Physiology Of Mammary Gland Flashcards
What is a mammary gland?
Specialized Skin structures
With simple tubulosecretory units of the sweat glands
How many ectoderm ridges does a mamary gland have
It has two on either side of ventral midline, with localized thickenings appearing on the mammary buds
What happens in men and women when it comes to mammary gland
In women mammary buds form duct system
In men development is suppressed by androgens= however martenal hormones cause some increase and milk secretion known as (witches milk) they however eventually become inactive
Explain hormones involved in mammary development
Estrogen= proliferation of mammary ducts Progesterone= development of lobules and alveoli (milk production) Prolactin= milk production Oxytocin= myoepithelial cell contraction-excretion
Puberty and mammary gland.
Estrogen is a major influence on breast growth during puberty
It acts by development of prolactin-dependent (Estrogen-receptors)
As estrogen levels increase there is a increase in size of breast, pigmentation of areola, and formation of a breast mass beneath the areola (thelache)
What hormone increases after menstruation and what phase develop?
Estrogen and proliferative phase (Uterine cycle) Folicular phase (ovarian cycle)
On day 14 what hormone spikes
Lutenizing hormone
On day 14 what does the increase of the LH lead to?
It leads to increase in progesterone and secretory phase
It also leads to corpus collosum and luteal phase
Does the cyclic changes of estrogen and progesterone affect the development of breast structures
Yes
When do levels of P&E fall during cycle
At the end of cycle
What does fall of p mean to prolactin
Prolactin-induced secretory changes become evident in alveolar lumen during first few days of menses
The breast are largest in this phase
Are smallest during day 4 -7 of cycle = breast exam
What happens during pregnancy
Differentiation of breasts to its mature functional status occurs by the 3rd month of pregnancy.
True glandular acini (true alveola) develop under influence of prolactin, human placenta, lactogen, estrodiol, progesterone, insulin, Cortisol, gh, IGF-1 and EGF.
Which hormones increase breast enlargement during pregnancy?
E and P, prolactin
Does milk occur in 2nd trimester
Yes
When is ideal time for milk
After birth, birth induces sudden increase in milk production with maximum production in 1-3 days
What other hormones promoter alveolar growth of glands
Thyroid hormones
Increase of estradiol levels during pregnancy at hypothalamic level increases the secretion of what hormone
Prolactin
Where does progesterone interfere with prolactin action
At the alveolar cell’s prolactin receptor level
Name three ways on how P antagonises pro
- Inhibiting up-regulation of the prolactin receptor
- Reducing Oestrogen binding (which reduces lactogenic activity)
- Competing for binding at glucocorticoid receptor
After pregnancy how many days does it take for hormones to reach non pregnancy state
7 days for prolactin deacrease up to 50%
3-4 days for E+P
There is still a two told increase with suckling up to 3 - 6 months of which hormone
Prolactin
How can prolactin be inhibited with drugs
With bromocriptine 2.5 mg b/d = an ergot alkaloid= dopamine agonist
Not for hypertension
Also breast binding
No nipple stimulation will cease lactation on 1week
Whatis breasts in malescalled
Gynecomastia which occurs in 75% of mole newborns
70% in boys
Men over 50 years
Which hormones lead to gynaecomastios
Increased estrogen levels = due to testicular and adrenocortical tumours, alteration in (SHBG), liver failure, oestrogen exposure
Increased aromatase activity= liver disease, hyperthyroidism, androgen insensitivity, obesity, XXY
