Endocrine System is the controlling system that maintains the body in balance through the release of hormones directly into the bloodstream. Endocrine systems are found in most animals such as mammals, non-mammalian vertebrates, and invertebrates. The endocrine system consists of a set of glands such as thyroid, parathyroid, pancreatic, pineal, gonads, thymus, adrenal, and pituitary glands and the hormones they produce such as thyroxine, estrogen, testosterone, and adrenaline. These hormones and glands help guide the development, growth, reproduction, and behavior of animals including human beings. The endocrine gland cells release hormones into the bloodstream for distribution throughout the entire body. Hormones are molecules produced by endocrine glands. They are chemical messengers which can alter the activity of many organs at once. They only bind with the receptors to cause a chain reaction which changes the activities of the cells. There can be different receptors for the same hormone hence; the same hormone can have different effects on different cells.
Different glands produce different hormones for specific purposes. The pituitary gland produces mainly tropic hormones. Others are growth hormones and prolactin. Growth hormones promote total body growth. Hyposecretion during childhood results in pituitary dwarfism and giantism and acromegaly in adulthood. Prolactin stimulates the production of breast milk. Thyroid-stimulating hormone stimulates the thyroid gland to release thyroid hormone. Adrenocorticotropic hormone stimulates the adrenal cortex to release its hormones. Gonadotropic hormones stimulate the male’s testes to produce testosterone and also promote sperm production. The posterior pituitary glands store and release hypothalamic hormones on command. Oxytocin stimulates powerful uterine contractions and causes milk ejection in the nursing woman. The antidiuretic hormone causes kidney tubules cells to re-absorb and conserve body water and increase blood pressure by constricting blood vessels. Hyposecretion leads to diabetes insipidus.
The thyroid gland is located in the anterior throat. The thyroid hormone is the body’s metabolic hormone. It increases the rate at which cells oxidize glucose and is necessary for normal growth and development. Hyposecretion of thyroxine results in cretinism in children and myxedema in adults. Calcitonin causes calcium to be deposited in bones.
Parathyroid glands are located behind the thyroid gland. They release parathyroid hormones (PTH) which cause bone calcium to be liberated into the bloodstream. Hyposecretion of PTH results in tetany and extreme bone wasting and fractures.
Adrenal glands are paired glands perched on the kidney. They produce steroid hormones. Mineralocorticoids regulate sodium ion (Na+) and potassium ion (K+) reabsorption by the kidney. Glucocorticoids enable the body to resist long-term stress by increasing blood glucose levels and depressing the inflammatory response, and sex hormones which are produced in small amounts throughout life. Hypersecretion can result in hyperaldosteronism, Cushing’s disease and/or masculinization.
Pancreatic islets release insulin and glucagon to the blood. Insulin released when blood levels are high increases the rate of glucose uptake and metabolism by body cells. Hyposecretion results in diabetes mellitus which severely disturbs body metabolism. Glucagon released when blood levels of glucose are low stimulates the liver to release glucose to blood by accelerating the conversion of glycogen to glucose. Thus, increases blood glucose levels.
The pineal gland releases melatonin which affects biological rhythms and reproductive behavior. The thymus gland hormone, thymosin, promotes the maturation of T lymphocytes which is important in body defense. Gonads’ glands release two hormones. Estrogens released by ovarian follicles stimulate the maturation of the female reproductive organs. Progesterone released from the corpus luteum of the ovary works with estrogens in establishing the menstrual cycle. Hyposecretion of gonadal hormones results in sterility in both females and males.
Conclusively, the endocrine system is an interesting topic given the nature of its content. Its function in the body is vital. The endocrine system regulates various body functions and activities. For instance, it works with the nervous system to prepare the body for emergency situations. Due to its various functions and activities, in-depth research has been carried out by scholars. Various glands secrete different hormones which perform specific functions. These hormones move through the circulatory system until they reach the tissue or organ they were designed to control.