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ANAT 261 > digestive system V and VI > Flashcards

digestive system V and VI Flashcards

1
Q

name liver functions

A

endocrine secretion
exocrine secretion
inactivation or elimination of substances
conversion of substances
hemopoiesis
storage of substancesd

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2
Q

describe endocrine secretion - liver functions

A

secreted into blood
somatomedin - GH, tells liver to produce this and tells cells of epiphyseal plate - chondrocytes to grow and multiply, albumin, fibrinogen, prothrombin, transferrin - iron carrier, vldl = very low density lipoprotein, precursor of ldl

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3
Q

describe exocrine secretion - liver functions

A

not to circulation
goes to bile, bile acids, billirubin, it also secretes, phospholipids and cholesterol

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4
Q

describe inactivation/secretion of substances - liver functions

A

glucuronyl transferase conjugates glucuronic acid to bilirubin - goes to bile, also to barbituates, antihistaminics, anticonvulsants, insecticides, and other drugs,
endocytosis of hormones and cholesterol - ldl particles- bad cholesterol
liver has ldl receptors - way to eliminate toxins from body hormones go to target organ to trigger a function, hormone cannot be circulating forever so its removed by receptor mediated endocytosis - live has receptors for hormone

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5
Q

describe conversion of substances - liver functions

A

tetra-iodothyronine (t4. thyroxine, thyroid hormone) –> tri-idodthyronine (t3 - more potent) converted by liver cells

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6
Q

describe hemopoiesis - liver functions

A

production of rbcs
during fetal development
after birth - bone marrow takes over

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7
Q

describe storage of substances - liver functions

A

glycogen - sugar and lipids - cholesterol, triglycerides

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8
Q

describe capsule of ct of liver

A

penetrates at level of porta hepatis
glissons
separates liver into hepatic lobules = prismatic structures

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9
Q

what is porta hepatis

A

entrance of 2 branches of hepatic arteries (start in abdominal aorta and then branches)
exit of hepatic duct = brings bile synthesized in liver to gallbladder

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10
Q

describe common bile duct

A

ends at level of si
bile will go to intestines
Emulsifies fat - digestion of lipids

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11
Q

describe hepatic vein

A

exits through hepatic vein and drains blood into inferior vena cava

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12
Q

describe histology of liver

A

ct between lobules = across and down
bile duct goes in opposite directions of hepatic artery and portal veins
located in portal space =
branch of hepatic artery = arteriole
branch of portal vein = venule
portal space = ct blood vessels and bile ducts, large areas of ct

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13
Q

describe hepatic lobule

A

subdivided by chords of hepatocytes

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14
Q

describe hepatocytes

A

pale colour, forms row of cells separated by blood vessels - liver sinusoids - go from periphery to central vein

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15
Q

describe veins of hepatocytes

A

sinusoids
central vein opens into sublobular vein
which drains in hepatic vein

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16
Q

what are bile canaliculi

A

opens into bile duct and takes bile to common bile duct and gallbladder
bile released when fatty meal

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17
Q

describe sinusoids

A

see endothelial cells
separates hepatocytes
NO BM
only reticular fibers, irregular in size
Permeable capillaries
separated = no tight junctions
everything goes through easy

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18
Q

describe kupffer cell

A

phagocytic cells - old rbcs, particulate matter, bacteria

bigger than edothelial cell
processes can extend to sinusoids - long

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19
Q

what opens into sinusoids

A

arteriole - branch of hepatic artery and venule - branch of hepatic vein

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20
Q

describe cholangiole and bile duct

A

equivalent to intercalated duct = between lobes, interlobular
cholangiole opens into bile duct
bile secreted by hepatocytes
bile duct covered by columnar or cuboidal cells - depends on size of bile duct

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21
Q

describe nuclei of hepatocytes

A

can be binucleated
small cubes forms plate = communication between plates = opening

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22
Q

what is at the end of bile canaliculi

A

tight junctions
changes directions where bile circulates, since do not want bile to be in circulation

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23
Q

what is space of disse

A

between endothelial cells and hepatocytes = space of disse
where exchange happens

