* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 1 A Perspective on Human Genetics
Survey
Document related concepts
Hormone replacement therapy (female-to-male) wikipedia , lookup
Neuroendocrine tumor wikipedia , lookup
Hypothyroidism wikipedia , lookup
Hormone replacement therapy (menopause) wikipedia , lookup
Hormone replacement therapy (male-to-female) wikipedia , lookup
Hyperandrogenism wikipedia , lookup
Graves' disease wikipedia , lookup
Bioidentical hormone replacement therapy wikipedia , lookup
Hyperthyroidism wikipedia , lookup
Pituitary apoplexy wikipedia , lookup
Hypothalamus wikipedia , lookup
Transcript
Chapter 18 The Central Endocrine Glands Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning Outline • General Principles of Endocrinology – Free vs. bound, disorders, receptors • Hypothalamus and pituitary – Relationship – Anterior pituitary – Posterior pituitary • Endocrine control of growth • Pineal gland and circadian rhythms GENERAL PRINCIPLES OF ENDOCRINOLOGY • Hormones exert a variety of regulatory effects throughout the body. • The effective plasma concentration of a hormone is normally regulated by changes in its rate of secretion. • The effective plasma concentration of a hormone is influenced by its transport, metabolism, and excretion. • Endocrine disorders result from hormone excess or deficiency or decreased target-cell responsiveness. • The responsiveness of a target cell can be varied by regulating the number of hormone-specific receptors. Solely endocrine function Pineal Hypothalamus Mixed function Complete function uncertain Pituitary Parathyroid Thyroid Thymus Heart *Know* Hormones function regulation transduction Testes in male Stomach Adrenal gland Pancreas Duodenum Kidney Skin Ovaries in female Placenta in pregnant female Fig. 18-1, p. 654 Table 18-2a, p. 659 Table 18-2b, p. 660 Table 18-2c, p. 660 Table 18-2d, p. 661 Table 18-2e, p. 661 Hormones • Two distinct groups of hormones based on their solubility properties – Hydrophilic hormones (Proteins, peptides) • Highly water soluble • Low lipid solubility – Lipophilic hormones (Steroids) • High lipid solubility • Poorly soluble in water • Peptides/catecholamines/iodinated tyrosines Fig. 4-23, p. 116 Fig. 4-22, p. 115 Fig. 4-26, p. 122 NH2 NH2 COOH COOH S S S S A-chain S S B-chain A chain and B-chain C- peptide Fig 15-4, pg 456 Tyrosine Growth hormone Monoiodotyrosine (MIT) Diiodotyrosine (DIT) T4 (thyroxine) Serotonin Insulin T3 (c) 2003 Brooks/Cole - Thomson Learning Fig. 4-24, p. 118 Fig. 4-25, p. 119 Endocrine System • Overall functions – Regulate organic metabolism and H2O and electrolyte balance (think of resting potentials) – Induce adaptive changes to help body cope with stressful situations (what is stress?) – Promote smooth, sequential growth and development (hypo/hyper) – Control reproduction (birth control/agriculture) – Regulate red blood cell production (EPO) – Along with autonomic nervous system, control and integrate both circulation and the digestion and absorption of food Tropic Hormones • Regulates hormone secretion by another endocrine gland • Stimulates and maintains their endocrine target tissues • Example – Thyroid-stimulating hormone (TSH) secreted from anterior pituitary stimulates thyroid hormone secretion by thyroid gland • Also maintains structural integrity of thyroid gland Vascular Link Between the Hypothalamus and Anterior Pituitary PIF/PRF Prolactin GnRH Gonadotropic hormones (FSH and LH) TRH CRF GHRH/somatostatin Thyroidstimulating ACTH hormone Two methods of transport Portal System = connects two secondary capillary beds Neurosecretory = from an axon Growth hormone Hormones • Plasma concentration of each hormone is normally controlled by regulated changes in rate of hormone secretion • Direct regulatory inputs that influence secretory output of endocrine cells – Neural input – Input from another hormone • Effective plasma concentration also influenced by – Rate of removal from blood by metabolic inactivation and excretion – Rate of activation or its extent of binding to plasma proteins – Being bound or free. Many hormones are not transported in their active form. They can be bound to a carrier or chemically modified Fig. 18-2, p. 655 Fig. 18-3, p. 656 N = noon M = midnight Light Dark Fig. 18-4, p. 656 Hormone Influence at Target Cell • Hormone can influence activity of another hormone at given target cell in one of three ways – Permissiveness • One hormone must be present in adequate amounts for full exertion of another hormone’s effect – Synergism • Occurs