Case 3 - Yaffas

Question 1

what are the pancreatic digestive enzymes secreted by

Answer 1

pancreatic acini

Question 2

what is secreted by the small ductules and larger ducts leading from the acini

Answer 2

large volumes of sodium bicarbonate solution

Question 3

what happens to this combination of enzymes and sodium bicarbonate

Answer 3

flows through a long pancreatic duct that normally joins the hepatic/bile duct immediately before it empties into the duodenum

Question 4

what does this solution enter the duodenum through

Answer 4

the papilla of Vater surrounded by the sphincter of Oddi

Question 5

when is pancreatic juice secreted most abundantly

Answer 5

in response to the presence of chyme in the duodenum

Question 6

what is secreted from the endocrine pancreas

Answer 6

insulin and glucagon

Question 7

what is insulin secretefd by

Answer 7

beta cells of the islet of langerhans

Question 8

what is glucagon secreted by

Answer 8

alpha cells of the islet of langerhans

Question 9

where are insulin and glucagon secreted into

Answer 9

directly into the blood

Question 10

what is the fundamental secretory unit of the endocrine pancreas

Answer 10

composed of an acinus and an intercalated duct, merged to form intralobular ducts, which in turn merge to form interlobular ducts, and then the main pancreatic duct

Question 11

what does pancreatic secretion contain

Answer 11

digestive enzymes
bicarbonate ions
water

Question 12

what are the three protein digestive enzymes secreted by the pancreas

Answer 12

trypsin
chymotrypsin
carboxypolypetidase

Question 13

describe trypsin

Answer 13

the most abundant of the protein digestive enzymes to be secreted. It splits whole and partially digested proteins into peptides of various sizes but do not cause release of individual amino acids.

Question 14

describe chymotrypsin

Answer 14

It splits whole and partially digested proteins into peptides of various sizes but do not cause release of individual amino acids.

Question 15

describe carboxypolypetidase

Answer 15

this splits peptides into individual amino acids, thus completing the digestion of some proteins all the way to the amino acid state.

Question 16

what is the inactive form of proteolytic enzymes termed

Answer 16

zymogens

Question 17

when is trypsinogen activated

Answer 17

activated by the enzyme enterokinase

it can also be autocatically activated by trypsin that has already formed from previously secreted trypsinogen

Question 18

where is enterokinase secreted from

Answer 18

intestinal mucosa when chyme comes into contact with the mucosa

Question 19

what is chymotrypsinogen activated and what does it form

Answer 19

activated by trypsin to form chymotrypsin

Question 20

what is Procarboxypolypeptidase activated by and what does if form

Answer 20

Activated by trypsin to form carboxypolypeptidase.

Question 21

when do they all become activated

Answer 21

only become activated after they are secreted into the intestinal tract

Question 22

what does secretion of trypsin inhibitor cause

Answer 22

prevents digestion of the pancreas itself

Question 23

what is important about the secretion of this trypsin inhibitor

Answer 23

it is important that the proteolytic enzymes of the pancreatic juice do not become activated until after they have been secreted into the intestine because the trypsin and the other enzymes would digest the pancreas itself

Question 24

where is trypsin inhibitor formed and what does it do

Answer 24

in the cytoplasm of the glandular cells, and it prevents the activation of trypsin both inside the secretory cells and in the acini and ducts of the pancreas

Question 25

what can happen if a duct is blocked

Answer 25

large quantities of pancreatic secretion can be pooled in the damaged areas.

under these conditions, the effect of trypsin inhibitor is often overwhelmed in which case the pancreatic secretions rapidly become activated, thus causing digestion of the pancreas

Question 26

what is this event called

Answer 26

acute pancreatitis

Question 27

what do acetylcholine and cholecystokinin do

Answer 27

stimulate the acinar cells to secrete large quantities of pancreatic digestive enzymes but relatively small quantities of water and electrolytes to go with the enzymes

Question 28

what does secretin do

Answer 28

stimulates ductal epithelial cells to secrete large quantities of water solution of sodium bicarbonate

Question 29

pathways for stimulating the insertion of zymogen granules and thus releasing digestive enzymes

Answer 29

ACh and CCK both activate Gαq, which stimulates PLC, which ultimately leads to the activation of PKC and the release of Ca2+.

Elevated [Ca2+]i also activates calmodulin (CaM), which can activate protein kinases (PK) and phosphatases (PP).

Finally, VIP and secretin both activate Gαs, which stimulates adenylyl cyclase (AC), leading to the production of cAMP and the activation of PKA.

The duct cells have receptors for secretin, GRP, all of which stimulate HCO3- secretion.

The duct cells have receptors for substance P which inhibits HCO3- secretion.

Question 30

what does sodium bicarbonate do

Answer 30

causes neutralisation of HCL

Question 31

what is CCk released by

Answer 31

I-cells in the duodenal and upper jejunal mucosa

Question 32

what does lactase do

Answer 32

splits lactose into galactose and glucose

Question 33

what does sucrase do

Answer 33

splits sucrose into fructose and glucose

Question 34

what does maltase do

Answer 34

splits maltose into multiple molecules of glucose

Question 35

what does alpha-dextrinase do

Answer 35

splits small glucose polymers into multiple molecules of glucose

Question 36

where are these enzymes located

Answer 36

in the enterocytes

Question 37

what do bile salts do to prevent further digestion

Answer 37

they form a micelle, around the fat globule that is to be digested

these develop because of the hydrophilic and hydrophobic nature of bile salts

Question 38

do triglycerides stimulate pancreatic secretion

Answer 38

they do not, but their hydrolytic products: monoglycerides and free fatty acids do

Question 39

how are vitamin b12 and intrinsic factor absorbed

Answer 39

endocytosis

Question 40

what is absorbed in the ileum

Answer 40

vitamin B12 and bile salts

Question 41

what are the three levels of the surface area of the small intestine

Answer 41

1. folds of Kerckring
2. villi (+ crypts of Lieberkuhn)
3. microvilli

Question 42

why does referred pain occur

Answer 42

due to convergence on second order neurones.

the same spinothalamic pathways carry nerves form adjacent skin and muscles - ‘visceromotor convergence’

the brain misinterprets the signals that originate from internal organs as coming from co-inervated somatic regions