IPHY 4440 1st Edition Lecture 11 Outline of Last Lecture I. HP axisOutline of Current Lecture II. Releasing hormones (RHs)III. Tropic hormones (controlled by RH hormones) IV. NonapeptidesV. HypothalamusVI. What is a portal system?VII.Pituitary=HypophysisCurrent LectureI. Releasing hormones (RHs)Can either be stimulatory or inhibitoryA. Releasing hormones increase tropic hormone secretion (never seen these hormones in the circulation) B. Releasing inhibiting hormones (RIHs) decrease tropic hormones - Produced in the hypothalamus- Transported to and stored in median eminence- Released from median eminence portal system adenohypophysisII. Tropic hormones (controlled by RH hormones) In order from most important to least important •GH (growth hormone) growth metabolism•PRL (prolactin)•TSH (thyroid-stimulating hormone) development metabolism•ACTH (adrenocorticotropic hormone) Stress metabolism •LH (luteinizing hormone) Reproductive metabolism •FSH (follicle-stimulating hormone) Reproductive metabolism•MSH (melanocyte-stimulating hormone)-Produced in adenohypophysis -Released from adenohypophysis ® general circulationIII. NonapeptidesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Produced in neurosecretory nucleiAxons project to neurohypophysis•Arginine vasopressin (AVP)=antidiuretic hormone (ADH) in humans•Oxytocin (OXY) -Produced by hypothalamus -Stored in and released from the neurohypophysis ® general circulationIV. HypothalamusA. Releasing hormones are produced (RH & RIH)- Produced in neurosecretory nuclei- Axons project to median eminence (neurohemal organ) portal systemV. What is a portal system?- A circulation that begins and ends in capillary beds- Capillary bed (ME) portal veins (general circulation) capillary bed (adenohyophysis) * Must go through general circulation before transported to adenohypophysisDelivers substances by the most direct routeA. Advantages of a portal system?- Speed (fast)- Dilution- Prevents the degradation of the releasing hormones because blood can be quite corrosive (metabolize neurohormones) VI. Pituitary=Hypophysis1. Adenohypophysis- Adeno= gland- Glandular portion of pituitary - Secretes tropic hormones a) Pars distalis (PD): Dediccated to the genera growth of the body. Stimulatory to the gonads - FSH, LH gonadotropic hormones (GTHs)= gonadotropins produced by gonadotropes- TSH= thyrotropin thyroid produced by thyrotropes- GH= somatotropin (STH) Liver, bone, muscle – produced by somatotropes b) Pars intermedia (PI)c) Pars tuberalis (PT) (not very important) Thought Question:If you cut off the portal system, what would happen to the secretion of tropic hormones?- Releasing hormones would stimulate different tropic hormones - For some groups of tropic hormones would go down for other tropic would go up bc respond to inhibiting hormones - Because can no longer release hormones- Both respond to stimulatory and
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