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Breast Anatomy

Learn the basic anatomy of the breast and how it's designed to nourish a baby with milk. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Stanford School of Medicine.

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  • purple pi purple style avatar for user Jonathan Williams
    Would the areola of an albino human darken with pregnancy? If it doesn't, does the baby have a lot of trouble finding the nipple to feed?
    (27 votes)
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  • ohnoes default style avatar for user leotrikim
    Can a mother still breastfeed after getting breast implants?
    (11 votes)
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  • blobby green style avatar for user Payal Maharaj Nandini
    Which part of the breast is most affected during breast cancer?
    (10 votes)
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  • leafers ultimate style avatar for user eightsquare
    If milk can come out one way can't other things like water go in? Or do the holes only open when milk comes out?
    (8 votes)
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  • male robot hal style avatar for user Penny
    What is an areola?
    (3 votes)
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  • leaf blue style avatar for user Serena Simmons
    At , You say that baby's vision isn't that great, So in the womb do they have their eyes closed and just have to get use to seeing when they are born or are their eyes still developing and they can't see properly?
    (4 votes)
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    • winston default style avatar for user Gavin A
      The baby's eyes are still developing in the womb.

      • The baby’s eyeball develops by 9 to 12 weeks when all the baby’s organs are formed but they continue to grow.
      • The baby’s eyelids open between 26 to 29 weeks.
      • The baby can start blinking the eyes at 30 to 33 weeks in reaction to light outside the womb.
      • When the baby is born they can only see 18 inches in front of their face.

      Here is a quote from Wikipedia:
      "Newborn infants have unremarkable vision, being able to focus on objects only about 18 inches (45 cm) directly in front of their face. While this may not be much, it is all that is needed for the infant to look at the mother’s eyes or areola when breastfeeding. Depth perception does not develop until the infant is mobile. Generally, a newborn cries when wanting to feed. When a newborn is not sleeping, or feeding, or crying, he or she may spend a lot of time staring at various objects. Usually anything that is shiny, has sharp contrasting colors, or has complex patterns will catch an infant's eye. However, the newborn has a preference for looking at other human faces above all else."

      Here is the full article: http://en.wikipedia.org/wiki/Infant

      Hope you found this helpful! :-D
      (8 votes)
  • blobby green style avatar for user Aileen Xu
    I have heard that most part of the breasts are made of fat. Is it just a rumor? I could not tell which part is the fat part from the anatomy diagram. In the video says when girls hit puberty, the mammary glands grow. So are they made up of mostly fat?
    (4 votes)
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    • leaf red style avatar for user Damián
      A large part of mammary tissue can be described as being adipose (fat tissue), however, fibrous tissue (connective tissue) and lactation ducts also make-up a significant portion of a breast as a whole. The amount of fat a woman has in her breasts depends on numerous factors (i.e. mammary size dictated by genetics, body fat percentage, age, hormone levels). For example, it's obvious that an obese, post-menopausal woman with large breasts has more adipose mammary tissue than a young, thin girl with small breasts. During puberty, hormonal signals stimulate mammarian growth by increasing the size of the breasts' lactation ducts, connective tissue and adipose tissue. This prepares them for future lactation. Put simply, the amount of adipose tissue in a woman's breasts is highly variable. However, regularly, as a woman ages she develops more adipose tissue as it begins replacing its, increasingly obsolete, connective counterpart and lactation ducts. A woman's breast contains around 50% fat tissue. As she ages, this percentage increases gradually until the majority of her breasts are composed of fat. Hope I helped. Cheers.
      (7 votes)
  • piceratops seedling style avatar for user BeatrizAyaSato
    In , she says that both males and females have mammary glands. She also says how most of the time, male mammary glads do nothings when they hit puberty. What would happen if they do something? Is this a disorder or disease?
    (4 votes)
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  • piceratops seedling style avatar for user BeatrizAyaSato
    Does breast cancer occur in the mammary glands? If a woman has breast cancer, but has a baby, will she be unable to breastfeed her baby?
    (2 votes)
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    • female robot grace style avatar for user 00015651
      Yes ,breast cancer does occur in the mammary glands. Yes, if a woman has double mastectomy, she cannot breast-feed. If a woman is still suffering from radiation side-effects cannot breast-feed. But some survivors of breast cancer can breast-feed
      (4 votes)
  • aqualine ultimate style avatar for user joshua.a.sorenson
    Great video! I wasn't aware that men have mammary glands. Are there cases (perhaps during a sympathetic pregnancy) when men produce milk?
    (1 vote)
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    • leaf green style avatar for user Nahn
      So this can happen (called male galactorrhea), but it is not quite as easy as that...
      What would need to happen first is the man would have to have gynecomastia (eg: his breast tissue would have had to been exposed to high estrogen/ low testosterone and actually developed into more mature female-like glandular tissue). Then, the man would have to have a a brain tumor, brain trauma, or other rare hormonal or medication induced condition that caused his levels of [Prolactin] to be very high. Prolactin is the hormone that increases in pregnancy so that the mother is able to produce milk, but it increases up to 20 times! So a male could not have the concentrations of prolactin go that high by just experiencing emotional stress. However, if prolactin levels do get too high from something like a pituitary tumor in males with gynecomastia, they do produce breast milk.
      (3 votes)

Video transcript

Let's draw a diagram of the human breast and talk about some of the amazing functions of this organ. Now, the human breast in both males and females contains mammary glands. And in females, around the time of puberty, these mammary glands develop. In males, they usually remain undeveloped. And the main function of these glands-- and I'll just write in the name over here. These are called the mammary glands, and the main function of the mammary glands is to secrete milk to nourish the human infant. Now, these mammary glands, each of them drains toward the nipple by a little duct called a lactiferous duct. And I remember when I was expecting my first baby, and I remember thinking, where is the milk going to come out from? I don't see a hole there. And the answer is, there isn't a single hole. There are many tiny holes that are so small that you can't actually see them with the naked eye. And so these lactiferous ducts-- and I'll just label them for you here. These are the lactiferous ducts. And the lactiferous ducts empty, or drain, towards the nipple and towards that darker area of skin that we see when we look at the human breast. And that area skin is called the areola. And the reason the areola exists, is because when the newborn first comes out, newborns actually don't see very well. And in order to help them find their source of food, we have this darkened area of the breast that actually gets quite a bit darker during pregnancy. OK. So now, these mammary glands are lined with what we call myoepithelial cells. And let me just break down that word for you. Myo is a prefix that we use when we're talking about anything that has to do with muscles or anything contracts. So these are, we know, contractile cells. And they're also epithelial cells, and epithelial cells in the body are the cells that line things. So these cells, these red ones, these myoepithelial cells, are cells that both line the mammary glands and have the ability to contract to eject the milk out through the lactiferous ducts. Now, all of these structures are supported by quite a bit of connective tissue. And we're usually talking about-- in the breast the main ones are collagen and elastin. And all of these connective tissue framework comes together in these ligaments, strong ligaments that anchor the breast to the chest wall. And these ligaments are called Cooper's ligaments. In medical school, we used to remember this by saying the phrase Cooper's droopers. But after having had three children and breast fed for a long time, I don't think that's so funny anymore. Anyway, the only other thing in the breast that makes it kind of a soft and squishy organ is the adipose tissue that also forms part of the framework, or the structure, and supports actually all of these glands along with the connective tissue, the collagen and elastic. So this is our adipose tissue. And we'll see in our next video what happens, how the body knows when to cause these myoepithelial cells to contract, to eject the milk out of the mammary glands.