Chemical Coordination and Integration - Hormones of heart, kidney and gastrointestinal tract

Hormones of the Heart: The atrial wall of our heart secretes a very important peptide hormone called Atrial Natriuretic Factor ($ANF$). When blood pressure increases, $ANF$ is secreted which causes dilation of the blood vessels. This results in the reduction of blood pressure.

Hormones of the Kidney: The Juxtaglomerular ($JG$) cells of the kidney produce a peptide hormone called Erythropoietin. This hormone stimulates Erythropoiesis, which is the process of formation of Red Blood Cells ($RBCs$).

Hormones of the Gastrointestinal (GI) Tract: Endocrine cells present in different parts of the GI tract secrete four major peptide hormones: Gastrin, Secretin, Cholecystokinin ($CCK$), and Gastric Inhibitory Peptide ($GIP$).

Gastrin: It acts on the gastric glands and stimulates the secretion of hydrochloric acid ($HCl$) and pepsinogen.

Secretin: It acts on the exocrine pancreas and stimulates the secretion of water and bicarbonate ions ($HCO_3^-$).

Cholecystokinin ($CCK$): It acts on both the pancreas and the gallbladder, stimulating the secretion of pancreatic enzymes and bile juice, respectively.

Gastric Inhibitory Peptide ($GIP$): This hormone inhibits gastric secretion and motility.

Growth Factors: Several other non-endocrine tissues secrete hormones called growth factors, which are essential for the normal growth of tissues and their repairing/regeneration.