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Endocrine System- my notes

Endocrine System- my notes - Endocrine System Overview of...

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Unformatted text preview: Endocrine System Overview of Endocrine Glands Human Anatomy and Physiology II Department of Kinesiology Temple University Integration and Coordination Accomplished by Nervous and Endocrine Referred to as Neuroendocrine System Work as Complements Maintain Homeostasis! Negative Feedback Mechanisms Stimulation increases secretion Secretion increases blood concentration Target organ affected Hormone release inhibited Nervous vs. Endocrine Nervous Electrochemical Very fast (110 ms) Only muscles/glands Ends quickly May stimulate hormone release Endocrine Chemical Slow (secs to days) Most tissues in body Continues for days? Stimulate and inhibit neurons Overview of Endocrinology Endo "within" Crine krinein "to separate" Major role in: secrete products to distant tissues Growth and Development Reproduction Total Body Metabolism Characteristics of ES Endocrine Paracrine Neurosecretory cells Secrete hormones into bloodstream Stimulates response in target tissue/organ "Local" hormones Secrete into tissue fluids to nearby cells tubes or ducts affect itself Exocrine Autocrine Transportation of Hormones Endocrine glands are highly vascularized Hormones is Released into ECF via exocytosis Hormones travel in blood vessels Transported to target organ Major Endocrine Organs Hypothalamus and Pituitary Closely integrated relationship Hypothalamus major link b/w NS and ES Pituitary "master" endocrine gland Regulation of growth Development Metabolism Homeostasis Hormones control pituitary Together, 16 different hormones Hypothalmus and Pituitary Hypothalamichypophyseal tract Hypophyseal portal system Nerve tract connecting to posterior pituitary Vascular connection to anterior pituitary Primary capillary plexus Hypophyseal portal vein Secondary capillary plexus Hypothalamus Derived from neural tissue Part of diencephalon of cerebrum Hormones produced Paraventricular nucleus Supraoptic nucleus Hypothalamic Hormones 9 different hormones Median Eminence to Anterior Pituitary Growth hormonereleasing hormone (GHRH) Growth hormoneinhibiting hormone (GHIH) Corticotropinreleasing hormone (CRH) Thyrotropinreleasing hormone (TRH) thyr. Stimulating hormone Gonadotropinreleasing hormone (GNRH) Prolactinreleasing hormone (PRH) Prolactininhibiting hormone (PIH) Hypothalamic Hormones 2 relate to Posterior Pituitary Oxytocin Antidiuretic hormone (ADH) Produced in paraventricular nucleus Produced in supraoptic nucleus Both secreted by Posterior Pituitary Pituitary Gland Called "hypophysis" Divided into anterior Pituitary Divided into Posterior Pituitary Adenohypophysis Derived from glandular epithelium Neurohypophysis Derived from neural tissue Anatomy of Pituitary Gland Adenohypophysis Five types of cells: Three produce tropic hormones Two produce effects on nonendocrine tissues 4. Somatropes GH 5. Lactotropes PRL 1. Corticotropes ACTH frm hypo to pituary 2. Thyrotropes TSH hyroid relaseing hormone 3. Gonadotropes ;\pituarty causing proucti opm pg : FSH, LH FSH Anterior Pituitary Hormones LH Eggs and sperm Ovulation/testosterone Thyroid growth/hormone Adrenal cortex Lactation Tissue growth TSH ACTH PRL GH Posterior Pituitary Hormones Oxytocin and ADH Nerve impulse from hypothalamus Release into ECF, then capillaries Neurosecretory cells in hypothalamus Move in vesicles Stored in axon terminals of Posterior Pituitary Hypothalamichypophyseal tract Thyroid Gland Anatomy Thyroid Largest gland Only gland to store hormones in large quantity As much as three or more months worth Major metabolic hormone of body Affects virtually every cell Except: adult brain, spleen, testes, uterus, thyroid gland Primary effect increase metabolic rate Thyroid Hormones Follicular cell hormones