Besides the major endocrine glands, certain organs like the heart, kidneys, and gastrointestinal tract also perform endocrine functions by secreting hormones. These hormones play an important role in maintaining homeostasis by regulating processes such as blood pressure, fluid balance, red blood cell formation, and digestion. Though not traditionally classified as endocrine glands, these organs contribute significantly to the hormonal control of the body.
Hormones of the Heart
These hormones are important in controlling the level and pressure of blood in our bodies.
Atrial Natriuretic Factor (ANF)
- It is secreted by the atria of the heart
- Released when blood pressure is high
- It helps reduce blood pressure by promoting the excretion of sodium and water
Hormones of the Kidneys
The kidneys make special chemicals that help keep regulating our body functions.
1. Erythropoietin (EPO)
- The kidneys make a hormone called EPO that helps our body in regulating red blood cells (RBCs) in the bone marrow.
- It is produced only when the body does not get sufficient oxygen.
2. Renin
- Renin made by special kidney cells called Juxtaglomerular cells.
- It controls blood pressure by turning on a system in the body called RAAS, i.e., the renin-angiotensin-aldosterone system.
- This system keeps sodium and water in the body, which makes the blood volume and blood pressure go up.
3. Calcitriol
- It increases the absorption of calcium and phosphate from the intestine.
- It helps maintain normal calcium levels in the blood.
Hormones of the Gastrointestinal Tract
The Gastrointestinal tract produces numerous hormones that regulate the digestion and appetite of the body.
1. Gastrin
- The stomach makes a substance called gastrin.
- Gastrin helps the stomach to make acid to break down food.
2. Cholecystokinin (CCK)
- Cells in the small intestine secrete cholecystokinin (CCK).
- It tells the pancreas and gallbladder to release juices like Bile that help digest food.
3. Secretin
- Secretin is made by cells in the duodenum and controls how much bicarbonate is released from the pancreas to balance out the acid from the stomach.
Applications in Everyday Life
Understanding these hormones is important in medicine and daily health management:
- Diagnosis and Treatment of Heart Diseases: Levels of ANP and BNP are used as markers to diagnose and monitor heart failure. Medicines that affect fluid balance and blood pressure are commonly used in treatment.
- Management of Kidney Disorders: Hormones like EPO are used in treating anaemia in patients with chronic kidney disease. Drugs targeting the RAAS system help control high blood pressure.
- Regulation of Digestion: Hormones such as gastrin, CCK, and secretin help regulate digestion. Certain medications target these hormones to treat digestive disorders like acid reflux.