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Scientific Basis of Midwifery > Lactation > Flashcards

Lactation Flashcards

1
Q

Describe the basic anatomy of the breast

A
  • Alveoli surrounded by fat
  • Ducts branch right to the end of the nipple
  • Glandular tissue lies very close to the nipple
  • Subcutaneous fat is minimal at the base of the nipple
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2
Q

What are the 4 stages of breast growth and development?

A
  1. Mammogenesis - the period of development from conception, through puberty and into pregnancy
  2. Lactogenesis I & II - transition from pregnancy to lactation - neuroendocrine response
  3. Galactopoiesis - maintenance of established milk production - autocrine response
  4. Involution - process that removes the milk producing cells on weaning
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3
Q

Describe the development of breasts during embryogenesis

A
  • Development begins at 4 weeks gestation for males and females
  • Week 12-16 = development of nipples and areola
  • Lactiferous ducts open into mammary pit which elevates to become the nipple and areola
  • No further development until puberty
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4
Q

Describe the development of breasts during puberty

A
  • Increasing levels of oestrogen and progesterone lead to growth of lactiferous ducts, alveoli, the nipple and areola
  • Increase in breast size caused by deposition of adipose tissue
  • Oestrogen and pituitary factor influence breast growth with proliferation of milk ducts
  • Progesterone stimulates alveolar development
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5
Q

Describe the development of breasts in week 3-4 of pregnancy

A
  • Prickling, tingling sensation, particularly around the nipple
  • Caused by increased blood supply
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6
Q

Describe the development of breasts in week 6-8 of pregnancy

A
  • Oestrogen promotes growth of lactiferous ducts
  • Progesterone, prolactin and hPL levels lead to proliferation and enlargement of alveoli
  • Veins become visible
  • Increase in size and become painful, tense and nodular due to hypertrophy of alveoli
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7
Q

Describe the development of breasts in week 8-12 of pregnancy

A
  • Montogmery’s tubercles become more prominent on areola
  • Pigmented area around nipple (primary areola) darkens, may enlarge and become more erectile
  • Caused by hypertrophic sebaceous glands secreting sebum which keeps nipple soft and by increased melanin activity
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8
Q

Describe the development of breasts in week 16 of pregnancy

A
  • Colostrum produced (lactogenesis I) due to prolactin and hPL
  • Complete milk production suppressed by oestrogen and progesterone
  • Secondary areola develops with further extension of pigmented area, causing a mottled appearance
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9
Q

Describe the development of breasts in week 24 of pregnancy

A
  • Colostrum may leak

- Nipples become more prominent and mobile due to progesterone

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10
Q

What is an epulis?

A

A specific angiogranuloma which can be caused by advanced gingivitis

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11
Q

What is leptin?

A

A peptide hormone secreted by placental and adipose tissue that plays a key role in regulation of body fat and energy expenditure

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12
Q

What is the first indication that a woman is pregnant?

A

Breast changes

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13
Q

Which hormones are involved in breast changes during pregnancy?

A
  • Progesterone
  • hPL
  • Prolactin
  • Oestrogen
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14
Q

Outline the major changes that occur to the breasts in pregnancy

A
  • Skin appears more thin/ translucent
  • Veins become more prominent
  • Areola diameter increases and nipple/areola become darker
  • Nipples become more erect
  • Ductal system proliferates (oestrogen)
  • Lobes, lobules and alveoli increase in size (progesterone)
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15
Q

Describe what happens to the Montgomery’s tubercles during pregnancy

A
  • Enlarge
  • Combination of sebaceous glands and mammary milk glands
  • Secretions provide maternal protection from mechanical stress of sucking and pathogenic invasion
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16
Q

How is the milk brought into the ducts?

A
  1. Stimulation of nipples initiates milk ejection via initiation of nerve impulses to the hypothalamus
  2. This stimulates posterior pituitary gland to release oxytocin into blood
  3. This causes myoepithlial cells surrounding alveoli to contract, forcing milk into ducts
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17
Q

Outline what occurs in lactogenesis I

A
  • Occurs during 2nd part of pregnancy and lasts until 2 days postpartum
  • Initiation of milk synthesis
  • Prolactin stimulates milk (colostrum) production as we all increasing breast mass
18
Q

Outline what occurs in lactogenesis II

A
  • Occurs day 3-8 postpartum
  • Triggered by delivery of placenta which causes rapid drop in progesterone levels, oestrogen, hPL and PIF
  • Onset of copious milk secretion
  • Retained placenta can inhibit milk production because hormone levels don’t drop
19
Q

What does PIL stand for?

