ESO 3 B & G 4

Reproduction in Humans

What to Learn

  • Overall view of the process of reproduction in humans. Key concepts: gonads, gametes, fertilisation, zygote, embryo, fetus, pregnancy, childbirth.
  • Sexual characteristics: primary and secondary. Puberty.
  • Structure of the male and female reproductive systems.
  • Features of the male and female gametes.
  • The menstrual cycle.
  • The reproductive process: fertilisation, implantation, fetal development and childbirth.
  • Hormonal control of the reproduction related activity (gametogenesis, menstrual cycle and nursing).
  • Contraception.
  • Assisted reproduction.

Key Information

Vocabulary: Male Reproductive System
[Adapted from Faqs.org]
ScrotumExternal sac enclosing the testes.
TestesMale gonads that produce sperm cells, a 2-5% of the seminal fluid, and secrete testosterone.
Seminiferous tubulesTightly coiled tubes within the testes that produce sperm.
EpididymisPortion of the testes in which sperm mature or fully develop.
Vas deferensAlso ductus deferens. Passageway that carries sperm from the epididymis to the ejaculatory duct.
Seminal vesiclesGlands located at the base of the bladder that produce around a 70% of the seminal fluid.
Ejaculatory ductDuct formed by the union of the ductus deferens and the duct of the seminal vesicle, that carries the semen up to the urethra.
ProstateMuscular gland in males that surrounds the first inch of the urethra. It produces almost a 30% of the seminal fluid.
Bulbourethral glandsAlso Cowper's glands. Glands located at the base of the penis, that at the beginning of sexual arousal secrete a fluid which helps to lubricate the urethra for spermatozoa to pass through, and to help flush out any residual urine. This fluid can carry sperms from previous ejaculations.
PenisMale organ of reproduction and urination.
PrepuceAlso foreskin. The fold of skin over the glans or tip of the penis.
CircumcisionSurgical removal of the prepuce of the penis.
ErectionStiffening, lengthening and rising of the penis, which occurs during sexual arousal, though it can also happen in non-sexual situations. It is primarily due to the dilation of the arteries that supply blood to the penis (which allows more blood to fill the three spongy chambers in the penis) and the constriction of the veins that carry blood away from the penis. This way, more blood enters than leaves the penis until an equilibrium is reached and a constant size is achieved.
EjaculationSudden ejection of semen from the penis.
SemenThick, whitish, somewhat sticky fluid composed of sperms and seminal fluid that is propelled out of a male's reproductive tract during ejaculation. Normal human ejaculated semen, as defined by the WHO, has a volume of 2 ml or greater, pH of 7.2 to 8.0 (slightly alkaline), sperm concentration of 20 million spermatozoa per ml or more, and a motility of 50% of the spermatozoa, with at least a 25% being able to move forward.
Vocabulary: Female Reproductive System
[Adapted from Faqs.org]
OvariesFemale gonads in which ova are produced and that secrete estrogens and progesterone.
Ovarian folliclesStructures within an ovary consisting of a developing egg surrounded by follicle cells.
Corpus luteumYellowish remains of a burst ovarian follicle that secretes progesterone.
OvulationRelease of a mature ovum from an ovary.
FimbriaeFingerlike projections at the end of a fallopian tube that partially surround an ovary.
Fallopian tubesAlso ovarian tubes. Tubes connecting an ovary to the uterus and through which an ovum is transported. They are the place of fertilization.
UterusAlso womb. The hollow organ in females that receives, retains, and nourishes a fertilized ovum or egg.
MyometriumMiddle layer of the uterus composed of interwoven muscle cells.
EndometriumInner layer of the uterus that provides nourishment for a developing embryo and fetus and that sloughs off during the regular menstrual cycle.
CervixLower necklike portion of the uterus leading into the vagina.
VaginaMuscular tube in women that extends from the cervix of the uterus to the vaginal opening.
VulvaFemale external genital organs, composed of the mons pubis, the labia majora, the labia minora, the clitoris, the urethral opening, the vaginal opening and the greater vestibular glands.
Mons pubisFatty, rounded, hairy area at the top of the vulva.
Labia majoraOuter, hairy skin folds of the vagina.
Labia minoraInner skin folds of the vagina.
ClitorisSmall protruding mass of erectile tissue at the top of the labia minora.
Greater vestibular glandsPair of mucus-secreting glands that lubricate the lower portion of the vagina.
HymenThin membrane partially covering the external opening of the vagina.
Vocabulary: Menstrual Cycle
[Adapted from Faqs.org]
MenarcheBeginning of menstruation or the first menstrual period.
MenopausePeriod in a woman's life when menstrual activity ceases.
MenstruationAlso menses. Periodic (monthly) discharge of blood, secretions, tissue, and mucus from the endometrium in the absence of pregnancy.
Vocabulary: Gametes
[Adapted from Faqs.org]
GonadsSex organs in which reproductive cells develop.
GametesReproductive or sex cells. They are different to any other cell in the body in which they only have half of the chromosomes than a normal somatic cell.
OvaFemale gametes or eggs (singular: ovum).
ZygoteFertilized ovum. By successive mitosis, it will convert into an embryo, then a fetus, and finally a newborn.
SpermAlso spermatozoon. Mature male sex or reproductive cell. They need to be produced at a slightly lower temperature than the usual in the inside of the human body.
AcrosomeTip of the head of a sperm cell that contains enzymes to digest the membrane of an ovum.
Vocabulary: Pregnancy, Childbird and Nursing
[Adapted from Faqs.org]
ChorionThe outermost membrane that surrounds the embryo/fetus during pregnancy. It is in contact with the amnion and generates the placenta.
AmnionFluid-filled sac that surrounds a developing embryo/fetus. It provides room and cushioning to the embryo/fetus.
PlacentaTemporary organ developed after the implantation of an embryo, when the chorionic villi invade the endometrium. It provides nutrients to a developing fetus, carries away wastes, and produces hormones such as estrogens and progesterone.
Umbilical cordStructure that connects the embryo/fetus to the placenta.
Alveolar glandsGlands within the mammary glands that produce milk.
Lactiferous ductsDucts that carry milk from the alveolar glands to the surface of the nipple of a breast.
AreolaCircular, darkened area surrounding the nipple of each breast.
Vocabulary: Hormonal Control of the Reproduction
[Adapted from Faqs.org]
Luteinizing hormoneHormone secreted by the anterior pituitary that stimulates, in women, ovulation and the release of estrogens and progesterone by the ovaries and, in men, the secretion of testosterone by the testes.
Follicle-stimulating hormoneHormone produced by the anterior pituitary gland that stimulates the development of follicles in the ovaries of females and sperm in the testes of males.
TestosteroneMale hormone secreted by the testes that stimulates the growth of the male reproductive organs and brings about the secondary sex characteristics.
EstrogensFemale hormones secreted by the ovaries that bring about the secondary sex characteristics and regulate the female reproductive cycle.
ProgesteroneFemale hormone secreted by the ovaries that makes the uterus more ready to receive a fertilized ovum and regulate the female reproductive cycle.
ProlactinHormone secreted by the anterior pituitary that stimulates the mammary glands to produce milk during nursing.
OxytocinHormone produced by the hypothalamus and stored in the posterior pituitary that stimulates contraction of the uterus during childbirth and secretion of milk during nursing.

