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THE ENDOCRINE PANCREAS

Learning Objectives

• Understand the structure of the Pancreas • Basic understanding of its function• Endocrine hormones secreted by the Pancreas• Diabetes Mellitus

• Types of Diabetes • Risk Factors • Pathogenesis • Clinical features • Complications •Management

•Islet Tumor

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The Endocrine Pancreas

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The Pancreas consists of two separate functional units. The exocrine Pancreas 80-85%

Secretes digestive enzymes into the doudenum The Endocrine Pancreas 20-15%

Secretes a number of different hormones

The Endocrine pancreas consist of One Million of Islets of Langerhans, which are

scattered throughout the gland. Each Islet is composed of a cluster of a

number of different cell types. Each cell type synthesizing and secreting a

different hormone.

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The Endocrine Pancreas

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Cell Type Hormone

Synthesize Hormone action

Beta Cells Insulin Increases glucose entry into cells Promotes glycogen synthesis Prevents its breakdown Promotes libogenesis and prevents lipolysis

Alpha Cells Glucagon Promotes glycogen breakdown Promotes gluconeogenesis

Delta Cells Somatostatin Inhibits secretion of insulin glucagon

PP Pancreatic polypeptide

Exerts a number of gastrointestinal affects

Entrochromafin Cells

Vasoactive intestinal polypeptide

Stimulates intestinal fluid secretion

D1 Serotonin Potent vasodilator increases intestinal motility

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The Endocrine Pancreas

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Insulin Glucagon These Hormones are responsible for maintaining blood

sugar levels. Insulin exerts hypoglycemic effect. Glucagon exerts hyperglycemic effect.

The two main disorders of the Islet cells are:Diabetes mellitus Islet Tumors

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Diabetes mellitus

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Is a chronic progressive disorder characterized by an absolute or relative deficiency of Insulin and/or Insulin resistance, inducing hyperglycemia.

Classification. There are two main types of Diabetes

mellitus 1- Type I ( Insulin dependent Diabetes mellitus ( IDDM )Also called juvenile onset diabetes, which occurs

10% of all cases.

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DM CLASSIFICATION

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Results from decreased insulin sensitivity and decreased pancreatic beta-cell function

2- Type II ( None Insulin dependent Diabetes Mellitus ) NIDDMAlso called adult onset diabetes, which accounts for 80-90% of all cases.

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Types of Diabetes Mellitus

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3- Gestational Diabetes.Induced pregnant diabetes, usually appear in women with a family history of diabetes. usually disappears after

delivery but about 1/3 will develop diabetes within 10 years

risks of developing are increased if obese family history

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DM - Risk factors

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Weight. Being overweight is a primary risk factor for type 2 diabetes. The more fatty tissue you have, the more resistant your cells become to insulin.

Fat distribution. If your body stores fat primarily in your abdomen, your risk of type 2 diabetes is greater than if your body stores fat elsewhere, such as your hips and thighs.

Inactivity. The less active you are, the greater your risk of type 2 diabetes. Physical activity helps you control your weight, uses up glucose as energy and makes your cells more sensitive to insulin.

Family history. The risk of type 2 diabetes increases if your parent or sibling has type 2 diabetes.

Race. Although it's unclear why, people of certain races — including blacks, Hispanics, American Indians and Asian-Americans — are more likely to develop type 2 diabetes than whites are.

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DM - Risk factors

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Age. The risk of type 2 diabetes increases as you get older, especially after age 45. That's probably because people tend to exercise less, lose muscle mass and gain weight as they age. But type 2 diabetes is also increasing dramatically among children, adolescents and younger adults.

Prediabetes. Prediabetes is a condition in which your blood sugar level is higher than normal, but not high enough to be classified as diabetes. Left untreated, prediabetes often progresses to type 2 diabetes.

Gestational diabetes. If you developed gestational diabetes when you were pregnant, your risk of later developing type 2 diabetes increases. If you gave birth to a baby weighing more than 9 pounds (4 kilograms), you're also at risk of type 2 diabetes.

