Endocrine energy regulation Flashcards
What other hormones apart from insulin and glucagon can influence glucose homeostasis
Epinephrine
Cortisol
Growth hormone
Thyroid hormone
Secretin
Cholecystokinin
What is the only hormone that lowers bood glucose
Insulin
What receptors are stimulated by insulin and which by glucagon/epinephrine
Insulin- RTK
Glucagon, epinephrine ->GPCR
how endocrine portion of pancreas in called
Islets of langernas
what is secreted by acinar and duct cells? to what portion of paracrine they are referred?
What cells are founf in islets of langerhans and what they secrete
where glucagon, somatostatin and pancreatic polypeptide are produced apart from pancreas?
Gastrointestinal mucosa
What is morphology of islets of Langerhans
islets highly vascularized (5 to 10 x blood flow of exocrine pancreas)
v blood first supplies centrally located B cells i.e. detects glucose levels
v then blood travels to more peripheral A and D cells i.e. exposed to insulin secreted by B cells
how islet cell hormones interact between each other?
How glucagon and insulin are produced?
what are nutrients, gastrointestinal hormones, hormones and autonomic nerves which control the release of insulin form beta cells
major factors controlling insulin secretion
epinephrine through alpha receptors
what nutrients, GI hormones, hormones and nerves control release of glucagon
What is the longest nerve in our body
Vagus nerve, number 10
what is the functional of vagus nerve
v Acts as a sensory neuron and
as a motor neuron (providing
and receiving signals from
peripheral organs)
v Main neuronal coordinator of
appetite control, digestion
and metabolism
v Release of acetylcholine
(cholinergic) in the pancreas
stimulates insulin release
how insulin get released from beta cells
- v Uptake of glucose by the type 2 facilitative glucose transporter (Glut 2)
- Aerobic glycolysis and increase of the ATP/ADP ratio.
- Inhibition of ATP-sensitive K+ channels → reduction of K+ efflux → membrane depolarization
- Opening of voltage gated Ca2+ channels (VDCC)
- Increased intracellular Ca2+ triggers exocytosis of insulin containing granules
- Opening of Ca2+ activated potassium channels (K-Ca), leading to the repolarization of the membrane (resetting)
- Metabolic coupling factors generated during glucose metabolism facilitate exocytosis and/or proinsulin synthesis (amplification pathway). Examples are plasma FFA (stimulates exocytosis via G-protein receptor) and intracellularly formed succinate.
- Glucagon-like peptide 1 (GLP-1 from intestine) or related peptides bind to GLP-1 receptors and trigger cAMP production. It potentiates the amplification pathway, ion channels and exocytosis
what is happeing with glucose metabolism overall after meal and when fasting
what is normal glucose level during fasting , after meal and when glycosuria
v Serum glucose in the fasting stage 3-5 mM
v Rise to 7 mM after meal (glycosuria if exceeding 10 mM)
anabolic effects of insulin
synthesis of protein, lipid and glycogen and
inhibition of their degradation (usage of glucose)
v Insulin promotes cell growth. It is essential for normal growth and
development
Key target tissues of insulin
Insulin promotes glucose uptake in muscle and adipose tissue
by increasing the Glut 4 transporters on the cell surface
and cardiac muscle
is insulin stopped to be secreted ever?
Insulin is continuously secreted to enable peripheral tissues to uptake glucose
Glucose supresses ___ (hormone) secretion
GH, which reduces glucose uptake and increases lypolysis
where glut2,glut 3, glut 4 is found and their specifics
how facilitated uptake via glut 2 is maintained
The concentration gradient of (non-phosphorylated) glucose
insulin receptor-> ___ pathway->glut 4 is brought to the surface
PI3K pathway
glucagon functions through which GPCR
adenylyl cyclase and PKA
how glucagon increases glucose blood concentration
it induces phosphorylase-> increased glycogenolysis
does glucagon affect muscles?
No, because msucles do not have glucagon receptors
compare glucagon, GLP-1, GLP2
Name functions of insulin on liver, muscle and adipose tissue
what viruses cacn destroy beta cells
Enterovirus, Rotavirus, Mumpsvirus and Cytomegalovirus
what immune cells kill beta cells
Autoantibodies from CD4+ and CD8+ T-cells
what locus is the strongest risk factor for T1DM
3 stages where T2DM can be developed
Pre-receptor
v Autoantibodies against insulin
v Mutant insulin (missing or
retained peptide)
Receptor
v Low number or affinity
v Autoantibodies against the
receptor
Post-receptor
v Deficient signal mediators
v Low expression of Glut4
how obesity predisposes t2DM
4 places on which somatostatin acts
function of PP
Reduces appetite
v Powerful inhibitor of the secretion of digestive
enzymes of the pancreas
v Blocks contraction of the gall bladder (inhibitor of bile
secretion)
PP concentration increases when
Usually gut hormones inhibit hunger,except for one, which one
Hunger
