Anat, Physio, and Devo of Breast Flashcards Preview

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Flashcards in Anat, Physio, and Devo of Breast Deck (37)
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1
Q
What are 2 "mosts" that breast cancer holds?
A
Causes most mortality of any cancer worldwide.
Most common cancer in women in the US.
2
Q
Other than nourishment for the baby, what are 3 functions of lactation?
A
1) Passive immunity (IgA)
2) Maternal-child bonding.
3) Promotes post-partum uterine involution.
3
Q
Layers of breast organization from origin to end?
A
Acinii -> lobules -> ducts -> nipple.
4
Q
What is the blood supply to the breast? What fraction of the blood supply does each contribute, approximately?
A
2/3 medial from internal mammary a.
1/3 lateral from lateral thoracic a.
5
Q
What is the lymphatic drainage of the breast like? Implication?
A
95% goes lateral up into the axilla. This is where you must biopsy lymph nodes to check for spread.

Small % drains medially through internal mammary nodes
6
Q
What are the 2 major divisions of epithelium in breast tissue? What cells types are in each?
A
1) Ducts (cuboidal epithelial cells and myoepithelial cells)

2) Lobules (acini/ alveolar epithelial cells that make the milk)
7
Q
What are the 2 major divisions of stroma in the breast? What cell types are in each?
A
1) Connective tissue (fibroblasts / fibrous connective tissue.
2) Fat (sdipocytes)
8
Q
What are the 2 types of stroma in the TDLU of the breast? How do they contrast histologically?
A
1) Intralobular: fibrous, relatively cellular
2) Extralobular (aka interlobular): lots of collagen, few cells, appear as DENSE BANDS and can see whorls of collagen
9
Q
What type of cells surround the ducts to help them expel milk?
A
Myoepithelial cells.
10
Q
6 stages of breast development / change?
A
Fetal, Puberty, Pregnancy, Lactation, Post-lactational involution, Menopause.

Controlled by hormones and growth factors
11
Q
What are 4 cells that "ER +/- Multipotent Progenitors" can give rise to?
A
Ductal myoepithelial cells
Ductal luminal cells
Secretory alveolar luminal cells
Alveolar myoepithelial cells
(more importantly... multipotent progenitors give rise to all the different epithelial cells)
12
Q
What part of breast development occurs during puberty? What drives it?
A
Ductal morphogenesis, esp. elongation, driven by ESTROGEN

Requires normal pituitary function
13
Q
What part of breast development occurs during pregnancy? What drives it? (2 things)
A
Lobuloalveolar development, driven by progesterone and prolactin.
14
Q
What drives lactation? (1 major thing, 2 maybe things)
A
Prolactin
(cortisol and insulin are added in parentheses)
15
Q
What breast structures' development in embryogenesis is horomone-independent?
A
Milk streak -> mammary bud -> primordial ductal tree.

If this goes awry- can result in extra nipples or breast tissue!
16
Q
What two events in breast development do placental sex steroids drive?
A
Canalization of ducts.
Parenchymal differentiation--> colostrum (first milk) formation... .
17
Q
During what phase of the menstrual cycle is the mitotic rate of glandular breast tissue the greatest?
A
The luteal phase
E and P together are more mitogenic than E alone!
18
Q
What causes changes in breast volume, nodularity, and sensitivity during luteal phase?
A
Tissue edema and hyperemia.
I.e. these symptoms don't have anything to do with the ducts/ epithelial development, though the ducts are changing
19
Q
Why don't women start lactating until after birth?
A
Progesterone and estrogens inhibit lactogenic action of prolactin.
After birth, placenta is no longer there cranking out hormones, and thus lactation can start.
20
Q
Gene expression changes in breasts during pregnancy?
A
Genes for cell proliferation are upregulated.
21
Q
Pharmaceuticals that affect lactation?
A
Dopamine agonists inhibit lactogenesis.
Dopamine antagonists cause lactogenesis (recall this side effect of some antipsychotics).
22
Q
2 neural reflex arcs involved in milk production and letdown?
A
Stimuli associated with nursing (eg. baby crying) -> oxytocin -> myoepithelial contraction -> milk ejection.
Suckling -> prolactin release -> milk production.

23
Q
3 things you need for lactation, and one thing you don't.
A
1) Regular removal of milk
(Stimuli and nursing results in continued prolactin release)
2) Intact HPA axis.
3) Adequate nutrition.

You don't need ovaries to lactate (e.g. post-menopausal breast-feeding).
24
Q
Take home point about lactation-induced amenorrhea?
A
It has an effect on fertility at the population level, but it's not an effective form of contraception.
25
Q
What 2 things happen after breast feeding stops?
A
1) Lactation ceases within 7-10 days.
2) Involution (apoptosis of 80% of epithelium) happens over the course of 3-4 months and results in permanent breast tissue remodeling
26
Q
Breast changes in menopause? (3 things)
A
1) Involution of ductal and glandular elements.
2) Decreased density of stroma (more amenable to mammography).
3) Decreased estrogen/progesterone
27
Q
What are 2 disorders of breast development? (causes)
A
1) Hypoplasia/amastia - (biopsy/trauma, radiotherapy)
2) Supernumerary nipples/polymasia (milk streak doesn't completely regress)
28
Q
Two syndromes involving sexual differentiation that can cause breast development problems?
A
1) Turner syndrome
2) Precocious puberty

These disorders can give you information about the underlying endocrine disturbance!
29
Q
Definition of galactorrhea?
A
Milk discharge in absence of partuition, or discharge >6mo post-partum if not nursing.
30
Q
What can cause galactorrhea? (3 things)
A
Hyperprolactinemia (from prolactinoma or drugs)
Breasts more sensitive to prolactin.
31
Q
What is Sheehan's syndrome? What is often the first presenting sign?
A
Infarct of pituitary during labor/delivery (due to hypotension)
No lactation may be first sign.
32
Q
What's the cause of gynecomastia common to different etiologies?
A
Reduced androgen:estrogen ratio.
33
Q
What causes terminal differentiation of alveolar epithelial cells?
A

- Neural arc reflex of LACTATION leads to...
1) Transcription of milk protein genes
2) Induction of enzymes for lactose synthesis
3) Induction of cell differentiation
34
Q
What two events does weaning induce in the breast (that leads to involution)?
A
1) Prolactin and oxytocin release no longer stimulated
2) Un removed milk leads to increase of acinar pressure
35
Q
What are some etiologies of gynecomastia in men?
A
- Transient imbalance in hormones during puberty
- Obesity (fat--> estrogen)
36
Q
What are some major risk factors for breast cancer ? (REVIEW)
A
Obesity in postmenopausal women
- For evert 25 pound increase, increase your risk 80%
- Early 1st period, late menopause
37
Q
What are some protective factors against breast cancer?
A
- Being SUPER young at 1st birth (under 18)
- Ovariectomy