THE BREAST Flashcards
what hormones does the growth and differentiation of the mammary depend on?
LH, oestrogen , proges`terone, human placental lactogen, prolactin, adrenocorticotropic hormone, human growth hormone
what produces oestrogen and progesterone during pregnancy?
ovaries and then the placenta takes over from the 10th week as the corpus luteum degenerates
what’s the role of oestrogen in mammary growth?
stimulating milk ductal growth and proliferation
what’s the role of progesterone on mammary growth?
stimulates production of milk glands
where is human placental lactogen secreted from?
the placenta
note: its also known as human chorionic somatomammotropin
whats the role of human placental lactogen in mammary development?
stimulates ductal and aereolar growth
where is prolactin secreted from?
lactotrophs in anterior pituitary
whats the role of prolactin in mammary development?
promotes the growth of the alveoli
where is adrenocorticotropic hormone released from?
anterior pituitary
where is human growth hormone released from?
anterior pituitary
what is mammogenesis?
the process of growth and development of the mammary gland in preparation for milk production
when is mammogenesis fully complete?
after pregnancy and lactation - about 35
outline the embryological derivatives of the breasts?
the ectoderm is responsible for the formation of the ducts and alveoli and the mesenchyme is responsible for the connective tissue and its vessels.
what happens at 4 gestational weeks in mamogenesis?
two milk lines form from axilla to groin caused by a thickening of epithelia cells
what happens at 7/8 gestational weeks in mammogenesis?
thickening and inward growth of epithelia cells causes milk hillocks
what happens at 12-16 gestational weeks in mammogenesis?
epithelial cells form mammary buds which branch to form a network of alveoli
what happens at 28-32 gestational weeks in mammogenesis?
canalization of branch epihtleial tissue. Primary milk ducts are formed
what happens at 32-40 gestational weeks in mamogenesis?
lobular-alveolar structures containing colostrum develop
ducts open onto the area which becomes the nipple
nipple and areola develop and become pigmented
Outlien the difference in growth pattern of te breast through childhood and puberty?
in childhood there is isometric growth of the breast
in pubert we get allometric growth of the breast caused by oestrogen and progesterone
what happens to the breasts in puberty?
budding and branching of glandular tissues to form small ductules and then alveoli. Fat deposition creates the shape and size of the breast
what happens to our breatss in every reproductive cycle?
proliferation and active growth of mammary glands - this is why we get breast tenderness
what is the areolar?
a circular area of pigmented skin that includes openings for about 20 sebaceous glands and is attached to a lactiferous lobule
whats the structure of the nipple?
surrounded by the areolar
it has 10-20 nipple openings connected to lactiferoud ducts which allow milk out
what are the tubercules of montgomery?
sebaceous glands that appear as small bumps around the areolar. they are important for lubrication, keeping germs away from breasts and for secreting pheremones
what is the Axillary tail of Spence?
A tail of breast tissue extending towards the axilla
where would a supernumery nipple appear?
somewhere along the embryonic milk line
how does the different sizes in breast affect milk production?
women produce milk based on the amount of glandular tissue not adipose tissue so size doesnt affect it, however, small breasts do have less storage capacity so may have to feed more often
outline the structure of the secretory unit of the breast?
each breast lobule consists of clusters of hollow alveoli lined by a single layer of lactocytes (milk secreting epithelial cells). These are continuous with the lactiferous duct which is lined by myoepithelial cells
there is a efficient blood supply here too
whats the blood supply to the breast?
60% from internal thoracic artery and 30% from lateral thoracic artery
whats the venous drainage of the breast?
axillary, internal thoracic and second to fourth intercostal veins.
what do the lymphatics of the breast drain into?
central and deep axillary nodes
what nerves stimulates the breasts?
neural supply from branches of 2nd-6th intercostal nerves
what does each tubercle of montgomery contains?
trye mammary lobule connected to 2 sebaceous glands that open up onto the areolar
whats the important of tubercle of montgomery in breastfeeding?
the pheromones released from sebaceous glands attract baby and help allow baby to attach more quicly
outline the stages of lactation?
mammogenesis lactogenesis galactokinesis galactopoiesis involution
what is lactogenesis
synthesis and secretion of milk from the breast alveoli
outline the first stage of lactogenesis?
colostrum is produced from about 16 weeks
outline the second stage of lactogenesis?
