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Anatomy > Breast Physiology and Histology > Flashcards

Breast Physiology and Histology Flashcards

1
Q

What’s the biggest difference between healthy and cancerous breast cell proliferation?

A

Healthy: separation between steroid receptor expression and proliferation (steroid cells send paracrine signals that induce adjacent cells to proliferate)

Cancerous: ER+/PR+ cells proliferate on their own (autocrine/autonomous proliferation)

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2
Q

What are SERMs?

A

Selective Estrogen Response Modulators

- bind to estrogen receptors but final response is tissue specific (can be agonists or antagonists)

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3
Q

What hormones inhibit lactation during pregnancy? Does prolactin concentration increase during pregnancy even if there’s no lactation?

A

Estrogen and progesterone

YES! (by estradiol)

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4
Q

What secretes prolactin (PRL)? Inhibited by?

Negative feedback loop for PRL?

A

Secretion is by lactotrophs in the anterior pituitary
Tonic inhibition by dopamine (increased suckling = decreased dopamine = increased prolactin) – there’s no negative feedback loop for PRL

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5
Q

How does prolactin stimulate milk synthesis?

A

Binds to receptors on breast epithelial cells – prolactin receptors dimerize = induce synthesis of milk proteins (ex: casein)

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6
Q

Describe how suckling results in oxytocin release?

A

suckling/other neural cues – dorsal horn of spinal cord – brainstem – medial forebrain bundle – activation of magnocellular neurons PVN and SON – release of oxytocin from the posterior pituitary

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7
Q

Prolactin and Oxytocin both increase in response to suckling but how is their timing different?

A

Prolactin is secreted ONLY in response to suckling; oxytocin can be secreted in response to other cues also

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8
Q

Oxytocin causes contractions of what cells?

A

Myoepithelial cells

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9
Q

What are the 5 main mechanisms of milk synthesis and secretion (just the names)?

A
  1. Exocytosis of milk components
  2. Apical secretion of Ions
  3. Apocrine Secretion of Fat
  4. Transcellular secretion of immunoglobulins, proteins
  5. Paracellular passage of cells, some plasma components
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10
Q

Describe the synthesis of calcium for milk (PTH-RP, CASR)

A
  • lactating breast cells make PTH-RP = causes maternal bone to release calcium that is then pumped into the mammary cells against concentration gradient
  • calcium sensing receptor (CASR) on the breast cells regulates PTH-RP
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11
Q

Describe fat addition/synthesis in milk

A

Fat is made in mammary cells - added to milk at later feeding in response to PRL through apocrine secretion

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12
Q

What is the only ion that the mammary gland reabsorbs from milk?

A

Sodium! (milk is hypotonic with respect to plasma sodium concentration)
- alveolar cells don’t typically absorb things once they’ve been secreted into milk

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13
Q

Describe the secretion of immunoglobulins into milk

A

Alveolar cells uptake immunoglobulins through pinocytosis (transcellular transport) and exit via exocytosis

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14
Q

Describe the transport of immune cells into milk

A

Paracellular: tight junctions seal behind them, preventing the transport of non-selective things

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15
Q

Why would lactation prevent ovarian cancer?

A

Reduced number of ovulations over lifetime = less damage to ovarian surface

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16
Q

Why would lactation protect against breast cancer?

A

Lactational amenorrhea and low levels of estradiol/progesterone

17
Q

When is colostrum secreted? It’s high in?

A

1st postpartum week

High in immunoglobulins, immune cells, protein, fat-soluble vitamins, minerals

18
Q

When is transitional milk secreted? Content?

A

7 - 14 days post-partum

Increasing lactose, water-soluble vitamins, fat, total calories

19
Q

Content of mature milk

A

Rich in lipids, CHO (mainly lactose)

20
Q

How does breast milk composition change during a single feeding?

A 
Early in the feed ("fore milk"): greatest milk volume; little fat, lactose rich 
Later on ("hind milk"): greatest caloric value (when lipids are added in response to PRL)
21
Q

What are the 4 components of the breast?

A

Nipple-areolar complex, ductal system, glands, fibroadipose tissue

22
Q

From what 2 places do breast tumors arise and what percentage?

A 
Ductal epithelium (90%) 
Lobar alveolar ductal epithelium (10%)
23
Q

What is the terminal duct lobular unit (TDLU)?

A

Functional unit of milk production

- 20 - 40 lobes organized as alveoli, ducts, intralobular connective tissue

24
Q

What are the 4 steps of breast development? (no difference between genders!)

A
  1. Epithelium down-growth as primary mammary bud
  2. Branching of secondary buds stimulated by mesenchymal cells
  3. Lumen develops
  4. Luminal epithelial cells differentiate
25
Q

Roles of estrogen during breast remodeling at puberty

A

Stimulates lactiferous duct development

26
Q

Roles of progesterone during breast remodeling at puberty

A

Stimulates development of new alveolar buds

27
Q

Roles of prolactin during breast remodeling at puberty

A

Steroid hormone effects

28
Q

Changes during pregnancy regarding lobular size and fat

A

Increased lobular size

Decreased lobular fat in intralobular connective tissue

29
Q

Changes during 1st trimester regarding terminal ductules and epithelial/myoepithelial cells

A
  • terminal ductules: elongate and branch

- cells proliferate and differentiate from progenitor cells

30
Q

Changes during 2nd trimester regarding alveoli and immune cells

A
  • alveoli: differentiate from the growing ends of the terminal ductules
  • immune cells: infiltrate intralobular connective tissue
31
Q

Changes during 3rd trimester regarding alveoli, TDLU vascularity, interlobular stroma, secretory cells

A
  • alveoli: develop rER, secretory granules, lipid droplets
  • increased vascularity in TDLU
  • stroma: regresses
  • secretory cells: proliferate
32
Q

Apocrine vs. merocrine secretion

A
  • apocrine: plasma membrane forms the vesicles

- merocrine: exocytosis from secretory cells

33
Q

What are the 4 main changes that occur as the breasts begin to age during the third decade of life?

A
  1. Loss of elasticity
  2. Increased adipose tissue
  3. Few TDLUs
  4. Regression of lobules via apoptosis

Anatomy (10 decks)

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