The Endocrine Pancreas 2 Flashcards
What type of hormone is glucagon?
Peptide hormone
Where is glucagon made?
alpha cells in pancreatic islets
What is the role of glucagon?
Raise blood glucose
Glucose-mobilising hormone
Glucagon acts on what?
The liver
What is the half life of glucagon?
5-10mins
What hormones make up the counter-regulatory control system for glucose?
Glucagon
Epinephrine
Cortisol
GH
When is glucagon most active?
Fasted state
Glucagon binds to what?
G-protein coupled receptors linked to the adenylate cyclase/cAMP system
What happens when glucagon binds to G-protein coupled receptors?
Phosphorylation of specific liver enzymes
What is the effect of the Phosphorylation of specific liver enzymes by glucagon?
Increased Glycogenolysis
Increased gluconeogenesis
Formation of ketones from FAs (lipolysis)
What happens to Liver glycogen in the presence of glucagon?
Conversion of glycogen to glucose
What happens to lipids in adipose tissue in the presence of glucagon?
Lipids become free fatty acids and glycerol
What happens to muscle cells in a low [Glucose] environment?
Use of glycogen
FAs/Breakdown of proteins to amino acids for energy
What can the brain use for energy?
Glucose
Ketone bodies
Glycogen is converted into what in muscles/
Pyruvate/lactate –> Glucose (gluconeogenesis)
Amino acids in the plasma stimulate what?
Increased insulin and glucagon
What is the benefit of a high protein meal with little carbohydrate stimulating Insulin AND glucagon?
Prevents hypoglycaemia following insulin release in response to aa.
Stimuli that promote glucagon release?
Low [BG] (<5mM)
High [amino acids] .
sympathetic innervation and epinephrine, beta2 effect
Cortisol
Stress e.g. exercise, infection
Stimuli that inhibit glucagon release?
Glucose
FFAs and Ketones
Insulin
Somatostatin
What effect does increased parasympathetic (vagal) activity have on islet cells?
Increased insulin
(somewhat) increased glucagon
ANTICIPATORY DIGESTION
What effect does increased sympathetic activity have on islet cells?
Increased glucose mobilisation
Increased Glucagon, epinephrine
Inhibited insulin
Where is somatostatin secreted from?
D-cells (pancreas)
Hypothalamus
What is the pancreatic action of somatostatin?
Inhibit GIT activity
Slow down absorption of nutrients
Prevent peaks in plasma concentrations
What is a use of synthetic somatostatin?
Treating life threatening diarrhoea associated with gut/pancreatic tumours
What is the paracrine effect of somatostatin?
Suppress release of glucagon and insulin
What is the effect of somatostatin on the anterior pituitary?
Inhibits secretion of GH
What is the other name of somatostatin?
GHIH - Growth Hormone Inhibiting Hormone
What causes a stimulation of somatostatin release?
↑[aa]plasma
↑[Glucose]plasma
How is entry of glucose into muscle increased during exercise?
Increased insulin sensitivity
Insulin-independent ↑ in number of Glut-4 transporters
How long does increased insulin sensitivity last after exercise?
Several hours
How does the brain adapt in starvation?
Adapts to use ketones for energy
How are nutrients provided in starvation?
Adipose tissue is broken down into fatty acids
Fatty acids -> Ketones
Which store is depleted last in starvation? Why?
Protein - weakening, makes person vulnerable to infection
What is the cause of T1DM?
Autoimmune destruction of pancreatic beta cells
Why does diabetes cause ketoacidosis?
Lack of insulin depresses the uptake of ketone bodies, which are acidic
What is considered an acid blood pH?
ph<7.1
Why do tissues no longer respond normal levels of insulin in T2DM?
Abnormal response of insulin receptors
Reduction in insulin receptor numbers
Typical risk factors for T2DM?
Obesity
>40yrs
High sugar/fat diet
What is the initial treatment for T2DM?
Exercise
Dietary change
What is the first line therapy for T2DM?
Metformin (oral hypoglycaemic drugs)
How does Metformin work?
Inhibit hepatic gluconeogenesis
Antagonise glucagon action
How do Sulphonylureas work?
Close Katp in B cells
Stimulate Ca2+ entry and insulin secretion
What is the diagnostic test for DM?
Glucose tolerance test
Ingest glucose after fasting [BG] is measured
Elevation after 2hrs indicates DM
What are the most common diabetes complications?
Retinopathy
Neuropathy
Nephropathy
Cardiovascular disease
Coma appears at what [BG] levels?
1.7mM
Death occurs at what hypoglycaemia [BG]?
0.6mM
At what [BG] is cortisol secreted?
3.2mM
