Unit 15. Reproduction in Humans (1)

Reproduction in Humans

Chapter Overview

• Structure and function of male and female reproductive systems.

• Fertilization and development of the embryo.

• Roles of the placenta.

• Antenatal care and birth.

• The menstrual cycle.

• Hormones: estrogen, progesterone, and testosterone.

• Methods of birth control.

• Sexually transmitted infections (STIs).

Human Reproductive Organs

• Male Reproductive System:

  • Prostate gland: Produces seminal fluid.

  • Seminal vesicle: Contributes fluid to semen.

  • Vas deferens: Transports sperm from the testis.

  • Testis: Produces sperm and testosterone.

  • Scrotum: Holds testis outside the body for temperature regulation.

  • Penis: Delivers sperm to the female reproductive system.

• Female Reproductive System:

  • Ovary: Produces eggs (ova) and hormones.

  • Fallopian tube: Site of fertilization and connects ovary to uterus.

  • Uterus: Houses the developing fetus.

  • Cervix: Opening to the uterus, protecting against infection.

  • Vagina: Muscular canal facilitating entry of sperm.

Female Reproductive Organs: Structure and Function

• Oviduct (Fallopian tube): Ciliated cells push the ovum towards the uterus; fertilization occurs here.

• Ovary: Contains immature ova; hormones drive maturation.

• Uterus: Thick, muscular wall where the zygote implants to develop.

• Cervix: Keeps the fetus in place during pregnancy.

• Vagina: Receives sperm during intercourse; passage for childbirth.

Male Reproductive Organs: Structure and Function

• Prostate gland: Produces semen providing nutrients for sperm.

• Vas deferens: Sperm pass through and mix with fluids before reaching urethra.

• Urethra: Carries sperm or urine, preventing mixing by muscle action.

• Testis: Produces sperm and testosterone, located in scrotum for optimal temperature control.

• Penis: Facilitates sexual intercourse and urine expulsion.

Gamete Anatomy

• Sperm (Spermatozoa): Includes a tail (flagellum) for motility and enzymes in the acrosome for penetrating the egg.

• Ovum (Human Egg): Contains cytoplasm for energy, and a jelly coating that becomes impenetrable after fertilization.

Fertilization and Development

• Fertilization: Fusion of male and female gametes.

• Ejaculation: Release of sperm into the vagina; driven by muscular contractions.

• Ovulation: Egg moves into the oviduct aided by cilia.

• Implantation: Zygote develops into an embryo while traveling down the oviduct.

Placenta and Gestation

• The placenta facilitates nutrient and waste exchange, preventing harmful substances from affecting the fetus.

• Major organ development occurs in the first 12 weeks of pregnancy when nutrients are diffused through the uterine lining.

Birth Stages

• Amniotic sac breaks.

• Uterine contractions begin.

• Cervix dilates.

• Baby is delivered through the vagina.

• Umbilical cord is tied and cut.

• Afterbirth is expelled.

Antenatal Care

• Importance of a balanced diet and exercise for the mother.

• Folic acid intake to prevent fetal developmental issues.

• Health precautions: avoiding infections and harmful substances (tobacco, alcohol).

Breastfeeding vs. Bottle Feeding

• Breastfeeding: All necessary nutrients provided, antibodies help prevent infections, promotes bonding.

• Bottle Feeding: Allows shared responsibility, greater freedom for mothers, but can increase infection risks and costs.

Birth Control Methods

• Natural Methods: Abstinence, rhythm method.

• Barrier Methods: Condoms, Femidom, diaphragm.

• Chemical Methods: Pills, injections, IUD/IUS.

• Surgical Methods: Female sterilization, vasectomy.

Fertility Treatments

• Artificial insemination (AI) and IVF:

  • AI: Sperm collection, processing, and insertion.

  • IVF: Ovarian stimulation, egg collection, fertilization, and embryo transfer.

Sexually Transmitted Infections (STIs)

• Transmitted via body fluids during sexual contact.

• Prevention: Abstinence, fewer partners, communication, condom use, vaccination, regular testing.