What Even Is A Breast?

Breasts are more than just supple hunks of flesh that dangle off of a person's body and get shoved into bras. They're also functional glands that produce milk, fun erogenous zones to stimulate, and body parts that can sometimes develop cancer — but that's probably about where your knowledge of breasts stops. Even if you are acquainted with your own pair, have you ever wondered what, exactly, they are?

Breasts are made up of three types of tissue: glandular tissue, which produces milk; fatty tissue that gives breasts their shape; and connective tissue that ties everything together, explains Deborah Lindner, MD, FACOG, a gynecologist and chief medical officer at Bright Pink, a breast cancer organization that focuses on education and prevention. The female breast is mostly made up of fatty tissue that extends from a person's collarbone to the armpit, and across the ribcage, according to the National Breast Cancer Foundation. On the outside of the breast, most people have a raised nipple, with dark-colored skin surrounding it, called the areola. And that's a breast!

Although many people get wrapped up in how breasts look, they're also glands with an important job to make milk, says Neal Reisman, MD, clinical professor of plastic surgery, specializing in breast surgery, at Baylor College of Medicine. Fun fact: everyone with breasts has the parts involved in making breastmilk, Lauren Levine, MD, assistant professor of pediatrics at Columbia University Medical Center told Refinery29 in January. They just aren't "activated" until you actually give birth and have the hormonal releases responsible for milk production.

And the substance of your breasts is just as important as what they can do.

Everyone's breasts are slightly different in shape and size, depending on hereditary factors and the amount of fatty tissue they contain, Dr. Reisman says. You might have heard the phrase "dense breasts" before, and that really refers to the amount of connective tissue a person has compared to fat. "Fat is a very low-density material; connective tissue and duct material is higher density," Dr. Lindner explains. On a mammogram, dense breasts show up solid white, which makes it harder for doctors to see a tumor or cancer, she says. According to the Mayo Clinic, about half of women have dense breasts, but it's unclear why this occurs.

And that brings us to breast cancer, which, like any cancer, is "cell division gone bad," Dr. Lindner says. When a person gets breast cancer, cells in the breast start to divide, multiply, and grow out of control, according to the American Cancer Society. Many breast cancers start in the ducts that carry milk to the nipple, but they can also start in the glands or tissues of the breast. It's important to know your breast cancer risk (if you don't, you can take a quick quiz on Bright Pink's website), so you can take the appropriate actions to reduce it.

Ultimately, part of knowing your breast cancer risk includes knowing what your breasts are like on a daily basis, and what it is you're dealing with. If you have questions or something seems off, always ask your primary care doctor or Ob/Gyn. There are plenty of bodily things that you're just "supposed" to know about, but many of us don't — and what's really up with breasts can certainly fall in that category.