Hormonal Regulation of Human Reproduction

Hormonal Regulation of Human Reproduction

Hypothalamic-Pituitary-Gonadal (HPG) Axis

• The HPG axis is a complex system that regulates reproductive function in both males and females
• The axis consists of the hypothalamus, pituitary gland, and gonads (ovaries and testes)

Hormones Involved in HPG Axis

• Gonadotropin-Releasing Hormone (GnRH)
  • Produced by the hypothalamus
  • Stimulates the pituitary gland to release gonadotropins
• Follicle-Stimulating Hormone (FSH)
  • Produced by the pituitary gland
  • Stimulates follicular growth and development in the ovaries
• Luteinizing Hormone (LH)
  • Produced by the pituitary gland
  • Stimulates ovulation and progesterone production in the ovaries
• Testosterone
  • Produced by the testes
  • Regulates spermatogenesis and male reproductive function
• Estrogen and Progesterone
  • Produced by the ovaries
  • Regulate the female reproductive cycle and prepare the uterus for implantation

Negative Feedback Mechanism

• The HPG axis is regulated by a negative feedback mechanism
• High levels of sex steroids (estrogen and testosterone) inhibit the production of GnRH and gonadotropins
• Low levels of sex steroids stimulate the production of GnRH and gonadotropins

Clinical Significance of Hormonal Imbalance

• Hypogonadism (low sex steroids) can lead to infertility and sexual dysfunction
• Hypergonadism (high sex steroids) can lead to polycystic ovary syndrome (PCOS) and precocious puberty
• Hormonal imbalance can also lead to menstrual irregularities, erectile dysfunction, and low libido

Hormonal Regulation of Human Reproduction

HPG Axis

• Regulates reproductive function in both males and females
• Consists of the hypothalamus, pituitary gland, and gonads (ovaries and testes)

Hormones Involved in HPG Axis

• GnRH
  • Produced by the hypothalamus
  • Stimulates pituitary gland to release gonadotropins
• FSH
  • Produced by the pituitary gland
  • Stimulates follicular growth and development in ovaries
• LH
  • Produced by the pituitary gland
  • Stimulates ovulation and progesterone production in ovaries
• Testosterone
  • Produced by testes
  • Regulates spermatogenesis and male reproductive function
• Estrogen and Progesterone
  • Produced by ovaries
  • Regulate female reproductive cycle and prepare uterus for implantation

Negative Feedback Mechanism

• HPG axis is regulated by a negative feedback mechanism
• High levels of sex steroids inhibit GnRH and gonadotropin production
• Low levels of sex steroids stimulate GnRH and gonadotropin production

Clinical Significance of Hormonal Imbalance

• Hypogonadism
  • Low sex steroids
  • Leads to infertility and sexual dysfunction
• Hypergonadism
  • High sex steroids
  • Leads to PCOS and precocious puberty
• Menstrual Irregularities
  • Caused by hormonal imbalance
  • Leads to erectile dysfunction and low libido