Female Reproductive System (Parturition and Lactation) Flashcards
PARTURITION
- Definition =
- Involves biochemical and mechanical changes in ____ and ____
- Hormones involved (5):
- Mechanical factors (2):
PARTURITION
- Definition = termination of pregnancy and delivery and separation of fetus from the mother
- Involves biochemical and mechanical changes in MYOMETRIUM and CERVIX
- Hormones involved (5): PROGESTERONE, ESTROGEN, PROSTAGLANDINS, OXYTOCIN, RELAXIN
- Mechanical factors (2): Uterine distension + Cervical stretching
State the 3 stages of parturition.
- cervical dilatation
- fetal expulsion
- delivery of placenta
State everything you know about the 3 stages of PARTURITION
STAGE 1 - CERVICAL DILATATION
- From when effaced cervix is 3cm dilated to full dilation (~10cm)
- Duration = 8-10 hours (first childbirth/primiparous) to 1 hour (multiparous)
STAGE 2 - FETAL EXPULSION
- From when the cervis is fully dilated to when the baby is born
- Duration = varies depending on parity/fetal size
STAGE 3 - DELIVERY OF PLACENTA
- From fetal expulsion to delivery of placenta
- Duration = 10-15 minutes
Recap: State the hormones involved in parturition
- progesterone
- estrogen
- prostaglandins
- oxytocin
- relaxin
State the functions of PROGESTERONE and ESTROGEN in parturition
PROGESTERONE
1. hyperpolarises myometrial cells and suppresses uterine contractions
2. inhibits phospholipase A2 and subsequent prostaglandin synthesis
ESTROGEN (opposes functions of progesterone)
1. stimulates phospholipase A2 and subsequent prostaglandin synthesis –> stimulate uterine contractions
PROSTAGLANDINS
- Produced by ____, ____ and ____ due to activation of ____
- MOA = increase in intracellular ____ (____ cells) to activate the ____ ____
- Effects (2):
PROSTAGLANDINS
- Produced by MYOMETRIUM, DECIDUA (MOTHER) and CHORION (FETUS) due to activation of PLA2 (PHOSPHOLIPASE A2)
- MOA = increase in intracellular CA2+ (MYOMETRIAL cells) to activate the ACTIN MYOSIN
- Effects (2): Stimulate uterine contractions + Causes cervical ripening and dilation
OXYTOCIN
- Hormone type:
- Produced in ____ and stored in ____ ____
- MOA = binds to ____ receptors which are ____ and expressed in both ____ and ____ of uterus at the end of pregnancy and are promoted by ____ (and minorly by ____)
- Functions (4):
OXYTOCIN
- Hormone type: 9 AA peptide
- Produced in HYPOTHALAMUS and stored in POSTERIOR PITUITARY
- MOA = binds to OXYTOCIN receptors which are GPCR and expressed in both MYOMETRIUM and ENDOMETRIUM of uterus at the end of pregnancy and are promoted by ESTROGEN (and minorly by RELAXIN)
- Functions (4):
(1) Uterine contraction
(2) Lactation
(3) Social behaviour - love, sexual arousal, bonding
(4) Inflammation and wound healing
RELAXIN
- Type of hormone:
- Produced in corpus ____ of ____ and ____ during pregnancy
- MOA = binds to ____ receptors (____ and ____) which are ____ and expressed in ____ muscles
- Functions:
(1) During pregnancy - ____ cardiac output, renal blood flow, arterial compliance
(2) During parturition - increase ____ receptor, assist in cervical ripening and ____ pubic symphysis
RELAXIN
- Type of hormone: PROTEIN HORMONE (heterodimer of 2 peptide chains of 24 and 29 AA linked by disulfide bond)
- Produced in corpus LUTEUM of OVARY and PLACENTA during pregnancy
- MOA = binds to RELAXIN receptors (LGR7 and LGR8) which are GPCR and expressed in SMOOTH muscles
- Functions:
(1) During pregnancy - INCREASES cardiac output, renal blood flow, arterial compliance
(2) During parturition - increase OXYTOCIN receptor, assist in cervical ripening and SOFTENS pubic symphysis
State the functions of RELAXIN
- During pregnancy
- During parturition
During pregnancy
1. increases cardiac output
2. increases renal blood flow
3. increases arterial compliance
During parturition
1. increases oxytocin receptor (increases sensitivity)
2. assists in cervical ripening
3. softens pubic symphysis
Recap: State the functions of progesterone in parturition
- hyperpolarises myometrial cells and suppresses uterine contractions
- inhibits phospholipase A2 and subsequent prostaglandins (PG) synthesis
Recap: State the function of estrogen in parturition
estrogen opposes actions of progesterone
1. stimulates phospholipase A2 (PLA2) and subsequent prostaglandins (PG) synthesis –> uterine contractions
State the functions of prostaglandins and oxytocin in parturition
PROSTAGLANDINS
1. stimulate uterine contractions
2. cervical ripening and dilation
OXYTOCIN
1. stimulate uterine contractions
2. lactation
3. social behaviour (love, sexual arousal, bonding)