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24
Q

what are cholangioles also called

A

herings canals
bile ductules

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25
what are sinusoids lined by
endothelial cells and kupffer cells sometimes
26
name main activities of hepatocyte
endocytic and secretory activities
27
describe endocytic activity of hepatocyte
receptor mediated endocytosis of ligands = hormones, ldl, hdl, chylomicrons digested and stored as aas triglycerides, monosaccharides etc Dissociation of ligand and then receptor will be recycled to cell surface to continue cycle - important, liver degrades these substances after since they should not be circulating
28
describe secretory activity of hepatocyte
rer = synthesizes apolipoproteins and sends to golgi - ser stores long chain fatty acids, triacylglycerols, phospholipids and cholesterol and sends to golgi golgi = packs complex and secrets into space of disse and lumen vldl - apolipoprotein complex, contains cholesterol secreted by liver, produced by hepatocytes
29
why is removing ldl important
could lead to plaque in artery
30
what are other functions of hepatocytes
peroxisome ser
31
describe peroxisome of hepatocyte
similar to lysozyme - has crystalline structure catalyses reaction - turns hydrogen peroxide to water and oxygen removes hydrogen peroxide beta oxidation of long fatty acid chains - FA - by product = hydrogen peroxide catabolism of alcohol breakdown of purines amp/gmp to uric acid - eliminated by kidneys cholesterol synthesis
32
describe SER of hepatocyte
synthesized bile cholesterol + taurine = taurocholic acid bilirubin conjugated to glucuronic acid will be elimated at level of bile canaliculi - do not want it to go to circulation
33
describe a portal lobule
surrounded by portal spaces 3 central veins all drain into the same portal space = makes portal lobule
34
describe hepatic acinus
metabolic effects hepatocytes closer to portal space = metabolically active since closer to oxygen as go towards central vein = less oxygen and more elements from waste metabolism
35
what do all bile ducts drain into
hepatic duct and all goes to gall bladder
36
what is turnover of hepatocytes
150 days very low expanding - expanding population of cells
37
what is mitotic index
1 cell every 20 000
38
what is surgical excision
cells divide actively until organ reaches normal size
39
describe repeated damage to hepatocytes
like alcoholism = results in proliferation of ct = cirrhosis - liver will not recover and be small
40
what is hepatitis
tight junctions affected and bile leaks out = leads to jaundice
41
describe pancreas
The pancreas is a mixed exocrine & endocrine gland endocrine portion is composed of islets of langerhans exocrine portion is a compound acinar gland similar in structure to parotid gland
42
describe exocrine pancreas
exocrine pancreas produces a slightly alkaline fluid & proteins consisting 15 or more of main enzymes (mainly) & pro-enzymes (zymogens - Zymogenic granules) capable digesting the components of ingested food in small intestine i.e. Carbohydrates (breakdown to mnosaccharides lipids (to triglycerides), proteins to amino acids) & nucleic acids (phosphate group Remove from nucleic acids by enzymes - like alkaline phosphatase)
43
both pancreas and salivary glands derive from...
evaginations of endodermal lining of embryonic primitive intestine
44
describe accessory pancreatic duct
drains secretory products into duodenum
45
describe main pancreatic duct
join to common bile duct coming from gallbladder Together = drain into duodenum
46
what does bile promote
digestion of fat and pancreas provides lipids and other zymogens or enzymes
47
describe exocrine and endocrine pancreas
endocrine = islets of langerhans serous acini = exocrine
48
describe formation of pancreas
blind ended tubules are lined by undifferentiated simple columnar epi cells which undergo sequential branching - many ducts epithelial rudiments begin to organize into acini and lobules some cells further differentiate from these forming acini = form islets of langerhans
49
describe exocrine pancreas
Divided in lobes and lobules compound acinar = similar to salivary glands
50
describe ct of pancreas
capsule penetrates at level of pancreatic duct and separates liver into lobes and lobules
51
describe interlobar duct and ct
large amounts of ct large ducts
52
describe interlobular duct and ct
thin septi of ct = subdivides lobe into small lobules
53
describe intercalated duct
drain into small lobular duct - equivalent to intercalated duct of salivary glands short cells, pale, sometimes cuboidal or squamous connected to serous acini
