The Breast And Lactation Flashcards Preview

MIDW1002 Scientific Underpinnings of Midwifery Care > The Breast And Lactation > Flashcards

Flashcards in The Breast And Lactation Deck (15)
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1
Q

Describe the changes that happen to the breast during pregnancy?

A
  • increased vascularisation (8 weeks) -> tends to result in a marbled appearance of the skin du to the marked dilation of the superficial veins
  • thickening of nipple skin
  • tenderness of breasts, especially nipple areas due to engorgement of blood (4 weeks)
  • full development of lobules (hypertrophy)
  • dilation of alveoli and ducts
  • pigmentation of nipple and areola (12 weeks)
  • secondary areola may appear in darker skinned women
  • montgomery’s tubules become prominent
  • small quantity of clear colostrum may be expressed in latter half of pregnancy (16 weeks secretion)
2
Q

Describe the process of mammogenesis

A
  • begins in the embryonic stage by 4th week of gestation
  • primitive milk streaks from axilla to groin, this continues to thicken with inward growth to chest wall
  • 12 to 13 weeks specialised cells differentiate further into smooth muscle areola and nipple
  • epithelial cells develop into mammary buds, develop into a treelike pattern and proliferate to become alveoli
  • placental sex hormones enter fetal circulation which stimulates formation of canals which continues until the fetus is 32 weeks
  • from then lobular alveolar structures containing colostrum develop
    • > fetal mammary glands increase 4 times in mass
    • > nipple and areola develop further and pigment
  • after birth neonates mammary tissue may secrete colostral milk
3
Q

Describe the structure of the breast

A
  • extends from 2nd-6th rib tail of breast into axilla
  • glandular cells
  • ducts
  • adipose tissue
  • connective tissue
  • divided into lobes (15-20) by fibrous septae run from behind nipple to pectoral muscle
    • > connections between lobes present
  • attaching deep layer of subcutaneous tissue to skin are the suspensor ligaments or coopers ligament
4
Q

Describe the structure of the nipple

A
  • the nipple is at the centre, ducts open into the nipple but approx 9 open onto surface
  • areola surrounds nipple and both contain erectile tissue
  • within areolar are montgomerys tubercles which consist of milk glands and sebaceous glands (together known as areolar glands)
  • glandular tissue is arranged in a ductal alveolar system (4- 18 per breast)
  • grouped in grapelike lobules around branching system of ducts which join to form main lactiferous duct leading to nipple
  • lactiferous ducts dilate into the ampulla
5
Q

Describe the breast fatty tissue

A
  • the external shape or size of the breast is not predictive of its lactation potential
  • the ratio of glandular tissue to fat tissue rises to 2:1 in the lactating breast compared to a 1:1 ratio in non lactating women
  • 65% of the glandular tissue is located within 30mm from the base of the nipple
  • between 4 and 18 milk ducts are exiting the nipple
  • the network of milk ducts is complex not homogenous, it is not always arranged symmetrically nor in a radial pattern
  • the milk ducts near the nipple do not act as reservoirs for milk
6
Q

What are acini cells?

A
  • alveoli contain acini cells which produce milk

- the acini cells are surrounded by myoepithelial cells which contract an propel milk along the ducts

7
Q

What happens when an infant breastfeeds?

A
  • when an infant breastfeeds, the infant draws the nipple and areola into their mouth
  • the mothers nipple elongates to about twice its normal length
  • the nipple height is compressed between the tongue and the palate
  • milk is ejected about 0.03 seconds per maximum nipple elongation
  • suckling infants compress the areola with their gums which stimulates oxytocin release
    • -> the oxytocin release causes an increase in the diameter of the milk ducts and movement of milk in the ducts toward the nipple
  • mothers may feel a sensation of pins and needles or pressure in he breast with milk ejection
8
Q

