Pancreas Flashcards
(109 cards)
1
Q
How many peptide hormones does it secrete?
A
5
2
Q
What are the peptide hormones?
A
- insulin
- glucagon
- somatostatin
- pancreatic peptide
- ghrelin
3
Q
What is produced by beta cells?
A
Insulin
4
Q
What is produced by alpha cells?
A
Glucagon
5
Q
What is the function of insulin and glucagon?
A
Regulate glucose, FA and AA metabolism
6
Q
What is produced by gamma cells?
A
Somatostatin
7
Q
What is produced by F cells?
A
Ghrelin
8
Q
What are islets of langerhans?
A
Clusters of endocrine cells in the pancreas
9
Q
What is the mass of islets?
A
1-2%
10
Q
4 cell types of islets
A
- alpha
- beta
- gamma
- PP
11
Q
Where are alpha islets cells found?
A
Outer rim
12
Q
where are beta islet cells found?
A
central core
13
Q
where are gamma islet cells found?
A
interspersed
14
Q
what is the most abundant islet cell?
A
Beta
15
Q
blood supply of communication islets
A
venous blood of 1 cell type bathes the other cell types
16
Q
neural innervation of islet cells
A
sympathetic and parasympathetic
17
Q
examples of sympathetics in islet cells
A
adrenergic and peptidergic
18
Q
examples of parasympathetic in islet cells
A
cholinergic and peptidergic
19
Q
vagal stimulation via Ach and VIP stimulates the release of ___
A
insulin
20
Q
where do sympathetic preganglionic cells bodies originate
A
intermediolateral horn cells in the spinal cord
21
Q
where do sympathetic preganglionic cells synapse at with postganglionic fibers
A
paravertebral ganglia and celiac ganglia
22
Q
what does the activation of pancreatic sympathetic nerve fibers cause stimulation of?
A
glucagon
23
Q
what does the activation of pancreatic sympathetic nerve fibers cause inhibition of?
A
insulin release
24
Q
a rich complement of ___ joins the splanchnic nerve and enters the spinal cord
A
sensory fibers
25
insulin is synthesized and secreted by
beta cells
26
what is the hormone to be isolated from animal sources in a form that could be administered to humans
insulin
27
what hormone is measured by RIA
insulin
28
what hormone is known to be synthesized from a larger precursor
insulin
29
main parts of an insulin structure
a chain, b chain and a bridge to connect the chains
30
which chromosome is insulin synthesized on
11
31
where is the metabolism for insulin at
liver and kidneys
32
separate a and b chains are ___ excreted in urine
inactively
33
a signal peptide for preproinsulin is cleaved when
early
34
preproinsulin has a ___
connecting peptide (C peptide)
35
what is proinsulin
preproinsulin minus the signal peptide
36
where does proinsulin travel to
ER
37
C peptide is removed by ___
proteases
38
C peptide is the basis for the test of type ___ diabetes
1
39
the C peptide levels reflect ___ function in people with type 1 diabetes
beta cell
40
stimulatory factors affecting insulin secretion
increase in glucose, AA, FA concentrations, ketones, cortisol, GIP, GLP1, K+, vagal stimulation (Ach), sulfonylurea drugs, obesity, b-adrenergic agonists, GH/prolactin, glucagon
41
inhibitory factors affecting insulin secretion
decrease in glucose concentration, fasting, exercise, somatostatin, EP, NE, IGF1, leptin, diazoxide
42
t/f: c peptide is secreted in equimolar amounts with insulin and is excreted unchanged in the urine
true
43
t/f: intravenous glucose does cause the release of GIP
false- only acts directly
44
what are incretins
group of GI tract hormones that cause an increase insulin release after eating
45
what are 2 major incretins
GIP and GLP
46
a ___ rate of stomach emptying decrease food intake
slow
47
other factors affecting insulin secretion
FAs and Has use metabolic pathways, drugs to treat type 2 diabetes, closing K+ channels
48
what does insulin bind to on a receptor
alpha subunits
49
insulin activates ___ in the beta subunit which phosphorylates itself in the presence of ATP
tyrosine kinase
50
what is the insulin-receptor complex internalized by
endocytosis
51
insulin is either ___ or ___
degraded or stored to be used again
52
how does insulin down regulate its own receptor
by decreasing the rate of synthesis and increasing the rate of degradation
53
what is the hormone of abundance
insulin
54
when are excess nutrients stored
when the availability > body demands insulin
55
where is glycogen stored
liver
56
where is fat stored
adipose tissue
57
where is protein stored
muscle
58
actions of insulin
