Describe the physiology of lactation Flashcards
Discuss :
* the pregnancy related hormones and relevant feedback mechanisms.
* Lactogenesis is the onset of milk production.
Lactation is the process of milk production and secretion by the mammary glands in the breast. It is driven by a complex interplay of pregnancy-related hormones and feedback mechanisms that prepare the body for breastfeeding.
Pregnancy-Related Hormones and Feedback Mechanisms
Prolactin: During pregnancy, the hormone prolactin (released by the anterior pituitary gland) stimulates the alveolar cells in the mammary glands to begin milk production (lactogenesis). Although high levels of progesterone and estrogen during pregnancy inhibit full milk production, after birth, when these hormones drop, prolactin becomes the dominant hormone promoting lactation.
Oxytocin: The hormone oxytocin, released by the posterior pituitary gland, plays a key role in the let-down reflex, which is responsible for ejecting milk from the alveoli into the ducts. This hormone is released in response to the baby suckling at the breast.
Progesterone and Estrogen: During pregnancy, progesterone supports the development of the mammary alveoli, while estrogen promotes ductal growth. However, their levels fall dramatically after childbirth, allowing prolactin to act more effectively in milk production.
Lactogenesis: Onset of Milk Production
Lactogenesis I begins in mid-pregnancy, with the breasts producing small amounts of colostrum (a nutrient-rich first milk). This phase is hormonally controlled, with high progesterone and estrogen levels preventing full milk secretion.
Lactogenesis II occurs after birth, typically between 24 to 72 hours postpartum, when milk secretion begins in earnest. The fall in progesterone levels after the placenta is delivered allows prolactin to initiate copious milk production.
Lactogenesis III involves the maintenance of milk production, which is regulated by supply and demand. Milk removal through suckling stimulates continued milk production.
Discuss the physiology of the breast and the role that this plays in milk production and feeding.
Physiology of the Breast and its Role in Milk Production and Feeding
Mammary glands consist of alveoli, which are clusters of milk-secreting cells. The alveoli are surrounded by myoepithelial cells that contract in response to oxytocin, forcing milk into the ducts.
Milk flows through the lactiferous ducts toward the nipple, from where it is transferred to the baby during breastfeeding. The anatomy of the breast, including the size and number of lobes and ducts, does not significantly affect a woman’s ability to breastfeed.
Discuss both the rooting reflex of the baby and the ‘let down reflex’ and stimulus to this.
Rooting Reflex of the Baby and the Let-Down Reflex
Rooting Reflex: The rooting reflex is a natural reflex in newborns where the baby turns its head toward a touch on the cheek and opens its mouth in search of the breast. This reflex helps the baby locate the nipple and initiate breastfeeding.
**Let-Down Reflex: **The let-down reflex is triggered by the baby’s suckling, which sends signals to the hypothalamus, stimulating the release of oxytocin. This causes the myoepithelial cells around the alveoli to contract, pushing milk through the ducts and into the nipple for the baby to feed. This reflex can also be stimulated by emotional cues, such as hearing the baby cry.
Discuss the nutritional, immunological and developmental benefits of breastfeeding in
detail.
Immunological Benefits of Breastfeeding
Antibodies and Immune Cells: Breast milk contains antibodies, immune cells, and antimicrobial factors that protect the infant from infections. The immunoglobulin A (IgA) in breast milk coats the baby’s intestinal lining, preventing harmful pathogens from entering the bloodstream.
Lower Risk of Illnesses: Studies show that breastfed babies have a lower risk of respiratory infections, gastrointestinal diseases, otitis media, and allergies. The immune-modulating properties of breast milk contribute to the development of the baby’s immune system, reducing the risk of long-term conditions such as asthma and eczema.
Developmental Benefits of Breastfeeding
Cognitive Development: Breastfeeding has been linked to improved cognitive outcomes in children. The presence of docosahexaenoic acid (DHA), an omega-3 fatty acid found in breast milk, is essential for brain development.
Bonding: Breastfeeding fosters emotional bonding between the mother and infant due to the physical closeness and skin-to-skin contact.
**Oral and Dental Health: **Breastfeeding promotes proper jaw development and reduces the risk of malocclusions (misalignment of teeth and jaws) compared to bottle-feeding.
Discuss the nutritional properties of infant formula and when it is indicated.
Nutritional Properties of Infant Formula
Infant formulas are designed to mimic the composition of breast milk, though they lack some of the immune-protective properties.
**Macronutrients: **Formula provides a balance of carbohydrates (typically lactose or corn syrup solids), fats, and proteins. However, the protein composition in formula is generally derived from cow’s milk or soy, which may not be as easily digested as breast milk.
Fortification: Many formulas are fortified with iron, vitamin D, DHA, and arachidonic acid (ARA), which are important for growth and development. However, formulas lack live antibodies and immune-modulating factors found in breast milk.
Specialty Formulas: Some infants may require specialized formulas, such as hydrolyzed formulas for those with cow’s milk protein allergies or soy-based formulas for those who cannot tolerate dairy-based products.
When Formula is Indicated
Formula feeding is necessary or preferred in certain situations:
Insufficient Breast Milk Supply: Some mothers may struggle with milk supply, necessitating supplementation.
Medical Conditions: Certain conditions, such as galactosemia, require the avoidance of breast milk. Additionally, HIV-positive mothers may be advised to use formula in certain settings to avoid transmitting the virus through breast milk.
**Personal Preference or Convenience: **Formula feeding allows for shared feeding responsibilities and may be chosen for convenience or if breastfeeding is not feasible.
Compare and contrast the nutritional and related aspects of breastfeeding
versus formula feeding
Comparison Summary
**Breastfeeding **provides optimal nutrition, immune protection, and cognitive and emotional benefits, with tailored nutrition that adjusts to the infant’s needs.
Formula feeding provides a safe alternative when breastfeeding is not possible or desired, though it lacks the antibodies and immune benefits present in breast milk.
