University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2022
Views:

485

Pages:

5
Author:

Deandre Simmons

The Breasts • Breast tissue overlays the pectoralis major muscle. • Suspensory ligaments attach breast tissue to skin and muscle. • Size of breasts is mostly due to fat tissue, not the amount of glandular tissue. • If nonlactating, glandular tissue is reduced. • Glandular tissue consists of acini that drain into lactiferous ducts that come to confluence at lactiferous sinuses at the nipple. • Nipple is surrounded by the areola (colored zone) – melanocytes of areola (and other skin) may darken during pregnancy due to elevated estrogen levels. Anatomy of a Lactating Breast Development of Mammary Glands • Lactation = synthesis of milk from mammary glands. • Estrogen during pregnancy cause ducts to grow and branch. • Progesterone stimulates budding and development of the acini that produce milk. • Prolactin stimulates milk production after birth. • Oxytocin triggers milk ejection from breast tissue during nursing. Breast Milk • Colostrum – first milk produced after delivery of the baby – contains less fat than the milk that comes after a few days – contains abundant immunoglobulins (especially IgA) that boost the baby’s immunity • Colostrum and breast milk have a laxative effect that clears intestine of meconium (green, bile-rich fecal material in newborn). • Nursing colonizes the baby’s intestine with beneficial bacteria obtained from the breast skin. • Nursing woman can produce 1.5L of milk per day. • Only 5-10% of women become pregnant again while nursing because nursing inhibits GnRH and reduces ovarian cycling. • Cow’s milk is significantly different than human milk: – Cow’s milk has about 3 times more protein which makes it harder to digest. – Difficult digestion leads to more nitrogenous waste in urine and feces (which can cause worse diaper rash because there is more for bacteria to feed on). Breast Cancer • Affects 1 out of every 8 American women. • Tumors usually begin with cells from mammary ducts and may metastasize by way of lymphatics. • Symptoms may include a palpable lump, skin puckering, change in skin texture or drainage from the nipple. • Most breast cancer is nonhereditary – some forms are stimulated by estrogen • Risk factors include aging, ionizing radiation, carcinogenic chemicals, alcohol abuse, smoking, high fat intake. • However, as many as 70% of cases lack identifiable risk factors.