q

define peritonitis

A

infection of the peritoneal cavity due to something like a ruptured appendix

44
Q

what are rectal valves and what do they do

A

thick, transverse folds of the rectum
ensure fecal mater is retained during the passing of gas

45
Q

what are the levator ani muscles

A

pelvic floor muscles where the anal canal passes through

46
Q

what are anal columns

A

longitudinal ridges in the anal canal

47
Q

what are anal sinuses and what do they do

A

depressions between anal columns in anal canal
release mucous to lubricates canal during defecation

48
Q

what are teniae coli and what do they do

A

thin, longitudinal bundles of smooth muscle
bunch large intestine into sacs called haustra

49
Q

what are omental appendices

A

lobules of fat hanging off external surface of haustra

50
Q

what is haustral churning

A

haustrum fills until its distended
distension stimulates reflex contractions in the muscularis

51
Q

what are mass movements and what do they do

A

powerful, peristaltic-like contractions that involve teniae coli
proper fecal material towards the rectum

52
Q

what are the two major reflexes of the nervous system that are associated with motility in the large intestine

A

gastrocolic and defecation reflex

53
Q

what is the gastrocolic reflex and what does it do

A

initiated by stomach distension
causes a mass movement in an attempt to clear your intestines for incoming food

54
Q

what is the defecation reflex and what does it do

A

filling of rectum initiates urge to defecate
signals go to spinal cord which increase parasympathetic output to sigmoid and rectum
decreases output to internal anal sphincter

55
Q

what are the intestinal microbiota and what do they do

A

normal bacterial flora in large intestine
chemically breakdown complex carbs, proteins, and lipids
breakdown by bacteria releases gases and produces vitamins B and K
final product is feces

56
Q

what is Crohn disease

A

a type of inflammatory bowel disease
intermittent and relapsing episodes of cramping and diarrhea throughout the whole colon
typically in young adults

57
Q

what is ulcerative colitis

A

a type of inflammatory bowel disease
intermittent and relapsing episodes of cramping and diarrhea of large intestine

58
Q

what is irritable bowel syndrome

A

abnormal function of colon

59
Q

what are the three things used to test for colorectal cancer

A

fecal occult blood test
sigmoidoscopy
colonoscopy

60
Q

what are hemorrhoids

A

dilated and inflamed veins around rectum and anus

61
Q

what are anal fissures

A

oval shaped tears of the anus that often bleed

62
Q

what is sorbitol

A

sugar substitute that acts as a laxative by preventing reabsorption of water within the intestine

63
Q

where does most chemical digestion and absorption happen

A

small intestine

64
Q

what do enteroendocrine cells do

A

release hormones like cholecystokinin (CCK) and secretin

65
Q

what are the three functions of bile

A

1.) neutralizes acidic chyme through bicarbonate ions
2.) emulsifies lipids by bile salts and lecithin
3.) eliminates bilirubin