Chapter 6 Flashcards
Alveoli
Milk producing components of the breast
Apoptosis
Death of cells that occurs as a normal and controlled part of an organisms growth or development
Areola
Circular, dark pigmented area that surrounds the nipple
Cooper’s ligaments
Connected tissue in the breast that helps maintain structural integrity. Name for Ashley Cooper who was first to describe them in 1840
Feedback inhibition of lactation
Small active way protein that is synthesize by the lactocites and accumulates in the Aveolar lumen
Galactopoiesis
Maintenance of milk production
Involution
Removal of milk producing cells after weaning by apoptosis
Lactocytes
Specialized epithelial cells that line the interior of the aveolus
Lactogenesis
Process of cellular changes in Glanger tissue in the breast whereby memory epithelia cells are converted from a nonsecretory state (milk producing) to a secretory state (milk producing)
Lactogenesis I
Differentiation of alveolar epithelial cells into lactocytes that secrete colostrum
Lactogenesis II
Onset of copious milk production that begins 32 to 96 hours after birth
Montgomery glands
Sebaceous glands in the areola surrounding the nipple that make oily secretions to keep the areola and the nipple lubricated and protected
Myoepithelial cells
Sells that encase the aveloi and contract in response to oxytocin to eject milk into ductles
Parenchyma
Functional tissue of an organ is distinguished from the connective and supporting tissue
Poland syndrome
Unilateral hyperplasia of the breast combined with hyperplasia of the thorax and pectoral muscles
Prolactin receptor sites
Sites in the lattice sites that allow prolactin to be absorbed from the blood and enter into the alveoli to stimulate milk production
Sheehan syndrome
A pituitary infarct caused by severe postpartum hemorrhage
Tail of Spence
Mammory glandular tissue the projects into the axillary region
Breast development facts
Only organ that is not fully developed at birth
Capable of a full lactation from about 16 weeks of pregnancy onward
Under endocrine or hormonal control before delivery of the placenta. Changes to autocrine or local control during lactogenesis II
Breast development during embryonic and neonatal stages
Weeks 3 to 4 a primitive milk streak forms and runs bilaterally from the Axilla to the groin
Weeks 4 to 5 milk stream becomes a memory milk ridge or Galactic band. Pairedbreast develop from this line of glandular tissue
Week 7 to 8 thickening an inward growth into the chest wall continues
Weeks 12 to 16 specialize cells differentiate into smooth muscle of nipples and areola
Weeks 15 to 25 shallow epithelia depressions or mammary pits begin to form which represent future secretary of the alveoli
After 32 weeks a lumen or canal forms in each part of the branching system
Near-term 15 to 25 memory ducks form the fetal memory gland
Neonate galactorrhea also called witches milk begins which is the secretion of colostral like fluid from neonatal memory tissue coming from maternal hormones
Breast development continues through puberty
Breast growth keep pace with general physical growth
Growth of the breast parenchyma or functional parts of the breast produces ducts, lobes, alveoli, and surrounding fat pads
Onset of menses at age 10 to 12 continues breast development. Primary and secondary ducts grow and divide. Terminal endbuds form which later become alveoli. Proliferation and active growth of ductal tissue takes place during each menstrual cycle and continues to about age 35 years
Complete development of memory function occurs only in pregnancy. Breast size increases, skin appears thinner, and veins become more prominent. Areola diameter increases, Montgomery glands enlarge, and nipple pigment darkened.
Breast anatomy - exterior breast
Exterior breast is located in the superficial fascia between the second rib and the six intercostal space
Mammary glandular tissue the projection to the axillary region is called tale of Spence. It connects to the duct system. Potential area can be affected by mastitis
Skin surface contains the nipple, Ariola, and Montgomery glance. Size is not related to functional capacity. Fat composition of the breast gives it its size and shape
Nipple areolar complex
Target for the newborn to latch and feed.
Conical elevation located slightly below the center of the areola
Average diameter of a nipple is 1.6 cm, the average length is 0.7 cm.
Smooth muscle fibers function to close off milk.