Describe the action of prolactin

A
  • it is produced in the anterior pituitary gland and released into circulation
  • regulation of prolactin levels in the plasma is controlled by the dopaminergic system
  • prolactin acts on the human breast to produce milk
    • > occurs by binding to mammary epithelial cell receptors
    • > stimulates synthesis of mRNA of milk proteins
  • takes several minutes of infant suckling to cause prolactin secretion
  • prolactin is also important in inhibiting ovulation
9
Q

Describe the action of oxytocin

A
  • it is produced by the posterior pituitary gland (neurohypophysis)
  • suckling at the breast stimulates the posterior pituitary to produce and release oxytocin in an intermittent manner
  • oxytocin acts on the breast to produce milk ejection or ‘milk let down’
  • oxytocin also causes uterine contractions
  • opiates and B endorphins released during stress can block the release of oxytocin
10
Q

What is FIL?

A
  • it is feedback inhibitor of lactation
  • recently described active whey protein which inhibits milk production in a full breast
  • FIL seems to play an important role in regulation of milk supply
  • FIL acts locally on each breast -> it is secreted into breast milk
  • when the breast is not emptied FIL remains in contact with the alveolar cells
  • FIL appears to act on an apical receptor on the alveolar cell
    • > this inhibits secretion of milk constituents
11
Q

Describe the process of lactogenesis for breast milk production

A
  1. Mammogenesis -> breast growth increased
    - > proliferation of ducts and glands under influence of oestrogen and progesterone
  2. Lactogenesis 1 -> initiation of milk synthesis mid pregnancy
    - > differentiation of alveolar cells from secretory cells
    - > prolactin stimulates secretory cells to produce milk
  3. Lactogenesis 2 -> closure of tight junctions in alveolar cell - triggered by drop in progesterone levels
    - > onset of copious milk secretion
    - > switch from endocrine to autocrine control
    - > fullness and warmth in breasts
  4. Galactopoiesis (day 9 beginning of involution)
    - > Maintenance of secretion
    - > control by autocrine system (supply and demand)
    - > breast size decreases between 6-9 months Postpartum
  5. Involution (average 40 days after last breastfeed)
    - > decreased milk secretion from build up of inhibiting peptides
    - > high sodium levels
12
Q

What are the essential hormone changes for successful lactation?

A
  • drop in progesterone
  • release of prolactin from anterior pituitary
    • > stimulates Lactogenesis
    • > initiates milk secretion
  • removal of breast milk by infant
  • release of oxytocin from posterior pituitary
13
Q

Describe progesterones role in breastfeeding

A
  • lactation in pregnancy is inhibited by high levels of progesterone
    • > it interferes with prolactin action at alveolar cell receptor level
  • progesterone falls by about 10 times during the first 4 days
14
Q

Describe prolactins role during lactation

A
  • it follows a circadian rhythm - levels are higher at night than during the day
  • levels decline slowly over course of lactation but remains elevated as long as she breast feeds
  • prolactin rises with suckling - the more feeding the higher the prolactin levels
  • prolactin not related to milk yield especially after lactation is established
  • delays return of ovulation by inhibiting ovarian response to FSH
  • prolactin drops with cigarette smoking
  • rises with anxiety and stress
  • depressed mothers have lower serum prolactin
15
Q

Describe oxytocin’s role in breastfeeding

A
  • in response to suckling the posterior pituitary releases oxytocin
    • -> it causes milk ejection reflex
    • -> it also causes contracting of myoepithelial cells surrounding the alveoli, which is necessary for the removal of milk from the breast
  • it is released in pulsatile waves and carried through the bloodstream to the breast
    • -> here it interacts with receptors on myoepithelial cells causing contractions
    • -> this forces milk from alveoli into the ducts where it becomes available to the newborn
  • oxytocin plays a role in continuance of breastfeeding
  • levels rise within a minute of stimulation
  • contracts uterus
  • has peripheral effects increasing blood flow
  • increased thirst
  • breast massage increases levels