Menstrual Cycle

Menstrual Cycle Overview

  • Reference: Brunners Chapter 50

Important Structures - Ovary

  • Ovaries: Each girl is born with thousands of egg follicles halted at a developmental stage.

  • Maturation Process:

    • Monthly after puberty, many follicles begin to mature.

    • Only one follicle dominates and matures into an egg; others regress.

Important Structures - Graafian Follicle and Corpus Luteum

  • Graafian Follicle: The dominant egg follicle that eventually releases an egg.

  • Corpus Luteum:

    • Formed from the Graafian Follicle post-ovulation.

    • Acts as a temporary endocrine structure, releasing progesterone and estrogen to support the endometrium if fertilization occurs.

Important Structures - Uterus

  • Uterine Lining (Endometrium):

    • Inner lining of the uterus that sheds each month in the absence of pregnancy.

    • Rebuilt by estrogen during the follicular phase of the menstrual cycle.

    • If pregnancy occurs, the fertilized egg implants in the endometrium, leading to placenta formation.

Important Hormones Involved

  • Hypothalamus: Secretes Gonadotropin-Releasing Hormone (GnRH) which signals the pituitary gland.

  • Pituitary Gland: Releases Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) in response to GnRH.

Important Hormones

  • Graafian Follicle: Produces estrogen.

  • Corpus Luteum: Produces progesterone and estrogen.

  • Fertilized Egg: Secretes Human Chorionic Gonadotropin (hCG) until the placenta can take over its production.

Ovarian Cycle & Uterine Cycle

  • Cycle Breakdown:

    • Ovarian Cycle:

      • Follicular Phase: Days 1-14

      • Ovulation: Day 14

      • Luteal Phase: Days 15-28

    • Uterine Cycle:

      • Menstrual Phase: Days 1-6

      • Proliferative Phase: Days 7-14

      • Secretory Phase: Days 15-28

Putting It All Together

  • Ovarian Cycle:

    • Follicular Phase:

      • FSH induces growth in several follicles; one matures (Graafian Follicle).

      • Graafian Follicle releases estrogen, reducing FSH and increasing LH.

      • Ovulation occurs 24-36 hours after the LH peak.

      • Egg is viable for 24 hours, sperm for up to 5 days; fertilization typically occurs in the fallopian tube.

      • Fertility window: Days 9-16.

    • Luteal Phase:

      • Corpus luteum forms, releasing estrogen and progesterone.

      • If no pregnancy, corpus luteum degenerates within 14 days, causing estrogen/progesterone levels to drop, restarting the cycle with GnRH release.

      • If pregnant, the fertilized egg implants, and the placenta develops.

  • Uterine Cycle:

    • Menstrual Phase: Days 1-6; off shedding of the endometrium.

    • Proliferative Phase: Days 7-14; endometrium rebuilds due to estrogen.

    • Secretory Phase: Days 15-28; progesterone from cyst prepares endometrium for implantation.

Chapter 46 - Sexuality

  • Key Concepts:

    • Gender Identity: Psychological identification of oneself.

    • Sexual Orientation: Attraction towards individuals (physically, emotionally, romantically).

Gender-Related Terms

  • Gender Identity: Personal sense of being male, female, or nonbinary; may not align with biological sex.

  • Gender Expression: How one presents their gender externally.

  • Gender Diverse: A spectrum of gender expressions outside normative boundaries.

  • Gender Dysphoria: Distress from mismatch of gender assigned at birth and experienced gender identity.

  • Cisgender: Gender identity aligns with biological sex.

  • Transgender: Identifying as a different gender than assigned at birth.

Sexual Orientation

  • Heterosexual: Opposite gender attraction.

  • Gay/Lesbian: Same-gender attraction.

  • Bisexual: Attraction to multiple genders.

  • Questioning: Uncertainty regarding one's sexual orientation.

Sexual Behavior

Adaptive Behaviors:

  • Consensual between adults, mutually satisfying, non-harmful, non-coerced, private.

Maladaptive Behaviors:

  • Lack one or more criteria of adaptive behavior.

Factors Affecting Sexuality

  • Developmental Considerations: Psychological, emotional, and biological development throughout a lifespan.

  • Culture: Societal norms impacting views on sexuality.

  • Religion: Influence on sexual practices and beliefs.

  • Ethics: Consideration of moral implications of sexual behaviors.

  • Lifestyle: Impact of stress and responsibilities on sexual health.