Nipple is densely innervated with sensory nerve endings.
Longitudinal inner muscles and outer circular and radio muscles make nipple erect when contracted
Nipple becomes smaller, firmer, and more prominent to help the infant latch.
Areola is a circular, dark pigmented area that surrounds the nipple
The average diameter is 6.4 cm.
Constructed a smooth muscle and collagenous, elastic, connected tissue fibers in a radio and circular arrangement.
Increased in melanin deposits during pregnancy causes darkening to occur which is usually a company by enlargement
Montgomery tubercles are located around the areola. They contain ductal openings of sebaceous and lactiferous glands and sweat glands. They secrete a substance that lubricates and protects the nipples. Secretions produce a scent to help the infant locate the nipple.
Parenchyma
Functional parts of the breast.
Alveoli are the milk producing units in the breast
Lactocyte which are specialized epithelial cells line the interior of the alveol, absorb nutrients, immunoglobulin, and hormones from the bloodstream to compose milk
Prolactin receptor sites in the lactocytes allow prolactin to be absorbed from the blood and enter the alveoli to stimulate milk production
Myoepithelial cells encase the alveoli and contract in response to oxytocin to eject milk into ductules
Lobes are clusters of lobules that are filled with alveoli.
Breast contains 15 to 25 lobes the carry milk through the ductles from the alveoli to the nipple
Ducts branch very close to the nipple. Widen temporarily in response to milk ejection and then narrow when the duct is drained.
Milk not removed flows backward up the collecting ducks
Lactiferous ducts lead to openings in the nipple. Each nipple has 4 to 18 openings, there is an average of nine openings
Stroma supporting tissue of the breast include connective tissue, fat tissue, blood vessels, nerves, and lymphatics
Cooper’s ligaments run vertically through the breast and attach the deep layer of subcutaneous tissue to the dermis layer of the skin
Diagrams on page 86 and 87
Examine these figures and memorize
Breast is highly vascular
Internal mammary artery supply 60% of the blood to the breast. The lateral thoracic artery supplies 30% of the blood in the breast.
Blood vessels within the breast enlarge with an increase in progesterone
Surges of estrogen stimulate duct growth
Searches of progesterone cause glandular tissue to expand
Lymphatic system
Collects Excess fluid from tissue spaces, bacteria, and cast off sale parts. Drains mainly to the axillary lymph nodes.
Breast innervation - fourth intercostal nerve
Derives mainly from branches of the fourth intercostal nerve which is the primary nerve that affects lactation due to its importance in the endocrine loop that involves oxytocin and prolactin.
Supplies greatest sensation to areola, 4 oclock postion on left breast and at 8 oclock on righ
More superficial as reaches areola, divides into 5 branches,
Trauma to this nerve might result in loss of of senasation, aberrant sensory or autonomic nerve in nipple-areola complex can arrect milk ejection reflex and secretion of prolactin and oxytocin. Breast augmentation or reduction surgery may sever or cause nerve trauma.
Breast size, shape, color and placement on chest wall variation
Weight increases, nonpregnant woman weighs 200 g, pregnancy near term, 400-600 g and will lactation can be 600 to 800 g
Left breast is often larger than right breast
Test self on Table 6-1, breast types - page 90
Polythelia
Presence of extra nipples.
Accessory or supernumerary nipple develops along milk line between Axilla and the groin. Often prominent during pregnancy and lactation. May be associated with renal or other organ system anomalies - should be investigated
Polymastia
Presence of extra breast tissue. Accessory glandular tissue can lactate and undergo malignant changes
Hyperthelia
Nipple without accompanying mammory tissue
Hypertrophy
An abnormally large breast
Hypomastia
And abnormally small breast
Hyperplasia
Over development of the breast, hyperplastic breast
Hypoplasia
Insufficient glandular tissue.
Hyperplasia result in a tubular or tuberous shape because of the lack of glandular tissue. Breast may have large aerolas
Breast are frequently asymmetric and widely spaced.
Condition may present an increase risk for insufficient milk production.
