Comparison of Nervous and Intro to Endocrinology Endocrine Systems

„ Intercellular Communications „ Nervous System „ Endocrine System – neurons – chemical communicators – MESSENGERS – action potential – neurotransmitters – hormones „ Paracrines – communicate short – communicate long „ Neurotransmitters distances distances „ Hormones – very rapid – slower „ Neurohormones transmission(ms) transmission(min- days) – response short lived days) – response longer lived

Feedback Mechanisms „ Complex (multilevel) – hormonal feedback „ Simple _ – non-hormonal feedback Hypo TRH „ Glucose/Insulin Regulation _ Anti. Pit. HORMONE + TSH Thyroid ENDO TARGET CELL BIOLOGICAL Thyroxin Biological - RESPONSE (T4, T3) response

Synthesis Chemical Nature of Hormones Chemical Nature of Hormones „ Peptides and Proteins „ Steroids „ Amino Acid Derivatives Steroids

„ Peptide and Protein Hormones

„ Steroids

1 Mechanisms of Hormone Action

„ Proteins „ Steroids Hypothalamic-Pituitary – 2nd messenger – receptors on Relationships – change in nucleus membrane permeability

Embyrology

„ Anterior Pituitary – Rathke’s pouch

„ Posterior Pituitary – Infundibulum

Anterior Pituitary Cell Types „ Somatothroph Cell Types(cont) – 40-50% – Human Growth Hormone(HGH) „ Thyrotroph „ Lactotrophs – 10-15% – 3-5% – Prolactin – Thyroid stimulating hormone(TSH) „ Coricotroph „ Gonadotroph – 15-20% – 10-15% – Adrenalcorticotrophic hormone(ACTH) – Follicle stimulating hormone(FSH) – Melanocyte stimulating – Luteinizing hormone(LH) hormone(MSH)

2 Relationship of Hypothalamus Relationship of Hypothalamus and Post. Pituitary and Ant. Pituitary

Releasing/Inhibiting Hormones „ Growth hormone releasing Releasing/Inhibiting Hormones hormone(GHRH) – stimulates release of HGH „ Thyrotropin releasing hormone(TRH)

– stimulates release of TSH & Prolactin „ Growth hormone inhibiting „ Corticotropin releasing hormone(CRH) hormone(GHIH or somatostatin) – stimulates release of ACTH and MSH – inhibits release of HGH, „ Gonadotropin releasing hormone(GnRH) „ Prolactin inhibiting hormone (dopamine) – stimulates release of FSH and LH – inhibits release of prolactin

Relationships of Hypo and Anterior Pituitary Hormone Pituitary Review Functional Overview

„ Neural relationships „ Follicle stimulating hormone(FSH) – Posterior pituitary – growth and maturation of ovarian follicle

„ supra optic nucleus – influences estrogen secretion

„ paraventricular nucleus – stimulates sperm production

„ Circulatory relationships „ Luteinizing hormone(LH) – Anterior pituitary – ovulation

„ hypophyseal portal system – formation of corpus luteum

„ releasing/inhibiting hormones – secretion of testosterone by Leydig cells

3 „ Adrenocorticotropic hormone(ACTH) Intermediate Lobe Hormone – stimulates production of glucocorticoids by the adrenal cortex Overview „ Thyroid stimulating hormone(TSH) – growth/maintenance of thyroid tissue „ Melanocyte stimulating – stimulates secretion of thyroid hormone hormone(MSH) – no significant role in humans „ Prolactin – no significant role in humans – milk production/secretion in mammary glands – role in camouflage in some animals – ACTH influence „ Human growth hormone(HGH) – ACTH influence – role in body growth – regulates metabolism

Posterior Pituitary Functional Overview Pineal Gland „ ADH – produced by supra optic nucleus „ Melatonin – role in urine production – cycling effect – also called vasopressin which plays a role „ biological clock in regulating blood pressure biological clock „ effective disorders „ Oxytocin „ PMS – produced by paraventricular nucleus „ puberty onset – stimulates milk letdown „ seasonal breeding – may play a role in parturition

„ Pitocin

4