BIOL 2252 – The Reproductive System (Chapter 28)

Vocabulary flashcards covering major structures, hormones, processes, and physiological terms from BIOL 2252 Chapter 28 on the reproductive system.

Reproductive System

Body system that produces gametes, enables fertilization, and supports development and birth of offspring.

Gametes

Specialized sex cells—sperm in males and ova (eggs) in females—formed by meiosis.

Gonads

Primary sex organs (testes in males, ovaries in females) that produce gametes and secrete sex hormones.

Puberty

Adolescent period when external sex characteristics appear and gamete production begins, triggered by GnRH release.

HPG Axis

Hypothalamic-pituitary-gonadal hormone cascade regulating gamete production and sex-hormone secretion (GnRH → FSH/LH → gonadal hormones).

Perineum

Diamond-shaped region between thighs; divided into urogenital and anal triangles.

Gametogenesis

Process of forming male and female gametes through meiosis (spermatogenesis/oogenesis).

Meiosis

Special cell division reducing chromosome number by half, producing genetically unique haploid gametes.

Haploid (n)

Single set of 23 chromosomes found in gametes.

Diploid (2n)

Two complete sets (46 chromosomes) present in somatic cells and zygote.

Homologous Chromosomes

Maternal and paternal chromosome pair that carry genes for same traits.

Sister Chromatids

Identical copies of a chromosome joined at a centromere after DNA replication.

Crossing Over

Exchange of DNA between nonsister chromatids of homologous chromosomes during prophase I, increasing genetic diversity.

Reduction Division

Separation of homologous chromosomes in meiosis I, cutting chromosome number from diploid to haploid.

Oogenesis

Formation of female gametes; begins before birth, pauses, and completes upon fertilization.

Folliculogenesis

Sequential maturation of ovarian follicles from primordial stage to corpus luteum.

Primordial Follicle

Most primitive ovarian follicle with a primary oocyte and single flattened cells; arrested in prophase I.

Primary Follicle

Follicle with primary oocyte surrounded by granulosa cells that begin secreting estrogen and form zona pellucida.

Secondary Follicle

Growing follicle with many granulosa layers and thecal cells; secretes androgens → estrogen.

Antral (Vesicular) Follicle

Follicle containing fluid-filled antrum and corona radiata around oocyte.

Mature (Graafian) Follicle

Fully developed follicle that releases a secondary oocyte at ovulation.

Corpus Luteum

Endocrine structure formed from ruptured follicle; secretes progesterone and estrogen.

Corpus Albicans

Scar-like remnant of corpus luteum after degeneration if no pregnancy occurs.

Atresia

Programmed cell death of follicles that are not selected for ovulation.

Ovarian Cycle

Monthly series of follicular phase, ovulation, and luteal phase events in ovaries (~28 days).

Follicular Phase

Days 1–14: growth of antral follicles and rising estrogen levels; ends with ovulation.

Ovulation

Release of secondary oocyte on ~day 14, triggered by LH surge.

Luteal Phase

Days 15–28: corpus luteum activity; progesterone dominates.

Menopause

Cessation of ovarian cycles for 12 months, typically occurring at ages 45–55.

Human Chorionic Gonadotropin (hCG)

Hormone secreted by early embryo; maintains corpus luteum during first trimester.

Uterine Tube (Fallopian Tube)

Duct receiving ovulated oocyte and usual site of fertilization; transports egg to uterus.

Infundibulum

Funnel-shaped distal end of uterine tube bearing fimbriae that capture oocyte.

Ampulla

Middle region of uterine tube where fertilization commonly occurs.

Isthmus (Uterine Tube)

Narrow proximal segment of uterine tube opening into uterus.

Uterus

Hollow muscular organ that receives, retains, and nourishes fertilized ovum.

Endometrium

Mucosal lining of uterus that thickens and sheds during menstrual cycle.

Myometrium

Thick smooth-muscle middle layer of uterus that contracts during childbirth.

Perimetrium

Outer serous (peritoneal) layer of uterine wall.

Cervix

Narrow neck of uterus projecting into vagina; cervical canal connects uterus and vagina.

Vagina

Elastic muscular tube serving as birth canal, menstrual flow passage, and copulatory organ.

