Endocrinology is a medical discipline that focuses on the structure, function and disorders of the endocrine glands. The endocrine glands produce and secrete hormones into the bloodstream and are a part of the larger endocrine system. The endocrine system uses hormones as communication messengers to organs throughout the body by way of blood vessels. They regulate bodily functions like metabolism, tissue growth and function, development and mood.
Endocrine System
The endocrine system is a collection of glands that secrete chemical messages we call hormones. These signals are passed through the blood to arrive at a target organ, which has cells possessing the appropriate receptor. Exocrine glands (not part of the endocrine system) secrete products that are passed outside the body. Sweat glands, salivary glands, and digestive glands are examples of exocrine glands.
The endocrine system is a collection of glands that secrete chemical messages we call hormones. These signals are passed through the blood to arrive at a target organ, which has cells possessing the appropriate receptor. Exocrine glands (not part of the endocrine system) secrete products that are passed outside the body. Sweat glands, salivary glands, and digestive glands are examples of exocrine glands.
Hormones are grouped into three classes based on their structure:
- steroids
- peptides
- amines
- Steroids are lipids derived from cholesterol. Testosterone is the male sex hormone. Estradiol, similar in structure to testosterone, is responsible for many female sex characteristics.
- Peptides are short chains of amino acids; most hormones are peptides. They are secreted by the pituitary, parathyroid, heart, stomach, liver, and kidneys. Amines are derived from the amino acid tyrosine and are secreted from the thyroid and the adrenal medulla.
Endocrine Glands
The endocrine glands include the adrenal, hypothalamus, pancreas, ovaries, parathyroid, pineal, pituitary, testes and thyroid. Conditions like diabetes, goiter and hypoglycemia are examples of conditions that arise from an overactive or underactive endocrine gland.
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The major glands that make up the human endocrine system include the:
- Hypothalamus - It makes hormones that control the pituitary gland. It also makes the hormone ADH and oxytocin, which are stored in the pituitary gland.
- Pituitary gland - Known as the "Master Gland", this part of the brain consists of two lobes called "anterior" and "posterior". It also respond to signals from the hypothalamus, the pituitary gland releases hormones some of which control other endocrine glands.
- Parathyroid gland - They release parathyroid hormone, which plays a role in regulating calcium levels in the blood and bone metabolism.
- Thymus - Thymosin, which stimulates the development of T cells for the immune system, is secreted by the thymus.
- Pancreas - has patches of tissue called the islets of Langerhans. It produces insulin and glucagon that control the blood sugar level.
- Adrenal Gland - It produce hormones that help control heart rate, blood pressure, the way the body uses food, the levels of minerals such as sodium and potassium in the blood, and other functions particularly involved in stress reactions.
- Ovaries - The hormones estrogen and progesterone are made in the ovaries. They maintain the female reproductive system and secondary sex characteristics. Progesterone maintains the uterus during pregnancy.
- Testes - makes testosterone, a hormone that maintains the male reproductive system and secondary sex characteristics.
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