9.1 Lactation

Question 1

How does the weight of the mammary gland change during lactation?

Answer 1

More than doubles

Question 2

Describe the effects of oxytocin on milk release and how it’s triggered

Answer 2

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

Question 3

What draws milk into the baby’s mouth?

Answer 3

Oral negative pressure

Question 4

Describe the changes to the breast during pregnancy and during the first few days after birth (2)

Answer 4

1. Areola darkens and grows -> visually easier for newborn 2. Breast becomes very vascous

Question 5

What are Montgomery’s tubules and what do they do?

Answer 5

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)

Question 6

When does mammogenesis begin and what happens? (3)

Answer 6

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

Question 7

What does Lactogenesis I begin and what happens? *include the two phases and specifically what rises in the plasma

Answer 7

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

Question 8

When does Lactogenesis II begin and what happens?

Answer 8

Day 3-8 postpartum

1. Continued prolactin -> increases milk content
2. Progesterone -> closes spaces btwn alveolar cells * milk content (80-90% water, the rest are sugars, fats and proteins)

Question 9

What happens to HPL and prolactin serum levels throughout pregnancy and for the duration of the breast feeding period?

Answer 9

1. Progesterone -> both slowly rise during pregnancy.
2. 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)

Question 10

What can happen to prolactin and HPL levels if the placenta isn’t completely delivered?

Answer 10

HPL levels and progesterone stay high -> inhibits prolactin -> delays lactogenesis II.

Question 11

What happens if the mother’s nipples aren’t stimulated enough in the week following birth?

Answer 11

Prolactin receptor sites close off -> -ve impact on milk production

Question 12

When does Galactopoiesis occur and what happens? (2)

Answer 12

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.

Question 13

What is the final phase of breast development? When does it occur and what happens

Answer 13

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

Question 14

Where is milk synthesized? Name the five stages of synthesis?

Answer 14

Synthesized in the alveolar cells
Stages:
1. Early colostrum
2. Late colostrum3. Early transitional4. Late transitional5. Mature milk

Question 15

What is involved in the early-late colostrum stages?

Answer 15

Increase in protein and minerals for neonate, breast preps for lactogenesis II

Question 16

When do the early-late transitional stages begin and what happens generally?

Answer 16

Lactogenesis II, milk maturation

Question 17

What is meant by the term “biological specificity of human milk”

Answer 17

It’s a complex bio fluid important for hydration and immune protection, rich in many nutrients, hormones, enzymes, GFs and protective agents

Question 18

What is colostrum? When is it produced and how is it specific to the neonate’s needs? (4)

Answer 18

Initial meal produced in lactogenesis I

1. Small quantities for immature kidneys
2. Contains maternal phagocytes
3. More protein (IgG), less water/fat/sugar
4. Laxative effect; baby suckles -> peristalsis -> clears meconium and promotes gut activity

Question 19

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

Answer 19

1. FM induces blood sugars and damages the counter-regulatory effect
2. higher energy and fluid needs -> risk of obesity
3. Higher cholesterol and risk of heart disease *breast milk has high cholesterol so body metabolizes and adjusts to cholesterol early
4. Baby cannot absorb the high quantities of iron in bovine milk (lacks lactoferrin) -> high free iron attracts bacteria

Question 20

Name 8 important nutritional and non-bio active components of breast milk

Answer 20

Acids (i.e DHA, AA), Vitamins, Anti-infective properties, Lactose, Proteins, minerals

Question 21

What is the difference between preterm milk and normal “37 week/ birth time” milk?

Answer 21

Higher anti-inflammatory and immunomodulating components, energy (fats, proteins, nitrogen, vitamins/minerals) for baby growth

Question 22

What is lactoperoxidase, cytokines and chemokines in breast milk responsible for?

Answer 22

Lactoperoxidase: kills streptococci

Cytokines and chemokines: protein signals:
Cytokines: body’s response to fever, swelling, tenderness, maternal mental health
-Chemokines: activate immune system

Question 23

Name 5 components of non-antibody antibacterial protection in human breast milk

Answer 23

1. HMOs (human milk oligosaccharides) 2. Bifidus factor3. Lactoferrin4. Lactoperoxidase5. Cytokines and chemokines

Question 24

How does the mother’s breast milk immunologically adapt to the baby after birth?

Answer 24

Saliva drawn into ducts during breastfeeding -> mRNA in saliva changes milk composition

Question 25

What triggers the hormone prolactin and what does it do?

Answer 25

Suckling -> prolactin receptors -> hypothalamus -> anterior pituitary -> prolactin -> lactocytes -> milk production

Question 26

Name 5 major bioactive components of breast milk and briefly describe each

Answer 26

1. Lipids
2. Enzymes; amylase, lipase
3. GF and Hormones; cortisol, insulin, CCK, thyroxine, prolactin, insulin-like GF
4. Whey
5. Casein

Question 27

How is prolactin secreted and when are its levels highest?

Answer 27

Pulsatile ways, highest at night

Question 28

Describe the two main inhibitory pathways for prolactin

Answer 28

1. Dopamine
2. Dopamine-agonists like PIF (prolactin inhibiting factor)

*PIF inhibited by nipple stimulation

Question 29

Why might mothers experience severe contractions in the early post-partum stage?

Answer 29

Oxytocin being released pulsatile ways to stimulate breast milk

Question 30

How do normal vs high levels of cortisol affect the mammary system?

Answer 30

Normal: regulates water transport across cell membranes in lactation.

High: -ve oxytocin (no MER) and delays lactogenesis

Question 31

How does TSH affect the mammary system?

Answer 31

Promotes mammary growth and lactation

Question 32

Describe the local feedback inhibitor of lactation

Answer 32

Compound within the milk

*so milk staying in breast inhibits lactation

Question 33

List four general health risks for infants that aren’t breastfed and three for a mother who does not breastfeed

Answer 33

Infant: Infectious disease, resp infections, diarrhea, malocclusions

Maternal: Type 2 diabetes, breast/ovarian cancer

Question 34

Identify three symptoms of postpartum depression (PPD)

Answer 34

1. Difficulty bonding with the baby (only caring out of “duty”)
2. Frightening thoughts (i.e hurting the baby)
3. Worrying something is wrong with the baby

Question 35

Identify one charity or support group that can provide advice and support for people with PPD

Answer 35

National Childbirth Trust

Question 36

Name four conditions that may significantly affect a mother’s milk supply?

Answer 36

PCOS, diabetes, hypothyroidism or hypoplasia (both/single breast hasn’t developed fully during puberty)

Question 37

What do Bifidus factors do?

Answer 37

Supports growth of lactobacillus -> creates acidic environment where harmful bacteria cannot grow

*i.e HMOs! (human milk oligosaccharides)

Question 38

Describe the lobule and alveoli tissue of the breast

Answer 38

15-20 lobules with 10-100 alveoli per lobule, lobules separated by fibrous adipose tissue (bunches of blood vessels and lactiferous ducts)

Question 39

What determines how much lactation the mother will be able to do?

Answer 39

Density of breast tissue*not size of breast

Question 40

How does the control over milk production change in lactogenesis II?

Answer 40

Hormonally controlled -> autocrine controlled *influenced under stimulation of the infant

Question 41

Milk secretion decreases when what specifically builds up?

Answer 41

Inhibiting polypeptides and raised sodium levels.

Question 42

Which element of breast milk accounts for the majority of the carbohydrates? What does it do? (2)

Answer 42

Lactose

1. Enhances calcium absorption
2. Metabolizes galactose and glucose -> brain energy