28.6 Lactation
3 min read•june 18, 2024
Lactation is a fascinating process that transforms breasts into milk-producing powerhouses. From to nipples, each part plays a crucial role in nourishing newborns. Understanding this intricate system helps us appreciate the complexity of breastfeeding.
Breast milk isn't just one thing—it evolves to meet babies' changing needs. Starting with immune-boosting , it transitions to energy-rich . This tailored nutrition showcases the incredible adaptability of the human body in supporting infant growth.
Lactation and Breast Anatomy
Anatomy of lactating breasts
Top images from around the web for Anatomy of lactating breasts
Gland - wikidoc View original
Is this image relevant?
Gland - wikidoc View original
Is this image relevant?
Frontiers | Go with the flow—biology and genetics of the lactation cycle | Genetics View original
Is this image relevant?
Gland - wikidoc View original
Is this image relevant?
Gland - wikidoc View original
Is this image relevant?
1 of 3
Top images from around the web for Anatomy of lactating breasts
Gland - wikidoc View original
Is this image relevant?
Gland - wikidoc View original
Is this image relevant?
Frontiers | Go with the flow—biology and genetics of the lactation cycle | Genetics View original
Is this image relevant?
Gland - wikidoc View original
Is this image relevant?
Gland - wikidoc View original
Is this image relevant?
1 of 3
-
- Consist of , , and that work together to produce and deliver milk
- Alveoli
- Milk-secreting cells called synthesize and secrete milk
- Surrounded by that contract to expel milk into the ducts
- Cluster to form lobules (grapes)
- Lobules
- Each lobule contains multiple alveoli and drains into a lactiferous duct (tree branches)
- Lactiferous ducts
- Carry milk from the lobules to the
- Expand to form near the nipple for temporary milk storage (milk reservoirs)
- Nipple
- Contains the openings of the lactiferous ducts for milk delivery
- Smooth muscle fibers enable nipple erection during stimulation
-
- Pigmented area surrounding the nipple (bullseye)
- Contains that secrete lubricating fluid to protect the nipple and areola during breastfeeding
Process of milk production
- Milk production () begins when from the anterior pituitary stimulates milk synthesis in the lactocytes
- Infant suckling triggers sensory impulses from the nipple to the hypothalamus
- The hypothalamus signals the posterior pituitary to release into the bloodstream
- causes the myoepithelial cells surrounding the alveoli to contract
- Contraction of the myoepithelial cells forces milk from the alveoli into the ducts and out through the nipple (milk ejection or )
- Continued milk production () is maintained by regular breast emptying and hormonal stimulation
Breast Milk Composition
Evolution of breast milk composition
-
- Produced in the first few days postpartum (liquid gold)
- Rich in immunoglobulins, especially , to provide passive immunity to the newborn
- High in protein, low in fat and compared to mature milk
-
- Produced from day 3-14 postpartum as milk composition gradually changes
- Increase in volume and lactose content to meet the growing infant's energy needs
- Decrease in protein and immunoglobulin content as the infant's own immune system develops
- Mature milk
- Produced from day 14 onwards with a relatively stable composition
- Contains a balanced mix of nutrients (carbohydrates, proteins, fats, vitamins, minerals) to support infant growth and development
- Includes lactose as the primary carbohydrate, providing energy and promoting calcium absorption
- Contains , an iron-binding protein with antimicrobial properties
-
- Milk at the beginning of a feeding session, lower in fat content (skim milk)
-
- Milk at the end of a feeding session, higher in fat content (cream)
- Provides satiety and promotes weight gain in the infant
Common Lactation Challenges
- : Overfilling of breasts with milk, causing discomfort and potentially interfering with milk flow
Key Terms to Review (32)
Alveoli: Alveoli in the context of the ovarian reproductive system refer to the small, sac-like structures within the mammary glands where milk is produced and secreted during lactation. Each alveolus is lined with milk-producing epithelial cells and surrounded by myoepithelial cells that help expel milk into the ducts leading to the nipple.
Alveoli: Alveoli are the tiny air sacs located at the end of the respiratory tree in the lungs. They are the functional units of the respiratory system, responsible for the exchange of gases between the air and the bloodstream.
Areola: The areola is the pigmented area surrounding the nipple, typically darker than the surrounding skin. It plays a crucial role in lactation by helping to facilitate breastfeeding, as its texture and color can help guide infants to latch onto the nipple during nursing. Additionally, the areola contains specialized glands that secrete lubricating substances to keep the skin supple and protect it during lactation.
Breast Engorgement: Breast engorgement is a condition that occurs during lactation when the breasts become overly full, swollen, and painful due to an accumulation of milk, blood, and lymphatic fluid. It is a common experience for breastfeeding mothers as their milk supply increases to meet the infant's needs.
Colostrum: Colostrum is the first form of milk produced by the mammary glands of mammals, including humans, immediately following delivery of the newborn. It is rich in antibodies and essential nutrients, providing vital immune defense and nutritional support to the infant.
Colostrum: Colostrum is the first form of breast milk produced by a mother shortly after giving birth. It is a thick, yellow or golden-colored fluid that is rich in antibodies, nutrients, and other important components to support the newborn's immune system and early development.
Foremilk: Foremilk is the initial milk a nursing infant receives at the beginning of a feeding session, characterized by its lower fat content compared to the milk that follows (hindmilk). It is rich in proteins, vitamins, and minerals essential for infant health and development.
Foremilk: Foremilk is the first part of a breastfeed, which is thinner and more watery in consistency compared to the later, fattier hindmilk. It is produced at the beginning of a feeding and helps to quench the baby's initial thirst.
Galactopoiesis: Galactopoiesis is the process of maintaining and increasing milk production in the mammary glands during lactation. It involves the hormonal regulation of milk synthesis and secretion to ensure a continuous supply of milk for the nursing infant or young.
