5.9.4 Pancreas

Introduction

The pancreas is a unique gland that functions as both an endocrine and an exocrine gland. It is located in the abdominal cavity near the stomach. As an endocrine gland, it produces hormones that regulate blood sugar levels. As an exocrine gland, it produces digestive enzymes. This topic focuses on the endocrine functions of the pancreas.

Definition

The pancreas is a gland present in the abdominal cavity near the stomach. It is an endocrine as well as exocrine gland.

Main Idea

• Pancreas is present in the abdominal cavity near the stomach.
• It is an endocrine as well as exocrine gland.
• Within the pancreas are certain cells called Islets of Langerhans.
• The islets contain two special groups of cells called alpha and beta cells.
• Alpha cells secrete glucagon.
• Beta cells secrete insulin.

Core Concept

Hormones of the Pancreas

Detailed Explanation

1. Structure of the Pancreas

Pancreas is present in the abdominal cavity near the stomach. It is an endocrine as well as exocrine gland.

Simple explanation: The pancreas is a gland behind the stomach. It has two jobs: it produces digestive enzymes (exocrine) and hormones (endocrine).

Islets of Langerhans:

• Within the pancreas are certain cells called Islets of Langerhans.
• The islets contain two special groups of cells called alpha and beta cells.

Simple explanation: The Islets of Langerhans are clusters of cells within the pancreas that produce hormones.

2. Insulin

What it is: Insulin is a hormone secreted by beta cells of the Islets of Langerhans.

When it is secreted: Insulin is secreted when the level of blood sugar rises, such as right after a meal.

Function:

• The most important effect of insulin is to facilitate glucose transport across cell membrane.
• Insulin also enhances the conversion of glucose to glycogen.

Simple explanation: Insulin lowers blood sugar. It helps glucose enter cells and tells the liver to store extra glucose as glycogen.

Why this is important:

• Insulin prevents blood sugar from becoming too high.
• It helps cells get the glucose they need for energy.

3. Glucagon

What it is: Glucagon is a hormone secreted by alpha cells of the Islets of Langerhans.

Function:

• Glucagon has function opposite to the function of insulin.
• Its most important job is to increase glucose concentration by stimulating the liver to convert glycogen to glucose.

Simple explanation: Glucagon raises blood sugar. It tells the liver to release stored glucose (glycogen) into the blood.

Why this is important:

• Glucagon prevents blood sugar from becoming too low.
• It ensures the brain and other organs have a steady supply of glucose.

4. Diabetes Mellitus

What it is: Diabetes is caused when beta cells do not produce enough insulin.

What happens:

• When this happens, glucose accumulates in the blood and is excreted with urine.
• It requires treatment with regular injections of insulin or medicines prescribed by the physician.

Simple explanation: Diabetes mellitus is a disease caused by insufficient insulin. Blood sugar becomes too high, and glucose appears in the urine.

Symptoms:

• Increased thirst
• Frequent urination
• Fatigue
• Blurred vision
• Slow-healing wounds

Treatment:

• Regular insulin injections
• Oral medications
• Diet and exercise

5. Comparison of Insulin and Glucagon

Intermediate Level

The pancreas is both an endocrine and exocrine gland. Its endocrine part consists of the Islets of Langerhans.

Key points:

• Insulin lowers blood sugar.
• Glucagon raises blood sugar.
• Insulin is secreted when blood sugar is high.
• Glucagon is secreted when blood sugar is low.
• Diabetes mellitus is caused by insufficient insulin.

Diabetes mellitus:

Important Points

• - Pancreas is present in the abdominal cavity near the stomach.
• - It is an endocrine as well as exocrine gland.
• - Within the pancreas are certain cells called Islets of Langerhans.
• - The islets contain two special groups of cells called alpha and beta cells.
• - Alpha cells secrete glucagon.
• - Beta cells secrete insulin.
• - Insulin is secreted when the level of blood sugar rises, such as right after a meal.
• - The most important effect of insulin is to facilitate glucose transport across cell membrane.
• - Insulin also enhances the conversion of glucose to glycogen.
• - Glucagon has function opposite to the function of insulin.
• - Glucagon's most important job is to increase glucose concentration by stimulating the liver to convert glycogen to glucose.
• - Diabetes is caused when beta cells do not produce enough insulin.
• - When this happens, glucose accumulates in the blood and is excreted with urine.
• - It requires treatment with regular injections of insulin or medicines prescribed by the physician.

Remember

• - Pancreas = endocrine and exocrine gland
• - Islets of Langerhans = endocrine part
• - Alpha cells = glucagon
• - Beta cells = insulin
• - Insulin = lowers blood sugar; secreted when blood sugar is high
• - Glucagon = raises blood sugar; secreted when blood sugar is low
• - Diabetes mellitus = insufficient insulin
• - Insulin injections = treatment for diabetes

Common Mistakes

• 1. Confusing insulin and glucagon.
• - Insulin = lowers blood sugar.
• - Glucagon = raises blood sugar.
• 2. Mixing up alpha and beta cells.
• - Alpha cells = glucagon.
• - Beta cells = insulin.
• 3. Thinking the pancreas is only an endocrine gland.
• - The pancreas is both endocrine and exocrine.
• 4. Forgetting the role of the liver in blood sugar regulation.
• - The liver stores glycogen and releases glucose under the influence of insulin and glucagon.
• 5. Confusing diabetes mellitus with diabetes insipidus.
• - Diabetes mellitus = insulin deficiency → glucose in urine.
• - Diabetes insipidus = ADH deficiency → excessive dilute urine.
• 6. Believing insulin is only produced when you eat.
• - Insulin is produced when blood sugar rises, which can happen after meals but also at other times.
• 7. Thinking glucagon is only produced during fasting.
• - Glucagon is produced when blood sugar is low, which can happen between meals or during exercise.

Quick Revision

60-Second Revision

• Pancreas = endocrine and exocrine gland
• Islets of Langerhans = endocrine part
• Alpha cells = glucagon
• Beta cells = insulin
• Insulin = lowers blood sugar; secreted when blood sugar is high
• Glucagon = raises blood sugar; secreted when blood sugar is low
• Diabetes mellitus = insufficient insulin
• Insulin injections = treatment for diabetes
• Warning: Do not confuse insulin (lowers blood sugar) with glucagon (raises blood sugar). Do not confuse diabetes mellitus (insulin deficiency) with diabetes insipidus (ADH deficiency).