4 Feedback Mechanisms Stimulus Response change in homeostatic environmentsignal sent to CNSResponsesignal sent from CNSproduce effectbody returns to homeostasis
5 GLAND TYPES Exocrine gland Ducts Lumen and surfaces Endocrine gland Chemical messengersBlood stream
6 Hormones specific chemical compound produced by a specific tissue of the bodyreleased in the body fluidscarried to a distant target tissueaffects a pre-existing mechanismeffective is small amounts.
7 Hormones Chemical messenger Secreted by endocrine gland Specific to targetActivate cellular changeOf 4 different chemical types
8 Classes of Hormones:peptides – short chains of amino acids (most hormones) pituitary, parathyroid, heart, stomach, liver & kidneysamines - derived from tyrosine and secreted by thyroid and adrenal cortexsteroids - lipids derived from cholesterol secreted by the gonads, adrenal cortex, and placentaeicosanoid - Produced from 20-carbon fatty acid, arachadonic acid, produced in all cells except RBCs -Prostaglandins and leukotrienes
9 Peptide/Protein Hormones Most common hormonetranslated, packaged, & sentHydrophilic/LipophobicBind surface receptors at targetBinding mediates signal transduction/2nd messenger system
10 Protein/Peptide Hormones HydrophilicLargeCan't fit through membraneSecond messenger mechanism of actionMost hormonesExample: Insulin
11 peptide and aminesProtein hormones (1st messengers) - bind to receptor on target cell triggering 2nd messenger to affect cell’s activityhormone (1st messenger) does not enter the cell butbinds to receptor on the plasma membrane receptorshormone-receptor complex activates G proteingenerates chemical signal (2nd messenger) – most common is cAMP and IP32nd messenger chemical signal activates other intracellular chemicals to produce response in target cell
12 Amine Synthesized from a single amino acid Melatonin from tryptophan Thyroid hormone from tyrosineCatecholamines (EPI, DA) from tyrosine
13 Eicosanoid Produced from 20-carbon fatty acid, arachadonic acid Produced in all cells except RBCs2nd messengerProstaglandins and leukotrienesinflammation
15 Steroid Hormones Small Hydrophobic/Lipophilic Travel in blood w/carrierCytoplasmic or nuclear receptorschange protein synthesisExample: estradiol
16 Steroid HormonesSteroid hormones - bind to receptors within target cell and influence cell activity by acting on specific geneshormone diffuses freely into cell where cytoplasmic and/ or nuclear proteins serve as receptorshormone binds to receptor (hormone-receptor complex)complex bonds to steroid response element (sections of DNA receptive to the hormone-receptor complexhormone-receptor complex acts as transcription factor to turn target genes “on” or “off”
25 Posterior Pituitary Hormones Manufactured in Hypothalamus,released from Post. Pit.OxytocinTarget = smooth ms. Uterus and Breast (&brain)Function = labor and delivery, milk ejection,(pair bonding)ADH (Vasopressin AVP)Target = kidneysFunction = water reabsorption
26 Pituitary gland MASTER GLAND Anterior and posterior portions Posterior connected to hypothalamus by infundibulumAnterior connected via blood stream
34 Basic Structure of Feedback Loop Environmental StimulusStimulates Control Center (Brain-hypothalamus)Hypothalamic hormones stimulate PituitaryPituitary hormone stimulate Target areaTarget area produces changeChange acts negatively or positively on the cycle.
35 Specific Endocrine Events Thyroid HormoneGrowth HormoneAdrenal Cortex HormonesSex Steroids
36 Endocrine DisordersHyposecretion disorders are caused by too little hormone – they can be treated by addition of the hormoneHypersecretion disorders are caused by too much hormone – these are much harder to treat
37 Thyroid Hormone T3 & T4 stim. Or environmental stim. Hypothalamus TRH stim. Anterior PituitaryTSH stim. Thyroid T3 & T4 shuts off TRH and TSH production
38 Thyroid ProblemsWhat would happen if the thyroid could no longer produce T3 and T4?No negative feedback to hypothalamus and anterior pituitary
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