Lecture 25 - Key role of glucose

Question 1

Islets of langerhans?

Answer 1

within exocrine tissue 1-2% pancreatic tissue mass, neurovascular bundle enters through beta cell core, 20% pancreatic vascular supply, venous efferent to portal vein

Question 2

Glucose transporters 1-4?

Answer 2

1: Brain & RBC, 2: pancreas and liver, 3: neurons and placenta, and 4: fat and muscle

Question 3

Beta cell conversion of glucose into insulin?

Answer 3

DRAW IT MOTHER FUCKER

Question 4

Preproinsluin into insuline?

Answer 4

preproinsulin loses signal sequence to become proinsulin, whcih loses chain C to become insulin

Question 5

Insulin regulation?

Answer 5

basal secretion is pulsatile every 9-14 min, glucose initiates acute release followed by slow second phase, induced by arginine, glucagon and incretins (GLP1), inhibited by somatostatin

Question 6

Incretin pathway?

Answer 6

food ingestion -> incretin gut hormone release with GLP1 and gastric inhibitory polypeptide (GIP) -> glucose and GIP dependent insulin release from beta (leading to increased peripheral glucose uptake) AND decreased glucagon release from alpha - both leading to decreased hepatic glucose output

Question 7

Insulin action - carbs?

Answer 7

inhibit glycogenolysis and gluconeogenesis (liver, increase glucose transport and glycolysis (muscle and adipose)

Question 8

Insulin actions - fat?

Answer 8

increases triglyceride storage, decreases lipolysis, FFA production and ketone production

Question 9

Insulin actions - protein?

Answer 9

increased transport of A.A into liver and muscle

Question 10

Energy storage?

Answer 10

fat is majority but only quarter body weight (lipolysis, ketones), protein stores 20% energy (A.A), carbs little stores but readily available

Question 11

Krebs cycle?

Answer 11

DRAW IT MOTHER FUCKER

Question 12

Ketogenesis?

Answer 12

fuel for muscle and liver but not acutely for brain and RBC, oxidation of FFA into acetoacetate, acetone and beta hydroxybutyrate

Question 13

Insulin deficiency and ketogenesis?

Answer 13

hormone sensitive lipase being unchecked, combined with uncontrolled gluconeogensis, protein hydrolysis and inactive GLUT4 in diabetes leads to diabetic ketoacidosis

Question 14

Diabetic Keto acidosis?

Answer 14

DRAW IT MOTHER FUCKER

Question 15

Hypoglycaemia?

Answer 15

falling below normal fasting glucose of 3.5, insulin switched off, glucagon released from alpha cells, ACTH from pituitary stimulates adrenaline and cortisol release from adrenal gland

Question 16

Causes of hypoglycaemia?

Answer 16

insulin in diabetics, sulphonylurea therapy, insulinoma, Addison’s disease