Formed from iodine and thyroglobin Transported by thyroxinbinding globulin T3 triiodothyronine T4 tetraiodothyronine or thyroxin Most active thyroid hormone Thyroid Hormones Calcitonin Produced in parafollicular cells Promotes deposition of Ca into bone matrix Stimulates osteoblasts Decreases blood Ca levels Parathyroid Gland At least two pairs Parathyroid hormone (PTH) Produced by chief cells Helps raise Ca blood levels Stimulates osteoclasts Promotes intestinal reabsorption Inhibits urinary excretion Neuron transmission, muscle contraction, clotting Thymus Gland Large and conspicuous in children Diminishes through adulthood Regulate and activate Tlymphocytes Thymopoietin Thymosin Adrenal Glands Structurally and functionally two glands Major function help body cope with stress Adrenal Cortex Adrenal Medulla Adrenal Cortex Hormones Mineralcorticoids Zona glomerulosa Aldosterone Glucocorticoids Water and electrolyte balance Zona fasciculata Cortisol Gonadocorticoids Aids in chronic stress Zona reticularis Androgens Sex hormones Adrenal Medulla Cells modified postganglionic neurons Sympathetic innervation Hormones prolong effects of sympathetic stimulation: Epinephrine (80%) less potent Norepinephrine (20%) more potent, Pancreas Exocrine (acinar cells) secreted into a tube Endocrine digestive function 12% pancreatic cells Islets of Langerhans Alpha cells Beta cells Glucagonraises blood sugar by tking sugar Insulin lowers blood sugar Somatostatin Delta cells Gonads Testes and Ovaries Produce sex hormones Estrogen and Progesterone by female Testosterone by male JANUARY 21, 2010 Pineal Gland Both NS and ES functions Produces the hormone Melatonin Concentrations increase and decrease diurnally Possible role in sexual maturation Assumed role in physiological responses to light cycles Endocrine Functions of Other Organs Stomach/Small Intestine Kidney Enteric hormones coordinate digestion Calcitrol affects Ca handling Erythropoietin stimulates RBC production Atrial Natriuretic Factor affect BP Heart Modes of Stimulation Humoral stimulation Changing blood levels of ions and nutrients Insulin/Glucagon from Pancreas Neural stimulation Nerve Fibers directly innervate gland Catecholamines from adrenal medulla Oxytocin and ADH from hypothalamus Modes of Stimulation Hormonal stimulation From other endocrine glands Tropic hormones Anterior Pituitary hormones: TSH Thyroid stimulating hormone ACTH Adrenocorticotropic hormone FSH Folliclestimulating hormone LH Lutenizing hormone Chemical Classifications Steroid Hormones Peptide Hormones Cholesterol Monoamines Oligopeptide chains Polypeptide chains Glycoproteins Amino Acids Difference greatly affects hormone physiology! Amino Acid-Based Biogenic Amines Same as monomeens Modifications of AA Tyrosine thyroid hormones T3 and T4 catecholamines (norepi, epi) Peptides Glycoproteins chains of 3300 AA synthesized on the rough ER some proteins have an attached CHO Thyroid stimulating hormone (TSH) Chemical Classification of Amino Acid-Based Water soluble hormones Transportation "Free" Hormones peptide, protein, and catecholamines "Hydrophilic" In blood throughout the body diffuse through capillary walls Lipid Based Steroid hormones Derived from cholesterol Eicosanoids gonadal hormones,(easy for one to change into another ) adrenocortical hormones effects are very localized (do not circulate throughout body).. Cell next to it Eicosanoids subcategories: Prostaglandins and Leukotrienes Chemical Classification of Lipid Based Lipid soluble hormones Transportation "Bound" hormones "Hydrophobic" Hydrophilic transport proteins At target become free hormones i.e. albumins, globulins Diffuse through capillary walls Hormone Receptors and Mode of Action Target cells (recptors in or out for protein to bind to )in organs Must bind hormone to receptor or glycoproteins Response dependent upon hormone solubility Receptors exhibit Specificity and Saturation Once bound, metabolic pathways activated Determines receptor location Action of Water Soluble Hormones Biogenic Amines, Peptides, Proteins "Lipophobic"/"Hydrophilic" Peripheral proteins Cause effects on target cell through second messenger systems Receptor on plasma membrane Water Soluble Hormone Mode of Action Second Messenger Systems Binding of hormone to receptor causes cascade of events in target cell Best known: Others Cyclic adenosine monophosphate (cAMP) Used the most often; common Diacylglycerol Inositol triphosphate (IP3) 1. 