Chapter 14 The Pancreas and Diabetes Mellitus

1. Chapter 14 The Pancreas and Diabetes Mellitus The pancreas is a large, diffuse organ that functions as both an exocrine and endocrine gland. • Exocrine Functions of the Pancreas The exocrine functions of the pancreas involve the synthesis and release of digestive enzymes and sodium bicarbonate from specialized cells of the pancreas • Endocrine Functions of the Pancreas The endocrine functions of the pancreas involve the synthesis and release of the hormones insulin, glucagon, and somatostatin. These hormones are each produced by separate, specialized cells of the pancreas, called the islets of Langerhans.

2. Secretion of Insulin Insulin is released at a basal rate by the beta cells of the islets of Langerhans. A rise in blood glucose is the primary stimulus to increase insulin release above baseline. Fasting blood glucose level is normally 80 to 90 mg/100 mL of blood. When blood glucose increases to more than 100 mg/100 mL of blood, insulin secretion from the pancreas increases rapidly and then returns to baseline in 2 to 3 hours.

3. Secretion of Glucagon Glucagon is a protein hormone released from the alpha cells of the islets of Langerhans in response to low blood glucose levels . In most respects, glucagon works the opposite of insulin. Glucagon stimulates the used of fatty acids as an energy source instead of glucose.

4. Secretion of Somatostatin Somatostatinis secreted by delta cells of the islets of Langerhans. Somatostatin is also is released as well by the hypothalamus. Somatostatin from the hypothalamus inhibits the release of growth hormone . Somatostatin from the pancreas controls metabolism by inhibiting the secretion of insulin and glucagon. The exact function of somatostatin is otherwise unclear.

5. Tests of Pancreatic Function -Fasting Plasma Glucose Fasting blood glucose of 110 mg/100 mL on more than one occasion is diagnostic of diabetes mellitus. Non-fasting plasma glucose of greater than 200 mg/100 mL with symptoms of polyurea, polydipsia, and polyphagia is also diagnostic of diabetes. -Urine Glucose Tests Glucose in the urine may or may not be indicative of diabetes. Under most conditions, glucose is not present in the urine of healthy, non-pregnant individuals.

6. Conditions of Disease or Injury 1-Diabetes Mellitus - Type 1 Diabetes Mellitus • Hyperglycemia caused by an absolute lack of insulin is known as type 1 diabetes mellitus. • Type 1 diabetes results from autoimmune destruction of the beta cells of the islets of Langerhans. - Type 2 Diabetes Mellitus • Hyperglycemia caused by cellular insensitivity to insulin is called type 2 diabetes . • The number one risk factor for type 2 diabetes mellitus is obesity. In addition, the genetic tendency to develop the disease is strong. An individual with type 2 diabetes still secretes insulin. However, there is often a delay in the initial secretion and a reduction in the total amount released. This trend worsens as a person ages.

7. Clinical Manifestations • - Polyuria • - Polydipsia • - Fatigue and muscle weakness • - Polyphagia • - Increased rate of infections because of increased glucose concentration in mucus secretions, poor immune function, and reduced blood flow. • - Visual changes related to changes in water balance or, in more severe cases, retinal damage. • - Paresthesias, or abnormalities in sensation. • - Vaginal candidiasis (yeast infection), • - Muscle wasting may develop as muscle protein is broken down to meet the body's energy needs.

8. Acute Complications • Diabetic Ketoacidosis: Almost always restricted to type 1 diabetics. It is characterized by a worsening of all symptoms of diabetes. Diabetic ketoacidosis may occur after physical stress such as pregnancy or an acute illness or trauma. But sometimes it is the presenting symptom Long-Term Complications • These complications affect almost all body organs. • - Cardiovascular System: Long-term diabetes mellitus has a severe effect on the cardiovascular system. Microvascular damage occurs to the small arterioles, the capillaries, and the venules. • .

9. - Vision Loss • - Renal Damage • - Peripheral Nervous System: Diabetes mellitus damages the peripheral nervous system, including sensory and motor components of both the somatic and autonomic divisions. • - Neural disease related to diabetes mellitus is called diabetic neuropathy

10. 2- Acute Pancreatitis It is an inflammation of the pancreas characterized by autodigestion of the pancreas by pancreatic enzymes. Pancreatic cells are injured or killed, leading to areas of cell necrosis and hemorrhage. Pancreatitis may occur as a result of blockage of the pancreatic duct, usually caused by a gallstone in the common bile duct. Clinical Manifestations Pain, often in the epigastric area and radiating to the back, after a large meal or excess alcohol consumption is the usual presenting symptom. Pain is caused by the swelling and stretching of the pancreatic duct. Pain may be severe. Vomiting and nausea may occur. Diagnostic Tools • - Blood analysis typically demonstrates elevated levels of serum amylase and lipase. • - Hyperglycemia . • - Increased white blood cell count and rises further with infection.

11. 3- Pancreatic Cancer Pancreatic cancer may develop from either exocrine or endocrine cells. Cancers of the exocrine cells of the small pancreatic ducts are most common and lead to blockage of the ducts. These tumors frequently penetrate the pancreas and invade surrounding tissue. Metastasis via the portal vein or lymphatic system is common and rapid. Clinical Manifestations It may be asymptomatic (until advanced). Pain may be an early complaint or may occur only with advanced disease.

12. Advanced disease is associated with jaundice, severe pain, and pronounced weight loss. Metastases to the brain and lung are common. Mortality is nearly 100% within 5 years. Diagnostic Tools -Laparotomy(penetration of the abdomen with a fiberoptic tool for visualization and sampling) can confirm the diagnosis. -Ultrasound and computed tomography (CT scan) may be used. Treatment Surgery to relieve pain may include bypass of the blocked ducts.