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Chapter-11 Hormones

BOOK TITLE: Pharmacology for Nurses

Author
1. Sudhakar GK
ISBN
9788184489149
DOI
10.5005/jp/books/11357_11
Edition
1/e
Publishing Year
2010
Pages
32
Author Affiliations
1. Kasturba Medical College, Mangalore, Karnataka, India
Chapter keywords

Abstract

The pancreas is an endocrine gland that produces peptide hormones like Insulin, Glucagon and Somatostatin. These hormones regulate metabolic activities of the body and help to maintain homeostasis of blood glucose. The endocrine system consists of many glands that secrete hormones into blood stream. When these glands malfunction, they release either decreased or increased amount of hormone. Some of these hormones are available as drugs and are used as replacement therapy to treat diseases caused by too little of the hormone. Other hormone drugs are used to suppress the gland when it secretes too much hormone. Diabetes is not a single disease. But it is heterogeneous group of disorders characterized by elevated blood glucose and caused by defects in the secretion and/or actions of pancreatic hormone insulin. It is a major risk factor for heart disease and stroke. Complications of this disease include blindness in adults, renal failure and limb amputations. Administration of insulin preparations or hypoglycemic agents can prevent morbidity and reduce mortality associated with diabetes. The thyroid was one of the first of endocrine glands to be associated with clinical conditions like Hypothyroidism and Hyperthyroidism caused by its malfunction. This gland releases two very different types of hormones namely Thyroxine T 4 and Triiodothyronine T 3 and 2) Calcitonin. T 3 and T 4 are essential for growth and development and regulation of energy metabolism Calcitonin is important in regulation of calcium metabolism. Androgens are produced by testis, ovary and adrenal glands. Testosterone is the most important androgen in males. It stimulates virilization and is an important spermatogenic hormone. Within the ovary testosterone and androstenedione are precursor steroids for estradiol production, estral production. In both sexes Androgens stimulate body hair growth, positive nitrogen balance, bone growth, muscle development and erythropoiesis. The major use of anti androgens in clinical medicine is for replacement therapy in men whose production of testosterone is impaired. Testosterone synthesis inhibitors and Antiandrogens are used to limit the effects of Androgens in patients with Androgen-dependent disorders such as prostatic cancer, hirsutism and precocious puberty. Anabolic steroids (Example, Nandrolone Oxandrolone Stanozolol) change natural balance between anabolism (tissue building) and catabolism (tissue breakdown). These drugs increase tissue building and have been used for years by athletes to increase muscle mass strength and endurance. The use of two or more anabolic steroids at the same time is referred to as stacking. The use of parabolic steroids can cause decreased sperm count, shrunken testicles baldness and irreversible breast enlargement in men. In women these drugs can cause baldness and excessive growth of facial hair. The serious side effects of anabolic steroids include aggressive behavior, atherosclerosis and even liver cancer. They are classified as schedule III controlled substances because of their high potential for addiction and abuse. For AIDS patients they are legally prescribed to counteract the loss of muscle mass and strength that occurs with AIDS wasting syndrome. They may also be legally prescribed to promote weight gain following extensive surgery or trauma, to treat RBC count and treat anemia, or to treat metastatic breast cancer. Oxandrolone is also used to treat lack of growth in patients with Turner’s syndrome. The two major classes of female sex hormones are estrogens and progestin’s. They both serve important functions in development of female secondary sex characteristics control of pregnancy and ovulatory menstrual cycle, bone homeostasis and modulation of many metabolic processes. There are three endogenous estrogens in humans, namely: 1. 17 β Estradiol, the principal ovarian estrogen, 2. Estriol the principal placental estrogen, and 3. Estrone, a metabolite of 17β estradiol and a major ovarian and post menopausal estrogen. Estrogens coordinate systemic responses during ovulatory cycle, including regulation of reproductive tract, pituitary, breasts and other tissues. They also play a role in progression of some tumors. Adrenaline is released by sympathetic nervous system in response to pain, danger or stress. It prepares the body to respond with either flight or fight by causing the following changes: 1. Constriction of peripheral blood vessels due to stimulation of alpha receptors. This raises blood pressure, 2. Increased heart rate and cardiac output due to stimulation of beta receptors in the heart muscle, and 3. Relaxation of bronchial smooth muscle due to stimulation of beta 2 receptors. This causes bronchodilation and increased air flow to the lungs. During cardiac arrest if heart is in ventricular fibrillation, Adrenaline makes myocardium more responsive to use of defibrillator to restore normal rhythm. If heart has completely stopped beating (Asystole) Adrenaline can actually stimulate contractions of myocardium. It also constricts blood vessels, so it stimulates heart to beat; it also helps to maintain blood pressure and perfusion to heart and brain to improve chances of a successful resuscitative effort. Calcium concentration in plasma is maintained normally within narrow limits about 8.5 to 10.4 mg/dl. When ionized calcium concentration falls outside narrow physiological range, the functions of many tissues are affected. Hypocalcemia can lead to increased neuromuscular excitability and tetany and impairment of mineralization of skeleton. Hypercalcemia can result in life-threatening cardiac dysrhythmias, kidney stones and central nervous system abnormalities. In addition there are disorders of skeleton such as osteoporosis and Paget’s disease of bone that cause loss of normal structure. These changes in bone integrity result in increased susceptibility to fracture. Disorders associated with abnormal uterine motility range from minor aggravations to life threatening emergencies. The principal goals of drug therapy may be either to stimulate or relax uterine motility. Labor consists of uterine contractions and cervical dilatation (widening) and effacement (thinning). When cervix does not dilate and thin, Dinoprostone (PGE2) may be applied to cervix to ripen it. Normally oxytocin (produced by pituitary gland) stimulates uterus by binding to special oxytocin receptors on smooth muscle cells of the uterus. Oxytocin is not indicated when prolonged labor is due to cephalopelvic disproportion (the baby’s skull is too large to fit through mother’s pelvic outlet). Premature or preterm labor and delivery greatly increase morbidity and mortality in new born infants. Premature labor contractions can be inhibited by using uterine relaxing drugs known as tocolytics (in Greek, toco means childbirth and lysis means to dissolve or reduce).

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