Presentation on theme: "Endocrine System Nestor T. Hilvano, M.D., M.P.H."— Presentation transcript:
1 Endocrine System Nestor T. Hilvano, M.D., M.P.H. (Images Copyright Discover Biology, 5th ed., Singh-Cundy and Cain, Textbook, 2012.)
2 Learning ObjectivesDescribe the 3 types of hormones by chemical structure.Describe the endocrine system as to types and functions of endocrine organs including its regulatory control.- pituitary gland, pineal gland, thyroid and parathyroid glands, pancreas, adrenal glands, and gonads.4. Define hypothyroidism, hyperthyroidism, goiter, diabetes mellitus, and hypoglycemia.5. Describe the benefits and risks of using glucocorticoids.
3 Endocrine System Ductless glands Hormones – chemical signals secreted and pass directly into the blood circulation to reach the target organs
4 3 Types of HormonesProteins and peptides – most numerous group; H2O soluble; ex. TSH, LH, FSH, ADH, prolactinAmine – derivatives of tyrosine; some H2O soluble, some lipid soluble; ex. TH, Epi, Nor-Epi, dopamineSteroids – not H2O soluble ex. sex hormonesMechanisms of Action on target cells:Lipid soluble hormones – bind to cytoplasm or nuclear receptors (inside the cell)Water soluble hormones – bind to receptor on plasma (cell) membrane; w/ second messenger
5 Figure 29.3 Hormonal Signals Are Amplified within the Cell and Elicit Specific Responses in the Target CellHormones are active at very low concentrations because tiny amounts of a hormone can generate a large internal signal within a target cell. A hormone that docks to a plasma membrane receptor triggers an internal signal relay, known as a signal transduction pathway, in the course of which the original signal becomes magnified. In addition to changing gene expression (1), hormones can bring about a change in cell activity by altering metabolism (2), cytoskeletal organization (3), or membrane transport (4).
6 Figure 29.1 The Endocrine System Is Composed of Hormone-Secreting Cells The endocrine system consists of ductless glands, as well as scattered endocrine cells and tissues, that release hormones directly into the circulatory system. The hypothalamus is the main coordinator of the endocrine system; it also integrates the endocrine system with the nervous system.
7 Hypothalamus Master control center Signals pituitary gland, which in turn secretes hormones that influence many body functionsSecretes releasing and inhibitory hormonesBrainPosterior pituitaryAnterior pituitaryBoneHypothalamus
9 Pituitary GlandPosterior pituitary – stores and secretes hormones made in the hypothalamus- ADH, and oxytocinEffect of ADH- increase reabsorption of water in kidney tubules (DCT/ CT)Effect of oxytocin- uterine contraction; milk ejectionHypothalamusNeurosecretorycellHormonePosteriorpituitaryBlood vesselOxytocinADHUterine muscles Mammary glandsKidney tubulesAnterior
10 Pituitary Gland 1. Tropic hormones (control other glands) NeurosecretorycellBlood vesselReleasing hormones from hypothalamusPituitary hormonesTSHACTHFSH and LHGrowth hormone (GH)Prolactin (PRL)EndorphinsThyroidAdrenal cortexTestes or ovariesEntire bodyMammary glands (in mammals)Pain receptors in the brainEndocrine cells ofthe anterior pituitaryPituitary Gland1. Tropic hormones (controlother glands)TSH (thyroid stimulating hormone)ACTH (adrenocorticotropic hormone)LH and FSH (luteinizing hormone and follicular stimulating hormone)2. GH (growth hormone)3. Prolactin (lactogenic hormone)4. Endorphins (pain receptors inbrain)5. MSH (melanocytes stimulatinghormone)
11 Anterior pituitary Thyroxine Figure 26.4EHypothalamusInhibitionTRHAnterior pituitaryInhibitionTSHFigure 26.4E Control of thyroxine secretionThyroidThyroxine11
12 Pineal Gland Brain outgrowth Secretes melatonin, with rhythmical activity and biologic clock functionsSAD syndrome
13 Thyroid Gland Located beneath the larynx Secretions: Thyroid Hormones (T3, T4); increase BMRCretinism – congenital deficiency of thyroxine in children resulting to physical and mental retardation___ – increase TH___ – decrease TH___ – enlarged gland; causedby iodine deficiencyHypothyroidismGoiterHyperthyroidism
14 Calcium HomeostasisCalcium level in the blood and interstitial fluids are essentialMaintained by calcitonin (to decrease calcium) from thyroid gland and PTH (parathyroid hormone, to increase calcium) from the parathyroid glandsPTH- increase blood calcium level by: increase bone destruction, increase calcium reabsorption in kidneys, and increase calcium absorption in GIT
15 Figure 29.7 Balancing Calcium Levels in the Blood The thyroid and parathyroid glands secrete hormones that control calcium levels in the blood. The width of the red circuit indicates the relative levels of calcium in the bloodstream at different times.
16 Pancreatic Hormones Regulate blood glucose levels Islets of Langerhans – endocrine part- Insulin is a protein hormone produced by beta cells; lower BS- Glucagon is a peptide hormone produced by alpha cells; increase BSDiabetes Mellitus:Type I = destruction of beta cells; no insulin producedType II = low or not responsive toinsulin (insulin resistance)*DM= hyperglycemia, glycosuria (polydipsia, polyuria,polyphagia)Hypoglycemia – secrete too much insulin, lower the blood sugar
17 Figure 29.4 Balancing Levels of Glucose in the Blood Two hormones—insulin and glucagon—work in opposite ways to regulate blood levels of glucose. The width of the red circuit indicates the relative amounts of glucose in the bloodstream at different times.
18 Adrenal GlandAdrenal cortex – produces hormones that provide slower, longer term responses to stress; secretes steroid hormones – mineralocorticoids (aldosterone), glucocorticoids, and androgens* Glucocorticoids offer relief of pain; suppress body’s defense systemAdrenal medulla – ensures a rapid, short term response to stress; releases epinephrine and norepinephrine.* Secretions stimulate liver and muscle cells to release glucose for energy use
19 Figure 29.6 Adrenal Hormones Produce a Rapid Response to Stress The adrenal glands produce epinephrine (adrenaline) and norepinephrine (noradrenaline), which trigger rapid release and delivery of stored energy.
20 Gonads Male = testes; testosterone Female = ovaries; estrogen; progesteroneSex hormonesaffect growth and developmentregulate reproductive cycles and sexual behavior.
21 HomeworkDefine terms: endocrine gland, hormones, goiter, hyperthyroidism, hyperglycemia, hypoglycemia, and hypothyroidism.Discuss the hormonal effects in regulation of blood calcium level and regulation of blood glucose level.List the hormones secreted and its functions (effects) of the following endocrine organs: thyroid, posterior pituitary, anterior pituitary, adrenal gland, pineal gland, pancreas, testes, and ovaries.