Female Reproductive System (Pregnancy) Flashcards
State the lifespan of an OVUM and SPERM
OVUM - 12-24 hours after ovulation
SPERM - <72 hours in female genital tract
Define the term ‘FERTILISATION’
fertilisation = fusion of 2 haploid gametes, sperm and ovum, to produce a diploid zygote
State the factors in MALES and FEMALES that determine successful fertilisation
MALES
- production of adequate number of healthy sperm
- successful delivery of sperm into vagina
FEMALES
- ability to ovulate to produce ovum
- ability to provide passage for transport of sperms towards ovum
State the changes that sperms undergo for fertilisation (3)
- transport of sperm (affected by (a) own mobility, (2) assisted by contractions of uterus and oviduct, (3) chemical attraction to ovum)
- capacitation
- acrosome reaction
Regarding CAPACITATION, state
- where this process occurs
- what occurs during this process
CAPACITATION = activation process required for successful fertilisation for sperms to penetrate the egg
- where = after ejaculation in female genital tract
- how = seminal plasma protein contents removed to expose molecules that bind to zona pellucida of oocyte to get ready for acrosome reaction
Regarding ACROSOME REACTION, state
- when this process occurs
- what occurs during this process
ACROSOME REACTION
- when = at the time sperm binds to zona pellucida of ovum
- how = redistribution of membrane constituents –> increase membrane fluidity and permeability (exposing contents of acrosome –> leads to break down of zona pellucida and membrane of the oocyte)
State the changes that ovum undergoes upon/after fertilisation (3)
- cell membrane depolarises –> prevents membrane fusion with other sperm
- cortical/zona reaction - inactivation of sperm receptor and hardening of zona to impair subsequent sperm binding
- resumption of the second meiotic division (oocytes are arrested in metaphase of meisosis II)
State the 2 processes that prevent polyspermy.
- cell membrane depolarises –> prevents membrane fusion with other sperm
- cortical reaction/zona reaction - inactivation of the sperm receptor and hardening of the zona to impair subsequent sperm binding
State the 8 steps in fertilisation
- sperm cell approaches an egg
- contact between the sperm and zona pellucida
- entry of sperm and contact with oolemma (egg membrane)
- resumption of the second meiotic division of the oocyte
- completion of meiosis
- formation of male and female pronuclei
- migration and union of male and female pronuclei
- zygote ready for first mitotic division
PREGNANCY
- Normal human pregnancy: ____ - ____ weeks
- Starts with fertilisation and ends with childbirth
- Calculated from ____ to ____ (____ rule)
- 3 Phases:
PREGNANCY
- Normal human pregnancy: 38 - 40 weeks
- Starts with fertilisation and ends with childbirth
- Calculated from LMP to DATE OF DELIVERY (NAEGELE’S rule)
- 3 Phases:
(1) Pre-embryonic period - first 2 weeks
(2) Embryonic period - 3rd-8th week
(3) Fetal period - 9th-38th week
Arrange the following from start of fertilisation to implantation:
- 1 cell zygote
- 4 cell zygote
- blastomere
- early morula
- late morula
- blastocyst
1 cell zygote –> blastomere –> 4 cell zygote –> early morula –> late morula –> blastocyst
IMPLANTATION OF ____:
- Process in which the ____ buries in the ____
- Timing: ____ - ____ days after ovulation
- ____ cells secrete ____ to digest the ____ cells to invade into the ____
IMPLANTATION OF BLASTOCYST:
- Process in which the BLASTOCYST buries in the ENDOMETRIUM
- Timing: 7 - 10 days after ovulation
- TROPHOBLASTIC cells secrete ENZYMES to digest the UTERINE cells to invade into the ENDOMETRIUM
State the parts of the human body that develop from
- Ectoderm
- Endoderm
- Mesoderm
ECTODERM - epidermis, nervous system
ENDODERM - epithelial lining of GI and organs
MESODERM - connective tissues, muscle, bone, blood, lymph system
State the 2 parts of the placenta.
