MJ

Reproductive System - In-depth Notes

Introduction

  • Sexual Reproduction: The process by which organisms produce offspring using germ cells known as gametes.
  • Reproductive Organs Grouping:
    • Gonads: Produce gametes and secrete hormones.
    • Ducts: Transport, receive, and store gametes.
    • Accessory Sex Glands: Produce materials that support gametes.
  • Gynecology: The branch of medicine focusing on the female reproductive system's diseases.
  • Urology: The field studying the urinary system and male reproductive system diseases.

Reproductive System Overview

  • Primary Sex Organs (Gonads):
    • Males: Testes
    • Females: Ovaries
  • Gametes:
    • Male Gametes: Sperm
    • Female Gametes: Egg
  • Sex Hormones:
    • Males: Androgens (e.g., testosterone)
    • Females: Estrogens and progesterone

Female Reproductive System Anatomy

  • Components:
    • Ovaries: Gonads that produce eggs and hormones.
    • Accessory Organs:
    • Uterine Tubes: Transport fertilized ova.
    • Uterus: Site for fetal development.
    • Vagina: Passageway for childbirth.
    • Mammary Glands: Produce milk.

Ovaries

  • Description: Paired glands on either side of the uterus, held by ligaments.
  • Functions:
    • Produce female gametes (oogenesis).
    • Secrete hormones (estrogen & progesterone).
  • Structure Details:
    • Ovarian Cortex: Contains ovarian follicles.
    • Ovarian Medulla: Contains blood and lymphatic vessels, and nerves.

Ovarian Follicles

  • Definition: Sac-like structures containing immature eggs (oocytes).
  • Development Stages:
    • Primordial Follicle: Early stage of oocyte development.
    • Primary Follicle: Initial development stage.
    • Secondary Follicle: Develops from primary follicles.
    • Mature (Graafian) Follicle: Ready to rupture and release the secondary oocyte (ovulation).
    • Corpus Luteum: Contains remnants of the mature follicle post-ovulation.

Ovulation & Hormones

  • Hormonal Events Leading to Ovulation:
    • Estrogen secreted by follicular cells.
    • Increase in Gonadotropin-Releasing Hormone (GnRH).
    • Luteinizing Hormone (LH): Promotes ovulation and corpus luteum formation.

Uterus

  • Positioning: Hollow, thick-walled organ located in the pelvis.
  • Major Structures:
    • Fundus: Rounded region superior to uterine tube entrances.
    • Body: Major portion.
    • Cervix: Narrow neck projecting into the vagina.

Uterine Histology

  • Layers:
    • Endometrium: Mucosal lining, functions:
    • Stratum Functionalis: Sloughs off during menstruation.
    • Stratum Basalis: Regenerates the functional layer post-menstruation.
    • Myometrium: Thick smooth muscle layer.
    • Perimetrium: Outermost serous layer.

Vagina

  • Structure: Thin-walled tube between the bladder and rectum.
  • Functions: Passageway for birth and menstrual flow.
  • Components:
    • Fornix: Recess surrounding vaginal attachment to the cervix.
    • Rugae: Folds allowing vaginal expansion.
    • Hymen: Membranous border at the vaginal opening.

External Genitalia (Vulva)

  • Components:
    • Mons Pubis: Fatty area over pubic symphysis.
    • Labia Majora: Fat-covered skin folds.
    • Labia Minora: Hair-free folds within labia majora.
    • Clitoris: Erectile tissue and nerve-rich tissue.
  • Vestibule: Area between labia minora containing various gland openings (e.g., paraurethral glands, greater vestibular glands).

Hormonal Regulation in Female Reproductive Cycle

  • Cycles:
    • Ovarian Cycle: Includes stages of oocyte maturation and ovulation.
    • Uterine (Menstrual) Cycle: Changes in endometrium in preparation for potential implantation of fertilized ovum.
  • Hormonal Players: GnRH, FSH, LH, estrogen, progesterone, inhibin relaxin, and their roles in the cycle regulation.

Male Reproductive System

  • Main Components:
    • Gonads: Testes produce sperm and lie in the scrotum.
    • Accessory Organs: Ducts for sperm transport (epididymis, ductus deferens), glands (seminal vesicles, prostate gland), and penis.
  • Functions: Sperm production and secretion of testosterone.

Scrotum & Testes

  • Scrotum: Maintains testes at a lower temperature necessary for sperm production.
    • Internally divided into two sacs for each testis.
  • Testes Structure:
    • Tunica: Double-layered tissues, lobules housing seminiferous tubules for sperm production.
    • Sertoli Cells: Support spermatogenic (sperm-producing) cells.
    • Leydig Cells: Secrete testosterone.

Spermatogenesis Process

  • Stages: Spermatogonia → primary spermatocyte → secondary spermatocytes → spermatids → spermatozoa.
  • Hormonal Regulation: FSH & LH promote spermatogenesis; inhibin regulates FSH production.

Conclusion

  • Understanding the anatomy and physiology of both the male and female reproductive systems is crucial for comprehending human reproduction and associated medical fields.