Endocrine System

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Endocrine System What is an Endocrine system Comprised of a widely distributed group of organs that work together to maintain the body s metabolic equilibrium Achieve this by secreting molecules which are frequently called hormone Hormones can be classified into several broad catego ries o Hormones that act by binding to cell surface receptors This large class of compounds is composed of two groups Peptide hormones Growth Hormone Insulin hormone Small molecules epinephrine o Hormones that act by binding to intracellular receptors includes Steroids estrogen progesterone glucocorticoids Retinoids Vitamin A Thyroxine Endocrine diseases generally are caused by o Under production or over production of hormones o End organ resistance to the effects of a hormone o Neoplasms Pituitary is a small bean shaped structure that lies at the base of the brain within the confines of the sella turcica Along with the hypothalamus the pituitary has a central role in the regu is composed of lation of most of the other endocrine glands o the anterior lobe adenohypophysis o posterior lobe neurohypophysis The anterior pituitary or adenohypophysis produces trophic hormones that stimulate the production of hor mones from the thyroid adrenal and other gland The anterior pituitary or adenohypophysis produces trophic hormones that stimulate the production of hor mones from the thyroid adrenal and other gland Rarely signs and symptoms of pituitary disease may be caused by overproduction or underproduction of hypotha lamic factors rather than a primary pituitary abnormality Symptoms and signs of pituitary disease fall into the following categories Hyperpituitarism related effects Hypopituitarism related effects o Hyperpituitarism arises from excessive secretion of trophic hormones It most often results from an anterior pituitary adenoma but also may be caused by other pituitary and extrapituitary lesion o Hypopituitarism is caused by deficiency of trophic hormones and results from a variety of destructive processes that may damage the pituitary o including ischemic injury surgery radiation and inflammatory reactions In addition nonfunctional pituitary adenomas may encroach upon and destroy the normal anterior pituitary causing hypopituitarism Local mass effects o including sellar expansion bony erosion and disruption of the diaphragma sellae Because of the close proximity of the optic nerves and chiasm to the sella expanding pituitary lesions often compress decussating fibers in the optic chiasm This can give rise to visual field abnormalities classically in the form of defects in the lateral temporal visual fields a so called bitemporal hemianopsia As in the case of any expanding intracranial mass pituitary tumors may produce signs and symptoms of elevated intracranial pressure including headache nausea and vomiting Pituitary neoplasms that extend beyond the sella turcica into the base of the brain produce seizures or obstructive hydrocephalus involvement of cranial nerves can result in cranial nerve pals pituitary apoplexy acute hemorrhage into a pituitary neoplasm is asso ciated with rapid enlargement of the lesion and loss of consciousness Thyroid Your thyroid is a small butterfly shaped gland located at the front of your neck under your skin thyroid s main job is to control the speed of your metabolism metabolic rate which is the process of how the body transforms the food you consume into energy Function of the thyroid As an endocrine gland thyroid makes and secretes hormones o Thyroxine T4 This is the primary hormone your thyroid makes and releases Although your thyroid makes the most of this hormone it doesn t have much of an effect on your metabolism Once your thyroid releases T4 into your bloodstream it can convert to T3 through a process called deiodination o Triiodothyronine T3 Your thyroid produces lesser amounts of T3 than T4 but it has a much greater effect on your metabolism than T4 o Reverse triiodothyronine RT3 Your thyroid makes very small o Calcitonin This hormone helps regulate the amount of calcium in amounts of RT3 which reverses the effects of T3 your blood thyroid hormones affect the following bodily functions How your body uses energy metabolism Heart rate Breathing Digestion Body temperature Brain development Mental activity Skin and bone maintenance Fertility The four main conditions that affect your thyroid include Hypothyroidism underactive thyroid Hyperthyroidism overactive thyroid Goiter enlarged thyroid Thyroid cancer Hypothyroidism Hypothyroidism underactive thyroid happens when your thyroid doesn t produce and release enough thyroid hormones This causes aspects of your metabolism to slow down It s a fairly common condition that affects approximately 10 million people in the United States It is treatable Causes of hypothyroidism include Hashimoto s disease an autoimmune disease Thyroiditis inflammation of the thyroid A nonfunctioning thyroid gland when the thyroid doesn t work correctly Iodine deficiency from birth Over treatment of hyperthyroidism through medication Thyroid gland removal Hyperthyroidism Hyperthyroidism overactive thyroid happens when your thyroid produces and releases more thyroid hormones than your body needs This causes aspects of your metabolism to speed up Approximately 1 out of 100 people over the age of 12 have hyperthyroidism in the United States It is treatable Causes of hyperthyroidism include Graves disease an autoimmune condition Thyroid nodules Thyroiditis inflammation of the thyroid Postpartum thyroiditis inflammation of the thyroid that happens after giving birth Excess iodine in your blood from diet and or medication Over treatment of hypothyroidism through medication A benign noncancerous tumor in your pituitary gland Goiter Goiter is an enlargement of your thyroid gland Goiters are relatively common they affect approximately 5 of people in the United States Goiters have different causes depending on their type Simple goiters These goiters develop when your thyroid gland doesn t make enough hormones to meet your body s needs Your thyroid gland tries to make up for the shortage by growing larger Endemic goiters These goiters occur in people who don t get enough iodine in their diet iodine is necessary to make thyroid hormone Iodine is added to table salt in the United States and several other countries so people who live in those countries usually don t get endemic goiters Sporadic goiters These goiters have no known cause in most cases In

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