18.10 PANCREATIC ISLETS

Question 1

What kind of gland is the pancreas (endocrine or exocrine)

Answer 1

both

Question 2

99% of the exocrine cells of the pancreas are arranged in clusters called?

Answer 2

acini

Question 3

What do the acini produce?

Answer 3

digestive enzymes, which flow into the GI tract through a network of ducts

Question 4

Scattered among the exocrine acini are 1-2 million tiny clusters of endocrine tissue called

Answer 4

pancreatic islets (or islets of langerhans)

Question 5

each pancreatic islet includes 4 types of hormone secreting cells which are?

Answer 5

1. alpha or A cells
2. beta or B cells
3. delta or D cells
4. F cells

Question 6

Which cell constitutes 70% of pancreatic islet cells

Answer 6

Beta or B cells

Question 7

Which cell constitutes about 17% of pancreatic islets

Answer 7

alpha or A cells

Question 8

which cell constitutes about 7 % of pancreatic islet cells?

Answer 8

delta or D cells

Question 9

What do alpha cells secrete?

Answer 9

glucogen

Question 10

what do beta cells secrete

Answer 10

insulin

Question 11

what do delta cells secrete

Answer 11

somatostatin

Question 12

what do F cells secrete

Answer 12

pancreatic polypeptide

Question 13

what does somatostatin do?

Answer 13

-acts in a paracrine matter to inhibit both insulin & glucagon release from neighboring A and B cells
-may also act as a circulating hormone to slow absorption of nutrients from the GI tract
-inhibits the secretion of growth hormone

Question 14

What does pancreatic polypeptide do?

Answer 14

inhibits somatostatin secretion, gallbladder contraction & secretion of digestive enzymes by the pancreas

Question 15

Hypoglycemia stimulates secretion of?

Answer 15

glucagon from alpha cells of the pancreatic islets

Question 16

What does glucogen act on to accelerate the conversion of glycogen into glucose (glycogenolysis) & to promote formation of glucose from lactic acid and certain amino acids (gluconeogenesis)

Answer 16

hepatocytes (liver cells)

Question 17

hyperglycaemia ____ the release of glucagon

Answer 17

inhibits (negative feedback)

Question 18

hyperglycaemia stimulates secretion of?

Answer 18

insulin by beta cells of the pancreatic islets

Question 19

INDIRECTLY what stimulates secretion of insulin because they act to elevate blood glucose? (2)

Answer 19

growth hormone (GH) and adrenocorticopic hormone (ACTH)

Question 20

What is another way insulin secretion is stimulated by? the neurotransmitter?

Answer 20

acetylcholine - the neurotransmitter liberated from axon terminals of parasympathetic vagus nerve fibres that innervate the pancreatic islets

Question 21

Which amino acids would be present in the blood at higher levels after a protein-containing meal?

Answer 21

arginine and leucine

Question 22

What is a hormone released by enteroendorcine cells of the small intestine in response of glucose in the GI tract?

Answer 22

glucose-dependent insulinotropic peptide (GIP)

Question 23

Digestion and absorption of food containing both carbohydrates & proteins provide?

Answer 23

strong stimulation for insulin release

Question 24

What is glycogen secretion stimulated by? which division of the ANS

Answer 24

increased activity of the sympathetic division of the ANS

Question 25

if meal is eaten that is mainly protein and blood glucose level is low, what would happen to your amino acids in order to secrete glucogen?

Answer 25

they would rise