decrease blood glucose concentration, decrease blood FA and ketoacid concentration, decrease blood AA concentration, promotes K+ and glucose uptake, direct effect on satiety center
59
from where is the satiety center stimulated
ventromedial nucleus in the hypothalamus
60
how does insulin decrease blood glucose
getting transported to target cells via GLUT4
61
a decrease in blood glucose promotes ___
the formation of glycogen and inhibits glycogenolysis
62
t/f: the liver does not require insulin for glucose uptake
true
63
low blood glucose inhibits ___
gluconeogenesis
64
how does insulin decrease blood FA and ketoacids
by decreasing their concentrations
65
how do you decrease blood FA and ketoacid concentrations
inhibit the mobilization and oxidation of FA and increase storage
66
adipose inhibits ___
lipolysis
67
liver inhibits ketoacid formation by ___
decreasing FA degradation
68
how does insulin decrease blood AAs
increase AA and protein uptake, increase protein synthesis and decrease protein degradation
69
what are the tissues that don't need insulin for glucose uptake
BRICKLE
| brain, RBCs, intestine, cornea, kidney, liver, exercising skeletal muscle
70
is GLUT2 insulin dependent
yes
71
how does glucose enter pancreatic beta cells
via GLUT2
72
which type of diabetes is insulin dependent
1
73
what is type 1 diabetes characterized by
destruction of beta cells, loss of lean body mass and adipose, glucosuria, hyperkalemia
74
characteristics of type 2 diabetes
insulin resistance of target tissues, associated with obesity
75
what is type 2 diabetes caused by
down regulation of insulin receptors and insulin resistance
76
in t2d, normal insulin concentrations cannot ___
activate receptors
77
the main treatment for t2d is ___
exercise
78
incretin effect on oral glucose tolerance test
GLP1
79
*graph over oral glucose tolerance test*
a normal person's blood glucose will decrease throughout the day after they wake up. someone with diabetes will have a constant increase in blood glucose after they wake up
80
what is glucagon synthesized by
islet alpha cells
81
what is the opposite of insulin
glucagon
82
what is the hormone of starvation
glucagon
83
function of glucagon and other fuel-mobilizing hormones
counterbalance the fuel-storing effects of insulin
84
t/f: states of glucagon excess or deficiency always lead to overt disease due to other hormonal compensation
false- rarely
85
what do peptides include
GI hormones, secretin and GIP
86
what is glucagon synthesized as
preproglucagon
87
how is preproglucagon stored
in dense granules
88
stimulatory factors affecting glucagon secretion
fasting, decrease glucose concentration, increase AA concentration, CCK, EP, NE, Ach, GIP
89
inhibitory factors affecting glucagon secretion
glucose, insulin, somatostatin, increase FA and ketoacid, GLP1
90
what are the actions of glucagon
maintains blood glucose in the fasting state, increase glycogenolysis, glucogenesis, lipolysis, FA, ketoacids
91
what is the most important function of glucagon
stimulates the liver to produce and secrete glucose and ketone bodies
92
physiologic actions of glucagon
stimulates a hepatocyte to produce glucose, glycogenolysis, inhibits the formation of glycogen from glucose, gluconeogenesis, lipogenesis, ketogenesis, ureogenesis
93
where are amino groups removed
in urea
94
what is the most important determinant of glucagon secretion
concentration of glucose
95
at what level of secretion is glucagon maximally inhibited
>200
96
___ inhibits glucagon secretion
insulin and FFA
97
when is glucagon secreted
by a protein rich meal
98
function of glucagon
prepares the liver for gluconeogenesis and signals the liver to release glucose
99
what is somatostatin secreted by
gamma islet cells
100
what inhibits somatostatin
insulin
101
pancreatic somatostatin inhibits the secretion of ___
insulin and glucagon
102
function of somatostatin
modulate or limit the responses of insulin and glucagon to ingestion of food
103
what is pancreatic polypeptide secreted by
F cells
104
function of PP
self-regulate the pancreas's secretory activities
105
when is pp secreted
after a protein meal
106
when is ghrelin secreted
in between eating
107
where is ghrelin produced
stomach mucosa, pancreas, brain, ovary, adrenal cortex
108
function of ghrelin
increases feelings of hunger, increases gastric acid secretion, gastric motility and gastric emptying
109
what is the only hormone that promotes food intake
ghrelin
