Endocrine part of Pancreas
(Islets of Langerhans)
The pancreas is a mixed exocrine-endocrine gland
 Exocrine function Synthesis and release of digestive enzymes
 Endocrine function Synthesis and release of hormones affecting carbohydrate
metabolism
Endocrine part (Islets of Langerhans):
• endocrine function of pancreas is performed by the islets of Langerhans. Human pancreas
• The islets represent about 2% of the weight of pancreas
• contains about 1 to 2 million islets. Islets of Langerhans consist of 4 types of cells:
1. A cells or α cells which secrete glucagon
2. B cells or β cells which secrete insulin
3. D cells or δ cells which secrete somatostatin
4. F cells which secrete pancreatic polypeptide
Functions of Insulin
(polypeptide hormone OF 51 amino acid)
1. On carbohydrates metabolism: it is the only hypoglycemic hormone in the body:
transport and uptake of glucose by the peripheral cells specially muscle, liver &
adipose tissue (insulin dependent-tissues)
B.  glycogenesis (glycogen synthesis ) in muscle and liver.
C. Inhibits glycogenolysis (glycogen breakdown) & Inhibits gluconeogenesis and
A.
2. On protein metabolism : it is anabolic hormone
•
enhance amino acid transport & conserves & stores proteins in the body.
3. On fat metabolism : it is a lipogenic hormone
•
It stimulates lipogenesis in the adipose tissues.
4- On electrolyte metabolism:
Insulin increases cellular uptake of K+
plasma K+ level.
NB: Insulin independent tissues: they utilize glucose independently on insulin
• Brain, RBCs, Intestine, Cornea, Kidney, Liver, Islet (β) cells, placenta, & Spermatocytes
Control of insulin secretion
(Factors stimulate insulin secretion)
1. level of plasma glucose (hyperglycemia is the most powerful factor in
stimulating insulin secretion).
2.  level of plasma amino acids e.g arginine
3.  level of plasma free fatty acids.
4.  level of plasma K+.
5.  GIT hormones
-e.g Gastric inhibitory polypeptide (GIP) & glucagon-like polypeptide 1
(GLP-1), Gastrin, secretin, CCK & glucagon
Diabetes mellitus (DM)
Definition
•DM is a clinical syndrome due to deficiency of insulin
Causes and types of DM
•Type1 DM =Insulin Dependent Diabetes Mellitus (IDDM)= Juvenile DM(10%)
•Is due to autoimmune destruction of β cells of pancreas
•Type2 DM =Non-Insulin Dependent Diabetes Mellitus (NIDDM)= Maturity onset
diabetes (90%)
• Is due to increase insulin resistance
Manifestations
1. Disturbed carbohydrates metabolismHyperglycemia and glucosuria Ployuria ,
Polydepsia & Polyphagia.
2. Disturbed Proteins metabolism protein catabolism, MuscleWasting, Weight loss
3. Disturbed fat metabolism lypolysis & Hyperlipidemia
4. Hyperkalaemia.
Characteristic
Type 1 ( 10% )
Type 2
Onset (Age)
Usually < 30
Usually > 40
Type of onset
Abrupt
Gradual
Nutritional status
Usually thin
Usually obese
Clinical symptoms
Polydipsia, polyphagia,
polyurea, Wt loss
Often asymptomatic
Ketosis
Frequent
Usually absent
Endogenous insulin
Absent
Present, but relatively
ineffective
Related lipid
abnormalities
Hypercholesterolemia
frequent, all lipid fractions
elevated in ketosis
Insulin therapy
Required
Cholesterol & triglycerides
often elevated; carbohydrateinduced hypertriglyceridemia
common
Required in only 20 - 30% of
patients
Hypoglycemic drugs
Should not be used
Clinically indicated
Diet
Mandatory with insulin
Mandatory with or without
drug
(polypeptide hormone =29 amino acids)
1. On CHO metabolism: hyperglycemic
•
•
It blood glucose level by  glycogenolysis &  gluconeogenesis. By the Liver
which is the primary target of glucagon.
N.B.: Glucagon has little or no influence on glucose utilization by
peripheral tissues.
2. On fat metabolism: has lipolytic and ketogenic actions.
3. On protein metabolism
has no effect on muscles
NB:
• glucagon Has a positive inotropic effect on the heart moderate increase of cardiac output
• glucagon act as a local CNS hormone for the regulation of appetite.
1. blood glucose level (hypoglycemia is the most powerful factor
in stimulating glucagon secretion).
2. Protein rich meal and, most powerfully, by th amino acids such
as arginine and alanine.