9.1 Lactation Flashcards
How does the weight of the mammary gland change during lactation?
More than doubles
Describe the effects of oxytocin on milk release and how it’s triggered
Suckling, when mother smells or sees baby -> hypothalamus -> posterior pituitary -> Oxytocin -> contracts myoepithelial cells around alveoli -> squeezes lactocytes -> milk ejection reflex
*milk flows down lactiferous ducts and out via nipple
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 1. Mammary milk glands -> breast milk 2. 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 2. Epithelial develops into-Sm muscle of nipple or areola-Those developing wards become future alveoli 3. 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 pregnancy2nd 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?
- Progesterone -> both slowly rise during pregnancy.
- Birth (expulsion of placenta) -> HPL drop, prolactin levels rise rapidly & spike when baby suckles (autocrine response) -> more milk production + entering lactogenesis II.
*Prolactin levels decrease in 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 stay high -> inhibits prolactin -> delays lactogenesis II.
What happens if the mother’s nipples aren’t stimulated enough in the week following birth?
Prolactin receptor sites close off -> -ve impact on milk production
When does Galactopoiesis occur and what happens? (2)
Day 9-breast involution (child no longer requires the breast/6-9 months).
- Maintenance of secretions
- IgG and total protein decline, fat and sugar rise to produce mature milk.
What is the final phase of breast development? When does it occur and what happens
Involution; ~40 days post partum but can take longer (i.e continued autocrine stimulation)
Demand ceases -> decreased milk secretion -> apoptosis of epithelia -> replaced by adipocytes
Where is milk synthesized? Name the five stages of synthesis?
Synthesized in the alveolar cells
Stages:
1. Early colostrum
2. Late colostrum3. Early transitional4. Late transitional5. Mature milk
What is involved in the early-late colostrum stages?
Increase in protein and minerals for neonate, breast preps for lactogenesis II
When do the early-late transitional stages begin and what happens generally?
Lactogenesis II, milk maturation
What is meant by the term “biological specificity of human milk”
It’s a complex bio fluid important for hydration and immune protection, rich in many nutrients, hormones, enzymes, GFs and protective agents
What is colostrum? When is it produced and how is it specific to the neonate’s needs? (4)
Initial meal produced in lactogenesis I
- Small quantities for immature kidneys
- Contains maternal phagocytes
- More protein (IgG), less water/fat/sugar
- Laxative effect; baby suckles -> peristalsis -> clears meconium and promotes gut activity
What is the baby at risk of if fed with formula milk?
Describe the detrimental effect formulas can have on the process of lactation*4 things
- FM induces blood sugars and damages the counter-regulatory effect
- higher energy and fluid needs -> risk of obesity
- Higher cholesterol and risk of heart disease *breast milk has high cholesterol so body metabolizes and adjusts to cholesterol early
- Baby cannot absorb the high quantities of iron in bovine milk (lacks lactoferrin) -> high free iron attracts bacteria
Name 8 important nutritional and non-bio active components of breast milk
Acids (i.e DHA, AA), Vitamins, Anti-infective properties, Lactose, Proteins, minerals
What is the difference between preterm milk and normal “37 week/ birth time” milk?
Higher anti-inflammatory and immunomodulating components, energy (fats, proteins, nitrogen, vitamins/minerals) for baby growth
What is lactoperoxidase, cytokines and chemokines in breast milk responsible for?
Lactoperoxidase: kills streptococci
Cytokines and chemokines: protein signals:
Cytokines: body’s response to fever, swelling, tenderness, maternal mental health
-Chemokines: activate immune system
Name 5 components of non-antibody antibacterial protection in human breast milk
- HMOs (human milk oligosaccharides) 2. Bifidus factor3. Lactoferrin4. Lactoperoxidase5. Cytokines and chemokines
How does the mother’s breast milk immunologically adapt to the baby after birth?
Saliva drawn into ducts during breastfeeding -> mRNA in saliva changes milk composition
What triggers the hormone prolactin and what does it do?
Suckling -> prolactin receptors -> hypothalamus -> anterior pituitary -> prolactin -> lactocytes -> milk production
Name 5 major bioactive components of breast milk and briefly describe each
- Lipids
- Enzymes; amylase, lipase
- GF and Hormones; cortisol, insulin, CCK, thyroxine, prolactin, insulin-like GF
- Whey
- Casein
How is prolactin secreted and when are its levels highest?
Pulsatile ways, highest at night
Describe the two main inhibitory pathways for prolactin
- Dopamine
- Dopamine-agonists like PIF (prolactin inhibiting factor)
*PIF inhibited by nipple stimulation
Why might mothers experience severe contractions in the early post-partum stage?
Oxytocin being released pulsatile ways to stimulate breast milk
How do normal vs high levels of cortisol affect the mammary system?
Normal: regulates water transport across cell membranes in lactation.
High: -ve oxytocin (no MER) and delays lactogenesis
How does TSH affect the mammary system?
Promotes mammary growth and lactation
Describe the local feedback inhibitor of lactation
Compound within the milk
*so milk staying in breast inhibits lactation
List four general health risks for infants that aren’t breastfed and three for a mother who does not breastfeed
Infant: Infectious disease, resp infections, diarrhea, malocclusions
Maternal: Type 2 diabetes, breast/ovarian cancer
Identify three symptoms of postpartum depression (PPD)
- Difficulty bonding with the baby (only caring out of “duty”)
- Frightening thoughts (i.e hurting the baby)
- Worrying something is wrong with the baby
Identify one charity or support group that can provide advice and support for people with PPD
National Childbirth Trust
Name four conditions that may significantly affect a mother’s milk supply?
PCOS, diabetes, hypothyroidism or hypoplasia (both/single breast hasn’t developed fully during puberty)
What do Bifidus factors do?
Supports growth of lactobacillus -> creates acidic environment where harmful bacteria cannot grow
*i.e HMOs! (human milk oligosaccharides)
Describe the lobule and alveoli tissue of the breast
15-20 lobules with 10-100 alveoli per lobule, lobules separated by fibrous adipose tissue (bunches of blood vessels and lactiferous ducts)
What determines how much lactation the mother will be able to do?
Density of breast tissue*not size of breast
How does the control over milk production change in lactogenesis II?
Hormonally controlled -> autocrine controlled *influenced under stimulation of the infant
Milk secretion decreases when what specifically builds up?
Inhibiting polypeptides and raised sodium levels.
Which element of breast milk accounts for the majority of the carbohydrates? What does it do? (2)
Lactose
- Enhances calcium absorption
- Metabolizes galactose and glucose -> brain energy
