Physiological role of insulin • Release of insulin by beta cells – Response to elevated blood glucose level – Effects of insulin • Somewhat global • Major effects on muscle, adipose tissues, and liver – Increased glucose uptake • Glucose – Energy source – Glycogen synthesis
Physiological role of insulin. Release of insulin by beta cells Response to elevated blood glucose level Effects of insulin Somewhat global Major effects on muscle, adipose tissues, and liver Increased glucose uptake Glucose Energy source Glycogen synthesis. - PowerPoint PPT Presentation
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Physiological role of insulin
• Release of insulin by beta cells– Response to elevated blood glucose level– Effects of insulin
• Somewhat global• Major effects on muscle, adipose tissues, and
– Stimulation of insulin secretion– Inhibition of glucagon synthesis
• Adrenal and neural catercholamines– Adrenal epinephrine
• Inhibition of insulin secretion– Alpha receptor-mediated– Glucose availability during stress
• Stimulation of glucagon secretion– Epinephrine and norepinephrine– Activation of beta receptors
• Amino acids and other metabolites (acetoacetic acid)– Increased insulin secretion
• Protein synthesis
• Fatty acid synthesis
– Increased glucagon secretion• Prevention of hypoglycemia
– Counteracts effects of insulin
• Abolished when CHO and proteins are ingested together
• Stimulation by GI tract (entero-insular axis)– Secretion of gastrointestinal inhibitory peptide
(GIP) and glucagonlike peptide 1 (GLP-1)• Response to orally ingested glucose• Stimulates secretion of insulin• GLP-1 stimulates cAMP production• Secretion of insulin above the level secreted in
response to glucose alone– Beta cells must be “competent” to respond to increased
glucose level
• Stimulation by GI tract (entero-insular axis)– Secretion of gastrointestinal inhibitory