4. inflammation and wound healing
Recap: State the functions of relaxin in parturition and pregnancy
During pregnancy
1. increase cardiac output
2. increase renal blood flow
3. increase arterial compliance
During parturition
1. increase oxytocin receptors (increase sensitivity)
2. assist in cervical ripening and dilation
3. softens pubic symphysis
State the steps involved in the positive feedback loop for parturition. (6)
- estradiol (e3) from placenta increases the number of oxytocin receptors in myometrium and endometrium of uterus
- fetus’ head pushes against cervix and stimulates stretch-sensitive sensory neurons which send stimulatory signals to hypothalamus
- hypothalamus stimulated to secrete oxytocin from posterior pituitary
- oxytocin binds to oxytocin receptors in uterus to stimulate stronger uterine contractions
- prostaglandins produced in uterus enhance uterine contractions
- enhanced contractions increases stimulation to stretch-sensitive sensory neurons –> signals to hypothalamus to release more oxytocin –> positive feedback loop
BREAST
- Mammary glands for production of milk
- Development of breast is mainly driven by ____
- ____ converts epithelium into ____ cells in breast
- Development of breast requires 3 hormones:
- ____ and ____ help to inhibit milk secretion during pregnancy
- ____ and ____ suddenly reduce after birth to trigger milk secretion
BREAST
- Mammary glands for production of milk
- Development of breast is mainly driven by ESTROGEN
- PROGESTERONE converts epithelium into SECRETORY cells in breast
- Development of breast requires 3 hormones:
- ESTROGEN and PROGESTERONE help to inhibit milk secretion during pregnancy
- ESTROGEN and PROGESTERONE suddenly reduce after birth to trigger milk secretion
LACTATION
- Definition =
- Controlled by 2 hormones -
- Main components of human milk (4)
LACTATION
- Definition = secretion of milk from mammary glands for purpose of feeding a newborn baby
- Controlled by 2 hormones - PROLACTIN + OXYTOCIN
- Main components of human milk (4) - WATER, PROTEIN, FAT, CARBOHYDRATE (LACTOSE)
State the functions of PROLACTIN and OXYTOCIN in lactation
PROLACTIN - important hormone for milk production
OXYTOCIN - stimulates myoepithelial cells for milk ejection
PROLACTIN
- Type of hormone =
- Secreted from ____ ____
- Functions (4):
PROLACTIN
- Type of hormone = PEPTIDE HORMONE
- Secreted from ANTERIOR PITUITARY
- Functions (4):
(1) Lactation
(2) Immunity
(3) Hematopoeisis
(4) Angiogenesis
State how a drop in FSH and LH results in lactation
- Decrease in FSH and LH from anterior pituitary gland transported to ovaries via bloodstream
- Ovaries stimulated to release less estrogen and progesterone
- Decreased inhibition of milk secretion
- Increase prolactin (PRL) from anterior pituitary and increase oxytocin (OT) from posterior pituitary
State the cells in breast that release OXYTOCIN and PROLACTIN
OXYTOCIN - myoepithelial cells
PROLACTIN - milk-secreting alveolar cells
State the LACTATION REFLEX involved in
1. Baby suckling breast
2. Baby crying
BABY SUCKLING BREAST
1. Mechanoreceptors in nipple stimulated
2. Signal sent via ascending sensory information to higher brain centres
3. Potentiates oxytocin neuron + inhibits PIH (prolactin inhibiting hormone)
4. Increases oxytocin secretion from posterior pituitary and prolactin secretion from anterior pituitary
BABY CRYING
1. Higher brain centres stimulated by sound of child crying
2. Potentiates oxytocin neuron + inhibits PIH (prolactin inhibiting hormone)
3. Increases oxytocin secretion from posterior pituitary and prolactin secretion from anterior pituitary
How does lactation act as a form of ‘contraception’?
Lactation decreases GnRH –> suppresses gonadal function and ovulation
State the benefits of breastfeeding to MOTHERS (5)
- reduces risk of breast and ovarian cancer
- reduces risk of T2DM
- reduces stress levels and prevents post-partum depression
- increases bonding with child
- increases intervals between pregnancies (suppresses gonadal function and ovulation)
State the benefits of breastfeeding to BABIES (6)
- immunity - breast milk contains substances with antimicrobial and immunological properties
- brain development - breast milk contains long chain polyunsaturated fatty acids and other nutrients important
- prevention of inflammation - facilitates bacterial and hormonal interactions between mother and infants
- suckling and swallowing motions reduces risk of bacterial colonisation of tubes
- promotes proper craniofacial development
- reduces risk of otitis media and malocclusion
