Lecture Notes

Males and females have some of the same sexual anatomy. Most of these structures do not serve a reproductive function but are often involved in or affected by sexual activities. These structures include the breasts, rectum, and anus. The reproductive function of the female breasts is to nourish offspring through lactation, or milk production. A mature female breast, also known as a mammary gland, is composed of fatty tissue and 15 to 25 lobes that radiate around a central protruding nipple. Around the nipple is a ring of darkened skin called the areola. In response to hormonal signals directly following childbirth, small glands within the lobes called alveoli begin producing milk. The milk passes into the ducts, which open to the outside at the nipple. The amount of milk produced does not vary with breast size because there's very little variation in the amount of glandular tissue among women. In women who are not lactating, breast size depends mainly on fat content, which is determined by heredity.