pancreatic hormones glucagon insulin. pancreas histology

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