Human Reproductive Systems, Menstrual Cycle, and Development Study Guide (copy) (copy)

Female Reproductive System Anatomy and Functions

  • Primary System Role: The role of the female reproductive system is to produce ova (eggs) and to support the development of offspring throughout pregnancy.

Female Reproductive System Diagram

  • Anatomical Structures and Functions:

    • Ovary: Primary female reproductive organ containing thousands of undeveloped ova (eggs).

    • Fallopian tube: The canal or tube through which the released ova travels to reach the uterus; the site where fertilization typically occurs.

    • Uterus: The muscular organ in which a fertilised egg implants and develops into a foetus.

    • Endometrium: The specialized inner lining of the uterus that thickens to nourish a potential embryo or sheds during menstruation.

    • Cervix: The narrow, cylindrical neck connecting the bottom of the uterus to the top of the vagina.

    • Vagina: The elastic, muscular tube that connects the cervix to the outside of the female body.

Numbered Female Reproductive System Diagram

  • Anatomical Reference Identifications (Diagram Numbers 1–5):

    • 1 — Fallopian tube: Transports ova from ovary to uterus.

    • 2 — Ovary: Contains thousands of ova and releases one egg per month during ovulation.

    • 3 — Cervix: Connects uterus to vagina; dilates during childbirth.

    • 4 — Uterus: Muscular chamber where offspring develop.

    • 5 — Vagina: Canal leading outside the body.

The Menstrual Cycle and Ovulation

  • Definition: The menstrual cycle is a repeating series of biological changes within the female body designed to prepare the reproductive system for pregnancy.

  • Timing and Duration:

    • An average menstrual cycle lasts around 28 days28\,\text{days}.

    • The cycle repeats monthly starting from puberty and continues until menopause.

Menstrual Cycle Graph

  • Phases of the 28-Day Menstrual Cycle:

    • Days 1–4 (Menstruation): If pregnancy did not occur in the previous cycle, menstruation (a period) takes place. This is the breaking down and shedding of the endometrial lining, which leaves the body via the vagina.

    • Post-Menstruation Rebuilding: The endometrium lining begins rebuilding and thickening again under hormonal control to prepare a safe, nutrient-rich environment for a potential fertilised egg.

    • Day 14 (Ovulation): Ovulation occurs when one mature ova is released from the ovary into the fallopian tube. This release is triggered by a chemical signal from the hormone oestrogen.

    • Days 15–28 (Lining Maintenance / Breakdown):

    • If the egg is not fertilised, the endometrial lining cannot be maintained; it breaks down near Day 28, causing menstruation to begin again on Day 1, restarting the cycle.

    • If the egg is fertilised, the lining is maintained to support pregnancy.

Fertilization, Early Embryonic Development, and Pregnancy

  • Fertilization Process:

    • For fertilisation to occur, a male sperm cell must meet and fuse with the released female ova inside the fallopian tube.

Sperm Fertilizing Egg CellFertilization, Zygote, Blastocyst, and Implantation

  • Sequential Steps from Ovulation to Implantation:

    1. Ovary releases an ova (ovulation).

    2. Ova travels through the fallopian tube.

    3. Ova is fertilised by sperm inside the fallopian tube.

    4. The fertilized egg becomes a single-celled zygote.

    5. The zygote undergoes cell division as it moves toward the uterus, developing into a multi-celled structure called a blastocyst.

    6. The blastocyst implants into the endometrial lining of the uterus.

  • Developmental Stages of Pregnancy:

    • Implantation: The blastocyst embeds into the thickened endometrium, which provides nourishment and a safe environment for development, initiating pregnancy.

    • Embryonic Stage: The blastocyst develops into an embryo.

    • Foetal Stage: After approximately 8 weeks8\,\text{weeks} of development, all major organs and body systems have formed; from this point onward, the developing organism is called a foetus.

Stages of Labour and Childbirth

Stages of Labour

  • Stage 1 (Latent and Active Phase):

    • The strong muscular walls of the uterus contract rhythmically, pushing the baby downward against the cervix.

    • The force of contractions causes the cervix to efface (thin out) and dilate (open up).

  • Stage 2 (Delivery of the Baby):

    • Once the cervix fully dilates to 10 cm10\,\text{cm} in diameter, the mother actively pushes during contractions.

    • The baby moves through the dilated cervix and vagina (crowning of the head occurs) and is delivered.

