9.1: Breastfeeding and Human Lactation Flashcards
How does the weight of the mammary gland change during lactation?
More than doubles
Describe how milk is released from alveoli including the stimulant involved
Oxytocin -> contracts myoepithelial cells around alveoli -> squeezes lactocytes -> triggers milk production -> flows down lactiferous ducts and out via nipple
*presence of prolactin is required for milk production
What draws milk into the baby’s mouth?
Oral negative pressure
Describe the changes to the breast during pregnancy and during the first few days after birth (2)
- Areola darkens and grows -> visually easier for newborn
2. Breast becomes very vascous
What are Montgomery’s tubules and what do they do?
Little lumps surrounding the areola, ‘Brail for the newborn’.
Has
- Mammary milk glands -> breast milk
- Sebaceous glands -> fluid smells/tastes like amniotic fluid (familiar for infant)
When does mammogenesis begin and what happens? (3)
4 weeks gestation..
1. Fetus develops 2 milk streaks from axilla -> groin -> becomes the ‘mammary ridge’; a thickening of epithelial cells
- Epithelial develops into
- Sm muscle of nipple or areola
- Those developing wards become future alveoli - Born with few ducts but breast tissue grows at puberty and with each ovulation
* duct branches develop buds under the influence of estrogen and progesterone
What does Lactogenesis I begin and what happens?
*include the two phases and specifically what rises in the plasma
1st phase - proliferation/hypertrophy of ductal-lobular-alveolar system at pregnancy
2nd phase - secretion from 16wks-post natal day 2
- alveoli accumulate colostrum
- breast, areola and nipple size increase
- fat droplets accumulate in alveoli cells Plasma lactose and alpha lactalbumin rise during this phase
When does Lactogenesis II begin and what happens?
Day 3-8 postpartum
- Continued prolactin -> increases milk content
- Progesterone -> closes spaces btwn alveolar cells
- milk content (80-90% water, the rest are sugars, fats and proteins)
What happens to HPL and prolactin serum levels throughout pregnancy and for the duration of the breast feeding period?
- Both slowly rise (due to progesterone) during pregnancy.
- Birth (expulsion of placenta) induces an HPL drop, prolactin levels rise rapidly but spike when the baby suckles (autocrine response).
This increase in prolactin levels leads to the body producing more milk and entering lactogenesis II. (Prolactin levels decrease in the months following birth but rise again whenever the baby suckles (autocrine response))
What can happen to prolactin and HPL levels if the placenta isn’t completely delivered?
HPL levels and progesterone continues to be present which inhibits prolactin - this can cause a delay in lactogenesis II.
What happens if the baby’s mother’s nipples aren’t stimulated enough in the week following giving birth?
Prolactin receptor sites start to close off which impacts the mother’s milk producing capability for the breast feeding period
When does Galactopoiesis occur and what happens?
Day 9 to breast involution (child no longer requires the breast/6-9 months). Here there is primarily maintenance of secretions, IgG and total protein decline while fat and sugar rise to produce mature milk.
What is the final phase of breast development and what happens? When does it typically occur?
*hint; milk secretion decreases when what builds up?
Involution; decrease in milk secretion as demand ceases and causes apoptosis of epithelia cells which is replaced by adipocytes. Milk secretion decreases in the buildup of inhibiting polypeptides and raised sodium levels. Typically starts around 40 days post-partum but can take longer (i.e continued autocrine stimulation)
How and where is milk synthesized (include the organelles involved)? What are the 5 stages of synthesis?
Synthesized in the alveolar cells
- Fat produced in smooth ER
- proteins secreted by golgi
- sugars synthesized and then secreted
Stages:
- Early colostrum
- Late colostrum
- Early transitional
- Late transitional
- Mature milk
What is involved in the early-late colostrum stages?
First few days where neonate needs richer protein levels and minerals but have lower carbs, citrates, lactose and glucose
Next 24-48 hours there’s a sudden increase in these components as breast prepares for lactogenesis II
What happens in the early-late transitional stages?
Begins with lactogenesis II, early transitions gradually to late in the next 1-2 weeks until milk becomes mature. Starts rapidly and gradually slows, but the changes are also unique to individual mothers (i.e can be impacted by individual conditions, etc)
What is meant by the term “biological specificity of human milk”
Breast milk is a complex bio fluid important for hydration and immune protection, rich in many nutrients, hormones, enzymes, GFs and protective agents
What is colostrum and when is it produced? How much is produced in one day? Describe three of its effects
Colostrum is the initial meal produced in lactogenesis I in small quantities to enable the immature kidneys to cope; 37 ml/day
- Contains maternal phagocytes
- Less water, fat and sugar but has more protein (particularly immunoglobulins).
- Has laxative effect; as when the baby suckles it triggers peristalsis which helps clear meconium and promotes gut activity.
Describe the detrimental effect formulas can have on the process of lactation
*4 things
- Induces blood sugars and damages the counter-regulatory effect (colostrum much more effective than formula milk)
- A breastfed preterm infant has much lower energy and fluid needs than a formula-fed infant - forms the basis of the risk for obesity if the baby isn’t breastfed
- Lower cholesterol levels when older and lower risk of heart disease; since there’s a lot of cholesterol in breast milk it enables the body to metabolize and become used to high cholesterol levels early on
- Since bovine (cattle) milk lacks lactoferrin manufacturers will add high quantities of iron, but the infant is unable to absorb more than ~7% without lactoferrin. This leads to an abundance of free iron floating in the infant blood if they have formula and iron attracts bacteria
Name 8 important nutritional and non-bio active components of breast milk? Briefly describe each
Which element accounts for the majority of the carbohydrates?
- Acids (i.e DHA, AA) which are both important for vision and cognitive function)
- Vitamins (water-soluble increases lactation and fat-soluble decreases)
- Anti-infective properties: most constituents influenced genetically and epigenetically. Known as white blood and cannot be replicated
- Lactose (accounts for the majority of carbohydrates), enhances calcium absorption, metabolizes galactose and glucose supplying energy to rapidly growing brain. Its present in infant’s gut but these levels reduce over time (a certain level of lactose intolerance as they grow older)
- Proteins; some for digestion and immunological processes
- Mineral content; All are generally static except Mg which is high in the first few days and then drops and remains static
What is the difference between preterm milk and normal “37 week/ birth time” milk that the mother produces? How does the mother’s milk adapt to the baby’s time of birth?
A mother’s milk is specifically designed for the baby at its time of gestation (and can’t be replicated)
Has much higher anti-inflammatory and immunomodulating components (although these are always present in breast milk)
Higher in energy (fats, proteins, nitrogen, vitamins/minerals) to ensure the baby can grow.
How is active and passive immunity attained for the fetus *3 things
Placenta, GALT and BALT (gut and bronchus-associated lymphoid tissue)
What is lactoperoxidase, cytokines and chemokines in breast milk responsible for?
Lactoperoxidase: kills streptococci
Cytokines and chemokines: protein signals
- Cytokines: responsible for body’s response of fever, swelling and tenderness, thought to be the reason breastfeeding has a positive affect for maternal mental health
- Chemokines: activate the immune system
Name 5 components of non-antibody antibacterial protection in human breast milk
- HMOs (human milk oligosaccharides)
- Bifidus factor
- Lactoferrin
- Lactoperoxidase
- Cytokines and chemokines
