Abstract
The non-classical endocrine organs are those that have crucial additional functions apart from secreting hormones. They are characterized by the presence of unspecialized hormone-secreting cells.
The heart, kidney, thymus, placenta, and gastrointestinal tract (GIT) are prominent non-classical endocrine organs in animals. The natriuretic peptides secreted from the heart help in bringing back the circulatory volume to normal levels by promoting the renal excretion of sodium and water. The thymus too is implicated in the production of hormones such as thymulin, thymopoietin, and thymosins to potentiate the cell-mediated immunity in animals. The kidneys secrete a glycoprotein hormone known as erythropoietin (EPO), responsible for alleviating tissue hypoxia by stimulating erythropoiesis in the bone marrow. Likewise, enteroendocrine cells (EECs) in the GIT produce a wide range of peptide hormones that regulate digestion, motility, and appetite in animals. In addition to the nutrient transport function, the placenta in mammals evolved to produce key hormones such as progesterone, estrogen, and relaxin to maintain gestation and facilitate parturition. The gonads in animals are responsible for the secretion of steroid hormones implicated in sex-specific behavior, reproductive tract development, and reproductive phases such as the estrous cycle, gestation, and parturition.B. A. A. Sai Kumar (X)
Department of Veterinary Physiology, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry, India
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023
417
P. K. Das et al. (eds.), Textbook of Veterinary Physiology, https://doi.org/10.1007/978-981-19-9410-4_17
Graphical Abstract
Description of the graphic: Gonadal hormones and other hormones secreted from the non-classical endocrine organs.
[GIT gastrointestinal tract; ANP atrial natriuretic peptide; BNP brain/B-type natriuretic peptide; CNP C-type natriuretic peptide; eCG equine chorionic gonadotropin; hCG human chorionic gonadotropin.]Keywords
hormones enables the heart to participate in regulating the circulatory volume and systemic blood pressure in animals.
Aldosterone escape ∙ Erythropoietin ∙ Thymic hormones ∙ Placenta ∙ Gonadal hormones
17.1.1 Distribution in Tissues
Learning Objectives
• Natriuretic peptides in blood volume regulation
• Role of erythropoietin on erythropoiesis
• Thymic hormones and their role as immunomodulators
• Different gastrointestinal hormones and their importance in GIT functioning
• Placental hormones
• Gonadal hormones
The atrial cardiomyocytes are primarily responsible for the secretion of ANP although a small proportion is released from the ventricles. Originally isolated from the porcine brain tissue, BNP is produced chiefly from ventricles. These secretory types of cardiomyocytes are characterized by abundant rough endoplasmic reticulum (RER), golgi apparatus, and peptide storage granules. The CNP is a minor natriuretic peptide distributed in the cerebellum, hypothalamus, anterior pituitary, kidney, and endothelial cells.
17.1