Movies, Animations and Audios

Reproductive System
Female reproductive system

Female reproductive system

The female reproductive system with some detail.

Human ovulation

Human ovulation

Human ovulation captured on film for the first time.

The Menstrual cycle

The Menstrual cycle

Learn how hormones control the menstrual cycle.

Produced by How the Body Works

From Conception to Birth
Reproduction

Reproduction

Short introductory video to the reproductive process in humans.

Conception

Conception

See how conception takes place.

Cell to embryo

Cell to embryo

Watch the amazing transformation of a fertilized egg into an 8-week embryo in this video made from magnetic resonance images.

University of Michigan

From conception to the fifth month

From conception to the fifth month

Detailed video on the events of the first months of fetal development.

From weeks 6 to 12

From weeks 6 to 12

Animation showing the changes between the sixth and the twelfth week of gestation.

Development of the fetus (I)

Development of the fetus (I)

Stage by stage description of the changes during human fetal development.

Development of the fetus (II)

Development of the fetus (II)

Stage by stage depiction of the human fetal development.

Childbirth (I)

Childbirth (I)

Animation of a normal vaginal birth.

Childbirth (II)

Childbirth (II)

Detailed explanation on how a typical childbirth takes place.

Sexuality
Pill may change attraction

Pill may change attraction

In a recent study researchers note that the birth control pill may change a woman's choice in whom she finds attractive.

Streamed from Scientific American

Some Fun
Childbirth the Monty Python's way

Childbirth the Monty Python's way

Fragment from the Monty Python's film "The meaning of Life"… with the very expensive machine that goes "ping".

Transcript

Images