This document discusses the pancreas as an endocrine organ that regulates glucose homeostasis through insulin secretion. It describes the structure of the pancreas and mechanisms of insulin release, including first and second phase release in response to glucose levels. It discusses insulin receptors and effects, including stimulating glucose uptake and inhibiting lipolysis. It also covers control of insulin secretion by factors like glucose, hormones, the autonomic nervous system and potassium levels. The role of glucagon and somatostatin are briefly explained. Mechanisms of glucostasis involving the liver and hormones are summarized.

1. Pancreas as endocrine organ:
Glucose homeostasis & Insulin
Nermeen Bastawy
Physiology Department
Faculty of Medicine
Cairo University

6. F
60% 25 %

8. Pro insulin

9. Ribosomes ER /Golgi Golgi/Granules

11. Mechanism of insulin release
• Phases :
 1st phase: rapid, short, glucose dependent
 2nd phase: slow,sustained, glucose independent
• Oscillation pattern:
every 5 min.

13. Insulin receptors & effects
K, aa
Na/K ATpase IRS
Glucokinase
Lipase GLUT4

14. (Glucose transporters (9
2ry active transp. Facilitated Diffusion

15. GROWTH & METABOLISM
• Proteins & growth (anabolic(
• CHO : insulin sensitive tissues
( muscle, adipose, liver(
• Fat & KB

16. INSULIN
-- lipase Adipose
FFA
Glucose
ATP

17. GLUT2
GK
G6P ATP
TG & VLDL
GS
lipase
FFA
Lipase
Hs-
Adipose
Lipase

18. + ???Insulin & K
• Insulin  K shift into the cells by ++ Na/K
ATPase. That's why insulin is used in the
treatment of hyperkalemia.
• Hyperkalemia: more K will enter beta cell
++ insulin secretion
• Hypokalemia more K will leave beta cell
 -- insulin secretion.
• Why diuretics are contraindicated in DM?

19. Control of insulin secretion
• Hypothalamus/pituitary? NOT
• Feed back? Glucose / Insulin
• +++/- - - - ?
FOOD Hs ANS K+ cAMP

20. Insulin
Max
Basal
70 100 300
Glucose mg %

21. Control of insulin secretion
• Hypothalamus/pituitary? NOT
• Feed back? GLUCOSE/Insulin
• +++/- - - - ?
FOOD Hs ANS K+ cAMP

22. How dose food ++ insulin secretion?
W is better stimulant 4 insulin
secretion: oral or IV glucose?

23. Control of insulin secretion
• Hypothalamus/pituitary? NOT
• Feed back? GLUCOSE/Insulin
• +++/- - - - ?
FOOD Hs ANS K+ cAMP

24. Glucagon
• Pancreas (A cells)
• GIT & brain ( A & L cells)
• Actions:
1. Oppose insulin
2. ++ insulin, GH, SS secretion
3. +ve inotrope.
• Regulation : Food Hs ANS
stress & exercise glucocorticoids

25. Somatostatin
• GIT & Pancreas ( D cells)
• ++ by food & GIT hormones
• -- all hormones & GIT motility &
secretions

26. Important Qs
• Why exercise is benefit for DM?
It lower blood by ++ cAMP-kinase w moves
GLUT4.
• Why diuretics are contraindicated in DM?
K is important for insulin secretion, so
Diuretics -- K+  -- insulin secretion

27. Mechanism of Glucostasis
1. Liver (glycogenesis, glycogenolysis,
gluconeogenesis).
2. Hormonal mechanism
• Insulin / glucagon
• Catecholamine, GH & cortisol

28. 70-100 mg%
Glycogenolysis

29. Mechanism of Glucostasis
1. Liver
2. Hormonal mechanism
• Insulin / glucagon
• Catecholamine, GH & cortisol
++ energy sources :
++ glucose (glycogenolysis,
gluconeogenesis with IR)
++ FFA, KB & aa