PANCREAS Hormones PDF

**PANCREAS** **TLO 2.5 --- DESCRIBE THE MAIN FUNCTIONS AND SECRETION OF HORMONES FROM THE PANCREAS INVOLVED IN BGL HOMEOSTASIS.** **STRUCTURE OF THE PANCREAS** The pancreas is located in the upper abdomen, behind the stomach. The endocrine component of the pancreas is composed of clusters of cell...

**PANCREAS** **TLO 2.5 --- DESCRIBE THE MAIN FUNCTIONS AND SECRETION OF HORMONES FROM THE PANCREAS INVOLVED IN BGL HOMEOSTASIS.** **STRUCTURE OF THE PANCREAS** The pancreas is located in the upper abdomen, behind the stomach. The endocrine component of the pancreas is composed of clusters of cells known as the **Islets of Langerhans**. These islets contain several types of hormone-producing cells: **ALPHA CELLS** **BETA CELLS** ---------------------- ----------------------------------------------- ---------------------- --------------------------------------------------- **Location** Scattered throughout the Islets of Langerhans **Location** Centrally located within the Islets of Langerhans **Hormone produced** Glucagon **Hormone produced** Insulin **DELTA CELLS** **PP CELLS (F CELLS)** **Location** Distributed within the Islets of Langerhans **Location** Primarily in the head of the pancreas **Hormone produced** Somatostatin **Hormone produced** Pancreatic polypeptide **HORMONES INVOLVED IN BGL HOMEOSTASIS** The primary hormones secreted by the pancreas that regulate blood glucose levels are **insulin** and **glucagon**. +-----------------------------------+-----------------------------------+ | **INSULIN** | | +===================================+===================================+ | **Produced By:** | Beta cells of the Islets of | | | Langerhans. | +-----------------------------------+-----------------------------------+ | **Function:** | **Lowers blood glucose levels** | | | | | | Insulin facilitates the uptake of | | | glucose from the bloodstream into | | | cells, particularly muscle and | | | fat cells, where it can be used | | | for energy or stored as glycogen. | +-----------------------------------+-----------------------------------+ | | **Promotes glycogenesis** | | | | | | Insulin stimulates the liver to | | | convert excess glucose into | | | glycogen for storage | | | (glycogenesis). | +-----------------------------------+-----------------------------------+ | | **Inhibits Glycogenolysis and | | | Gluconeogenesis** | | | | | | Insulin suppresses the breakdown | | | of glycogen into glucose | | | (glycogenolysis) and the | | | production of glucose from | | | non-carbohydrate sources | | | (gluconeogenesis) in the liver. | +-----------------------------------+-----------------------------------+ | | **Promotes Lipogenesis** | | | | | | Insulin encourages the conversion | | | of glucose into fatty acids and | | | triglycerides for long-term | | | energy storage in adipose tissue. | +-----------------------------------+-----------------------------------+ | **Control of release:** | **Blood Glucose Levels** | | | | | | Insulin secretion is directly | | | stimulated by rising blood | | | glucose levels after a meal. | +-----------------------------------+-----------------------------------+ | | **Incretins** | | | | | | Hormones like GLP-1 | | | (glucagon-like peptide-1) | | | released from the gut in response | | | to food intake also stimulate | | | insulin secretion. | +-----------------------------------+-----------------------------------+ | | **Feedback Mechanism** | | | | | | As blood glucose levels decrease | | | due to insulin's action, insulin | | | secretion is reduced through | | | negative feedback. | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **GLUCAGON** | | +===================================+===================================+ | **Produced By:** | Alpha cells of the Islets of | | | Langerhans. | +-----------------------------------+-----------------------------------+ | **Function:** | **Raises Blood Glucose Levels** | | | | | | Glucagon acts on the liver to | | | increase blood glucose levels by | | | stimulating glycogen breakdown | | | (glycogenolysis) and the | | | synthesis of glucose from | | | non-carbohydrate sources | | | (gluconeogenesis). | +-----------------------------------+-----------------------------------+ | | **Mobilizes Energy Stores** | | | | | | Glucagon promotes the breakdown | | | of fat stores (lipolysis) to | | | provide additional