Carbohydrate, Fat, and Protein Control Flashcards
(33 cards)
What are the types of carbohydrates?
monosaccharides (ex. glucose), disaccharide (ex. sucrose), polysaccharides (ex. glycogen)
Define: Glycolysis
breakdown of glucose to generate energy
What is normal fasting plasma glucose level?
70-110 mg/dL
Define: Glycogenesis
glucose –> glycogen, occurs after meals
Define: Glycogenolysis
glycogen –> glucose, process done by the liver in the fasted state
Define: Gluconeogenesis
amino acids & glycerol –> glucose, process done by the liver in the PROLONGED fasting state
What is secreted by pancreatic alpha cells?
glucagon, prolucagon
What is secreted by pancreatic beta cells?
make up 75% of pancreatic cells that have endocrine function- insulin, C-peptide, proinsulin, amylin
What is secreted by pancreatic delta cells?
somatostatin
What is secreted by pancreatic epsilon cells?
ghrelin
What effect does Somatostatin have in regulation of nutrient homeostasis?
INHIBIT secretion of insulin and glucagon
What effect does Glucagon have in regulation of nutrient homeostasis?
STIMULATE secretion of insulin and somatostatin
What effect does Insulin have in regulation of nutrient homeostasis?
INHIBIT secretion of glucagon
Describe the role of Incretins
feeding induces release of incretins (insulinotropic peptide) from the gut (GIP= glucose-dependent insulinotropic polypeptide, GLP-1= glucagon-like peptide 1) that is PROPORTIONAL to the nutrient load ingested to regulate the pancreas to INCREASE INSULIN and DECREASE GLUCAGON release
What physiological effects does increased glucagon have?
stimulates lipolysis in adipose tissue, glycogenolysis/gluconeogenesis in the liver
In a healthy patient, when is insulin secretion highest?
during the early phase of meals
What factors increase insulin secretion?
-glucose
-amino acids
-high fatty acids
-glucagon
-GLP-1 (glucagon-like peptide 1)
-GIP (glucose-dependent insulinotropic polypeptide)
-acetylcholine (vagus stimulation)
-beta adrenoceptor receptor activation (fight or flight)
-sulfonylurea
What factors decrease insulin secretion?
-chronically elevated glucose
-low fatty acids
-insulin
-somatostatin
-leptin
-beta blockers
-alpha adrenoceptor activation
-K+ depletion
What are the primary target tissue for insulin?
liver, muscle, and adipose tissue
Describe the insulin receptor
tyrosine kinase, alpha subunit has affinity for insulin binding and beta subunit is membrane bound portion which can illicit tyrosine kinase activity- phosphorylates insulin receptor substrate (IRS) –> MAP kinase –> phosphatidylinositol-3 (PI-3) kinase pathways –> further trigger downstream events
What downstream events are triggered by activation of the insulin receptor?
-translocation of glucose transporter (GLUT4) to the cell member to increase glucose uptake
-increased glycogen synthase activity
-increased protein synthesis lipogenesis
What role does GLUT play in insulin action?
when activated after insulin binding, GLUT mediate facilitated diffusion of glucose into cells
Where is GLUT4 located?
muscle, adipose tissue
Where is GLUT1 located?
all tissues, but especially red blood cells and brain