Menstrual Cycle

Cyclic endometrial changes consisting of menstrual, proliferative, and secretory phases.

Menstrual Phase

Days 1–5: functional layer of endometrium sheds as menstrual flow.

Proliferative Phase

Days 6–14: estrogen-driven rebuilding of functional endometrium; ends with ovulation.

Secretory Phase

Days 15–28: progesterone-driven preparation of endometrium for implantation.

Estrogen

Primary female sex hormone promoting follicle growth, secondary sex traits, and endometrial proliferation.

Progesterone

Hormone from corpus luteum (and placenta) that stabilizes secretory endometrium and alters cervical mucus.

Mons Pubis

Fatty pad over pubic symphysis forming part of vulva.

Labia Majora

Hair-covered outer skin folds of vulva; homologous to scrotum.

Labia Minora

Inner hairless skin folds flanking vestibule.

Vestibule

Recess between labia minora containing urethral and vaginal openings.

Clitoris

Erectile organ anterior to vestibule; counterpart of penis.

Greater Vestibular Glands

Mucus-secreting glands flanking vaginal orifice; homologous to bulbourethral glands.

Mammary Glands

Modified sweat glands in breasts that produce milk for newborns.

Lactation

Production and ejection of milk from mammary glands after childbirth.

Prolactin

Anterior pituitary hormone stimulating milk production in alveoli.

Oxytocin

Posterior pituitary hormone triggering milk ejection and uterine contractions.

Spermatogenesis

Process in seminiferous tubules that forms sperm from spermatogonia.

Spermiogenesis

Final maturation step where spermatids transform into motile spermatozoa.

Seminiferous Tubules

Highly coiled ducts within testes where spermatogenesis occurs.

Sustentacular (Sertoli) Cells

Support cells of seminiferous tubules that nourish sperm and form blood-testis barrier.

Leydig (Interstitial) Cells

Cells between seminiferous tubules that produce testosterone in response to LH.

Blood-Testis Barrier

Tight junctions between sustentocytes protecting developing sperm from immune attack.

Androgen-Binding Protein (ABP)

Protein from Sertoli cells that concentrates testosterone around spermatogenic cells.

Inhibin

Hormone from Sertoli cells that inhibits FSH secretion to regulate spermatogenesis.

Testosterone

Primary male androgen stimulating spermatogenesis, secondary sex traits, and libido.

Scrotum

Skin and superficial fascia sac housing testes at temperature ~3 °C below body core.

Cremaster Muscle

Skeletal muscle that elevates testes to regulate temperature.

Dartos Muscle

Smooth muscle in scrotal wall that wrinkles skin to conserve heat.

Spermatic Cord

Bundle of nerves, blood vessels, lymphatics, and ductus deferens running through inguinal canal.

Epididymis

Coiled duct on testis posterior that stores and matures sperm.

Ductus (Vas) Deferens

Muscular tube transporting sperm from epididymis to ejaculatory duct.

Ejaculatory Duct

Short duct formed by ductus deferens and seminal vesicle; empties into prostatic urethra.

Urethra (Male)

Shared urinary-reproductive canal with prostatic, membranous, and spongy regions.

Seminal Vesicles

Paired glands producing alkaline, fructose-rich fluid comprising ~70 % of semen.

Prostate Gland

Single gland encircling urethra; secretes milky fluid with PSA that activates sperm.

Bulbourethral (Cowper’s) Glands

Pea-sized glands secreting clear mucus to lubricate urethra and neutralize acids.

Semen

Mixture of sperm and accessory gland secretions; 2–5 mL containing up to 150 million sperm per mL.

Corpora Cavernosa

Paired dorsal erectile bodies of penis that fill with blood during erection.

Corpus Spongiosum

Ventral erectile tissue surrounding urethra; forms glans and bulb of penis.

Erection

Parasympathetic reflex causing erectile tissues to engorge with blood, producing penile rigidity.

Emission

Sympathetic movement of semen into urethra preceding ejaculation.

Ejaculation

Forceful expulsion of semen from urethra, accompanied by orgasm.

Refractory Period (Male)

Post-ejaculatory time during which a male cannot achieve another orgasm.