  • Stage 3 (Delivery of the Placenta):

    • The placenta is detached from the uterine wall and delivered through the vagina.

    • Placenta Definition: A specialized temporary organ formed between the foetus and the uterus during pregnancy that facilitates the passage of oxygen and essential nutrients from the mother to the foetus, and removes fetal waste products.

    • An umbilical clamp is applied to the umbilical cord post-delivery.

Male Reproductive System Anatomy and Functions

  • Primary System Role: The primary role of the male reproductive system is to produce sperm cells and testosterone, and to deliver sperm into the female reproductive tract so it can reach and fertilise an ova.

  • Anatomical Structures and Functions:

    • Testes (Testis): Dual internal/external organs that produce sperm cells and synthesize the male sex hormone testosterone.

    • Scrotum: An external pouch of skin containing the testes that regulates their temperature to keep sperm viable.

    • Epididymis: A coiled tubular structure situated on top of each testis where sperm cells are stored and mature until ejaculation.

    • Vas Deferens: A muscular transport tube through which mature sperm travel from the epididymis toward the urethra.

    • Seminal Vesicles: Glands that produce and secrete an alkaline fluid that mixes with sperm to form semen.

    • Prostate Gland: A gland that secretes fluid that mixes into semen to nourish and protect sperm; during sexual arousal/ejaculation, it contracts to block the flow of urine from the urinary bladder so sperm can pass through the urethra unobstructed.

    • Urethra: A dual-purpose tube passing through the penis that transports urine from the bladder and semen/sperm from the reproductive ducts out of the body.

    • Penis: The male external copulatory organ through which semen exits the body to reach the female ova during intercourse.

  • Hormonal Regulation and Vocabulary:

    • Testosterone: The primary androgenic hormone responsible for the growth and development of the male reproductive system, as well as the expression of male secondary sexual characteristics during puberty (e.g., development of facial and body hair, increased muscle mass, deepening of the voice).

Pathway of Sperm and Fertilization Sequence

  • Sequential Path of Sperm Cell Development and Delivery:

    1. Testes produce sperm cells under hormonal influence.

    2. Sperm move into and are stored in the epididymis to mature.

    3. During ejaculation, sperm move out of the epididymis along the vas deferens.

    4. Fluids secreted from the seminal vesicles and prostate gland mix with the sperm to create semen.

    5. Sperm moves along the urethra to exit the body through the penis.

    6. Sperm enters the female reproductive tract, travels to the fallopian tube, and fertilises an ova.

  • System Classification Distinctions:

    • Organs belonging strictly to the Male Reproductive System: Testes, Glans Penis, Seminal Vesicles, Prostate Gland, Vas Deferens, Epididymis, Urethra.

    • Organs belonging to the Urinary System (NOT part of the male reproductive system): Urinary Bladder, Ureter.

Checks for Understanding (CFU) & Practice Answers

  • Female System CFU Questions:

    • CFU 1: What is the role of the female reproductive system?

    • Answer: To produce ova (eggs) and support the development of offspring throughout pregnancy.

    • CFU 2: What is menstruation?

    • Answer: Menstruation is the periodic shedding and breakdown of the endometrial lining of the uterus, which leaves the body through the vagina when an egg is not fertilised.

    • CFU 3: What is ovulation?

    • Answer: Ovulation is the release of a mature ova from the ovary into the fallopian tube, occurring around Day 14 of the menstrual cycle in response to oestrogen signals.

    • CFU 4: What happens if the egg is not fertilised?

    • Answer: The endometrial lining breaks down, menstruation occurs, and the 28-day cycle repeats.

  • Male System CFU Questions:

    • CFU 1: What is required for fertilisation to occur?

    • Answer: A sperm cell must successfully meet and merge with a mature ova inside the fallopian tube.

    • CFU 2: What is the role of the male reproductive system?

    • Answer: To produce sperm and testosterone, and to transfer sperm into the female body to fertilise an ova.

    • Anatomy Identification CFU (Part I / Testes):

    • Name: Testes.

    • Function: Produces sperm and the hormone testosterone.

    • Anatomy Identification CFU (Part D / Prostate Gland):

    • Name: Prostate gland.

    • Function: Produces fluid that mixes with sperm to form semen and blocks the flow of urine during ejaculation.

    • Anatomy Identification CFU (Part F / Epididymis):

    • Name: Epididymis.

    • Function: Stores sperm while it matures.