Lecturen 5: Parturition & Lactation & Reading

Question 1

Describe the process of lactation and its hormonal regulation.

Answer 1

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.

Question 2

Explain the composition of colostrum and its benefits for infants.

Answer 2

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.

Question 3

How does suckling influence milk production after birth?

Answer 3

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.

Question 4

Define the role of oxytocin in lactation.

Answer 4

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.

Question 5

What are the advantages of breast milk for infants compared to cow’s milk?

Answer 5

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.

Question 6

Explain how breast milk supports gut health in infants.

Answer 6

Breast milk provides oligosaccharides that help beneficial bacteria colonize the infant’s gut, promoting a healthy digestive system.

Question 7

Describe the natural laxative effect of breast milk.

Answer 7

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.

Question 8

How does the let-down reflex occur during breastfeeding?

Answer 8

The let-down reflex occurs when oxytocin binds to myoepithelial cells surrounding the mammary glands, leading to the ejection of milk from both breasts.

Question 9

What is the role of mechanoreceptors in lactation?

Answer 9

Mechanoreceptors in the nipple detect suckling and send action potentials to the hypothalamus, which stimulates the release of prolactin-releasing factors and oxytocin.

Question 10

Explain the importance of IgA antibodies in colostrum.

Answer 10

IgA antibodies in colostrum are resistant to digestion and help protect the infant’s digestive tract from infections.

Question 11

Describe the role of meconium in preventing physiological jaundice.

Answer 11

Meconium provides the route for eliminating bilirubin from the body, so clearing meconium quickly helps prevent physiological jaundice.

Question 12

Explain the impact of nursing on prolactin levels and milk production.

Answer 12

When nursing is discontinued, the stimulus for prolactin release ends, leading to a stop in milk production by the mammary glands.

Question 13

How does nursing affect calcium levels in mothers?

Answer 13

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.

Question 14

Define the relationship between suckling and ovarian function during nursing.

Answer 14

Suckling stimulates the hypothalamus to release beta endorphin, which inhibits the release of GnRH and gonadotropins, dampening the normal ovarian cycle.

Question 15

What is the significance of a balanced diet during pregnancy?

Answer 15

A balanced diet provides essential nutrients for fetal growth, energy, immune function, and prevents common issues like constipation.

Question 16

List the essential components of a balanced diet for pregnant women.

Answer 16

Protein, carbohydrates, fats, vitamins & minerals, and fiber are essential components of a balanced diet during pregnancy.

Question 17

Explain the importance of Vitamin D during pregnancy.

Answer 17

Vitamin D supports calcium absorption and is crucial for the baby’s bone development.

Question 18

Describe the role of folic acid in pregnancy.

Answer 18

Folic acid helps prevent neural tube defects and is vital during the first trimester.

Question 19

What is the function of iron in a pregnant woman’s diet?

Answer 19

Iron prevents anemia and supports the increased blood volume that occurs during pregnancy.

Question 20

Identify the three stages of parturition.

Answer 20

The three stages of parturition are the Dilation Stage, Expulsion Stage, and Placental Stage.

Question 21

Explain the Dilation Stage of parturition.

Answer 21

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.

Question 22

Describe the Expulsion Stage of childbirth.

Answer 22

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.

Question 23

What occurs during the Placental Stage of childbirth?

Answer 23

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.

Question 24

How does fetal cortisol contribute to the birth process?

Answer 24

Fetal cortisol plays a key role in preparing the baby for birth, particularly by stimulating the production of surfactant in the lungs.

Question 25

Describe the role of surfactant in the lungs of a newborn.

Answer 25

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.

Question 26

Explain the consequences of insufficient surfactant in newborns.

Answer 26

Without enough surfactant, a newborn may experience respiratory distress syndrome (RDS), struggling to breathe properly after birth.

Question 27

How does fetal cortisol contribute to lung development before birth?

Answer 27

Fetal cortisol rises late in pregnancy, stimulating placental estrogen production and aiding in the maturation of fetal organs, including the lungs.

Question 28

Define the role of estrogen during labor and delivery.

Answer 28

Estrogen increases uterine muscle excitability, enhances oxytocin receptor expression, and promotes the production of prostaglandins, which are crucial for labor.

Question 29

What happens to progesterone levels as parturition approaches?

Answer 29

Progesterone levels drop or its effects are functionally blocked, removing the inhibitory effect on uterine contractions.

