ENDOCRINE GLANDS AND THE HORMONES THEY PRODUCE GLAND HORMONE EFFECTS Hypothalamus Growth hormonereleasing hormone (GHRH) Growth hormoneinhibiting hormone (GHIH) Thyrotropin-releasing hormone (TRH) Corticotropinreleasing hormone (CRH) Gonadotropinreleasing hormone (GnRH) Prolactin-releasing hormone (PRH) Prolactin-inhibiting hormone (PIH) Oxytocin Causes anterior pituitary gland to release growth hormone Antidiuretic hormone Anterior Pituitary Gland Growth Hormone (GH) Adrenocorticotropin (ACTH) Thyroid Stimulating Hormone Follicle Stimulating Hormone (FSH) Luteinizing Hormone (LH) Inhibition of growth hormone on anterior pituitary gland Causes anterior pituitary gland to release thyroid stimulating hormone Causes anterior pituitary gland to release andrenocorticotropic hormone (ATCH) Causes anterior pituitary gland to release folliclestimulating hormone (FSH) and Luteinizing hormone (LH) Causes anterior pituitary to release prolactin (PRL) Inhibits release of prolactin by the anterior pituitary gland Transported to posterior pituitary gland where it is released into the bloodstream. See posterior pituitary gland Transported to posterior pituitary gland where it is released into the bloodstream. See posterior pituitary gland Directly influences protein, carbohydrate and lipid metabolism and controls the rate of skeletal and visceral growth Stimulates the cortex of the adrenal glands to produce adrenocortical hormones called corticosteroids Stimulates the thyroid gland to release the thyroid hormones thyroxine (T4) and Triiodothyronine (T3) Stimulates the growth and maturation of follicles in the ovary and sprematogenisis in the male. FSH is also called a gonadotrophic hormone This is also a godandatrophic that acts with FSH to cause ovulation of mature follicles and the Posterior Pituitary Gland Prolactin Antidiuretic Hormone ( ADH or vasopressin) Oxytocin Thyroid Gland Thyroxine (T4) Triiodothyrinine Calcitonin Parathyroid Gland Adrenal Cortex Parathyroid Hormone (PTH) Mineralocorticoids Glucocorticoids Adrenal Medulla Pancreas Androgenic Hormones Epinephrine Norepinephrine Insulin Glucagon Testes Ovaries Testosterone Estrogen secretion of estrogen (an ovarian hormone). In the male, LH stimulated the production of testosterone (the main male sex hormone) by the interstitial cells of Leydig in the testes. Promotes breast development and milk secretion Causes the kidneys to reabsorb water thereby increasing the water content of the body. It may also constrict the blood vessels throughout the body thus elevating blood pressure Stimulates the myometrium of the uterus to strongly contract during the birthing process. Oxytocin also stimulates the breast to express milk when the baby suckles These two hormones, known as the thyroid hormones increase metabolic rates in almost all tissues of the body Promotes calcium deposition in bones and lowers calcium concentrations in extracellular fluid Increases blood calcium levels by increasing activity of osteoclasts in bone. Aldosterone is the most abundant mineralocorticoid produced. It promotes sodium reabsorption and potassium secretion in the kidneys Cortisol is the most abundant glucocorticoid produced. It helps control protein, carbohydrate and fat metabolism. Con trolls major stressors. Produced I n small amounts and have similar effects as the male sex hormone testosterone. Both these hormones mimic the stimulation of the sympathetic nervous system Controls the rate of carbohydrate metabolism by promoting glucose transport into cells Stimulates glucose release from the liver thereby raising blood glucose levels Stimulates growth of male sex organs and secondary sex characteristics Stimulates the development of female sex organs, breasts and various secondary sexual characteristics. Important during the sexual cycle along with progesterone to produce an environment suitable for fertilization, implantation and nutrition of the early embryo Progesterone Placenta Prepares the uterus for the reception and development of the fertilized ovum by stimulating endometrial glands. Progesterone is also responsible for the development of the secondary apparatus of the breasts. Human Chorionic Promotes the growth of the corpus luteum (a Gonadatropin (HCL) yellow glandular mass in the ovary formed by an ovarian follicle that has matured and discharged its ovum) which secretes estrogens and progesterone. Estrogen Stimulates the growth of the mother’s sex organs and fetal tissue. Progesterone Promotes fetal tissue development and promotes the development of the secretory apparatus of the breasts. Human Promotes fetal tissue development and the Somatomammotropin development of the mother’s breasts. Chemistry of Hormones: Chemically, there are 3 principle classes of hormones: 1) Steroids 2) Derivatives of the amino acid tyrosine 3) Proteins and peptides 1) Steroids : Steroid hormones are derived from cholesterol. Examples of steroid hormones are: -aldosterone -cortisol -androgenic hormone -testosterone -estrogens -progesterone 2) Derivatives of the amino acid Tyrosin : Structurally these are the simplest and are synthesized by modifying the amino acid tyrosine. Examples are -thyroxine -triiodothyronine -epinephrine and norepinephrine (secreted by the medulla of the adrenal glands) 3) Proteins and Peptides : These hormones consist of chains of amino acids and include; -hypothalamic releasing and inhibiting hormones -oxytocin -antidiuretic hormone -all anterior pituitary hormones -insulin -glucagon -parathyroiud hormone -calcitonin The amount of hormones required to control most metabolic and endocrine functions are incredibly small with concentrations ranging from 1 picogram (1 millionth of millionth of a gram) per millimeter of blood to a few micrograms (1 millionth of a gram) per millimeter of blood. Sophisticated methods are needed to detect and measure these concentrations. Control of Hormone Secretion: Hormones are regulated primarily by negative feedback where once a physiologic effect is achieved, the information is then transferred either directly or indirectly back to the producing endocrine gland which inhibits further secretion. Positive feedback control of hormone secretion is uncommon because it leads to a larger response which acts as a greater stimulus for more response.
