Biology 30 - Unit B: Reproduction and Development

These flashcards cover key concepts in reproduction and development in humans, focusing on terms related to the reproductive systems, processes of fertilization, embryonic and fetal development, and hormonal control.

Fertilization

The fusing of a sperm nucleus with an egg nucleus to form a zygote; occurs in the oviduct.

Gamete

A haploid cell made during meiosis that participates in fertilization to make a zygote.

Embryo

The offspring in the period of development from the cleavage of the zygote to the ninth week, when the embryo becomes a fetus.

Fetus

The organism in the stages of development from nine weeks until birth.

Placenta

Embedded in the endometrium; provides a location where nutrients, gases, and wastes can be exchanged between fetal and maternal blood.

Uterus

The reproductive organ in which embryonic and fetal development occurs.

Menstrual Cycle

The female reproductive cycle of producing an egg and developing then shedding the endometrium every 28 days, on average.

Ovulation

The release of the mature ovum from the follicle of the ovary into the oviduct.

Androgens

Male group of steroid hormones; includes testosterone.

Estrogen

A female steroid sex hormone secreted by the developing follicle prior to ovulation and the corpus luteum after ovulation.

Inhibin

A hormone produced by Sertoli cells during spermatogenesis that inhibits GnRH, preventing excessive sperm production.

Sertoli Cells

‘Nurse’ cells in the seminiferous tubules that assist in spermatogenesis and produce the hormone inhibin.

Secondary Sex Characteristics

Characteristics that distinguish male from female but are not required for reproduction.

Sexual Reproduction

Creation of offspring through input of genetic material from two different organisms of opposite sexes (sperm from male and egg from female); increases variation.

Testosterone

Male sex hormone secreted by interstitial cells of the testes; results in male primary and secondary sex characteristics.

Negative Feedback

A mechanism where deviation from the optimum state causes a return to the optimum state; acts to eliminate any deviation from optimal conditions.

Primary Oocytes

The two cells produced prenatally by the mitotic division of the diploid oogonium.

Gonadotropin-Releasing Hormone (GnRH)

A hormone produced by the hypothalamus; stimulates the anterior pituitary to produce FSH and LH.

Ectoderm

Germ layer that forms hair, nervous system, and skin.

Endoderm

Germ layer that forms gut lining, pancreas, and liver.

Mesoderm

Germ layer that forms muscle, bone, and muscular organs.

Oogenesis

The process of egg production in females.

Cervix

The tightly constricted opening from the vagina into the uterus.

Vas Deferens

A smooth muscle tube that carries the semen from the epididymis to the penis.

Chlamydia

A sexually transmitted infection caused by Chlamydia trachomatis; often asymptomatic.

Gonorrhea

A sexually transmitted infection caused by Neisseria gonorrhoeae; can lead to serious reproductive problems if untreated.

Human Chorionic Gonadotropin (hCG)

Hormone released from the chorion after implantation; directs corpus luteum to continue making estrogen and progesterone.

Neurulation

The process of forming the embryo’s neural tube, which will develop into the brain and spinal cord.

Breastfeeding (Lactation)

The process of producing and secreting milk from the breast.

Menopause

The time in a woman’s life, at approximately age 50, when the production of estrogen and progesterone decreases, resulting in the cessation of menstrual cycles.