Exam 5 Review: Chapter 27 Mammary Glands
mammary glands - The accessory reproductive glands of the female which produce and secrete colostrum (briefly) and milk to nourish the growing infant; the glandular milk-producing alveolar cells are surrounded by contractile myoepithelial cells, fibrous connective tissue, and variable amounts of adipose tissue; they are highly specialized sudoriferous = sweat glands; they are located on the ventral chest wall superficial to the pectoralis muscles and the ducts drain to the nipple which is surrounded by the pigmented areola; they are regulated hormonally by estrogens and progesterone from the corpus luteum and placenta, and by prolactin (milk production) from the anterior pituitary and oxytocin (milk letdown) from the posterior pituitary; they also respond to autonomic NS impulses.
nipple - The small projection, covered by hairless skin, near the center of the areola of the mammary gland which contains dense fibrous connective tissue and some erectile tissue surrounding the outlets of the lactiferous ducts through which neonates obtain milk from the adult female. [Note: The A corresponding projection of the male breast is a functionless vestigial structure.]
areola - The small darkly pigmented oval of slightly raised tissue which surrounds the nipple of the breast; it has a peripheral border with occasional hair follicles, but is otherwise hairless skin; size and degree of pigmentation are variable and, within an individual, diameter can change with smooth muscle contractions associated with sexual arousal.
lactiferous ducts - The 15-20 tubular drains for the lobes of the mammary glands which converge to open at the tip of the nipple; their distal ends are expanded to form lactiferous sinuses to store milk, which is produced gradually, until it can be released during bouts of nursing.
alveoli - The clusters of milk producing glandular cells which comprise the various lobes of the mammary glands; they are regulated hormonally by estrogens and progesterone from the corpus luteum and placenta, and by prolactin from the anterior pituitary; they develop at puberty to partial structural and functional maturity and increase somewhat in size and complexity during each menstrual cycle, but do not develop into fully functional glands until late in pregnancy.
lactiferous sinus - The short oval enlarged dilation of each lactifierous duct in the breast tissue just beneath the nipple; in lactating females, this is a storage depot for milk, which is produced gradually by the alveoli, and will be expressed from the nipple by compression as the infant begins to nurse; the initial sensory feedback provided by nursing stimulates an autonomic reflex, assisted by oxytocin, which then triggers the letdown reflex.
lactation - The synthesis and secretion of milk by the female mammary glands; it is regulated hormonally by estrogens and progesterone from the corpus luteum and placenta, and by prolactin (milk production) from the anterior pituitary and oxytocin (milk letdown) from the posterior pituitary; milk letdown also responds to autonomic NS relex impulses.
milk ejection reflex - A neuroendocrine reflex in which afferent = sensory impulses report pressure, i.e., mechanical stimulation, to the paraventricular and supraoptic nuclei of the hypothalamus; neuroendocrine cells in these nuclei respond with visceral efferent action potentials which are delivered to the posterior pituitary gland = neurohypophysis where their axon terminals will release oxytocin into the bloodstream; the oxytocin then travels to the mammary gland via the blood, binds to oxytocin receptors on the myoepithelial cells, causing the myoepithelial cells to contract, and resulting in increased intra-lumenal (intramammary) pressure and ejection of milk from the alveolar lumen; elsewhere, in response to the same stimuli, autonomic impulses are sent to the smooth muscle in the lactiferous ducts and sinuses; their contractions move the milk toward the nipple.
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milk letdown - The release of milk from the breast following tactile stimulation of the nipple by the infant's suckling; it is regulated by an autonomic reflex, the milk ejection reflex: sensory impulses are routed to the hypothalamus which responds by causing oxytocin release which then triggers contraction of the myoepithelial elements in the breast as well as in the smooth muscle in the lactiferous ducts and sinuses; these actions move the milk toward the nipple.
List:
13. the risks for breast cancer.
early onset menses
late
menopause
no
pregnancies or pregnancies later in life (> age 34)
previous history of breast cancer
family history of breast cancer (especially in a sister or mother)
exposure to ionizing radiation
lifestyle: obesity, alcohol use/abuse, cigarette smoking
Sketch and label:
12. a cross-section of the breast. List the function of each part.
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