Lesson 9 of 11 · 6 min
Hormones of heart, kidney and gut
NCERT §19.3
Meher learns that her heart, her kidneys and her stomach all make hormones, though none is called an endocrine gland. What do they release, and why?
The lesson in notes
In short
Some tissues that are not endocrine glands also secrete hormones.
The atrial wall of the heart secretes a peptide hormone, atrial natriuretic factor (ANF), which lowers blood pressure. When blood pressure rises, ANF is released and makes the blood vessels dilate, which brings the pressure down.
The juxtaglomerular cells of the kidney make a peptide hormone, erythropoietin, which stimulates erythropoiesis, the formation of RBCs.
Endocrine cells in different parts of the gastrointestinal tract secrete four major peptide hormones: gastrin, secretin, cholecystokinin (CCK) and gastric inhibitory peptide (GIP).
Gastrin acts on the gastric glands, which then secrete hydrochloric acid and pepsinogen. The exocrine pancreas is the target of secretin, and responds by secreting water and bicarbonate ions.
CCK acts on both the pancreas and the gall bladder, stimulating secretion of pancreatic enzymes and of bile juice respectively. GIP inhibits gastric secretion and motility.
Growth factors are hormones made by several other non-endocrine tissues; tissues need them to grow normally and to repair and regenerate.