Question 30

Explain the function of prostaglandins in the labor process.

Answer 30

Prostaglandins promote cervical ripening (softening and dilation) and enhance uterine contractions, facilitating the labor process.

Question 31

Describe the positive feedback loop involved in the onset of labor.

Answer 31

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.

Question 32

How does the body respond after the baby is delivered?

Answer 32

After delivery, the uterus contracts further to expel the placenta, and hormone levels begin to shift towards postpartum recovery.

Question 33

What prevents labor from being initiated despite high oxytocin levels during late pregnancy?

Answer 33

Labor is not initiated because progesterone levels remain high and myometrial cells have an insufficient number of oxytocin receptors.

Question 34

Summarize the neuroendocrine regulation of parturition.

Answer 34

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.

Question 35

Describe the neuroendocrine reflex triggered by pressure on the cervix during labor.

Answer 35

The pressure of the head on the cervix stimulates a neuroendocrine reflex that leads to the release of oxytocin.

Question 36

Explain the role of oxytocin in the synthesis of prostaglandins during labor.

Answer 36

Oxytocin stimulates the placenta and uterus to synthesize prostaglandins, which promote strong uterine contractions.

Question 37

How do strong uterine contractions affect postpartum bleeding?

Answer 37

Strong uterine contractions compress uterine blood vessels, limit bleeding, and facilitate placental detachment.

Question 38

Define the hormonal changes that occur after the delivery of the placenta.

Answer 38

After the placenta is delivered, estrogen and progesterone levels drop sharply, removing the inhibition on prolactin and allowing milk production to begin.

Question 39

What is the role of prolactin in lactation?

Answer 39

Prolactin, secreted by the anterior pituitary gland, promotes milk synthesis in the alveolar cells of the breast.

Question 40

How does oxytocin contribute to milk ejection during breastfeeding?

Answer 40

Oxytocin, secreted by the posterior pituitary gland, causes contraction of myoepithelial cells around alveoli, pushing milk into ducts for the baby to drink.

Question 41

Explain the effects of estrogen and progesterone during puberty on breast development.

Answer 41

Estrogen stimulates the growth of the ductal system, while progesterone promotes the development of lobules and alveoli, leading to breast enlargement.

Question 42

Describe the hormonal changes that support breast development during pregnancy.

Answer 42

During pregnancy, estrogen and progesterone levels increase, further promoting growth and maturation of breast tissue, while prolactin prepares alveolar cells for milk production.

Question 43

What is the function of human placental lactogen (hPL) during pregnancy?

Answer 43

hPL supports breast growth and lactogenesis, contributing to the preparation for lactation.

Question 44

How do growth hormone (GH) and insulin-like growth factor 1 (IGF-1) affect breast tissue development?

Answer 44

GH and IGF-1 support overall breast tissue growth, contributing to the development of duct-lobular structures.

Question 45

Summarize the roles of prolactin and oxytocin in lactation.

Answer 45

Prolactin is responsible for milk production, while oxytocin is responsible for the release or ejection of milk.

Question 46

Describe the hormonal changes that occur after the delivery of the placenta.

Answer 46

After the delivery of the placenta, there is a drop in estrogen and progesterone levels, which triggers the onset of lactation.

Question 47

Explain the role of prolactin in milk production.

Answer 47

Prolactin is a hormone that stimulates milk production in the alveolar cells of the mammary glands.

Question 48

How does oxytocin contribute to lactation?

Answer 48

Oxytocin is responsible for milk ejection through the let-down reflex during lactation.

Question 49

Define the structure and function of an alveolus in the context of lactation.

Answer 49

An alveolus is a glandular structure involved in milk production, lined by a single layer of milk-secreting epithelial cells.

Question 50

What changes occur in the breast during pregnancy due to hormonal regulation?

Answer 50

During pregnancy, increased levels of estradiol and progesterone stimulate the growth and development of alveoli and ductal structures in the breast.

Question 51

Identify the permissive hormones that support breast development during pregnancy.

Answer 51

Permissive hormones that support breast development during pregnancy include glucocorticoids, prolactin, and human chorionic somatomammotropin (hCS).

Question 52

Discuss the effect of estrogen and progesterone on milk secretion during pregnancy.

Answer 52

High levels of estrogen and progesterone during pregnancy inhibit the action of prolactin, preventing actual milk secretion until after delivery.

Question 53

How are mammary glands structured in terms of lobes and lobules?

Answer 53

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.