22) Lactation Flashcards
Describe the structure of the mammary gland:
15-24 lobulated masses of tissue with fibrous and adipose tissue between lobes
Describe the structure of each lobe in the mammary gland:
Made up of lobules of alveoli with myoepithelial cells surrounding
Describe development of mammary glands in the fetus:
Invagination of epithelium forming lactiferous duct
Why does development cease until puberty?
Requires oestrogen and progesterone
Describe development of mammary glands during puberty:
Ducts sprout and branch, and alveoli begin development
What stops male mammary gland development?
Prevented by androgens (testosterone)
What are the stages of lactation?
Mammogenesis (prep of breast)
Lactogenesis (synthesis and secretion of milk from alveoli)
Galactokinesis (ejection)
Galactopoiesis (maintenance of lactation)
What changes occur to the mammary gland during pregnancy?
Hypertrophy of ductular-lobular-alveolar system
Prominent lobules form
Lumina of alveoli dilate
Alveolar cells differentiate (mid pregnancy)
What changes occur to the breast tissue near the end of pregnancy?
Nipple becomes erect
Areola enlarges
Montgomery tubercles form
Increased sensitivity
What do Montgomery tubercles produce?
Oil (lubricate and protect)
Pheromones (specific to mum)
Why isn’t much milk secreted in pregnancy?
High progesterone:oestrogen ratio, with progesterone blocking prolactin receptors
What is produced in alveolar cells for lactogenesis?
Fat (SER), protein (golgi) and sugars secreted
Why are nurse cells important?
Allow neutrophils and macrophages into alveolar lumen to protect against bacterial infections
What substance is secreted from the breast for the first few days?
Colostrum
How does colostrum compare to mature milk?
Less water, fat and sugar
More protein and immunoglobulins
Why is IgA contained in colostrum?
Coat intestinal mucosa preventing bacteria entering intestinal cells
What is the composition of mature human milk?
~90% water 7% lactose 3% fat Proteins Minerals and vitamins Endocannabinoids
What are the functions of endocannabinoids in human milk?
Stop baby suckling
Make baby sleepy
What causes pituitary prolactin secretion?
Suckling stimulates mechanoreceptors that send impulses to hypothalamus to reduce dopamine secretion, promoting prolactin release
What is the effect of prolactin?
Production of milk for next feed
How is milk production maintained?
Sufficient suckling stimulus at each feed and regular feed , every 1-3 hours
Why does milk production cease if no suckling?
Turgor induced damage to secretory cells
Describe the let down reflex:
Suckling activates hypothalamus to release oxytocin via posterior pituitary. Causes myoepithelial contraction to squeeze milk out
Give examples of events that maintain lactation:
Suckling
Crying of baby
Fondling baby
What are some mechanisms that cause lactation to cease?
Lost feedback (not enough suckling) Pain - increased turgor or infection Menstruation Suppression of prolactin Age
Why is breast feeding good?
Fewer infections in baby Bonding (oxytocin release) Less risk of breast and ovarian cancer Further contraction of uterus Weight loss