Unilateral hyperplasia of the breast combined with hyperplasia of the thorax and pectoral muscles is known as Poland syndrome
Nipple restricted protractility
Nipple should evert and become protractile when compressed or stimulated. Incidence of poor protactility prima women ranges from 10 to 35%.
Protractility improves during pregnancy.
Effect on latch is minimal when breast baby has a large mouth full of breast tissue.
Nipple inversion
Occurs in about 3% of women and is usually bilateral.
Truly everted nipple remains everted when compressed or stimulated which is also called the pinch test.
Pseudo everted nipple appears everted but everts when compressed or stimulated. Short shanked nipple appears everted but retracts with compressed or stimulated
Bulbous nipple
Large nipple that may be difficult for a baby to grasp and achieve a successful latch
Dimpled nipple
Increases the risk for maceration because the nipple is enveloped by the areola
Bifurcated nipple
A single nipple that is separated by a split into two or more sections
Double or multiple nipples close together
Skin tag
Small benign skin growth that may appear on the breast or nipple. Skin tags are more prevalent during pregnancy
Nipple piercings studs and bars
Nipple piercings generally do not affect milk production.
Can contribute to maternal discomfort, poor latch, altered milk flow during feeding, and increase milk leakage.
Wearing jewelry on nipple during feeding could put infant at risk of aspiration and injuries of the gums, soft palate and tongue.
Nipple jewelry should be removed when breast-feeding
Mamogenesis. Prenatal breast development
Final preparation for Lactation occurs during pregnancy.
First trimester memory epithelial cells proliferate, ductile sprouting and branching begin. Ducts proliferate into the fatty pad and the ductals and buds differentiate into alveoli. Increase in mamory blood flow.
New capillaries around the lobules grow.
Last trimester secretory cells fill with fat droplets and the alveoli are distended with colostrum
Memory cells become more confident to secrete milk proteins at mid pregnancy. Kept in check by high circulating levels of steroids, particularly progesterone
Milk products that are secreted during pregnancy find their way back into plasma by the leaky junction’s which are the spaces between the mammoryalveolar cells
Hormonal influences prenatal breast changes
Lactogenesis is hormonal driven by the endocrine control system.
Human placental lactogen, prolactin, and human chorionic gonadotrophin accelerate growth.
A form of estrogen called 17 beta estradiol required for memory growth and epithelial proliferation during pregnancy.
Glucocorticoids enhance formation of the lobules during pregnancy.
Estrogen increases during pregnancy and stimulates ductal sprouting.
Prolactin is necessary for complete growth of the gland. Secreted by the anterior pituitary gland. Stimulates prolactin receptor sites for initiation of milk secretion on alveolar cells surfaces.
Prolactin levels rise throughout pregnancy.
Prolactin is prevented from exerting influence on milk during pregnancy by high levels of circulating progesterone.
Prolactin inhibiting factor (PIF) is secreted by the hypothalamus to negatively control prolactin. Dopamine is an example of PIF. Does in respose to stress, fatigue or depression.
Progesterone increases during pregnancy. Stimulates lobularaveolar growth while suppressing secretary activity. Sensitizes memory cells to the effects of insulin and growth factors. May be involved in the final preparation of glandular tissue for copious milk production
Lactogenesis I or Secretory Differentiation
Lactogenesis I is the beginning of secretory cellular activity and milk production.
Occurs at about 16 week prenatal.
Stage at which breast is first capable of synthesizing unique milk components.
Thyroid hormones increase responsiveness of mammary cells to prolactin and can improve lactation performance.
Main hormones necessary for secretory differentiation include estrogen progesterone, placental lactogen, and prolactin.
Supportive metabolic hormones include glucocorticoids including cortisol, insulin, thyroid-parathyroid hormone, and growth hormone.
Antepartum secretion, or colostrum, shows a gradually increasing presence of lactose, casein, and alpha-lactaalbumin
Colostrum has an increase in concentrations of two immuno protective proteins, scretory immunoglobulin A and lactoferrin all occur after delivery
Lactogenesis II or Secretory Activation
Lactogenesis II is the onset of copious milk.
