Endocrine Pancreas Flashcards
What is the normal range of blood glucose?
4.2-6.3mM 980-120mg/dl)
What is the useful blood glucose reference for hypoglycaemia?
<3mM
What are the 2 key endocrine hormones produced by the pancreas?
Insulin
Glucagon
Where are pancreatic hormones produced?
Islets of Langerhans
What are the four types of islets of langerhans cells?
Alpha
Beta
Delta
F
What is the function of alpha cells?
Produce glucagon
What is the function of beta cells?
Produce insulin
What is the function of delta cells?
Produce somatostatin
What is the function of F cells?
Produce pancreatic polypeptide
What class of hormones does insulin belong to?
Peptide hormones
What is the function of insulin?
Stimulates glucose uptake by cells
What is the function of leptin?
Released by fat stores to depress feeding activity
What is the absorptive state?
Ingested nutrients supply the energy needs of the body and excess is stored. Anabolic phase
What is the post absorptive/fasted state?
Reliance on body stores to provide energy. Catabolic phase
What is the significance of insulin as a hormone?
Only hormone which lowers blood glucose
What type of channel is specific to beta cells?
Potassium ion channel that is sensitive to ATP within the cell
What are some of the additional actions of insulin?
Increases glycogen synthesis in muscle and liver
Increases amino acid uptake into muscle, promoting protein synthesis
Has a permissive effect on growth hormone
Promotes K+ ion entry into cells
Inhibits the enzymes of gluconeogenesis in the liver
What stimuli increase insulin release?
Increased blood glucose Increased amino acids in plasma Glucagon Vagal nerve activity Other hormones controlling GI secretion and motility
What stimuli inhibit insulin release?
Low blood glucose
Somatostatin
Stress
Sympathetic alpha 2 effects
What is the primary purpose of glucagon?
Raises blood glucose
When is glucagon most active?
Post-absoprtive state
What is the result of glucagon receptors being activated?
Increased glycogenolyis
Increased gluconeogenesis
Formation of ketones from fatty acids
Describe glucagon receptors
G coupled proteins linked to adenylate cyclase/cAMP
What stimulates glucagon secretion?
Blood glucose <5.6mM
Amino acids
What are the stimuli that promote glucagon release?
Low blood glucose High amino acid Cortisol Stress Sympathetic innervation and epinephrine, beta2 effect
What are the stimuli that inhibit glucagon release?
Glucose
Free fatty acids
Insulin
Somatostatin
What is the effect of increased parasympathetic (vagus) activity?
Increased insulin
Increased glucagon
What is the effect of sympathetic activation?
Increased glucagon
Increased epinephrine
Inhibition of insulin
What is the main action of somatostatin?
Inhibit activity in the GI tract
How does somatostatin function?
Slow down absorption of nutrients to prevent exaggerated peaks in plasma concentrations
What is the effect of exercise on blood glucose?
Entry of glucose into skeletal muscle increases
Increases insulin sensitivity of muscle
What is the effect of starvation on blood glucose?
Adipose tissue breaks into free fatty acids
Liver converts excess FFAs to ketone bodies
