Test #5 Notes 2

Female Reproductive System

Vagina Cervix Uterus – myometrium, endometrium Oviducts Ovaries Follicle – Estrogen production Thecal cells Granulosa cells Oocyte Follicular Development - Primordial follicle → maturation → ovulation → ovum + corpus luteum  Corpus Luteum – Progesterone and estrogen production          

Ovarian Hormone Production ~Estrogens - Estradiol (E2), Estriol (E3)  E2 -physiologically most important  E3 - produced by placenta Progesterone  Corpus Luteum – source in non-pregnant women  Placenta – source during pregnancy

Circulation of Ovarian Steroids  Estradiol – Sex steroid-binding globulin  Progesterone – Transcortin Actions of Estradiol and Progesterone  Developmental  Estradiol - reproductive tract 2° sexual characteristics

Adults Target Tissue Uterus Endometrium Myometrium Cervical mucus Mammary gland Other

Estradiol

Progesterone

Maintenance Proliferation ↑ Blood supply ↑ Contractions ↓ Viscosity Growth of ducts ↑ Follicular development ↑ Bone Density

Secretion ↑ Blood supply ↓ Contractions ↑ Viscosity Growth of alveoli ↑ Basal body temperature

Hormone Actions  Developmental Effects (Estrogen) -development of reproductive tract -2o sexual characteristics -pubertal growth spurt and fusion of epiphyseal plates

Ac tio ns o f Estrogen  Contraceptive. Why?

suppress FSH secretion and follicular maturation  Reproductive - “Preparatory”  uterus  endometrial growth & development

 myometrial excitability  vagina  growth & cornification of epithelium

 glandular secretion  mammary gland  growth & development ducts

Ac tio ns o f Estrogen  Metabolic  Cardiovascular  favorable lipoprotein profile

 vitamin K-dependent coagulation  Skeletal

 blocks PTH-induced bone reabsorption  Electrolytes  enhanced sodium and water retention  edema

 Reproductive - “Maintenance”  uterus  endometrial secretion - implantation

 myometrial relaxation  mammary gland

 growth & development - alveolar  ovary  suppress estrogen secretion

Acti ons of Prog esti ns  Contraceptive  suppress LH secretion and ovulation  increase viscosity cervical mucous

 decrease sperm motility & transit time  decrease ciliary & peristaltic movement fallopian tubes

 impede ovum transport

Mechanisms of Action  lipophilic hormones – cytosolic/nuclear receptors

Metabolism of Ovarian Steroids  Site - liver  Excretion - urine  Consequences – inactivation Regulation of Ovarian Function  Control of Follicular Development and Secretion  1. FSH  2. LH  3. Estradiol

Actions of LH, FSH, and estradiol on follicular development. LH binds to thecal receptors and increases testosterone (test) production by increasing the conversion of cholesterol (chol) to pregnenolone (preg) via the cAMP-protein kinase (PK) second messenger system. FSH uses the same system to control the conversion of testosterone to estradiol (E2) by granulosa cells.

 Ovulation – LH surge Control of Corpus Luteum  Steroid secretion  Luteal Life Span – luteotropins (LH, HCG)

Control of Gonadotropin Secretion Tonic

Feedback loops controlling tonic secretion of LH and FSH and steroidogenesis by the follicle and corpus luteum

LH Sur ge, day 14 th posi ti ve fee dba ck mechani sm GABA

Control of the Menstrual Cycle Pituitary

Blood

Age Related Changes in Reproductive Function  Prepuberty-GnRH levels are low  Puberty - ↑ GnRH → FSH + LH → 2° sexual characteristics  Adrenarche → Adrenal androgens → libido, pubic hair  Menopause – ovarian failure (cessation of menstrual cycles)

Pathophysiology Hypogonadism  1. Amenorrhea Hypergonadism  1. Before Puberty – Precocious puberty  2. Adults - Amenorrhea, Oligomenorrhea ~excessive estradiol which blocks LH & FSH

Pregnancy Roles of Progesterone to Maintain Pregnancy

Period Preimplantation

Source of Progesterone CL of menstrual cycle

Early postimplantation 2nd – 3rd trimester

CL of pregnancy stimulated by hCG Placenta

Actions Stimulates secretion of nutrients by oviduct and uterus Primes uterus so decidua forms at implantation Prevents menstruation; maintains decidual tissue Prevents uterine contractions

Hormonal changes duri ng pregnancy

Roles of Other Hormones Estrogens – Estriol (E3)  a. Stimulates myometrium  b. Mammary gland development → lactation  C. Parturition Initiation

Labor, Uteri contract ion secreti on

ne → oxytoc in

Positive feedback loop causing uterine contractions during labor. The initial uterine contractions force the fetus downward, stretching the cervix and triggering the neuroendocrine reflex

Lactation

Structure of the mammary gland and of an alveolus within the gland

Mi lk Producti on – requi res many hormones a. Prol acti n – requi red for mil k secreti on b. Oxy toci n – m ilk ej ecti on ref lex

Neuroendocrine reflex controlling milk secretion and ejection

Cessation of lactation - Absence of sucking → ↓ prolactin, oxytocin  Effects on other endocrine systems  Hyperprolactinemia → ↓ GnRH → postpartum amenorrhea