Lecturen 5: Parturition & Lactation & Reading Flashcards
Describe the process of lactation and its hormonal regulation.
Lactation is the production of milk by mammary glands, regulated by hormones such as estrogens, progesterone, and human placental lactogen, which stimulate the hypothalamus to release prolactin-releasing factors (PRFs) toward the end of pregnancy.
Explain the composition of colostrum and its benefits for infants.
Colostrum has less lactose and almost no fat compared to milk, but contains more protein, vitamin A, and minerals. It is rich in IgA antibodies that protect the infant’s digestive tract from infections.
How does suckling influence milk production after birth?
After birth, milk production relies on mechanical stimulation of the nipples by the suckling infant, which sends action potentials to the hypothalamus, stimulating the release of PRFs and resulting in prolactin release for milk production.
Define the role of oxytocin in lactation.
Oxytocin, released from the posterior pituitary, causes the let-down reflex, which is the ejection of milk from the mammary glands. It also stimulates uterine contractions during nursing.
What are the advantages of breast milk for infants compared to cow’s milk?
Breast milk allows better absorption of fats and iron, more efficient metabolism of amino acids, and contains beneficial chemicals like IgA and lysozyme that protect against infections.
Explain how breast milk supports gut health in infants.
Breast milk provides oligosaccharides that help beneficial bacteria colonize the infant’s gut, promoting a healthy digestive system.
Describe the natural laxative effect of breast milk.
Breast milk has a natural laxative effect that helps cleanse the infant’s bowels of meconium, a tarry substance containing sloughed-off cells and bile.
How does the let-down reflex occur during breastfeeding?
The let-down reflex occurs when oxytocin binds to myoepithelial cells surrounding the mammary glands, leading to the ejection of milk from both breasts.
What is the role of mechanoreceptors in lactation?
Mechanoreceptors in the nipple detect suckling and send action potentials to the hypothalamus, which stimulates the release of prolactin-releasing factors and oxytocin.
Explain the importance of IgA antibodies in colostrum.
IgA antibodies in colostrum are resistant to digestion and help protect the infant’s digestive tract from infections.
Describe the role of meconium in preventing physiological jaundice.
Meconium provides the route for eliminating bilirubin from the body, so clearing meconium quickly helps prevent physiological jaundice.
Explain the impact of nursing on prolactin levels and milk production.
When nursing is discontinued, the stimulus for prolactin release ends, leading to a stop in milk production by the mammary glands.
How does nursing affect calcium levels in mothers?
Nursing for six months or more can lead to a significant loss of calcium from the bones, but a sound diet usually replaces the lost bone calcium after weaning.
Define the relationship between suckling and ovarian function during nursing.
Suckling stimulates the hypothalamus to release beta endorphin, which inhibits the release of GnRH and gonadotropins, dampening the normal ovarian cycle.
What is the significance of a balanced diet during pregnancy?
A balanced diet provides essential nutrients for fetal growth, energy, immune function, and prevents common issues like constipation.
List the essential components of a balanced diet for pregnant women.
Protein, carbohydrates, fats, vitamins & minerals, and fiber are essential components of a balanced diet during pregnancy.
Explain the importance of Vitamin D during pregnancy.
Vitamin D supports calcium absorption and is crucial for the baby’s bone development.
Describe the role of folic acid in pregnancy.
Folic acid helps prevent neural tube defects and is vital during the first trimester.
What is the function of iron in a pregnant woman’s diet?
Iron prevents anemia and supports the increased blood volume that occurs during pregnancy.
Identify the three stages of parturition.
The three stages of parturition are the Dilation Stage, Expulsion Stage, and Placental Stage.
Explain the Dilation Stage of parturition.
The Dilation Stage begins with true labor contractions and ends when the cervix is fully dilated to 10 cm, with contractions becoming more frequent and intense.
Describe the Expulsion Stage of childbirth.
The Expulsion Stage begins once the cervix is fully dilated and ends with the delivery of the baby, aided by strong uterine contractions and pushing.
What occurs during the Placental Stage of childbirth?
The Placental Stage begins after the baby is delivered and ends with the delivery of the placenta, usually occurring within 15–30 minutes after childbirth.
How does fetal cortisol contribute to the birth process?
Fetal cortisol plays a key role in preparing the baby for birth, particularly by stimulating the production of surfactant in the lungs.
Describe the role of surfactant in the lungs of a newborn.
Surfactant is produced by alveolar cells in the lungs and reduces surface tension within the alveoli, preventing them from collapsing during exhalation, which is crucial for proper breathing after birth.
Explain the consequences of insufficient surfactant in newborns.
Without enough surfactant, a newborn may experience respiratory distress syndrome (RDS), struggling to breathe properly after birth.
