week 2 Reproductive Hormones and Disorders

CHE2 Week 4 Review Notes

Reproductive Hormone Production Overview

  • Key Structures:

    • Hypothalamus

    • Anterior Pituitary

    • Ovary

    • Testis

Hormones Involved

  • GnRH (Gonadotropin-Releasing Hormone)

    • Produced in the hypothalamus

    • Stimulates the anterior pituitary to release FSH and LH

  • FSH (Follicle-Stimulating Hormone)

    • Source: Anterior Pituitary

    • Action: Stimulates follicular development in ovaries and sperm production in males

  • LH (Luteinizing Hormone)

    • Source: Anterior Pituitary

    • Action: Triggers ovulation and converts follicle into corpus luteum in females; stimulates testosterone production in males

  • Estradiol

    • Source: Ovarian Follicles

    • Action: Stimulates growth of endometrial lining, negative feedback for GnRH

  • Progesterone

    • Source: Corpus Luteum

    • Action: Maintains endometrial lining, supports pregnancy

  • Inhibin

    • Source: Sertoli cells in testes, Ovarian follicles

    • Action: Provides negative feedback on FSH production

Male Hormones

  • Overview of the Male Reproductive Cycle

  • Hormone Interaction:

    • GnRH: Stimulates the anterior pituitary to secrete FSH and LH

    • LH: Acts on interstitial cells (Leydig cells) to produce testosterone

    • FSH: Facilitates spermatogenesis in seminiferous tubules

    • Inhibin: Secreted by Sertoli cells to inhibit FSH production from the pituitary

Key Effects of Male Hormones

  1. Development and growth of sex organs

  2. Secondary sex characteristics

  3. Regulation of sex drive

  4. Maturation of spermatozoa

Female Reproductive Cycle

  • Hormonal Control

  • Hormones Important to Female Processes:

    • FSH: Stimulates mature follicle development and estrogen production

    • LH: Triggers ovulation and corpus luteum formation

    • Estrogen: Promotes growth of endometrial lining

    • Progesterone: Maintains endometrial lining

Phases of the Menstrual Cycle

  1. Follicular Phase:

    • Increase of FSH and LH leading to follicle development

  2. Ovulation:

    • Midcycle peak of LH is critical in triggering ovulation

  3. Luteal Phase:

    • Corpus luteum secretes progesterone and estrogen

    • Negative feedback on GnRH and LH production

Hormonal Profiles

  • Blood Levels during menstrual cycle:

    • FSH and LH increase during follicular phase leading to ovulation, then taper off during luteal phase.

    • Estrogen peaks just before ovulation, while progesterone rises after ovulation due to corpus luteum.

Hormone Production and Precursors

Hormones and Sites of Production

  • Estrogens (Non-pregnant):

    • Source: Ovarian Follicle, Corpus Luteum, Placenta (during pregnancy)

    • Precursor: Cholesterol

    • Types: Estrone, Estradiol, Estriol

    • Important for fertility evaluations

  • Progesterone:

    • Source: Corpus Luteum

    • Precursor: Cholesterol

    • Metabolites: Pregnanediol, Pregnanetriol

  • Testosterone:

    • Source: Leydig Cells

    • Precursor: Cholesterol; exhibits a diurnal pattern of secretion

Hormone Levels and Disorders

Androgens and Estrogens

  • Inborn Conditions Affecting Hormone Levels:

    • Precocious Puberty, Klinefelter Syndrome, Turners Syndrome

  • Effects of elevated and decreased hormone levels can lead to fertility issues and developmental disorders

Disorders Related to Hormonal Imbalance

  1. Sex Hormone Disorders:

    • Examples include:

      • Hermaphroditism

      • Gonadal dysgenesis

      • Androgen insensitivity syndrome

  2. Hypogonadism:

    • Primary: Gonadal failure

    • Secondary: Pituitary hypofunction

  3. Pubertal Disorders:

    • Precocious puberty

    • Delayed puberty

Indicators of Disorders

  • Lab Indicators for assessing infertility:

    • Semen analysis

    • Hormone levels (e.g., FSH, testosterone)

  • Clinical indications like early secondary sex characteristics can signal disorders

Specific Conditions

  • Disorders of Androgen Resistance:

    • Description: Result of mutations leading to impaired testosterone conversion, resulting in predominantly female genitalia in XY individuals

  • Disorders of Secondary Puberty:

    • Characterized by precocious development of secondary sex characteristics before normal ages

  • Amenorrhea Types:

    • Primary amenorrhea and secondary amenorrhea connected to various factors like anorexia nervosa, tumors, and systemic diseases

Infertility

Disorders of Infertility (Male & Female)

  • Male Infertility Causes:

    • Pretesticular: Hypothalamic or pituitary lesions

    • Testicular: Congenital abnormalities like nondescending testes

    • Posttesticular: Mechanical impairments in sperm formation

  • Female Infertility Causes:

    • Most common cause: Ovulation failure

    • PCOS: Affects ovulation and hormone balance leading to infertility

    • Congenital adrenal hyperplasia creates issues due to elevated androgen levels

Specific Disorder Indicators

  • Disorders: Trisomy 21 (Down's Syndrome)

    • Indicators: Presence of an additional chromosome 21, altered hormone levels (decreased AFP, estriol; increased hCG, inhibin A).

  • Screening during pregnancy is crucial for early detection.