2The Endocrine Glands & their Hormones Basic principles in hormone actions:Many effects of one hormone areantagonized by another hormoneThis helps maintain HOMEOSTASIS
3The Endocrine Glands & their Hormones Pineal Gland-Main hormone secretedMELATONIN-Role Melatonin--Mammals : Regulatereproductive activity inresponse to environmentallight cyclese.g. Some mammals mate insummer (lot of light), whileothers mate in winter (lowlight).
4The Endocrine Glands & their Hormones Thyroid Gland-Produces 3 main hormones-Triiodothyronine (T3)-Thyroxine (T4)Regulate body metabolism and areimportant in bone growth and maturationof the brain-Congenital lack of thyroid hormones:Cretinism.-CalcitoninActs by reducing calcium levels
5The Endocrine Glands & their Hormones Parathyroid Gland-Parathyroid HormoneRaises Blood Calcium(antagonize Calcitonin)This hormone acts on bone, kidneyand the gut
6The Endocrine Glands & their Hormones Thymus Gland-Thymosin : Stimulates theproduction of Lymphocytes-Thymostatin : Inhibits theThymus : Important for the neonatalproduction of antibodiesThymus : Gland being at the centerof endocrine, neural, and immunesystems
7The Endocrine Glands & their Hormones Heart-Granular cells in the heart musclesecrete Atrial Natriuretic Factor (ANF)..ANF : Regulates blood pressure,blood volume, and excretionof water, sodium andpotassium..ANF : Also a neuropeptide inthe brain
8The Endocrine Glands & their Hormones Gastrointestinal Hormones-The mucosa of the GI tract secretes adozen PEPTIDE hormones3 most important:1. Secretin : Secreted in the small intestineStimulates the secretion ofpancreatic bicarbonate and hasother functions on digestion2. Gastrin: Secreted in the walls of stomachStimulate hydrochloric acid secretionstimulate pancreatic enzyme secretion3. Cholecystokinin : Secreted in the small intestineStimulate gall bladder contractionStimulate pancreatic enzyme secretion
9The Endocrine Glands & their Hormones PancreasEndocrine cells in the pancreas secrete2 major types of hormones1. Insulin : Secreted in response toincrease in blood glucose levels ;So insulin LOWERS glucose levels byINCREASING glucose UPTAKE in cellswhere it is stored as glycogen.2. Glucagon : Increases blood glucoselevels by stimulating the conversionof glycogen to glucose in the liver.
10A parte : Insulin & Diabetes Diabetes : Hyperglycemia, ie.Elevated Blood Sugar2 Types : The distinction is based uponwhether the blood sugar problem iscaused by insulin deficiency (Type 1)or insulin resistance (Type 2)Type 1- Insulin Deficiency : There is notenough insulin produced by the pancreasso the patient must inject insulin on a dailybasisType 2 - Insulin Resistance : There is plenty ofinsulin but the cells of the body are resistantto its action so, increase in blood sugarThis form is controlled by a strict diet
11The Endocrine Glands & their Hormones Adrenal Glands2 parts : Medulla & CortexAdrenal Cortex : 3 categories of steroidhormones1. Mineralocorticoids2. Glucocorticoids3. Sex SteroidsAdrenal Medulla1. Adrenaline2. Noradrenaline
12The Endocrine Glands & their Hormones Adrenal CortexInfluence sexual differentiationand bodily changes during pubertyAndrogenEstrogenStress Hormone, converts storedproteins to carbohydrate during stress.Antiinflammatory andImmunosuppressive functions.If there is a sodium deprivation,Aldosterone is secreted and actsto increase reabsorption ofsodium ions (NA+) in the kidneyssalivary glands, and sweat glands.
13The Endocrine Glands & their Hormones Adrenal MedullaAdrenaline : Released followingstress due to environmentalextremes; Increases heartrate and blood glucose levelsso, increases the amount of workthe muscles can do (FLIGHT)Noradrenaline : As Adrenaline, act as a NTin the brainPeriphery; increase blood pressureand constrict blood vessels(noradrenaline, stress, and heart disease…)
14The Endocrine Glands & their Hormones Gonads ; TestesThe male gonads : produces AndrogensPrimary androgen = TESTOSTERONEOther androgen : DihydrotestosteroneAndrostenedioneTestosterone : Important for masculinizationControl of sperm productionDevelopment of male sexualcharacteristicsActivation of sexual andaggressive behaviors
15The Endocrine Glands & their Hormones Gonads ; Ovaries2 major classes of hormonesESTROGENSPROGESTINSPrimary ESTROGEN : Estradiolothers : EstriolEstroneSynthetic estrogens : Birth control pillsEstrogens : -Development of sexualcharacteristics at puberty-Influence metabolic rate-Influence sexual andmaternal behavior
16The Endocrine Glands & their Hormones Gonads ; OvariesPROGESTIN : Progesterone-Stimulates breast and uterineenlargement at puberty & duringmenstrual cycle-Maintains pregnancy (inhibits menstrualcycle during pregnancy)Other hormone released at the end ofpregnancy : RelaxinActs to prepare the birth canal.Estrogen and Progesterone act in synergy.