How does fetal cortisol contribute to lung development before birth?
Fetal cortisol rises late in pregnancy, stimulating placental estrogen production and aiding in the maturation of fetal organs, including the lungs.
Define the role of estrogen during labor and delivery.
Estrogen increases uterine muscle excitability, enhances oxytocin receptor expression, and promotes the production of prostaglandins, which are crucial for labor.
What happens to progesterone levels as parturition approaches?
Progesterone levels drop or its effects are functionally blocked, removing the inhibitory effect on uterine contractions.
Explain the function of prostaglandins in the labor process.
Prostaglandins promote cervical ripening (softening and dilation) and enhance uterine contractions, facilitating the labor process.
Describe the positive feedback loop involved in the onset of labor.
Stretch receptors in the cervix are activated as the fetus pushes down, signaling the hypothalamus to release oxytocin, which leads to stronger contractions and further cervical stretch, continuing until birth.
How does the body respond after the baby is delivered?
After delivery, the uterus contracts further to expel the placenta, and hormone levels begin to shift towards postpartum recovery.
What prevents labor from being initiated despite high oxytocin levels during late pregnancy?
Labor is not initiated because progesterone levels remain high and myometrial cells have an insufficient number of oxytocin receptors.
Summarize the neuroendocrine regulation of parturition.
Parturition is regulated by fetal signals (like cortisol), maternal hormonal changes (estrogen and progesterone), a positive feedback loop involving oxytocin, and the completion of the process with uterine contractions to expel the placenta.
Describe the neuroendocrine reflex triggered by pressure on the cervix during labor.
The pressure of the head on the cervix stimulates a neuroendocrine reflex that leads to the release of oxytocin.
Explain the role of oxytocin in the synthesis of prostaglandins during labor.
Oxytocin stimulates the placenta and uterus to synthesize prostaglandins, which promote strong uterine contractions.
How do strong uterine contractions affect postpartum bleeding?
Strong uterine contractions compress uterine blood vessels, limit bleeding, and facilitate placental detachment.
Define the hormonal changes that occur after the delivery of the placenta.
After the placenta is delivered, estrogen and progesterone levels drop sharply, removing the inhibition on prolactin and allowing milk production to begin.
What is the role of prolactin in lactation?
Prolactin, secreted by the anterior pituitary gland, promotes milk synthesis in the alveolar cells of the breast.
How does oxytocin contribute to milk ejection during breastfeeding?
Oxytocin, secreted by the posterior pituitary gland, causes contraction of myoepithelial cells around alveoli, pushing milk into ducts for the baby to drink.
Explain the effects of estrogen and progesterone during puberty on breast development.
Estrogen stimulates the growth of the ductal system, while progesterone promotes the development of lobules and alveoli, leading to breast enlargement.
Describe the hormonal changes that support breast development during pregnancy.
During pregnancy, estrogen and progesterone levels increase, further promoting growth and maturation of breast tissue, while prolactin prepares alveolar cells for milk production.
What is the function of human placental lactogen (hPL) during pregnancy?
hPL supports breast growth and lactogenesis, contributing to the preparation for lactation.
How do growth hormone (GH) and insulin-like growth factor 1 (IGF-1) affect breast tissue development?
GH and IGF-1 support overall breast tissue growth, contributing to the development of duct-lobular structures.
Summarize the roles of prolactin and oxytocin in lactation.
Prolactin is responsible for milk production, while oxytocin is responsible for the release or ejection of milk.
Describe the hormonal changes that occur after the delivery of the placenta.
After the delivery of the placenta, there is a drop in estrogen and progesterone levels, which triggers the onset of lactation.
Explain the role of prolactin in milk production.
Prolactin is a hormone that stimulates milk production in the alveolar cells of the mammary glands.
How does oxytocin contribute to lactation?
Oxytocin is responsible for milk ejection through the let-down reflex during lactation.
Define the structure and function of an alveolus in the context of lactation.
An alveolus is a glandular structure involved in milk production, lined by a single layer of milk-secreting epithelial cells.
What changes occur in the breast during pregnancy due to hormonal regulation?
During pregnancy, increased levels of estradiol and progesterone stimulate the growth and development of alveoli and ductal structures in the breast.
Identify the permissive hormones that support breast development during pregnancy.
Permissive hormones that support breast development during pregnancy include glucocorticoids, prolactin, and human chorionic somatomammotropin (hCS).
Discuss the effect of estrogen and progesterone on milk secretion during pregnancy.
High levels of estrogen and progesterone during pregnancy inhibit the action of prolactin, preventing actual milk secretion until after delivery.
How are mammary glands structured in terms of lobes and lobules?
Each mammary gland is divided into 15-20 lobes, which are further subdivided into lobules, with the alveolus being the basic component of each lobule.
