Female Breast Flashcards
What are the female breasts/mammary glands?
Accessory organs of reproduction that are required to provide nourishment for the neonate after birth
Modified exocrine glands
What do the mature female breasts consist of?
One areola which provides lubrication during lactation
One nipple which milk is excreted
Many alveoli which milk is produced in
Tubules and ducts which the milk passes through
Describe the external structure of the breast
Situated either side of the midline of the anterior chest wall
Extend from 2nd to 6th rib, laterally from the sternum to the axilla.
Over pectoralis muscles where they are attached by connective tissue
Hemispherical in shape
Breast size varies
Midpoint of exterior surface lies the areola average measurement of 2.5cm diameter
Degree of pigmentation varies
Nipple at centre of areola, erectile, sensitive
What are Montgomery tubercles?
Sebaceous glands that secrete sebum like substance to lubricate the nipple during pregnancy and breast feeding
Describe the internal structure of the breast
16-20 lobes divided by bands of fibrous tissue
Each lobe has a lactiferous duct which leads to a lactiferous sinus (reservoir) beneath the nipple where the milk is stored
Each lobe divided into lobules which contains a lactiferous duct where milk is directed from the alveoli
Variable amounts of adipose tissue around the breast
Alveoli are clustered around lactiferous ducts
Alveoli are composed of milk secreting cells - acini cells
Myoepithelial cells enclose alveoli to contract under influence of oxytocin squeezing milk into the lactiferous ducts
What are acini cells?
Cells that extract nutrients necessary for milk production from the network of capillaries that surround the alveolus and produce milk.
Describe the blood, lymph and nerve supply to the breast
Blood supplied by mammary arteries and upper intercostal arteries
Venous drainage into the mammary and axillary veins
Lymphatic drainage is extensive and is into the axillary glands and some drainage into the mediastinal glands
Little nerve supply to the breasts however they are largely controlled by hormones
Skin is supplied by branches of the thoracic nerves from the 2nd-6th intercostal muscles
Nipple and areola supplied by autonomic nervous system
How do the breasts change in pregnancy?
Week 6- enlargement in response to increasing hormones oestrogen responsible for growth of lactiferous ducts and tubules, progesterone prolactin and human placental lactogen result in enlargement and proliferation of the alveoli
Increased sensitivity to touch and tingling feelings
Increased blood supply mean visible veins on surface
Week 12- nipple and areola become more pigmented, Montgomery tubercles become pronounced and secrete lubricants
Week 16- colostrum formed, high levels of oestrogen and progesterone prevent it from being secreted
Week 24- secondary areola form, areas of pigmentation around the areola
Average 5cm enlargement, 1500g weight increase
What is colostrum?
Precursor of milk
Highly nutritious and contains immunoglobulins which help protection against infection in the newborn
Immediately available to the neonate after birth
Yellow colour
Higher protein content than breast milk
High proportion of immunoglobulins
Carbohydrate and fat levels are lower than in breast milk
How does labour effect the breast?
Once third stage is compete, placenta and many hormones are no longer in the body resulting in dramatic decrease in oestrogen and progesterone which initiates lactation
How do inverted nipples effect breastfeeding?
Ultimately they do not
Can be reassured that the baby attaches to more than the nipple during attachment and therefore he or she can pull the nipple out themselves during suckling
How is the production of milk started?
Oestrogen and progesterone levels decrease and prolactin increases stimulating lactation
Suckling of the neonate (stimulation) causing colostrum to to change in composition to milk
Discuss the importance of skin to skin contact
Midwives responsibility
BFI UNICEF
Place the naked neonate on its mothers bare chest immediately after birth
If left undisturbed the baby will exhibit behaviour conducive of successful breast feeding as well as maintaining its body temperature
What are the two main hormones involved in lactation?
Prolactin- anterior lobe of e pituitary gland influences the production of milk
Oxytocin- from the posterior lobe controls the ejection of milk
How are prolactin levels influenced?
Suckling
Frequent breast feeding
Including night feeds
What is milk ejection?
Neuroendocrine response
Stimuli- baby crying, thinking of baby, baby suckling results in release of oxytocin
Oxytocin stimulates myoepithelial cells which contract and expel the milk form the alveoli
Outline the components of breast milk
Protein - easily and completely digested, leaves little waste
Lactalbumin and caseinogen
Amino acids cystine and taurine (not present in formula) important for growth and brain development
Fats- rapidly broken down by lipase
Lactose- sugar which is quickly absorbed important role in absorption of calcium
Vitamins
Minerals - prevent dehydration
Immune factors - protect infant from infection
Describe the breast of neonates
Rudimentary breasts of make and female infants can somewhat be enlarged at birth in response to the high levels of material hormones crossing the placenta during feta, development
Resolved within 3-4 weeks
What is mammogenesis?
Process of growth and development of the mammary gland in preparation for milk production
Begins at 4 weeks
Epithelial cells develop into mammary buds which develop and profliferate into alveoli
Under influence of oestrogen and progesterone
Describe the anatomy of the nipple
Approx 9 ducts open to the surface of the nipple
Areola surround nipple contain erectile tissue
Montgomerys tubercles consist of sebaceous glands
Presence of these effect breast feeding
Glandular tissue arranged in a ductal alveolar system, grouped in lobules joining to the main lactiferous ducts
What is the ratio of glandular to adipose tissue in lactating and non lactating women
2: 1 in lactating
1: 1 in non lactating
What occurs when an infant breastfeeds?
Infant draws the nipple and areola into their mouth
Mothers nipple enlarged to twice its normal size
Nipple is compressed between tongue and palate
Baby compresses areola with gums stimulating oxytocin release
Oxytocin release increases diameter of milk ducts and movement of milk towards the nipple
What is feedback inhibitor of lactation?
Active whey protein which inhibits milk production in a full breast
Acts locally in the breast
Secreted into the breasts
When breast is not emptied FIL remains in contact with the he alveolar cells
FIL appears to act on apical receptors on the alveolar cell which inhibits the secretion of milk constituents
What is lactogenensis 1?
Initiation milk synthesis mid pregnancy
Differentiation of alveolar cells from secretory cells
Prolactin stimulates secretory cells to produce milk
What is lactogenensis 2?
Closure of tight junctions in alveolar cells triggered by drop in progesterone levels
Onset of copious milk secretion
Fullness
Switches from endocrine to autocrine control
What is galactopoiesis?
Maintainence of secretion
Controlled by autocrine system,msupply and demand
Breast size decreases between 6-9 months postpartum
What essential hormone changes for successful lactation?
Drop in progesterone
Release of prolactin from the anterior pituitary stimulates lactogenensis and initiates milk secretion
Removal on milk from breast by the infant
Release of oxytocin from posterior pituitary