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Pathogenesis of DM

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1- Type I of DM

Typically present in the childhood and is characterized by complete lack of insulin. Insulin secretion is inadequate because of destruction of the beta cells in the Islets.

Three separate but interrelated mechanisms appear to have a role in this destructive process.

I. Genetic susceptibility II. Autoimmune reaction III. Environmental event

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Pathogenesis of DM

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It has been hypothesized that genetic susceptibility influences certain individuals to the development of an autoimmune reaction against the beta cells of the islets, and that this autoimmune reaction is triggered by an environmental events, e.g. viral infection. Exposure to chemical toxins.

Type II of DM This type of diabetes usually present in middle age. The

precise pathogenic mechanism is unknown, but obesity and the genetic factors are important,

Two mechanism have been theorized.

1- Defective secretion of Insulin by beta cells

2- Resistance of peripheral tissues to the effects of insulin due to obesity.

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How obesity causes diabetes

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It is ascertained that fat cells release a protein called pigment epithelium-derived factor (PEDF). when this protein is released into the

bloodstream, it causes the liver and muscles to become resistant to insulin. Insulin causes cells to take up glucose in the bloodstream, store it and convert it to energy for the body. When the cells resist insulin due to excess fat, more insulin is then produced by the pancreas to counteract the negative effects, thereby overworking the pancreas and eventually slowing and stopping insulin. OR

Target cell resistance to insulin. Due to decreased number of insulin receptors.

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Clinical Features

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Type I DM The chemical features are related to increased gluconeogenesis

and the hyperglycemia resulting for a lack of insulin. Polyuria, polydipsia Pholyphagia Ketoacidosis

Fats and proteins are metabolized excessively, and byproducts known as ketone bodies are produced. These are released to the bloodstream and cause:Decreased pH (so increased acidity)

Compensations for metabolic acidosis Acetone given off in breath

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Type II DM Clinical Features

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DM Complication

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Microvasuclar: damage to eyes, kidneys, nerves (retinopathy, nephropathy, neuropathy)

Macro vascular: 2X risk for heart attack and stroke, peripheral vascular disease

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DM Complication

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Eye disease important cause of blindness associated with

Microaneurysm Retinal hemorrhage retinal edema and exudates ( cotton wool spots )

Kidney disease diabetic nephrosclerosis most common cause of renal failure in US atherosclerosis of renal arteries infections of bladder & kidney

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Peripheral neuropathy

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With damage to the nervous system, a person with diabetes may not be able to feel his or her feet properly. Normal sweat secretion and oil production that lubricates the skin of the foot is impaired. These factors together can lead to abnormal pressure on the skin, bones, and joints of the foot during walking and can lead to breakdown of the skin of the foot. Sores may develop. 

Damage to blood vessels and impairment of the immune system from diabetes make it difficult to heal these wounds. Bacterial infection of the skin, connective tissues, muscles, and bones can then occur. These infections can develop into gangrene. Because of the poor blood flow,antibiotics cannot get to the site of the infection easily. Often, the only treatment for this is amputation of the foot or leg. If the infection spreads to the bloodstream, this process can be life-threatening. 

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Complications of GDM

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Pre-eclampsia Over weight babies

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Islet tumors

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These tumors are quite rare, and they can arise from any of the cell types present in the islets. The tumors become manifest through hypersecretion of the hormone produced by cell type from which the tumor is derived. Islet tumors may follow a benign or malignant course. The various types are:

1. Insulinoma: the commonest tumor, It produces insulin, resulting hypoglycemia.

2. Glucagonoma: induces diabetes. It produces glucagon and exerts hyperglycemia.

3. Gastrinoma: hypersecrates gastrin, which leads to acid hypersecretion, resulting zollinger-ellison syndrome.

4. VIPomas: induces watery diarrhea.

5. Somatostatinomas. It produces Somastotatin, which inhibits insulin secration, hence diabetes.

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Patient education

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Food, exercise, medsTreatment planGoals / targetsSelf-monitored blood

glucoseHypoglycemiaEmergency numbers

If insulin: injection technique, syringe disposal, storage, etc.

Foot careOphthalmic exams

Diabetes Survival Skills:

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THE END