Human Reproduction

Human Reproduction
Mr. Ramos
Introduction to Human Reproduction
 Reproduction is a process by which organisms make more
 Reproduction leads to population growth.
 Reproduction in humans is called sexual reproduction.
 Sexual reproduction results in genetic diversity.
The Male Reproductive System
 Main
function is to
sperm, or
male sex
The Male Reproductive System
 The second most important function is to deliver the sperm
into the female. The penis delivers the sperm.
 Sperm is made in the testes after puberty and matures in the
 The testes (or testicles) hang in a baglike structure called the
 Having the testes outside the pelvis keeps them at a lower
The testes also
produce the
The Male Reproductive System
 The urethra is a tube where urine and sperm leave the penis
in males.
 Men and women have a urethra.
 The seminal vesicles, prostate gland, and bulbourethral
glands produce the liquid called semen.
The Female Reproductive System
 The main function of the female reproductive system is to
make egg cells (ovum) and to carry the developing offspring.
The Female Reproductive System
 The vagina is the birth canal. It is a tube that leads from an
opening outside of the body to the uterus.
 The uterus, or womb, is a thick muscular organ that hold and
nourishes the developing offspring.
 The end of the vagina and beginning of the uterus is called
the cervix.
The Female Reproductive System
 The female sex cells (egg cells) are produced in the ovaries.
 The egg is released in a process called ovulation and moves
towards the fallopian tube, waiting to meet the sperm.
 Fertilization is when an egg cell and a sperm cell unite.
Fertilization occurs in the fallopian tubes.
 A zygote is a combination of a sperm and egg cell.
Embryonic and Fetal Development
 It all begins when a male ejaculates inside a female.
 The sperm and egg unite to form a zygote, and the zygote
eventually becomes a baby.
 The zygote goes through a series of cell divisions called
cleavage: 2, 4, 8, morula, blastula, gastrula, embryo.
 The period from fertilization to birth is called pregnancy or
the gestation period.
First Trimester
 Pregnancy in humans is discussed in three-month periods called
 During the first trimester (first three months)
1. The zygote divides several times to form a blastula.
2. Human embryo implants itself on the uterus about 8 to 9 days
after fertilization.
3. After implantation, cells continue to divide to form a gastrula.
The gastrula is composed of 3 germ layers: ectoderm,
mesoderm, endoderm.
4. Cell differentiation begins.
Ectoderm forms into skin, nerves, and sense organs.
Mesoderm forms into bones, muscles, and connective tissue.
Endoderm forms the digestive system and lungs.
The embryo is now called a fetus.
Second Trimester
 The second trimester are months 4, 5, and 6.
 The mother starts to feel the fetus moving.
 By the end of the second trimester, the fetus has fully
developed eyes, and the lungs are starting to develop.
Third Trimester
 The fetus continues to grow.
 The brain develops and the fetus has regular breathing
motions by the 7th month, though the lungs are still