AP 15

Reproductive Systems Overview

• Chapter 26 from "The Human Body in Health and Illness"

• Published by Elsevier

• Evolve study resources available for free with textbook purchase

Objectives

• Understand the role and structures of both male and female reproductive systems.

• Study hormonal control of the female reproductive cycle.

• Discuss dental hygiene treatment implications connected to reduced estrogen levels.

Key Terms

• Breasts (p. 510)

• Cervix (p. 504)

• Colostrum (p. 510)

• Endometrium (p. 504)

• Epididymis (p. 499)

• Estrogen (p. 504)

• External Genitals (p. 500)

• Fallopian Tubes (p. 504)

• Gametes (p. 496)

• Gonadotropins (p. 507)

• Gonads (p. 496)

• Graafian Follicle (p. 502)

• Lactation (p. 510)

• Mammary Glands (p. 510)

• Menopause (p. 510)

• Menses (p. 506)

• Milk Let-Down Reflex (p. 510)

• Myometrium (p. 504)

• Ovarian Cycle (p. 507)

• Ovarian Follicles (p. 502)

• Ovaries (p. 502)

• Ovulation (p. 502)

• Progesterone (p. 504)

• Prostate Gland (p. 500)

• Scrotum (p. 496)

• Semen (p. 500)

• Spermatogenesis (p. 499)

• Testes (p. 496)

• Testosterone (p. 496)

• Uterus (p. 504)

• Vagina (p. 505)

• Vas Deferens (p. 499)

Reproductive Systems Overview

Sexual vs Asexual Reproduction

• Asexual Reproduction:

  • Occurs in single-celled organisms (e.g., bacteria, some plants).

  • No partner is needed; organisms divide by themselves.

• Sexual Reproduction:

  • Requires both male and female partners.

Reproductive System Functions

1. Produces, nurtures, and transports ova and sperm.

2. Secretes hormones involved in reproductive processes.

Primary Reproductive Organs (Gonads)

• Testes: Male gonad, produces sperm.

• Ovaries: Female gonad, produces ova/eggs.

• Gonads secrete hormones and produce gametes.

• Other organs, glands, and ducts are considered secondary reproductive organs.

Male Reproductive System Functions

• Produces, nourishes, and transports sperm.

• Deposits sperm within the female reproductive tract.

• Secretes hormones (androgens, primarily testosterone).

  • Testosterone Functions:

    • Essential for sperm production.

    • Development of male secondary sex characteristics (e.g., facial hair, deeper voice).

Components of Male Reproductive System

• Scrotum: Houses the testes.

• Seminiferous Tubules: Site of sperm development (spermatogenesis).

• Epididymis: First part of the duct system, where sperm mature and become motile.

• Vas Deferens: Continuous with the epididymis; joins the seminal vesicle to form the ejaculatory duct.

Male External Genitals

• Scrotum: Sac containing testes.

• Penis: Carries urine through urethra; deposits sperm in female reproductive tract.

Hormonal Control of Male Reproduction

• Hypothalamus secretes releasing hormones.

• Releasing hormones stimulate anterior pituitary to secrete gonadotropins (FSH and LH).

• FSH stimulates spermatogenic cells to respond to testosterone (spermatogenesis).

• Negative feedback loop regulates testosterone production after puberty.

Female Reproductive System Functions

• Produces eggs.

• Secretes sex hormones: Estrogen and progesterone.

• Nurtures and protects a developing fetus during pregnancy.

Estrogen Functions

• Promotes maturation of the egg.

• Develops female secondary sex characteristics:

  • Development of reproductive organs

  • Breast development

  • Fat deposition (thighs, buttocks, breast)

  • Widening of pelvis

  • Onset of menstrual cycle

  • Closure of epiphyseal discs in long bones.

Progesterone Functions

• Works with estrogen to establish the menstrual cycle.

• Maintains pregnancy.

• Prepares breasts for milk production after pregnancy.

Female Genital Tract

• Consists of the Fallopian Tubes, Uterus, and Vagina:

  • Fallopian Tubes: 4" long tubes connecting uterus to ovaries; include the infundibulum (funnel-shaped end).

  • Uterus: Safe environment for fetus; shaped like an upside-down pear.

    • Parts: Fundus (upper dome), Body (central region), Cervix (narrow lower region).

    • Layers of Uterus:

      1. Epimetrium (Perimetrium): outer serosal layer.

      2. Myometrium: middle smooth muscle layer.

      3. Endometrium: inner layer.

  • Vagina: 4" muscular tube from cervix to vaginal opening with folds (rugae).

Female External Genitals

• Collectively called the Vulva:

  • Includes labia majora, labia minora, clitoris, and vestibular glands.

Egg Development

• Eggs develop within Ovarian Follicles (structures in ovaries).

  • Each follicle consists of an immature egg (oocyte) and follicular cells.

• Usually, one follicle fully matures each month and releases an egg during ovulation.

• After ovulation, follicular cells become the Corpus Luteum, which secretes large amounts of progesterone and smaller amounts of estrogen.

Corpus Luteum Fate

• If fertilization does not occur: transforms into Corpus Albicans (not hormonally active).

• If fertilization occurs: Corpus Luteum remains active and releases hormones until the placenta takes over.

Hormonal Control of Female Reproductive Cycle

• Two components: Ovarian Cycle and Uterine Cycle:

  • Ovarian Cycle: Involves phases of follicular and luteal phases driven by hormone secretion.

  • Uterine Cycle (Menstrual Cycle):

    • Phases include:

      • Menstrual Phase: (day 1-5) bleeding.

      • Proliferative Phase: (day 6-13) repair and growth.

      • Secretory Phase: (day 15-28) progesterone secretion to thicken the uterine lining.

Hormones and Dental Health

• Increase in estrogen and progesterone can lead to increased blood flow to gums, causing inflammation and sensitivity.

• Decrease in estrogen may cause dry mouth, burning mouth, and bone loss.