Occurs between 30 and 72 hours following delivery of placenta.
Women feel breast fullness around 50 to 72 hours after birth.
Initially under endocrine control now under autocrine or local control.
Maintain by stimulation of the nipple and regular milk removal.
Placenta expulsion precipitate abrupt decline in levels of human placental lactogen, estrogen, and progesterone.
Progesterone is a prolactin inhibitor. Dropping per lap and progesterone is beginning of lactogenesis capital I I.
Changes in milk composition occur including a sharp rise in citrate and alpha-lactoalbumin.
Risk factors for delayed onset of lactation include
Fluid volume overload in labor.
C-section or stressful vaginal birth with long stage to labor.
Maternal health status including type one diabetes mellitus, obesity, history of reduction mammaplasty, hypo plasia, polycystic ovarian syndrome, infertility, and thyroid dysfunction.
Any maternal illness interfering with early milk removal including Sheehan syndrome, a severe postpartum hemorrhage.
Paridy promas are at increased risk.
Retained placental fragments
Steps after placenta delivery - facts about prolactin
Prolactin levels increase sharply after placenta leaves and rise and fall with frequency, intensit and duration of nipple stimulation
Falls to 50% in 1st week postpartum
Found in milk up to 40 weeks postpartum
Circadian rhythm - higher at nigh, surging when baby suckling or pumpping
Frequent feeding in early lactation stimulates development of prolactin receptor sites - SITES MAY CONTROL MILK SUPPLY NOT PROLACTIN LEVELS
Milk comes in sooner if breastfed before possibly due to more receptor cells
Drops to prepreg level in 2 weeks if not breastfeeding
Lactogenesis III or Galactopoiesis
Later than 9 days after bbirth to beginning of involution
Maintenance phase of lactation
Depends on autocrine or local contol
Feedback Inhibition of Lactation (FIL)
Small active whey protein synthesized by lactocytes and accumlates in alveolar lumen
Moderate milk synthesis locally, based on fullness of breast
Rate of milk synthesis slows when milk accumulates in the breast because more FIL is present
Rate of milk synthesis speeds up when milk is removed and less FIL is preset
NOT JUST FIL - also B1-integrin, a-Lactalbumin, transorming growth factor B, insulin like growth factor finding protein 5 and lactoferrin
Prolactin receptor theory - local mechanism involving prolactin receptors in basement membrane of the alveoli - milk accumulates and lactocyte shape distorted and prolactin annot bind - inhibited by alveolar distension which down regulates milk syntesis.
Involution: Apoptosis of Secretor Cells
Involution occurs when milk producing system in breast is no longer being used.
Results in secretory epithelial apoptosis or cell death.
Complete involution happens about 40 days after cessation of breast-feeding.
Depends on the type of weaning if abrupt or gradual.
Anecdotally may take longer for milk production to stop longer breastfeedingg.
Milk production and synthesis
Affected by volume of milk removed from breast at feeding or during expression.
Elegant sample of supply and demand.
Increase sensitivity of prolactin receptors in muliparous women.
Breast hyperplasia, obesity, disease, and metabolism rate can affect milk production. Medication specifically prolactin inhibiting factors (also known as dopamine agonist) such as bromocriptine and ergotamine can inhibit prolactin secretion.
Milk storage
Milk stored in the alveoli and small ducts adjacent to cells that secrete milk.
Storage compresses and flattens the cells.
Storage capacity varies. Storage capacity of a breast increases with breast size.
Cells that line both the alveoli and the small ductiles appear to be capable of secreting milk
Rate of milk synthesis
Degree to which milk is removed signal the amount of milk to be made for next feeding. Degree Of fullness in a breast and rate of short-term synthesis are inversely related. Wide variability in rate of milk synthesis from 17 to 33 ML per hour.
Local control regulates short-term milk synthesis.
Controlled independently in each breath.
Small breasts are capable of secreting as much milk over a 24 hour period as large breasts.
Milk synthesis in the Latus site
Secretory epithelial cell. Synthesis occurs after the uptake of substrate from the blood that are necessary for milk production.