Case 14- Breasts and STI's Flashcards
Mammogenesis
Growth and development of the breast
Lactogenesis
Functional changes to allow for milk secretion
Galactopiesis
Maintaining milk production
Involution
Termination of milk production
The 4 hormones involved in Mammogenesis
- Oestrogen- growth and branching of the ductal system (where milk is stored). Increases fat storage in stroma, inhibition of milk production
- Progesterone- produced by the placenta, involved in the growth and increased number of alveolar cells. Where milk is produced
- Human Placental Lactogen (hPL)/Prolactin- hPL is produced by the placenta, prolactin is secreted by the pituitary gland. Both cause the development of secretory characteristics in alveolar cells. Allows milk components to be released by exocytosis when required.
Visible changes to the breast during pregnancy
The breast enlarges due to alveolar lobule formation, subcutaneous veins also enlarge. The areolar darkens and the Montgomery glands produce lipoid fluid to moisturise the nipple.
2 stages of Lactogenesis
- Stage 1- secretory differentiation, when the glands become sufficiently differentiated to secrete colostrum. Occurs in mid pregnancy till a few days after birth, it is triggered by a reduction in oestrogen and only a few mls is released. Colostrum production increases after birth till its replaced by mature milk
- Stage 2- Secretory activation, the onset of mature milk secretion. It is 3-8 days after birth. It is triggered by a reduction in Progesterone and volume increases to 0.75-1L. Prolactin stimulates milk production in the alveoli.
Galactopoiesis
Milk production is initially dependent on Prolactin. From 9 days following birth, production of milk is under autocrine control, continued milk production depends on regular milk removal. There is continuous secretion of milk in the alveoli, if the milk isn’t removed there is accumulation of the feedback inhibitor of lactation and an increase in intramammary pressure. The feedback inhibitor regulates the amount of milk produced so its dependent on the infants needs. When the milk is removed the inhibitor is removed.
Galactokinesis- milk ejection
Oxytocin stimulates milk ejection. When the infant suckles the nipple the touch sensitive mechanoreceptors are stimulated in the nipple. The sends nerve signals via the intercostal nerves to the dorsal root ganglion and then to the Hypothalamus. Oxytocin is made from Hypothalamic paraventricular cells and is secreted from the posterior pituitary gland into the blood stream and causes contraction of myoepithelial cells in the mammary glands. Pushes milk down the lactiferous duct and out through the nipple.
Cause of onvolution in the breast tissue
Alveolar cells shrink and loose their secretory function due to an accumulation of inhibitory peptides. Occurs when the feedback loop described above stops and the baby stops suckling. Normally starts 40 days after last breastfeeding. Epithelial cells no longer require their secretory function so are removed by apoptosis and required by adipocytes.
Variety in breast milk
The longer the intervals between feeds, the lower that fat content. The longer the baby suckles, the more fat and less lactose sugar in the feed. The fact content peaks mid-morning and is lowest overnight.
Composition of Colostrum
Primary role may be immunological not nutritional. It contains higher amounts of white blood cells and antibodies, especially IgA which coats the lining of the infants immature intestine. High concentration Protein, growth factors, antimicrobial products and electrolytes. There are low concentrations in fat and carbohydrate
Difference in mature breast milk
Produced in large volumes and predominantly nutritional role. High concentrations of carbohydrates (especially lactose), fat. Low concentration of proteins, growth factors, antimicrobial products, electrolytes. The composition of breast milk is dynamic and varies with feeding and over the lactation period
Composition of breast milk
- Proteins- over 400 different proteins. Low casein fraction. High soluble whey fractions i.e. immunoglobulins, lactoferrin and lysozyme. Maternal antibodies- most important secretory IgA.
- Carbohydrate- high lactose, Human milk oligosaccharides (HBO)- prebiotics they function to nourish gut microbiota.
- Fats- major energy source (50%), mainly triglycerides, carry fat soluble vitamins, fat content increases through feed
- Vitamins and minerals- low concentration of these, including iron, efficiently absorbed
Breastfeeding benefits
- Infant- species specific and can be adapted to meet the needs of the baby. Reduces morbidity and mortality from some infectious diseases i.e. respiratory infections. Reduced rates of SIDS
- Mother- reduces uterine bleeding, reduces risk of breast cancer, reduces rate of ovarian cancer, improves birth spacing due to lactational amenorrhoea
Difference in composition between breast milk a
1) Breast milk has low concentrations of vitamin D.
2) There is less efficient absorption of the components of formula milk.
3) Formular milk might not provide the right type of macronutrients and lacks in variety, in fats formula milk lacks DHA, cholesterol and lipase.
Problems with breast feeding
- Not enough milk being produced- the infant struggles
* Too much milk being produced
What makes a bad latch
A poor latch could be due to Cleft lip/palate or Tongue tie (Ankyloglossia) where there is unusually short/thick lingual frenulum. Sore or cracked nipples can be caused by a poor latch, this can cause a fistula
