Endocrine Glands and Their Hormones (Anterior and Posterior Pituitary Glands) Major Endocrine Glands and Structures • 10 Major Glands of the Endocrine System ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ Pituitary Gland Hypothalamus Thyroid Gland Parathyroid Gland Adrenal Gland Pancreas Testes Ovaries Thymus Pineal Gland Pituitary Gland • Pituitary Gland: Is a small gland about the size of a pea, located inferior to the hypothalamus in your brain. It helps indirectly control and regulate the other major endocrine glands. • The Pituitary gland is broken into two parts: ▫ Anterior Pituitary Epithelial cells ▫ Posterior Pituitary Nerve cells Hypothalamus and the Anterior Pituitary Gland • Stimuli with in the nervous system cause releasing and inhibiting hormones to be secreted by the hypothalamus • Releasing and inhibiting hormones pass through the hypothalamic-pituitary portal • Releasing and inhibiting hormones leave capillaries, and bind to membrane-bound receptors, and influence cells of the anterior pituitary gland to secrete hormones • Anterior pituitary hormones are carried in the blood to their target tissue Hypothalamus and the Posterior Pituitary Gland • Stimuli within the nervous system stimulates the hypothalamic nerve cells to produce action potentials. • Action potentials are carried to the posterior pituitary gland. Hormones are then stored in the pituitary gland. • Action potentials cause the release of the stored hormones into the circulatory system. • Hormones travel to their target tissues Hormones of the Anterior Pituitary • Growth Hormone (GH): Stimulates growth of bones, muscles, and organs ▫ A deficiency of growth hormone can result in pituitary dwarfism ▫ A excess of growth hormone can results in giantism. If the hormone is secreted after bone length is developed it will add to the growth of the diameter of the bone. This is called acromegaly. ▫ Rhythm of GH secretion peaks during deep sleep ▫ GH increases during fasting and exercise Hormones of the Anterior Pituitary • Thyroid-Stimulating Hormone (TSH): Binds to membrane-bound receptors on the thyroid gland and causes them to secrete thyroid hormone. ▫ A decrease of TSH results in decrease in size of the thyroid gland and less secretion of TSH. ▫ A increase of TSH results in the thyroid gland enlarging and secreting to much TSH Hormones of the Anterior Pituitary • Adrenocorticotropic Hormone (ACTH): Binds to membrane-bound receptors on cells in the cortex of the adrenal glands. ▫ ACTH increases the secretion of cortisol also known as hydrocortisone. ▫ ACTH prevents the adrenal cortex from degenerating. ▫ ACTH molecules bind to melanocytes in the skin and increase pigmentation. ▫ To much ACTH can result in darkening of the skin Hormones of the Anterior Pituitary • Gonadotropin: Hormones that bind to membrane-bound receptors on the cells of the gonads and regulate growth, development and function of the gonads. • Luteinizing Hormone (LH): In females it causes ovulation of oocytes and the secretion of sex hormones. (estrogen and progesterone) in males it stimulates testosterone and is referred to as Interstitial cell-stimulating hormone (ICSH) • Follicle-Stimulating Hormone (FSH): Stimulates the development follicles in the ovaries in females and sperm in the testes males. Hormones of the Anterior Pituitary • Prolactin: Binds to membrane-bound receptors in the breast. ▫ Decrease of prolactin results in inability to produce breast milk. ▫ Increase of prolactin results in production of breast milk • Melanocyte-stimulating hormone (MSH): Bind to melanocytes and causes them to synthesize melanin which helps protect from UV light. ▫ Over secretion results in dark skin ▫ Inability to secrete results in fair skin Hormones of the Posterior Pituitary • Antidiuretic Hormone (ADH): Binds to membranebound receptors and increases water reabsorption by kidneys tubules. Which results in less water lost as urine. ▫ ADH can cause blood vessels to constrict (vasopressin) ▫ Lack of ADH causes production of large amounts of dilute urine. ▫ Alcohol can affect ADH levels Hormones of the Posterior Pituitary • Oxytocin: Binds to membrane-bound receptors, and causes contraction of smooth muscle cells of the uterus as well as milk letdown from the breast in lactating women. ▫ Pitocin is a commercial preparation of oxytocin, which help assist in child birth.