when actions of several hormones are complimentary • Combined effect is greater than the sum of their separate effects – Antagonism • Occurs when one hormone causes loss of another hormone’s receptors • Reduces effectiveness of second hormone Fig. 4-21, p. 112 Endocrine Control of Growth • Growth depends on growth hormone but is influenced by other factors as well – Genetic determination of an individual’s maximum growth capacity – An adequate diet – Freedom from chronic disease and stressful environmental conditions – Normal levels of growth-influencing hormones • Including insulin, thyroid and steroid hormones Fig. 18-12, p. 673 Growth Rate • Not continuous • Factors responsible for promoting growth are not the same throughout growth period • Fetal growth – Promoted largely by hormones from placenta – GH plays no role in fetal development • Postnatal growth spurt – Displayed during first two years of life • Pubertal growth spurt – Occurs during adolescence Normal Growth Curve Growth Hormone • Primarily promotes growth indirectly by stimulating liver’s production of somatomedins – Primary somatomedin is insulin-like growth factor (IGF-1) • Acts directly on bone and soft tissues to bring about most growth-promoting actions • Stimulates protein synthesis, cell division, and lengthening and thickening of bones • Inhibits apoptosis • Exerts metabolic effects not related to growth – Increases fatty acid levels in blood by enhancing breakdown of triglyceride fat stored in adipose tissue – Increases blood glucose levels by decreasing glucose uptake by muscles Fig. 18-11, p. 671 Articular cartilage Bone of epiphysis Epiphyseal plate Bone of diaphysis Cartilage Marrow cavity Calcified cartilage Bone Fig. 18-11a, p. 671 Cartilage Bone of epiphysis Bone Epiphyseal plate Resting chondrocytes Calcified cartilage Chondrocytes undergoing cell division Older chondrocytes enlarging Causes thickening of epiphyseal plate Calcification of extracellular matrix (entrapped chondrocytes die) Diaphysis Dead chondrocytes cleared away by osteoclasts Osteoblasts swarming up from diaphysis and depositing bone over persisting remnants of disintegrating cartilage Fig. 18-11b, p. 671 Endocrine Dysfunction • Can arise from a variety of factors • Most commonly result from abnormal plasma concentrations of a hormone caused by inappropriate rates of secretion – Hyposecretion • Too little hormone is secreted – Hypersecretion • Too much hormone is secreted Hyposecretion • Primary hyposecretion – Too little hormone is secreted due to abnormality within gland – Causes • • • • • • • Genetic Dietary Chemical or toxic Immunologic Other disease processes such as cancer Iatrogenic Idiopathic (spontaneously) • Secondary hyposecretion – Gland is normal but too little hormone is secreted due to deficiency of its tropic hormone Hypersecretion • Causes – Tumors that ignore normal regulatory input and continuously secrete excess hormone – Immunologic factors • Primary hypersecretion – Too much hormone is secreted due to abnormality within gland • Secondary hypersecretion – Excessive stimulation from outside the gland causes oversecretion Growth Hormone Abnormalities • Growth hormone deficiency – Due to pituitary defect or hypothalamic dysfunction – Hyposecretion of GH in child is one cause of dwarfism – Deficiency in adults produces relatively few symptoms • Growth hormone excess – Most often caused by tumor of GH-producing cells of anterior pituitary – Symptoms depend on age of individual when abnormal secretion begins • Gigantism – Caused by overproduction of GH in childhood before epiphyseal plates close • Acromegaly – Occurs when GH hypersecretion occurs after adolescence The world's tallest man, Bao Xishun, who stands 2.36 meters (7.9 feet), shakes hands with He Pingping, who only measures 73 centimeters (2.4 feet),in Baotou, China's Inner Mongolia Autonomous Region Friday, July 13, 2007. Nineteen-year-old He is applying for the Guinness World Record as the world's shortest man. (AP Photo) CHINA OUT Fig. 18-14, p. 675 Growth • Other hormones besides growth hormone are essential for normal growth – Thyroid hormone • Growth severely stunted in hypothyroid children • Hypersecretion does not cause excessive growth – Insulin • Deficiency often blocks growth • Hyperinsulinism often spurs excessive growth – Androgens • Play role in pubertal growth spurt, stimulate protein synthesis in many organs • Effects depend on presence of GH – Estrogens • Effects of estrogen on growth prior to bone maturation are not well understood poorly