54
describe interlobular duct and ct of adult pancreas
line by columnar ep cells pale dont stain well
55
describe serous acini
exocrine pancreas pyramidal shaped cells, round nucleus, tends to be basophilic, apex = acidophilic due to zymogen secretory granules with enzymes - picks up eosin
56
describe centroacinar cells
pale center of serous acini
57
describe islets of langerhans
surrounded by thin capsule of ct - fibrocytes, reticular fibers, diagnostic - use as landmark
58
describe serous acinus cell
no myoepithelial cells in serous acini secreting into lumen so tight junctions
59
describe serous acinar cell
pyramidal tight junctions ribosomes - ribonucleoproteins, react well with hematoxylin so basophilic at base rer - well devlopped and mitochondria - active cell golgi prominent - packs enzymes into condensing granule zymogen granules - has protein, dark in em, electron dense, fully mature exocytosis
60
describe pancreatitis
medical emergency can happen after excess alcohol = enzymes start to dissolve own pancreas - leaks out, enzymes more powerful than stomach
61
what regulates the exocrine pancreas
cck secretin Unconstituted, only when digestion
62
describe cck
produced by enteroendocrine cells of duodenum promotes exocytosis
63
describe secretin
stimulates secretion of water and bicard produced by enteroendocrine cells of duodenum
64
what do centroacinar cells produce
water and bicarbonate
65
describe zymogen granules
contain proenzymes all converted by enterokinase trypsinogen to trypsin (remove aa from trypsinogen and convert to active trypsin) procarboxypeptidase to carboxypeptidase proelastase to elastase pro phospholipase a to phospholipase a
66
describe enterokinase
located in microvilli of enterocytes of duodenum small enzyme - protease
67
describe active enzymes of pancreas
15 active enzymes lipase - important of tj, role in pancreatitis amylase RNase DNase
68
what is role of trypsin inhibitor
Secreted by centroacinar cells prevents early activation of trypsin provides protection against reflux of trypsin from gut
69
describe endocrine pancreas
Islets of langerhans will organize in 2 ways = follicles like in thyroid or cords associated to fenestrated capillaries pancreatic cells of islets of langerhans associated to fenestrated capillaries
70
how many islets of langerhans in pancreas
5x10^5-10^6 = 2% of pancreas 200um in diameter considered to be endocrine microunits
71
name cell types
alpha beta delta pancreatic polypeptide cells
72
describe alpha cells of endocrine pancreas - %, size, location, hormone, function
15-20% large periphery glucagon glycogen breakdown and gluconeogenesis
73
describe beta cells of endocrine pancreas - %, size, location, hormone, function
70% smaller central insulin - opposite of glucagon uptake of glucose by liver and lower glucemia when eating only one gene encodes insulin
74
describe delta cells of endocrine pancreas - %, size, location, hormone, function
5% large periphery and central somatostatin inhibits release of glucagon and insulin via paracrine action and HCl secretion by parietal cells
75
describe pancreatic polypeptide cells of endocrine pancreas - %, size, location, hormone, function
1% large periphery and central pancreatic polypeptide stimulates activity of chief cells
76
describe role of glucagon
plays major role in maintaining normal concentrations of glucose in blood and has opposite effect of insulin
77
what is glucagon. synthesized as
proglucagon and proteolytically processed ro glucagon within alpha cells of pancreatic iselts final product = linear peptide of 29 aas primary sequence highly conserved in vertebrates
78
where is proglucagon expressed
also expressed within intestinal tract where it is processes to glucagon, like peptides = enteroglucagon - not into glucagon
79
what is major effect of glucagon
major effect of glucagon = increase blood concentration of glucose as brain has an absolute dependence on glucose as fuel When blood levels of glucose begins to fall below normal Range -glucagon stimulates breakdown of glycogen stored in liver and/or activates hepatic gluconeogenesis like when asleep
80
why are fenestrations important in islet cells
allows passage of hormones into lumen of capillary
81
what does chronic ingestion of alcohol lead to
acute pancreatitis = due to obstruction of duct system and activation of trypsin or release of enzymes into intercellular space
82
explain type 1 diabetes
insulin dependent diabetes mellitus develops before age of 15 which is apparently cause by an autoimmune destruction of the beta cells of islets

ANAT 261 (27 decks)

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