17The Endocrine Glands & their Hormones Placenta-Hormones secreted by the fertilized egg(Used in pregnancy tests)Human Chorionic Gonadotropin (HCG)Act by keeping progesterone high at thebeginning of a pregnancyHuman Placental Lactogen (HPL)Stimulates the mammary glands to beginto secrete milk
18The Pituitary Gland & its Hormone PART IIThe Pituitary Gland & its HormoneAlso calledthe HYPOPHYSIS
19The Pituitary Gland & its Hormone -Attached to the HYPOTHALAMUS-Secretion of the pituitary hormonesis regulated by hypothalamus-HYPOTHALAMIC-PITUITARYconnection
21The Pituitary Gland & its Hormone PVNSON-Neuroscretory Cells-Paraventricular nucleus (PVN)-Supraoptic nucleus (SON)-Hormones secreted-OXYTOCIN-VASOPRESSINAXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumNeurohypophysis
22The Pituitary Gland & its Hormone PVNSONOXYTOCIN & VASOPRESSIN-Are really HYPOTHALAMIChormones-OXYTOCIN :2 main functions--> promotes uterine contractions--> stimulates milk ejection frommammary glands duringlactationAXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumNeurohypophysis
23The Pituitary Gland & its Hormone PVNSON-VASOPRESIN :--> Antidiuretic hormone--> Raises blood pressure--> promotes water reabsorptionby kidneys--> centrally : may promotememory- Binding proteins for bothoxytocin & vasopressin--> NeurophysinsAXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumNeurohypophysis
24The Pituitary Gland & its Hormone ADENOHYPOPHYSIS (ANTERIOR)Mechanism for release of hormonesTrue endocrine gland becauserelease hormone in the bloodstream(hypophysal portal system)AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
25The Pituitary Gland & its Hormone 1. Neurosecretory cells of thehypothalamus release their hormonesat the median eminence2. Hormones circulate in bloodstream3. Carried to the adenohypophysis4. Stimulates secretion of otherhormones from the adenophysis5. These hormones are then releasedin the bloodstream to reachtheir target cells.Median eminence
26The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones1. Growth Hormone (GH)(also called ‘somatotropin’)…’tropic’=stimulating effectGH = promotes growth in almostall body cellsA lot of attention for degenerativedisease…..-Alzheimer-Parkinson-Anti-Agingetc.AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
27The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones2. Adrenocorticotropic HormoneACTHRole : Stimulates synthesis andrelease of glucocorticoidhormones‘Hypothalamic-pituitary-adrenalaxis’1970’s : Role of memory….little problems…..AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
28The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones3. Thyroid Stimulating HormoneTSHRole : Stimulates the synthesis andrelease of thyroxine (T4)and triiodochyronine (T3)from the thyroid.AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
29The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones3 last hormones=….gonadotropic hormones4. Follicle stimulating hormone (FSH)Role : In both sexes, promotes thedevelopment of reproductivecells (gametes) andpromotes secretion ofgonadal hormonesMales : stimulates sperm productionFemales : stimulates growth ofprimary follicle of ovaryAXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
30The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones3 last hormones=….gonadotropic hormones5. Luteinizing hormone (LH)Role :Female : Stimulates ovulation andformation of progesterone-secreting cellsMales : Stimulates cells that secreteandrogens (e.g. testosterone)AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
31The Pituitary Gland & its Hormone Adenohypophysis : 6 hormones3 last hormones=….gonadotropic hormones6. Prolactin (PRL)Role : Initiates milk synthesis inmammary glandsOther functions related togrowth & parental behaviorInteraction with serotonin also(important in depression)AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
32The Pituitary Gland & its Hormone Non traditional hormone from theadenohypophysis--> beta-endorphinDerivative from POMCPOMC : synthesized in the parsdistalis and pars intermediaBroken down into ACTH, MSH &beta-endorphins by enzymesAXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumAdenohypophysis
33The Pituitary Gland & its Hormone Beta-Endorphin : Role to play in --> Analgesia--> Learning and Memory--> Psychiatric diseases--> Feeding, Thermoregulation,--> Blood pressure--> also called the ‘drug of the jogger’…..
34The Pituitary Gland & its Hormone Pars Intermedia :Not present in adult humans butpresent in fetal humans and mammalsSynthesize the hormone calledMelanocyte stimulating hormoneswhich acts in amphibian to changeskin color….Our friend Watson :Sex & SunshineMSH…..AXONSAttaches thehypothalamus to thepituitary. Also calledthe InfundibulumPars Intermedia