It also produces insulin, which converts glucose into glycogen. Hormones & Glands: The Pancreas The pancreas acts a gland that excretes enzymes into the small intestine. They are an important gland for the immune system in that they are responsible for releasing hormones that activate T-cells. Hormones & Glands: The Thymus During infancy, the thymus controls the growth of lymphoid tissues and immune system responses to pathogens. Hormones & Glands: The Thyroid Gland The thyroid gland in the neck is responsible for secreting hormones that regulate the amount of energy the body uses, as well as calcium intake to the bones. Hormones & Glands: Pineal Gland Located in the brain, the pineal gland secretes melatonin which regulates the pituitary gland and is thought to be the cause of the “biological clock.” Aldosterone is important in controling the solute concentration in blood plasma. The adrenal glands also regulate kidney function by secreting a hormone called aldosterone. Hormones & Glands: Adrenal Glands The adrenal glands are situated above the kidneys, and they release hormones in response to stress. The pituitary gland is a major regulator of the endocrine system and homeostasis. The pituitary gland is important for the growth and production of nine different hormones including: human growth hormones, thyroid stimulating hormones, Corticotropin-Releasing Hormones, and others. Hormones & Glands: The Pituitary Gland Hypothalamic hormones control hormone secretion in the pituitary gland, which then directs other major organs and glands in the body. Blood vessels connect the hypothalamus and the pituitary gland, allowing the hypothalamus to control the secretion of hormones from the pituitary gland. Hormones & Glands: The Hypothalamus The hypothalamus is a connecting point between the nervous system and the endocrine system and is crucial for maintaining homeostasis. If too many thyroid hormones are produced, the production of excess thyroid hormones inhibits the continued production of more of those same hormones.The anterior pituitary releases more hormones that stimulate the thyroid gland to make more hormones.Hypothalamin is released and it stimulates anterior pituitary cells responsible for secretion.The hypothalamus detects a deficiency in thyroid-produced hormones.Negative Feedback Mechanism Example An example of negative feedback and hormones is the regulation of the thyroid gland, which controls energy consumption, protein production and calcium in the blood. Levels of certain hormones in the body move in cycles. Negative Feedback Mechanisms Just as in the reproductive system, hormones are controlled by a system of negative feedback mechanisms. Some aspects of the human body that must be maintained are body temperature, protein production, energy consumption etc. Homeostasis A part of the endocrine system, the hypothalamus is acts as a mediator in the brain between the nervous and endocrine systems, and one of its functions is to maintain homeostasis. Glands make hormones that help to control metabolism, sexual development and bodily growth. This review discusses the potential utility of GH, IGF-I, and IGFBPs as growth biomarkers for those manipulations most relevant to the aquaculture industry, namely, feeding regimen, diet composition, temperature, photoperiod, and stress.Function of the Endocrine System The function of the endocrine system is to regulate the production and use of hormones within the body.
However, other endocrine indices, such as GH and IGF-binding proteins (IGFBPs), are also important contributors and may in some instances prove a strong corollary to growth rate. This is based on the direct contributions of IGF-I in regulating cell proliferation and ultimately somatic growth, along with its previously established correlations with the specific growth rate in fish under various conditions that alter growth. While the most appropriate endocrine biomarkers for growth can be both species and situation specific, IGF-I may be the most promising candidate for measuring instantaneous growth in fish.
Ultimately, by understanding the hormones that control growth and utilizing them as biomarkers, we hope to achieve optimal growth conditions in the aquaculture environment with less need for lengthy and costly grow-out trials. For this reason, it has been of interest to aquaculture researchers and the industry to establish endocrine biomarkers that can both reflect and predict growth rates in fish subject to various biotic and abiotic manipulations. Growth in fish and other vertebrates is under endocrine control, particularly through the growth hormone (GH)–insulin-like growth factor (IGF) axis.
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