Biology of Reproduction Summers |
Endocrinology Homeostasis/Feedback Adult Female Steroid Production Ovulation |
Adult Male Gonadal Axis Regulation Sexual Differentiation Sexual Behavior Puberty |
Reproductive Cycling Estrous Cycles Menstrual Cycle Menopause Fertilization |
Fertilization Systems Gamete Interaction Pregnancy Labor and Parturition Lactation |
Sexual Response & Behavior Pheromones STDs text: Human Reproductive Biology2nd Edition- RE Jones & KH Lopez,: pp 24-28 Acronyms/Abbreviations end |
VI. Feedback A. Homeostasis 1. regulation of hormone levels a. control of basal levels b. control of pulsatile release 2. Set Point a. level around which hormone concentrations are regulated B. Negative Feedback 1. e.g. Thermostat 2. Long-Loop Feedback a. gonad is an intermediate b. feed back at locus ceruleus, hypothalamus and pituitary i. ®- = site of feedback 3. Short-loop feedback a. direct feedback by tropic hormones i. LH + FSH inhibit GnRH (at the hypothalamus and brain) 4. Ultrashort Feedback a. releasing hormones and tropic hormones feedback on themselves i. negatively (and positively for GnRH) C. Positive Feedback 1. Females a. Controls LH surge and therefore Ovulation b. Anterior Hypothalamic - Supraoptic - Suprachiasmatic - Center = APS i. regulated by estrogen levels (1) a positive count of how much E2 is in the blood c. Threshold E2 levels trigger APS stimulation of ARC + PON GnRH neurosecretory neurons i. NE + glutamate + Kiss1 + NKB activate GnRH surge 1) inhibited by End, Dyn, GABA & RFrp 2) GnRH stimulates surge of LH 2. Superultrashort = Paracrine GnRH feedback a. GnRH feedback on ARC GnRH cells plays a role in regulating pulsatile release