onset of copious milk secretion occurring at 32-96 hours after birth caused by drop in progesterone as placenta is removed= prolactin release which can act on lactocytes
what is galactokinesis?
the ejection of milk outsdie of the breast
outline the physiology of galactokinesis?
oxytocin is released from posterior pituitary after nipple stimulation from suckling baby
it stimulates myo-epithelial cells to contract, squeezing milk out into the alveolus sac
what is milk let down?
the release of milk from the breast
what is galactopoiesis?
maintenance of lactation
what is involution?
process following weaning during which the mammary gland undergoes massive cell death and tissue remodeling as it returns to the pre-pregnant state.
what is galactopoiesis reliant on?
delivery of prolactin to mammary glands and the removal of milk
why does the removal of milk allow more milk to be created?
as a feedback inhibitor of lactation is removed with the milk
if milk isnt removed, FIL accumulates and secretion of milk slows down
how many times should you feed a baby in 24 hours?
8-12 times
why is it important to keep the mother close to the baby?
so that mother’s oxytocin levels rise which maintains lactation
outline the key difference between prolactin and oxytocin?
prolactin helps make the milk whilst oxytocin causes the breast to eject the milk
what is the prolactin receptor theory
frequent milk removal in the early weeks will increase the number of receptor sites so milk production capacity is increased
filling of alveoli stretched lactocytes and changes conformation of prolactin receptors so prolactin wont attach to trigger lactation
when are prolactin levels higher?
at night
what can inhibit oxytocin?
stress
whats the role of colostrum?
contains antibodies to protect the newborn against disease and infection, and immune and growth factors and other bioactives that help to activate a newborn’s immune system
how does colostrum prevent jaundice?
it acts as a laxative which helps clear the system of meconium which rids of bilirubin
how does breast feeding prevent obesity in children?
it allows babies to better regulate food intake
what are the benefits of human breast milk over formula?
more digestable, contains viral fragments, antibodies, hormones, WBCs, bifidus factor, transfer factors, anti-infalmmatory molecules, less processed, sterile
what is mastitis?
inflammation of the breast tissue that sometimes involves infection (30% of the time)
what are some infectious causes of mastitis?
microorganism introduction from breast feeding infant’s motuh/nose
e.g. staphylococcus aureus
what are non-infectious causes of mastitis?
milk stasis- prolonged engorgement, infrequent or inefficient feedings, clogged ducts
what are some risk factors for mastitis?
abrupt weaning, damaged nipples, poor hygeine, ineffective breast feeding technique, diabetes, imapure immunity
what is the complication of mastitis?
infectious progression - abscess could form
what are the symptoms and sigsn of mastitis?
localised firmness, redness, swelling, heat
palpable lump
breast pain, tender/enlarged axillary nodes, flu like symptoms
what is the treatment for mastitis??
analgesics and treat cause to prevent recurrence
increase feeding and expressing to keep milk flowing
antibiotics if infective
what is pregnancy-associated breast cancer?
breast cancer diagnosed during pregnancy or witin 12 months of birth
is there a link between pregnancy and breast cancer?
no its just due to greater breast awareness and clinical professionals examining maternal breastss
why may pregnancy or lactation cause a delay in diagnosis of breast cancer?
glandular growth and icnreased density and water content can make a lump more difficult to find so if its found then it may mean its at a more advanced stage
how can you distinguish breast cancer from mastitis?
breast cancer lumps wont resolve with analgesics and increased breast feeding
breast cancer lumps will have irregular borders and can be fixed
how many lobules are in each breast?
15-20
why dont we lactate until the baby is born?
high levels of oestrogen and progesterone produced by the placenta inhibit milk production so when placenta is removed along with baby, lactation begins
why can breast feeding be used as contraception?
because increased prolactin levels cause inhibition of GnRH which leads to lowered production of FSH and LH which means development of follicles and ovulation doesnt occur
what produces oxytocin and what are its 2 functions?
supraoptic and paraventricular nuclei in the hypothalamus
- contraction of myoepithelial cells around lactocytes
- contraction of uterus in labour
where is oxytocin stored once its produced?
Herring bodies in the posterior pituitary gland
what does the hypothalamus secrete to promote prolactin release?
Prolactin releasing hormone which stimulates anterior pituitary to release prolactin and this then stimulates the hypothalamus
what does the hypothalamus release to inhibit prolactin release?
dopamine- prolactin inhibitor
