Pancreas [TRH] Flashcards
(35 cards)
Where is glycogen stored?
the majority is stored in liver and sk.m= 500g or approx. 12hrs of energy
**TG stores in adipose= unlimited
When will the brain switch to using ketone bodies instead of glucose for fuel?
what steps happen during fasting/starvation
Fasting
- Gly stores in liver & muscle must be depleted–> 24hrs
- adipose TG’s are catbolized in2 glycerol & free FA’s
- glycerol –> glu via GluNeo in liver
- FA’s [acetoacetate & B-hydroxybutyrate] made in liver
- ketone bodies are converted to acetylCoA in tissues [brain, muscle]
- eventually you would get muscle wasting
What is the role of insulin?
- inhibits?
- promotes?
inhibits: intracellular lipases –I breakdown of fat/adipose tissue
promotes: facilitates glu entry into fat & liver cells–>TG accumulation in adipose
- adipose: glu can be used to synth glycerol
- liver: glu synth into FA’s once glycogen stores are maximal
- these FA’s are pkged as lipoproteins & secreted as FFA
- adipose picks up FFA+glycerol = TG
What do B cells of the pancreas secrete?
insulin
**in fed state
***also secretes amylin
What do alpha cells of the pancreas secrete?
glucagon
**in fasted state
what does the delta [kinda looks like this: oς] cell secrete?
somatostatin
what is the overall effect of insulin on metabolism after eating?
reduce serum Glu!!!
^^Glu ox
^^Glycogen synth
^^Fat synth
^^protein synth
What is the overall effect of glucagon on metabolism in the fasted state?
increase serum Glu!!!!
^^glycogenolysis
^^GNeo
^^Ketogenesis
What is normal blood glu levels?
fasting levels?
normal= 70-120 mg/dl
norm fasting = <100 mg/dl
What do E cells secrete?
ghrelin!
What effect does the SNS have on the islets of langerhans cells?
SNS: inhibit insulin & amylin secretion [fight or flight]
*don;t want to store energy when busy running from a bear & you need it!
What is the PNS effect on islets of lengerhans?
-where does this PNS innervation come from
- PNS via the vagus
- involved in cephalic phase of insulin secretion
How are both insulin and glucagon secretion regulated?
- plasma glucose levels trigger secretion [depends on if hi or low]
- negative feedback involves further glu sensing by a & B islet cells
How is insulin processed and what is it’s mature form?
Which part of insulin contains essential info for biologic activity?
Preproinsulin–>proinsulin–>*insulin
Mature form: 2 chains
- alpha chain [acidic]
- beta chain [basic]
- 22-26 sequence essential for biologic activity
- 2 disulfide bridges connact a & B chains
*C-peptide is cleaved here
What is the significance of C-peptide?
proinsulin is cleaved into–> C-peptide & insulin
- It can be measured to determine if the patients insulin is endogenous [made by the pt] or exogenous [medication]
- present Cp= endogenous
- low/none= exogenous
What are the pharmokinetics of insulin?
- t1/2 < 10 mins
- circulates in free plasma
- metabolized by K & liver
- via glutathione-insulin transhydrogenase in microsomes
- proteolytic enzymes
- 50% on 1st pass
- via glutathione-insulin transhydrogenase in microsomes
What type of R is the insulin R?
InsulinR= tyrosine kinase!
- promotes glu uptake in2 cells & synth into storage molecules, glycogen, & TGs
What is amylin?
- what R does it bind?
- what is its main fxn(s)?
amylin= insulin’s co-conspirator
- co-pkged & -secreted w/ insulin from B cell [1:1 ratio]
- t1/2 = mins
- calcitonin R dimerized w/ R activity-modifying protein
- **inhibits glucagon secretion **@ level of pancreatic alpha cell
- role:
- reduce food intake
- delay gastric emptying
- inhibit secretion of digestive enzymes, stom.acid, & bile
Glucagon…
- what form is it made in?
- when does it ^^ or decrease?
Glucagon is made in a cells of pancreas
- synthesized as proglucagon
-
increases w/ or when:
- hypoglycemia
- AA’s
- SNS & vagal stimulation [latter to temper insulin effects]
-
decreases w/:
- amylin present
What R does glucagon act through/bind?
What does glucagon promote?
glucagon ats on Gprotein coupled Glucagon R’s [GCGR]
- promotes liver GNeo
- ” “ glycogenolysis
- ” “ lipolysis
Which H’s does Somatostatin affect?
what triggers/inhibits SST?
what are its effects on GI?
SST: inhibits insulin [B cells], glucagon [alpha], & ghrelin [e cells] prodxn
- triggered by ^^insulin
- inhibited by ^^ghrelin [hunger]
in GI: SST reduces the rate of food absorption
What does Ghrelin do to other pancreatic H levels?
Ghrelin:
^^glucagon
decreases Insulin & SSt
What are Incretins?
- hormones that promote B cell insulin release after eating [intestinal phase]
- slow gastric emptying–> slows the rate of nutrient absorption in2 blood
- may also reduce food intake
ex) GLP-1 & GIP
WHat is GLP-1?
GLucagon like peptide 1
- AA peptide produced by L cells of the lower SI & colon
- produced by alt. splicing of proglucagon gene
- in pancreas = glucagon, SI & colon= GLP-1
- stimulates insulin in hi glu environment [fed]
- inhibits glucagon secretion in hypoglycemia
- degreaded by dipeptidyl-peptidase-4
