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Pancreatic Hormones
• Glucagon
• Insulin
Pancreas Histology
Pancreas
13-34
Islets of Langerhan (Pancreatic Islets)
Pancreatic Hormones, Insulin & Glucagon Regulate Metabolism
Figure 22-8: Metabolism is controlled by insulin and glucagon
Insulin Stimulates Cellular Glucose Uptake
LiverSkeletal Muscle
Adipocytes
Intestine & Pancreas
InsulinInsulin
Insulin
Glucagon and Insulin
Action of Insulin on Adipose Tissue
• Stimulates glucose uptake
• Stimulates glycolysis
• Stimulates lipogenesis
• Inhibits lipolysis and ketogenesis
Actions of Glucagon on the Liver
• Stimulates glycogenolysis
• Stimulates gluconeogenesis
• Inhibits glycolysis
• Stimulates lipolysis and ketogenesis
Actions of Insulin on the Liver
• Stimulates glucose uptake• Stimulates glycogenesis• Stimulates glycolysis• Stimulates HMP shunt activity• Inhibits glycogenolysis• Inhibits gluconeogenesis• Stimulates lipogenesis • Inhibits lipolysis• Stimulates cholesterol synthesis• Increases VLD lipoprotein• Increases potassium and phosphate uptake
Actions of Insulin on Muscle
• Stimulates glucose uptake• Stimulates glycogenesis• Stimulates glycolysis• Inhibits glycogenolysis• Inhibits FFA uptake and oxidation• Stimulates proteogenesis• Inhibits proteolysis• Stimulates uptake of potassium, phosphate and
magnesium• Increases blood flow
GLUCAGON
Alpha cells
Hypoglycemia =
glucagon secretion
Actions
increased glycogenolysis
increased gluconeogenesis
Result = normoglycemia
hypoglycemia (<90mg%)
alpha cells secrete glucagon
liver cells: increase glycogenolysis increased gluconeogenesis
normoglycemia (>90mg%)
( -)
negative feedback
increased blood glucose
INSULIN
Beta cells
Hyperglycemia =
insulin secretion
Actions
increased glucose uptake
increased glycogenesis
increased lipogenesis
hyperglycemia (<110mg%)
beta cells secrete insulin
increased glucose uptake into body cells increase glycogenesis (skeletal muscle, liver)increased lipogenesis
normoglycemia (<110mg%)
( -)
negative feedback
decreased blood glucose
Result = normoglycemia
Diabetes mellitus
Normal
LPL
Triglyceride
LipolysisGlycerol
Free fatty acids
Free fatty acids
Glucose
Synthesis
Insulin
Insulin
Triglyceride
LPL
Type 1 Diabetes Mellitus
LipolysisGlycerol
Free fatty acids
Free fatty acids
Glucose
Synthesis
Diabetes Mellitus• This is a disease caused by elevated glucose levels
• 2 Types of diabetes:
Type I diabetes (10% of cases)
Type II diabetes (90% of cases)
Type I Diabetes (10% of cases)
• Develops suddenly, usually before age 15
• Caused by inadequate production of insulin because T cell-mediated autoimmune response destroys beta cells
• Controlled by insulin injections
Type II diabetes (90% of cases)
• Usually occurs after age 40 and in obese individuals
• Insulin levels are normal or elevated but there is either a decrease in number of insulin receptors or the cells cannot take it up.
• Controlled by dietary changes and regular exercise
• Glucose homeostasis
Figure 26.8
Insulin
Beta cellsof pancreas stimulatedto release insulin intothe blood
Bodycellstake up moreglucose
Blood glucose leveldeclines to a set point;stimulus for insulinrelease diminishes
Liver takesup glucoseand stores it asglycogen
High bloodglucose level
STIMULUS:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal) Homeostasis: Normal blood glucose level
(about 90 mg/100 mL) STIMULUS:Declining bloodglucose level(e.g., afterskipping a meal)
Alphacells ofpancreas stimulatedto release glucagoninto the blood
Glucagon
Liverbreaks downglycogen and releases glucoseto the blood
Blood glucose levelrises to set point;stimulus for glucagonrelease diminishes
Glucose
Insulin
I
I
I
II
I
I
I
G
G
G
G
G
G
GG
I
G
G
G
Beta CellDysfunction
Increased SGO
Exxagerated lipolysis
Insulin Resistance
Decreased Glucose Uptake
Type 2 diabetes: patophysiology
Pancreas
Glucose
Insulin
I
I
I
II
I
I
I
G
G
G
G
G
G
GG
I
G
G
G
InsulinSecretion
Insulin Effects
FOOD
Pancreas
Restrain of HGO Uptake of glucose
Storage In Fat DepotsInhibition of Lipolysis
Prevention of obesityشرا ) وعاء آدمي مأل ما وسلم عليه الله صلى قال
فان صلبه، يقمن لقيمات آدم ابن بحسب بطنه، منوثلث لشرابه وثلث لطعامه فثلث فاعال البد كان
والترمذي(. أحمد رواه لنفسه