Reproductive System

Reproductive System

After studying this chapter, the reader should be able to

1. Describe the components of the male reproductive system.

2. Specify the normal composition of semen.

3. Explain the hormonal mechanisms that regulate male reproductive functions.

4. Outline the process of spermatogenesis.

5. Describe the structure of the penis.

6. Describe the components of the female reproductive system.

7. Identify the phases and events of the female reproductive cycle.

8. Identify and describe the ligaments that support the uterus and hold it in place.

9. Describe the structure of a mammary gland.

10. List the general symptoms of sexually transmitted infections.

Overview

The reproductive system is the only body system that is not essential to the survival of an individual but is needed to ensure the continued existence of the human species. The reproductive systems of both males and females contain organs and glands that create sex cells and transport them to areas where fertilization can occur. The male and female repro-ductive systems are functionally very different, but the primary sex organs of both are called gonads. The gonads of the male are the testes and of the female, the ovaries. The reproductive systems of both genders become functionally active at puberty.

Sex cells, regardless of gender, are called gametes­. Male sex cells are called sperm and female sex cells are called oocytes or eggs. Sex cells carry genetic instructions via 23 chromosomes. Other types of cells in the body carry 46 chromosomes. When sex cells from a male and female unite during fertilization, the 23 chromosomes from each ­partner unite to form 46 chromosomes. Certain reproductive organs secrete sex hormones, which are actually­ steroid hormones needed for development­ and maintenance of ­secondary sex characteristics and for reproduction. In males, sex hormones are called androgens, and in females, they are estrogens and progesterone­.

The accessory reproductive organs include various ducts, glands, and the external genitalia. When sexual intercourse results in fertilization, a sperm and an egg unite to form a fertilized egg, which is called a zygote. This is the original cell of a new human being and all other cells form from it. After fertilization, the female uterus protects the embryo as it develops.