Endocrine System

The posterior pituitary gland stores and releases two important hormones that are synthesized in the hypothalamus

1. Antidiuretic hormone (ADH), also called vasopressin—Stimulates the reabsorption of water by the kidney tubules. In addition, ADH also increases blood pressure by constricting arterioles. 2. Oxytocin (OT)—Stimulates the uterus to contract during childbirth and maintains labor during childbirth. OT also is secreted during suckling and causes the production of milk from the mammary glands.

The adrenal medulla secretes two types of catecholamine hormones:

1. Epinephrine (adrenaline)—Increases heart rate and blood pressure, dilates bronchial tubes, and releases glucose (sugars) from glycogen (storage substance) when the body needs it for more energy. 2. Norepinephrine (noradrenaline)—Constricts blood vessels to raise blood pressure.

The major hormones of the anterior pituitary gland are:

1. Growth hormone (GH), or somatotropin (STH)—Promotes protein synthesis that results in the growth of bones, muscles, and other tissues. GH also stimulates the liver to make insulin-like growth factor (also called IGF), which stimulates the growth of bones. It increases blood glucose levels and is secreted during exercise, sleep, and hypoglycemia. 2. Thyroid-stimulating hormone (TSH), or thyrotropin—Stimulates the growth of the thyroid gland and secretion of thyroxine (T4) and triiodothyronine (T3). 3. Adrenocorticotropic hormone (ACTH), or adrenocorticotropin—Stimulates the growth of the adrenal cortex and increases its secretion of steroid hormones (primarily cortisol). 4. Gonadotropic hormones—Several gonadotropic hormones influence the growth and hormone secretion of the ovaries in females and the testes in males.In the female, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) stimulate the growth of eggs in the ovaries, the production of hormones, and ovulation. In the male, FSH influences the production of sperm, and LH (an interstitial cell-stimulating hormone) stimulates the testes to produce testosterone. 5. Prolactin (PRL)—Stimulates breast development during pregnancy and sustains milk production after birth.

Corticosteroids

A group of hormones, including cortisol, released by the adrenal glands at times of stress

The ductless, internally secreting endocrine glands are listed as follows

[1] thyroid gland [2] parathyroid glands (four glands) [3] adrenal glands (one pair) [4] pancreas (islets of Langerhans) [5] pituitary gland [6] ovaries in female (one pair) [7] testes in male (one pair) [8] pineal gland

Hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

Catecholamines

dopamine, norepinephrine, epinephrine

pituitary gland

small, pea sized master gland; hypophysis

endocrine system

the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream

Both epinephrine and norepinephrine are sympathomimetic agents because they mimic, or copy, the actions of the sympathetic nervous system. They are released to help the body meet the challenges of stress in response to stimulation by the sympathetic nervous system.

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The adrenal cortex secretes three types of corticosteroids.

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