Lactation

Question 1

Describe breast anatomy

Answer 1

• Subcutaneous fat (variable, around nipple)
• Lactiferous ducts (4-18, early branching / complex intertwining)
• Lobes (contain lobules, glandular alveoli, temporary milk storage)
• Coopers ligaments (attach breast to muscle fascia / dermis)
• Lactocytes (secretory unit, large rough ER, absorb fat soluble substances from blood)

Question 2

What is lactation

Answer 2

• Production of milk by the hormone-prepared mammary glands
• Provides milk of appropriate composition and quantity
• Fully sustain the growth and development of young until weaning

Question 3

What is secretory differentiation

Answer 3

• Breast development during pregnancy
• Lactogenic hormone complex leads to breast growth
• Oestrogen, progesterone, GF, PTH and human placental lactogen

Question 4

What is secretory activation

Answer 4

• Copious milk production / secretion after birth
• Birth of placenta leads to fall in progesterone
• Colostrum: Yellowish fluid, less lactose, no fat, rich in protein
• Mature Milk: High lactose / water, decreased protein

Question 5

What are the hormones required for lactation

Answer 5

• Permissive: Prolactin, insulin, adrenal cortisol)
• Trigger: Removal of progesterone
• Milk Ejection: Oxytocin
• Lactose synthesis determines milk volume (osmotic)

Question 6

What is the let down reflex

Answer 6

• Actual ejection of milk from the alveoli of the mammary glands, suckling of nipple involves suck, swallow, breath cycle
• Oxytocin: Triggers milk let down reflex, calming and connecting hormone
• Stimulus (suckling) causes stimulation of sensory nerves in spinothalamic tract
• Stimulate brain stem, hypo and PP causing oxytocin release
• Maternal circulation, receptor binding, myo-epithelial cell contraction
• Milk ejection

Question 7

How is milk synthesis controlled

Answer 7

• Autocrine: Supply and demand feedback
• Local: Short (hours), medium (days - weeks) and long term (weeks - months)
• Inconsistent / absence of breast feeding can lead to mastitis, sore nipples, reflux, colic, unsettled baby, low / over supply

Question 8

List the compositional factors of breast milk

Answer 8

Nutritional:
- Protein, fat, carbohydrates
- Vitamins, minerals
- Adapt to infants digestive capacity / metabolic requirements
Non-Nutritional:
- Antimicrobial factors, growth factors, cytokines, anti-inflammatory factors
- Aid digestive, hepatic, renal, visual, skeletal, endocrine, vascular, immune and CNS development

Question 9

What are digestive, renal and nervous factors of breast milk

Answer 9

Digestive:
- Enzymes, FAA, oligosaccharides
- Influence normal gut flora
- Promote gut maturation / repair and intestinal growth 
Renal:
- Less sodium, potassium and chloride
- Inability for infants to concentrate urine 
Nervous:
- Enhance brain development 
- Dose dependent effect
- Visual and motor development

Question 10

What are the immune factors of breast milk

Answer 10

Specific Defence
- Mothers response to environment
Non-Specific Defence:
- Presence of protective factors
- B12 binding protein
- Bifidus factor 
- Fatty acids (disrupt virus membrane)
- Fibronectin (activate macrophages / repair)
- Gamma-Interferon (activate immune cells)
- Lactoferrin (binds Fe)
- Lysozyme (disrupt bacteria)
- Oligosaccharide (prevent attachment of bacteria)
- B cells (antibodies)
- Macrophages (kill microbes)
- Neutrophils (phagocytes)
- T cells (kill infected cells, mobilise defences)

Question 11

What are the endocrine factors of breast milk

Answer 11

Hormones:
- Insulin, thyroxine, prostaglandins, erythropoietin
- Oxytocin, prolactin, relaxin, adrenal / ovarian steroids
Growth Factors
- EGF, IGF, HMGF
Nucleotides:
- cAMP, cGMP, AMP, ADP