page_title: Nipple
section_title: Function
hierarchical_section_title: Nipple / Function
caption_attribution_description: English: Breastfeeding an infant Português: Um recém-nascido em aleitamento Deutsch: Ein Säugling wird gestillt
context_page_description: The nipple is a raised region of tissue on the surface of the breast from which, in females, milk leaves the breast through the lactiferous ducts to feed an infant. The milk can flow through the nipple passively or it can be ejected by smooth muscle contractions that occur along the ductal system. The nipple is surrounded by the areola, which is often a darker color than the surrounding skin. A nipple is often called a teat when referring to non-humans. Nipple or teat can also be used to describe the flexible mouthpiece of a baby bottle. In humans, nipples of both males and females can be stimulated as part of sexual arousal. In many cultures, human female nipples are sexualized, or "regarded as sex objects and evaluated in terms of their physical characteristics and sexiness."
context_section_description: The physiological purpose of nipples is to deliver milk to the infant, produced in the female mammary glands during lactation. During breastfeeding, nipple stimulation by an infant will simulate the release of oxytocin from the hypothalamus. Oxytocin is a hormone that increases during pregnancy and acts on the breast to help produce the milk-ejection reflex. Oxytocin release from the nipple stimulation of the infant causes the uterus to contract even after childbirth. The strong uterine contractions that are caused by the stimulation of the mother's nipples help the uterus contract to clamp down the uterine arteries. These contractions are necessary to prevent post-partum hemorrhage.
  When the baby suckles or stimulates the nipple, oxytocin levels rise and small muscles in the breast contract and move the milk through the milk ducts. The result of nipple stimulation by the newborn helps to move breast milk out through the ducts and to the nipple. This contraction of milk is called the “let-down reflex.” Latching on refers to the baby fastening onto the nipple to breastfeeding. A good attachment is when the bottom of the areola (the area around the nipple) is in the baby's mouth and the nipple is drawn back inside his or her mouth. A poor latch results in insufficient nipple stimulation to create the let down reflex. The nipple is poorly stimulated when the baby latches on too close to the tip of the nipple. This poor attachment can cause sore and cracked nipples and a reluctance of the mother to continue to breastfeed. After the birth of the infant, the milk supply increases based upon the continuous and increasing stimulation of the nipple by the infant. If the baby increases nursing time at the nipple, the mammary glands respond to this stimulation by increasing milk production.
caption: Infant latched on to nipple.
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