HomeBiologyB3: Reproduction and InheritanceB3.2 Sexual Reproduction in Humans

B3: Reproduction and Inheritance

B3.1 Sexual Reproduction in PlantsB3.2 Sexual Reproduction in HumansB3.3 DNA, Genes, and ChromosomesB3.4 Inheritance and PedigreesB3.5 Cell Division - Mitosis and MeiosisB3.6 Variation and Evolution
B3: Reproduction and Inheritance

Sexual Reproduction in Humans

Reproductive systems, menstrual cycle, and human development

Human reproductive system illustration

Human Life Begins

From gametes to birth

Male Reproductive System
Production and delivery of sperm

The male reproductive system produces and delivers sperm (male gametes) for fertilization.

Testes (Testicles)

Produce sperm and testosterone hormone. Located in scrotum (outside body) for temperature control

Epididymis

Coiled tube where sperm mature and are stored

Sperm Duct (Vas Deferens)

Carries sperm from testes to urethra

Urethra

Tube in penis that carries sperm (and urine) out of body

Prostate & Seminal Vesicles

Glands that add fluid to sperm, forming semen. Fluid provides nutrients and helps sperm swim

Female Reproductive System
Production of eggs and supporting pregnancy

The female reproductive system produces eggs (female gametes) and provides an environment for fertilization and fetal development.

Ovaries

Produce eggs and hormones (estrogen, progesterone). Release one egg per month (ovulation)

Oviduct (Fallopian Tube)

Carries egg from ovary to uterus. Fertilization occurs here. Cilia help move egg along

Uterus (Womb)

Muscular organ where embryo implants and develops. Lining thickens monthly to prepare for pregnancy

Cervix

Ring of muscle at bottom of uterus. Opens during childbirth

Vagina

Muscular tube connecting uterus to outside. Birth canal during delivery

Interactive Menstrual Cycle
28-day cycle controlled by four hormones
Days 1-5
Menstruation

Menstruation

Uterus lining breaks down and is shed. Bleeding occurs.

Hormone Levels:
FSH: Rising
LH: Low
Estrogen: Low
Progesterone: Low
FSH (Follicle Stimulating Hormone)

From pituitary gland. Stimulates follicle and egg development

LH (Luteinizing Hormone)

From pituitary gland. Triggers ovulation on day 14

Estrogen

From ovary. Repairs uterus lining, inhibits FSH, stimulates LH

Progesterone

From corpus luteum. Maintains thick uterus lining for pregnancy

Fertilization and Implantation
The beginning of a new life
1
Sexual Intercourse

Sperm deposited in vagina, swim through cervix and uterus to oviduct

2
Fertilization

One sperm fuses with egg in oviduct. Nuclei combine to form zygote with 46 chromosomes

3
Cell Division

Zygote divides by mitosis as it travels to uterus, forming a ball of cells (embryo)

4
Implantation

Embryo embeds in thickened uterus lining (about 7 days after fertilization)

Pregnancy and Development Timeline
From fertilization to birth (40 weeks / 9 months)
Week 1
Implantation

Fertilized egg (now a ball of cells called blastocyst) implants into thick uterus lining. Placenta begins to form.

Key Terms Flashcards
Card 1 of 15
Term
Gamete
Human Reproduction Quiz
Question 1 of 8 | Score: 0/8

Where does fertilization occur?