A

Prolactin Inhibiting Factor

20
Q

What does hPL stand for?

A

Human Placental Lactogen

21
Q

How are the alveoli adapted for lactation?

A
  • Contain acini cells which produce milk

- Surrounded by myoepithlial cells which contract and propel the milk out

22
Q

What is the purpose of the lactiferous ducts?

A
  • Carry milk to alveoli
  • Several large ducts = Lactiferous tubules (emerge on nipple surface)
  • Myoepithlial cells lie longitudinally along ducts and, under influence of oxytocin, these smooth muscle cells contract and tubule becomes shorter and wider - called the let down reflex
  • Tubule distend during active milk flow while myoepithelial cells maintain state of contracting
  • Fuller breast = greater ductal distension
23
Q

What does distend mean?

A

Swell or cause to swell by pressure from inside

24
Q

What happens as lactation progresses?

A
  • Prolactin response to suckling diminishes and milk removal becomes driving force behind milk production
  • Due to whey proteins in milk able to inhibit synthesis of milk constituents
  • Protein accumulates in breast as milk accumulates and exerts negative feedback control on continued milk production
  • Removal of this autocrine inhibitory factor by removing milk allows milk production to increase again; this is the Feedback Inhibitor of Lactation
25
Q

What is the role of progesterone?

A
  • Most is secreted from placenta
  • Maintains pregnancy
  • Inhibits lactation
  • Lactogenesis II is triggered by decrease in progesterone levels
26
Q

Where is prolactin released from?

A

Anterior pituitary gland

27
Q

What are the main functions of prolactin?

A
  • Acts on alveoli
  • Essential for initiating and maintaining milk production
  • Production influenced by nipple sensation
  • Involved in suppression of ovulation, so BF mothers less likely to get pregnant
28
Q

What is Circadian rhythm?

A

Prolactin levels are higher at night

29
Q

What causes the prolactin levels to rise and fall?

A
  • Frequency, intensity and duration of feed
  • Always a baseline level present
  • Increases with anxiety/ psychological stress and beer drinking
  • Decreases with smoking
30
Q

What happens if too many feeds occur in 1 day (8 feeds)?

A

Prevents decrease in prolactin concentration between feeds

31
Q

How long do prolactin levels stay high for if BF is delayed?

A

1 week

32
Q

Describe the relationship between feeding frequency and milk output

A

Frequent feeding in early lactation stimulates faster increase in milk output due to development of more prolactin receptors in response to suckling

33
Q

Describe the Prolactin Receptor Theory

A
  • Receptor sites need to be activated
  • Number of receptors per cell increases in early lactation, then remains constant
  • People with small number of prolactin receptor sites may not produce enough milk
  • Number of receptor sites switched on depends on prolactin levels
34
Q

What are milk-secreting cells called?

A

Lactocytes

35
Q

Describe the bell curve distribution of prolactin receptor sites

A
  • Small population have few prolactin receptor sites
  • Small population have loads of prolactin receptor sites
  • Majority have an average number of prolactin receptor sites
36
Q

Where is oxytocin produced?

A

Posterior pituitary gland

37
Q

What is the milk ejection reflex?

A

Oxytocin acting on myoepithelial cells, causing them to contract

38
Q

Describe the effects of oxytocin

A
  • Role in the continuance of BF
  • During suckling, released in discrete impulses
  • Levels rise with a minute of stimulation, returning to baseline level within 6 minutes after feed finishes
39
Q

What effect does oxytocin have on the mother’s emotions?

A
  • Has calming effect
  • Perceived that stress levels are lower in mothers who BF
  • Nipple sensation appears to have no influence to oxytocin levels
  • Associated with ‘love, labour and lactation’
40
Q

What positive effects does skin to skin contact have?

A
  • BF incidence at 1-3 months
  • BF duration
  • Maintenance of infant temp
  • Infant blood glucose
  • Infant crying
41
Q

Explain the endocrine vs. autocrine action in breastfeeding

A
  • The shift in lactation from hormonal control to being driven by milk removal
  • BF not major factor in initiating lactation but is essential for continuation of lactation
42
Q

Describe the Feedback Inhibitor of Lactation

A
  • Autocrine feedback mechanism
  • Locally controls milk synthesis
  • Presence of FIL in milk inhibits milk synthesis - slows milk production when breast is full
  • Protein accumulation exerts negative feedback control on continued milk production
  • Demand and supply

Scientific Basis of Midwifery (22 decks)

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