lecture 19/20

Question 1

function of the liver

general list

Answer 1

• endocrine secretion
• exocrine secretion
• inactivation of substances
• conversion of substances
• hemopoeisis
• storgae of substances

Question 2

what does the liver secrete (endocrine)

Answer 2

somatomedin, albumin, fibrinogen, prothrombin, transferrin, VLDL

Question 3

what does the liver secrete (exocrine)

Answer 3

bile acids, bilirubin, phospholipids/cholesterol

Question 4

what are some examples of the inactivations/elimination done by the liver?

Answer 4

• glucuronly transferase conjugates glucuronic acid to bilirubin but also to barbituates, antihistamines, anticonvulsants, insecticides, etc.
• endocytosis od hormones and cholesterol (LDL particles)

Question 5

an example of a conversion done in the liver

Answer 5

T4 (thyroxine) to T3, which is more potent

Question 6

what substances does the liver store?

Answer 6

glycogen and lipids

Question 7

what is the space between the endothelial cells and the hepatocytes called?

Answer 7

space of disse

Question 8

what is present in the portal space?

Answer 8

• hepatic arteriole
• portal venule
• cholangiole
• bile duct

Question 9

what structure provides stability to the hepatocytes?

Answer 9

reticular fibers

Question 10

role of the sER in the hepatocyte

Answer 10

• store long-chain fatty acids, triglycerols, phospholipids, and cholesterol
• synthesize bile

Question 11

role of the rER in the hepatocyte

Answer 11

synthesize apolipopoteins

Question 12

role of the peroxisome in hepatocytes

Answer 12

• catalase that converts hydrogen peroxide (byproduct of b-oxidation) into water and oxygen
• b-oxidation of long fatty acids
• catabolsim of ETOH
• break down pruines to uric acid
• cholesterol synthesis

Question 13

where are tight junctions located in the liver and why?

Answer 13

above and below the bile canaliculus so nothing escapes

Question 14

what is contained in bile and how is it synthesized?

Answer 14

taurocholic acid = tauine + cholesterol
glycocholic acid = cholesterol + glycine
bilirubin conjugated to glucuronic acid

Question 15

direction of blood and bile flow in a helaptic lubule

Answer 15

blood from both hepatic arteriole and prtal vein go toward the central vein
bile goes from the bile canaliculi to the cholangiole/bile duct

Question 16

what is the difference between a classic lobule, portal lobule, and hepatic acinus

Answer 16

• classic: central vein in the middle with many portal spaces around (“natural” deliniation via CT)
• portal lobule: portal space in the middle and 3 central veins make the corners
• hepatic acinus: oval around 2 portal spaces and 2 central veins

Question 16

turnover of hepatocytes

Answer 16

150 days

Question 17

can the liver regenerate when damaged?

Answer 17

yes, normally it can but when it has undergon repeated damage, CT proliferates, cauing cirrhosis

Question 18

is the pancrease an endocrine or exocrine gland? explain.

Answer 18

a combination of both:
* endo: islet of langerhans
* exo: compound acinar gland (similar to parotid)

Question 19

what is the embryonic origin of the oancreas and salivary glands?

Answer 19

from envaginations of the endodermal lining of the embryonic intestine

Question 20

what does the exocrine pancreas make?

Answer 20

a slightly alkaline fluid and proteins consisting of more enzymes and pro=emzymes capable of digesting the main components of ingested food in the small intestine

Question 21

how does the endocrine pancreas form?

Answer 21

some cells from the developing acinus detach and further differentiate to form the islet of langerhans

Question 22

what is the shape of the pancreas gland?

Answer 22

compound acinar gland

Question 23

the pancreas is surrounded by ___________

Answer 23

a capsule of CT

Question 24

what surrounds the islet of langerhans?

Answer 24

thin capsule of CT and reticular fibers

Question 26

what type of interlobular duct is found in the pancreas?

Answer 26

intercalated duct only

Question 27

pancreatic acini contain what granules?

Answer 27

zymogenic

Question 28

centro-acinar cells are derived from ________

Answer 28

intercalated duct that goes into the serous acinus

Question 29

what do zympgenic granules contain?

Answer 29

proenzymes: * trysinogen -> trypsin * pro-carboxypeptidase -> carboxypeptidase * pro-elastase -> elastase * pro-phospholipase A -> phsopholipase A active enzymes: * lipase * amylase * RNAse * DNAse

Question 30

how is glucagon produced?

Answer 30

synthesized as proglucagon and cleaved in the a-cells of the islet of langerhans, where the final product is 29 AAs

Question 31

proglucagon can also be converted to what? and where does this occur? | other than glucagon

Answer 31

into glucogon-like peptides, when it is expressed in the intestinal tract and processed there

Question 32

function/effect of glucagon

Answer 32

- maintain normal concentration of glucose in the blood (opposite effect of insulin) - so, increase concentration - atimulates breakdown of glycogen stored in the liver and/or activate hepatic gluconeogenesis

Question 33

which type of capillaries are found in the islet of langerhans?

Answer 33

fenestrated capillaries

Question 34

what cell types are found in the islet of langerhans? what are their general abundance, location, hormone produced and function

Answer 34

- a-cell: 15-20%, periphery, glucagon, glycogen breakdown/gluconeogenesis - b-cell: 70%, central, insulin, uptake of glucose.lower glucemia - delta-cell: 5%, everywhere, somatstatin, inhibit release of glucagon&insulin/HCL secretion via parietal cells - PP cells: 1%, everywhere, pancreastic polypeptide, stimulate activity of cheif cells

Question 35

what causes acute pancreatitis?

Answer 35

chronic alcohol ingestion b/c cause obstruction of the duct system and activation of trypsin or release of enzyme into the intercelullar space

Question 36

what causes type 1 diabetes?

Answer 36

auto-immune disorder causing destruction of B-cells