bio unit 1 topic 5-8

Testes

The two male gonads that produce sperm and testosterone.

Gonads

Organs that produce reproductive cells and hormones (testes in males, ovaries in females).

Scrotum

Pouch of skin that contains the testes and regulates their temperature (~35°C).

Seminiferous Tubules

Coiled tubes inside the testes where sperm are produced.

Interstitial Cells

Cells between seminiferous tubules that produce testosterone.

Epididymis

Duct on top of the testes where sperm mature and are stored.

Vas (Ductus) Deferens

Tube that carries mature sperm from the epididymis to the urethra.

Penis

Organ used for sexual intercourse and to transfer sperm into the female reproductive system.

Seminal Vesicle

Gland that produces fluid rich in sugar to nourish sperm.

Prostate Gland

Produces alkaline fluid that protects sperm from acidic environments.

Cowper’s (Bulbourethral) Gland

Produces mucus-like fluid that lubricates and neutralizes urine acidity.

Urethra

Tube through which semen and urine leave the male body.

Semen

Mixture of sperm and glandular fluids released during ejaculation.

Ovaries

Female gonads that produce eggs and female hormones (estrogen, progesterone).

Follicle

Structure in the ovary where an egg matures.

Ovulation

Release of a mature egg from a follicle in the ovary.

Fimbriae

Finger-like projections that sweep the egg into the fallopian tube.

Oviduct (Fallopian Tube)

Tube connecting the ovary to the uterus; site of fertilization.

Uterus

Muscular organ where a fertilized egg implants and develops.

Endometrium

Lining of the uterus that thickens to support pregnancy.

Cervix

Muscular opening from uterus to vagina.

Vagina

Muscular canal leading from cervix to outside; receives sperm and serves as birth canal.

Abstinence

Choosing not to engage in sexual activity.

Condoms

Protective barriers that reduce risk of STI transmission.

(MALE) GnRH (Gonadotropin Releasing Hormone)

From hypothalamus; triggers pituitary to release FSH and LH.

(MALE) FSH (Follicle Stimulating Hormone)

From pituitary; stimulates sperm production.

(MALE) LH (Luteinizing Hormone)

From pituitary; stimulates testosterone production.

Testosterone

Male sex hormone; develops secondary sex traits and supports sperm production.

Inhibin

From testes; inhibits FSH to regulate sperm production.

Negative Feedback Loop

Process where increased hormone levels inhibit further hormone release.

(FEMALE) GnRH

From hypothalamus; stimulates FSH and LH release.

(FEMALE) FSH

From pituitary; stimulates follicle maturation and estrogen production.

(FEMALE) LH

From pituitary; triggers ovulation and corpus luteum formation.

Estrogen

From ovaries; thickens endometrium and develops female traits.

Progesterone

From corpus luteum; maintains uterine lining.

Ovarian Cycle

Cycle of follicle development and ovulation.

Uterine Cycle

Cycle of endometrium thickening and shedding (menstruation).

Follicular Stage

First phase of ovarian cycle; follicle matures, estrogen rises.

Luteal Stage

After ovulation; corpus luteum secretes progesterone.

Corpus Luteum

Structure formed from follicle after ovulation; secretes progesterone.

Fertilization

Fusion of sperm and egg to form a zygote

Zygote

First cell formed after fertilization.

Cleavage

Rapid mitotic cell divisions without growth.

Morula

Solid ball of ~16 cells.

Blastocyst

Hollow ball of cells that implants in the uterus.

Trophoblast

Outer layer of blastocyst; becomes the chorion and placenta.

Inner Cell Mass (Embryoblast)

Inner group of cells that becomes the embryo.

Implantation

Embedding of blastocyst into the endometrium.

hCG (Human Chorionic Gonadotropin)

Hormone secreted after implantation; maintains corpus luteum.

Gastrulation

Formation of three germ layers (ectoderm, mesoderm, endoderm).

Ectoderm

Outer layer; forms skin and nervous system.

Mesoderm

Middle layer; forms muscles, bones, and blood vessels.

Endoderm

Inner layer; forms digestive and respiratory tracts.

Neurulation

Formation of neural tube (brain and spinal cord).

Morphogenesis

Formation of body shape and organs.

Chorion

Forms the placenta.

Amnion

Fluid-filled sac protecting the embryo.

Yolk Sac

Site of early blood cell formation.

Allantois

Forms part of the umbilical cord.

First Trimester (Weeks 1–12)

Organ systems form; external organs develop.

Second Trimester (Weeks 13–24)

Bones form, heartbeat audible, movement begins.

Third Trimester (Weeks 25–38)

Rapid brain growth; fetus gains weight.

Parturition

Process of giving birth.

Dilation Stage

Cervix opens; amniotic sac breaks.

Expulsion Stage

Baby is delivered.

Placental Stage

Placenta and umbilical cord are expelled (afterbirth).

Oxytocin

Hormone that causes uterine contractions and milk letdown.

Prostaglandins

Chemicals that enhance uterine contractions.

Prolactin

Hormone that stimulates milk production.

Positive Feedback Loop

Process that enhances or reinforces a change (e.g., childbirth or milk ejection).

Teratogen

Any agent causing birth defects during pregnancy.
Examples: Alcohol, drugs, smoking, infections, radiation, pollutants.

Thalidomide

Drug that caused limb deformities when taken during pregnancy.

Placenta

Organ that connects fetus to mother for nutrient and waste exchange

Umbilical Cord

Connects fetus to placenta; carries oxygen and nutrients

Home Pregnancy Test

Detects hCG in urine; confirms pregnancy.

Maternal Blood Test

Measures hCG or screens for genetic conditions.

Ultrasound

Uses sound waves to visualize fetus; non-invasive.

Amniocentesis

Samples amniotic fluid for genetic testing; invasive.

Chorionic Villus Sampling (CVS)

Samples chorion cells; creates karyotype; invasive.

Cell-free DNA Screening

Analyzes placental DNA fragments; non-invasive.

Fetoscopy

Direct visual observation of fetus with endoscope; invasive.

Sterile

Unable to produce offspring.

Infertile

Difficulty conceiving after one year of unprotected intercourse.

Artificial Insemination (AI)

Sperm are placed directly into the vagina or uterus.

In Vitro Fertilization (IVF)

Egg and sperm fertilized outside the body; embryo implanted in uterus

Surrogacy

Another woman carries and gives birth to a baby for the parents.

Superovulation

Hormone treatment to stimulate multiple egg release.

Cryopreservation

Freezing of gametes or embryos for later use.