Human Reproduction Mr Ramos Introduction to Human Reproduction

Human Reproduction Mr. Ramos

Introduction to Human Reproduction �Reproduction is a process by which organisms make more organisms. �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 make sperm, or male sex cells (gametes)

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 epididymis. �The testes (or testicles) hang in a baglike structure called the scrotum. �Having the testes outside the pelvis keeps them at a lower temperature. The testes also produce the hormone testosterone

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 trimesters. � 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. • • • 5. 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 7 th month, though the lungs are still developing.