energy | | | substrates. | +-----------------------------------+-----------------------------------+ | **Control of release:** | **Blood Glucose Levels** | | | | | | Glucagon secretion is stimulated | | | by low blood glucose levels | | | (hypoglycaemia). | +-----------------------------------+-----------------------------------+ | | **Amino Acids** | | | | | | A high concentration of amino | | | acids in the blood after a | | | protein-rich meal can also | | | stimulate glucagon release. | +-----------------------------------+-----------------------------------+ | | **Feedback Mechanism** | | | | | | As blood glucose levels rise due | | | to glucagon's action, glucagon | | | secretion decreases through | | | negative feedback. | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **SOMATOSTATIN** | | +===================================+===================================+ | **Produced By:** | Delta cells of the Islets of | | | Langerhans. | +-----------------------------------+-----------------------------------+ | **Function:** | **Inhibits Hormone Secretion** | | | | | | Somatostatin inhibits the release | | | of both insulin and glucagon, | | | helping to fine-tune the balance | | | of these hormones and prevent | | | excessive fluctuations in blood | | | glucose levels. | +-----------------------------------+-----------------------------------+ | **Control of release:** | **Nutrient Levels** | | | | | | The release of somatostatin is | | | triggered by the presence of | | | glucose, amino acids, and fatty | | | acids in the bloodstream. | +-----------------------------------+-----------------------------------+ | | **Autocrine and Paracrine | | | Effects** | | | | | | Somatostatin acts locally within | | | the pancreas to modulate the | | | release of insulin and glucagon. | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **PANCREATIC POLYPEPTIDE (PP)** | | +===================================+===================================+ | **Produced By:** | PP cells (F cells) in the | | | pancreas. | +-----------------------------------+-----------------------------------+ | **Function:** | **Regulation of Pancreatic | | | Secretions** | | | | | | Pancreatic polypeptide helps | | | regulate the exocrine function of | | | the pancreas and may also play a | | | role in appetite regulation. | +-----------------------------------+-----------------------------------+ | **Control of release:** | **Nutrient Intake** | | | | | | The release of pancreatic | | | polypeptide is influenced by food | | | intake, particularly protein-rich | | | meals. | +-----------------------------------+-----------------------------------+ **INTEGRATION AND REGULATION OF BLOOD GLUCOSE LEVELS** **Fed State (Postprandial):** After a meal, blood glucose levels rise, leading to increased insulin secretion. Insulin facilitates glucose uptake by cells, promotes glycogen storage, and inhibits glucose production by the liver, thereby lowering blood glucose levels. **Fasting State:** During fasting, blood glucose levels drop, triggering the release of glucagon. Glucagon stimulates the liver to release stored glucose into the bloodstream, ensuring a steady supply of energy and preventing hypoglycaemia. **Exercise:** During physical activity, insulin levels decrease, and glucagon levels increase to maintain blood glucose levels and ensure that muscles have sufficient energy. **CLINICAL RELEVANCE** **Diabetes Mellitus** Type 1 Diabetes: An autoimmune condition where the body's immune system attacks and destroys beta cells, leading to little or no insulin production. This results in chronic hyperglycaemia. Type 2 Diabetes: A condition characterized by insulin resistance, where cells do not respond effectively to insulin. Over time, the pancreas cannot produce enough insulin to overcome this resistance, leading to elevated blood glucose levels. **Hypoglycaemia:** A condition where blood glucose levels fall below normal, leading to symptoms such as dizziness, confusion, and fainting. It can occur due to excessive insulin production or insulin therapy, especially in diabetic patients. **Hyperglycaemia:** A condition where blood glucose levels are abnormally high, often due to insufficient insulin action. Chronic hyperglycaemia is a hallmark of diabetes and can lead to serious complications like cardiovascular disease, neuropathy, and kidney damage.