2. 3. 4. 5. 6. Cyclic Hormone binds to receptor Gprotein (communicator) activated Gprotein activates AC () AC produces cAMP (activates kinase) cAMP activates PKs PKs activates AMP ACTH FSH LH PTH TSH Glucagon Calcitonin Catecholamines Cyclic AMP Activated Hormones Diacylglycerol and IP3 1. 2. 3. 4. Hormone to receptor Gprotein activated Gprotein activates phospholipase PL activates: 1. Diacylglycerol activates protein kinases 2. IP3 Ca into cell 1. Binds Calmodulin activates protein kinases Examples ACTH GHRH TSH Oxytocin Catecholamines Lipid Soluble Hormones Steroid Hormones "Hydrophobic"/"Lipophilic" Diffuse into cell to nucleus Binds to receptor on chromatin Activates DNA transcription (mRNA) mRNA produces protein Protein could be enzyme or protein structure Lipid Soluble Hormone Mode of Action Lipid-Soluble Hormone Mode of Action Examples Estrogen Progesterone Testosterone Cortisol Aldosterone Calcitrol* T3 and T4* (released as bound hormone) Mechanisms of Hormone Action Alter cellular activity Increase and decrease rates of cell processes(metabolism) Response determined by target cell type Cellular changes produced by hormones: Alter plasma membrane permeability Synthesis of protein or regulatory molecules Activation and deactivation of enzymes Induction of secretory activity Stimulation of mitosis Ie: if u hav a fite/flight then u want energy to go to muscle rather than gut STUDY QUESTIONS What are the water soluble and lipid soluble biogenic amines? What is the precursor for lipidbased hormones? COLESTORAL Which hormone is responsible for reglulating sodium? What triggers its release? What hormone is released during longterm stress? Acute srress? What is the mode of action of lipodbased hormones? Binding Success Factors Concentration in blood Number of receptors Direct relationship [if theres a high level of hormones in blood, it wil be on the other oen too ] Direct relationship Affinity or strength of bond Between hormone and receptor Alterations in Hormone Sensitivity 1st type: Upregulation Increases # of receptors Greater sensitivity to hormone Alterations in Hormone Sensitivity Downregulation [more common] Reduces # of receptors Less sensitivity to hormone Common in pathological conditions Enzyme Amplification Low concentrations of a hormone can induce large effects One hormone = thousands of enzyme molecules that initiates a cascade or chain reaction Result: amplification effect, allowing low [hormone] to induce a considerable effect Enzyme Amplification Hormone Interactions Synergistic Effect Synergistic Effect Permissive Effect one has to go first 2 or more work together greater than alone FSH and testosterone on sperm in gonads Antagonistic Effect different, cancel each other out Opposing actions Insulin [storage] and Glucagon[breaking down storage ] on blood glucose One enhances effects of other makes it even greater Estrogen and progesterone in uterus Deactivation and Excretion Degraded by enzymes in target cell Most removed from blood by enzyme systems in the kidney and liver Excreted in Urine Persistence of Hormone Referred to as "HalfLife" Water soluble (hydrophilic) Lipid soluble (hydrophobic) Short half life Deposed by Enzymes in blood/liver Filtered in kidney Long half life Protected by protein carrier End of Endocrine Material ...
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