Breast Anatomy Flashcards
Where are the pectoral muscles located?
Between the intercostal muscles and retro glandular fat
Approx how many lobes are in each breast?
4-18 lobes
Divided by adipose tissue and connective tissue.
What is contained in the alveolus and what is their function?
Acini cells
Function: to produce milk. The acini cells are surrounded by myo-epithelial cells composed of smooth muscle that help with milk secretion.
How is milk transporting out of the breasts?
Through the ductal system which is composed of lactiferous ducts. They arise from the alveoli and unite to form larger ducts. They contain valves to encourage milk to flow out of the breasts.
How much can the nipple ducts dilate when milk is ejaculated ?
Upto 58%
Normal resting diameter is 1- 1.4 mm.
What has changed between the old and new diagram of the breasts?
1) ducts branch closer to the nipple
2) glandular tissue is closer to the nipple
3) subcutaneous fat is minimal at the base of the nipple.
At puberty, what changes occur to the breast.
Becomes a globular gland
Primary areola develope- becomes pigmented
Cyclical changes occur.
What hormones are responsible for the changes to the breast at puberty?
Oestrogen and progesterone
What changes occur to the breast during pregnancy?
4 weeks - tingling and tenderness
8 weeks - increase in size , veins prominent.
12 weeks- nipples darken, Montgomery tabernacles, secondary areola.
16 weeks- secretion of colostrum
Late pregnancy- nopples more prominent.
What hormones are responsible for changes to the breast during pregnancy ?
Progesterone- responsible for glandular development
Oestrogen - further ductal development
Placental hormone - responsible for supressing lactation.
What does suckling of the nipple trigger?
Sensory nerves impulses in the areola.
Hypothalamus in the Brain receives signals from sensory neurons and secretes oxytocin made by the neurosecretory cells. This then travels down the hypothalmohyphyseal tract into the posterior pituitary gland. Oxytocin secretes from posterior pituitary gland . Oxytocin is responsible for the the let down reflex.
Oxytocin triggers myo-epithelial cells to squeeze milk from alveoli so it drains into lactiferous ducts.
How is prolactin triggered ?
Baby sucking in nipple
Baby crying
How and where is prolactin released?
Released into the blood from.the anterior pituitary gland to the breasts.
How and where is prolactin released?
Released into the blood from.the anterior pituitary gland to the breasts.
What is the role of prolactin?
To travel to the acini cells and stimulate milk production.
Prolactin also primes receptor sites in the acini cells for the production of milk for the next feed. The more prolactin released the more milk is likely to be produced.. thus, more suckling more milk.
Unprimed sites shut down eventually, reducing potential for milk production.