Hindmilk: Hindmilk, also known as the last milk, is the thick, creamy milk that is produced towards the end of a breastfeeding session. It is richer in fat and calories compared to the initial, more watery foremilk that is produced at the beginning of a feeding.
Lactiferous Ducts: Lactiferous ducts are the network of tubes within the breast that transport milk from the milk-producing glands to the nipple during lactation. These ducts play a crucial role in the process of lactation, allowing the efficient delivery of milk to the nursing infant.
Lactiferous sinuses: Lactiferous sinuses are specialized cavities located within the mammary glands that store milk before it is released during breastfeeding. These sinuses serve as reservoirs, allowing for a temporary holding of milk produced by the mammary glands, which is essential for efficient nursing. During lactation, when a baby suckles, the pressure stimulates the release of milk from these sinuses through the lactiferous ducts.
Lactocytes: Lactocytes are specialized epithelial cells found in the mammary glands that are responsible for synthesizing and secreting milk during lactation. They play a crucial role in the production of milk components, including lactose, lipids, and proteins, which are essential for nourishing infants. Lactocytes facilitate the process of lactation by responding to hormonal signals and working in conjunction with other cells in the breast tissue.
Lactoferrin: Lactoferrin is an iron-binding glycoprotein found in various exocrine secretions, including breast milk, saliva, tears, and other mucosal fluids. It plays a crucial role in the context of lactation, providing antimicrobial and immune-modulating properties to support the health and development of the nursing infant.
Lactogenesis: Lactogenesis is the physiological process of initiating and establishing milk production in the mammary glands. It is a critical component of the lactation cycle, allowing a mother to provide nourishment for her newborn child.
Lactose: Lactose is a disaccharide sugar found naturally in the milk of mammals. It is composed of two monosaccharides, glucose and galactose, and is an essential nutrient for the growth and development of infants and young animals.
Let-down reflex: The let-down reflex is a physiological response in lactating mothers where the nervous system stimulates milk glands in the breasts to release milk into the ducts, making it available for the infant. This reflex is triggered by hormonal signals, particularly oxytocin, in response to an infant suckling or other stimuli related to feeding.
Let-down Reflex: The let-down reflex, also known as the milk ejection reflex, is a physiological response that occurs during breastfeeding. It is a key component of the lactation process, facilitating the release of milk from the mammary glands for the infant to consume.
Lobules: Lobules are small, functional subunits found within certain organs, which help to organize and compartmentalize the tissues for specific functions. In the context of various systems, lobules play key roles, such as in the liver where they are essential for bile production and metabolism, and in the mammary glands where they are involved in milk production and secretion during lactation.
Mammary glands: Mammary glands are specialized organs in mammals responsible for producing and secreting milk to nourish newborns. They are part of the reproductive system and undergo significant changes during pregnancy and lactation.
Mammary Glands: Mammary glands are exocrine glands located in the breasts of females that produce and secrete milk for the nourishment of offspring. They are a key component of the female reproductive system and play a crucial role in the process of lactation.
Mature Milk: Mature milk is the breast milk produced by a mother after the first few weeks of lactation. It differs from colostrum, the initial milk produced shortly after birth, and transitional milk, which bridges the gap between colostrum and mature milk. Mature milk provides the primary nutrition for the growing infant during the breastfeeding period.
Milk Ejection Reflex: The milk ejection reflex, also known as the let-down reflex, is a physiological response that occurs during breastfeeding or breast pumping. It is the mechanism by which milk is released from the breast alveoli and made available for the infant to feed.
Montgomery's Glands: Montgomery's glands, also known as Montgomery tubercles, are specialized sebaceous glands located around the areola of the nipple. They play a crucial role in the context of lactation by providing lubrication and protection to the nipple and areola during breastfeeding.
Myoepithelial Cells: Myoepithelial cells are a specialized type of contractile cells found in certain exocrine glands, such as the mammary and sweat glands. They play a crucial role in the process of lactation by contracting and facilitating the expulsion of milk from the glandular tissue.
Nipple: The nipple is a small, raised, and pigmented area on the breast that protrudes from the skin. It is the primary structure involved in the process of lactation, where milk is produced and expelled from the mammary glands to nourish an infant.
Oxytocin: Oxytocin is a hormone produced in the hypothalamus and released by the pituitary gland, playing a crucial role in childbirth and lactation as well as in bonding and social behaviors. It facilitates uterine contractions during labor and helps with milk ejection during breastfeeding.
Oxytocin: Oxytocin is a hormone produced in the hypothalamus and released by the posterior pituitary gland. It plays a crucial role in various physiological processes, including homeostasis, central control, and the regulation of the endocrine system, as well as during pregnancy, labor, birth, and lactation.
Prolactin: Prolactin is a hormone produced by the anterior pituitary gland that stimulates milk production in the mammary glands after childbirth. It plays a crucial role in maintaining milk supply for breastfeeding.
Prolactin: Prolactin is a hormone produced primarily by the anterior pituitary gland. It plays a crucial role in the development and function of the mammary glands, as well as in the regulation of various physiological processes related to lactation and reproduction.
Secretory IgA: Secretory IgA (sIgA) is a specialized antibody that plays a crucial role in the immune response against pathogens and in the context of lactation. It is the predominant antibody found in mucosal secretions, such as saliva, tears, and breast milk, providing a first line of defense against invading microorganisms at these entry points into the body.
Transitional Milk: Transitional milk is the type of breast milk produced in the days following childbirth, transitioning from the initial colostrum to the mature milk that will nourish the infant. It serves as a bridge between the two stages, providing the newborn with essential nutrients and antibodies as they adjust to life outside the womb.