Chapter 13 Endocrine System The Endocrines The endocrine system has ductless glands. They rely on the blood vessels and lymph vessels. The secretions of the endocrine system are called hormones. The secretion of hormones is controlled by a feedback mechanism. The amount of the hormone in the blood stream regulates the amount being released. The loop helps maintain the proper amount. Pituitary Gland It is a small organ that has been called the “orchestra leader” because it controls all the other glands. Structure Lies protected within the sphenoid bone The steam of the pituitary glands connects to the hypothalamus of the brain. It is actually made up of two separate glands with different embryonic organs and functions. Anterior lobe/Anterior pituitary gland Develops as an upgrowth from the pharynx Posterior lobe/ Posterior pituitary gland Develops as a downward extension of the brain Thyroid Paired bilateral glands located near the trachea below the larynx The hormone secreted by the thyroid is controlled by the anterior pituitary gland. Iodine is the essential element of the thyroid hormone. Most disorders of the thyroid are caused by overproduction or underproduction of the thyroid hormone. Parathyroid Glands Small, smooth, shiny, round glands There are usually two on each side in close proximity to the thyroid gland. Adrenal Glands Small glands located close to the kidney Structure Made up of two parts the cortex (outer portion) and medulla Pineal Gland Small, firm, oval body located near the base of the brain Pancreas Specialized cells of the pancreas are called Islands of Langerhans which secrete insulin, glucagons, and pancreatic polypeptide (PP) Gonads As endocrine glands, the ovaries and testes produce hormones important to the functioning of the reproductive system. These glands become active during puberty under the influence of the anterior pituitary lobe and produce secondary sex characteristics and reproductive behavior Name ABBR Location Produced Function Somatropin GH Anterior Lobe of Pituitary Promotes bodily growth of both bony and soft tissues Thyrotropic (thyroid stimulating)H TSH Anterior Lobe of Pituitary Influences the thyroid gland and causes secretion of the thyroid hormones Follicle-stimulating Hormone FSH Anterior Lobe of Pituitary Females-Stimulates growth of mature graafin follicles and the secretion of estrogen Males- the development of the seminiferous tubules and sperm cells Luteinizing Hormone LH Anterior Lobe of Pituitary Females-stimulates the formation of the corpus luteum and secretion of estrogen and progesterone Interstitial cell-stimulating Hormone ICSH Anterior Lobe of Pituitary Males - stimulates development and secretion of testosterone in the interstitial cells of the testes Prolactin Anterior Lobe of Pituitary Responsible for mammary gland development during pregnancy Adrenocorticotropic Hormone ACTH Anterior Lobe of Pituitary Influences growth of the adrenal glands Appears to have a relationship to skin pigmentation Melanocyte- stimulating Hormone MSH Anterior Lobe of Pituitary Stimulates formation of melanin pigment in the skin and hair Antidiuretic Hormones vasopressin ADH Posterior Lobe of Pituitary Limits the development of large volumes of urine by stimulating water reabsorption by the distal and collecting tubules of the kidneys Oxytocin Posterior Lobe of Pituitary Stimulates both the let down of milk into the mammary ducts and contraction of the pregnant uterus during parturition Thyroxine (T4) and Triiodothyronine (T3) together called thyroid Hormone T4 and T3 Thyroid This hormone is high in iodine and vital for growth and metabolism. Calcitonin Thyroid Produces a decrease of the calcium concentration in the blood Parathyroid Hormone PTH Parathyroid Glands Regulates the calcium and phosphorus content in the blood and bones. It increases blood calcium. Mineralocorticoids Adrenal (Outer) Concerned with the regulation of sodium and potassium, which maintains electrolyte and water balance Glucocorticoids Adrenal (Outer) Secreted mainly by the middle zone of the outer cortex. Including cortisol (hydrocortisone) and corticosterone; general effect is on metabolism, of carbohydrates, fats, and proteins, resistance to stress, antibody formation, lymphatic functioning, and recovery from inflammation and injury. Sex Hormones Adrenal These are produced not only by the adrenals but also by the ovaries and testes Epinephrine (adrenaline) Adrenal Medulla Aids the body in meeting stressful situations such as defense, flight, attack, or pursuit by stimulating the sympathetic nervous system Norepinephrine (noradrenaline) Adrenal Medulla Aids with coping stress, increases heartbeat, blood pressure, blood glucose level, and blood clotting rate Melatonin Pineal Gland Believed to inhibit ovarian function and secretion of the pituitary luteinizing hormone Insulin Pancreas Necessary for the use and storage of carbohydrates and acts to decrease blood glucose levels Glucagon Acts to incases the blood glucose levels Pancreatic polypeptide PP Pancreas Produces glucagons and gastric juices and has been identified as having additional functions in digestion and metabolism Estrogenic hormones (estadiol, estrone) Ovaries Promotes secondary sex development and estrus after puberty Testosterone Testes Promotes secondary sex development after puberty Page 1 of 5