- fetal part - chorionic plate
- maternal part - decidua basalis
State the functions of placenta (5)
- endocrine roles - production of hormones
- nutritional roles - transports nutrients (glucose, AA, FA, minerals, vitamins) from mother to fetus
- respiratory roles - transportation of oxygen from mother to fetus and carbon dioxide to mother
- immune roles - transportation of maternal Ab (esp IgG) into fetal blood to confer passive immunity to fetus
- excretory roles - transportation of nitrogenous waste (ammonia, urea, uric acid, creatinine) from fetal to maternal blood
State the hormones synthesised by placenta.
- estrogen
- progesterone
- relaxin
- hCG
- hPL (human placental lactogen)/ hCS (human chorionic somatomammotropin)
State the nutrients transported by placenta from mother to fetus
- glucose
- AA
- FA
- minerals
- vitamins
Describe the chnages in hormone serum levels during PREGNANCY
- hCG rises and peaks 10 weeks into gestation before decreasing to a plateau
- progesterone (increases faster initially) and oestrogen rise throughout pregnancy
- PRL increases (helps protect against ovulation and unplanned pregnancy + stimulates production of milk and growth of breast tissues)
hCG:
- Produced by ____ in ____ about ____ - ____ days after fertilisation
- ____ hormone composed of 237 amino acids
- ____ (____ and ____ units)
- Binds to ____ receptor on corpus luteum to promote function
- Functions:
hCG:
- Produced by SYNCTIOTROPHOBLASTS in PLACENTA about 6 - 8 days after fertilisation
- GLYCOPROTEIN hormone composed of 237 amino acids
- HETERODIMER (ALPHA and BETA units)
- Binds to LH receptor on corpus luteum to promote function
- Functions:
(1) promotes function of corpus luteum to secrete progesterone for first 8-10 weeks before placenta takes over
(2) promotes progesterone production by placenta
(3) promotes testosterone production by fetus
(4) coordinates sexual differentiation of baby (hCG binds to LH receptor)
Recap: State the functions of hCG (4)
- promotes function of corpus luteum to secrete progesterone for first 8-10 weeks before placenta takes over
- promotes progesterone production by placenta
- promotes testosterone production by fetus
- coordinates sexual differentiation of baby
State the test used to detect pregnancy. State any abnormalities that can occur
urine hCG positive about 30 days after the LMP (last menstrual period)
False negative - too early/too diluted
False positive - gestational trophoblastic disease (hydatiform mole), choriocarcinoma
Explain how …. in urine hCG tests can occur
(1) False negative
(2) False positive
False negative
- too early - inaccurate estimation of ovulation time
- too diluted
False positive
- gestational trophoblastic disease (hydatiform mole)
- choriocarcinoma
PRODUCTION OF HORMONES (estrogen and progesterone) IN PREGNANCY
- In early stage (<8 weeks), both ____ and ____ are mainly produced in the corpus ____
- >8 weeks, _____ cells in placenta become main soruce of ____ (early pregnancy) and ____ (late pregnancy)
PRODUCTION OF HORMONES (estrogen and progesterone) IN PREGNANCY
- In early stage (<8 weeks), both PROGESTERONE and ESTROGEN are mainly produced in the corpus LUTEUM
- >8 weeks, TROPHOBLAST cells in placenta become main soruce of PROGESTERONE (early pregnancy) and ESTROGEN (late pregnancy)
Recap: State the functions of ESTROGEN and PROGESTERONE
ESTROGEN
1. promotes uterus growth and uterine blood flow
2. enhances progesterone and oxytocin function
3. enhances fetal development
4. stimulates breast cell proliferation and fat deposit
PROGESTERONE
1. supports endometrium for nurturing fetus (converts endometrium to secretory change for implantation)
2. inhibits myometrial contraction in uterus
3. suppresses maternal immunologic responses to fetal antigens
State the main form of estrogen produced
estriol (E3)
State the 3 other hormones important in pregnancy(other than progesterone and estrogen) and their functions
hPL - HUMAN PLACENTAL LACTOGEN
- Supports fetal nutrition
PRL - PROLACTIN
- Stimulates milk production/lactation in pregnant mother
RELAXIN
- Soften cervix
- Loosen connective tissues of pelvis
State some maternal adaptations during pregnancy (4)
- increased function of respi, cvs, renal
- weight gain
- upregulation of endocrine system
- metabolism - fat depsoit and insulin resistance
