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57 terms

Week 3

STUDY
PLAY
Three ways to make a baby...
sex, IVF, cloning
pregnancy =
gestation
pregnancy begins at fertilisation which occurs within ______________ ie on day ___-____ of the menstrual cycle
24 hrs of ovulation, 14-15
at the time of fertilisation (in the mother): _____________ is decreasing following its peak on day 13; progesterone is exceptionally ____, it is just increasing after ovulation
oestrogen, low
the true period of gestation, counted from the day of fertilisation =
38 wks
the calculated length of a pregnancy = ____ =; this is the value used by obstetricians and midwives;
40 wks
once fertilisation has occurred the fertilised ovum = _______ --> once formed moves down the fallopian tube towards the uterus
zygote
When a sperm fuses with an egg....
Fertilisation
Three stages of gestational development:
•Pre-embryonic ---first 2 weeks following fertilisation •Embryonic---Week 3 to 8 after fertilisation •Fetus---week 9 through to birth
An oocyte is fertilizable for up to __________
24hrs
Most sperm are viable within the female reproductive tract for _____ to _____ days
1-3 days
Hundreds of sperm must release their ___________ to break down the eggs _________ and ___________
acrosomal enzymes, corona radiata, zona pellucida
When one sperm binds to receptors on the egg, it triggers first the fast block to __________ (membrane depolarization) and then the slow block (release of ___________)
polyspermy, cortical granules
Following sperm penetration, the secondary oocyte completes __________. Then the ovum and sperm pronuclei fuse (fertilization), forming a ________
meiosis II, zygote
Pre-embryonic Development: Day 0
Fertilization & first cleavage division
Pre-embryonic Development: Day 1
2 cell stage
Pre-embryonic Development: Day 2
4 cell stage
Pre-embryonic Development: Day 3
early morula
Pre-embryonic Development: Day 4
advanced morula --> hatching
Pre-embryonic Development: Day 6
blastocyst
Pre-embryonic Development: Days 7-10
implantation to uterine wall
Trophoblast =
placenta formation
Inner cell mass =
embryonic disc
Human Chorionic Gonadotropin
absolutely essential in first 12 weeks of pregnancy to maintain secretion of oestrogen and progesterone from the ovaries which maintains the pregnancy in 1st 12 wks until the placenta is big enough to take over in the foetal stage
Human Chorionic Gonadotropin: site of secretion
pre-embryonic: the trophoblast cells of the blastocyst; embryonic: chorionic cells; foetal: the foetal (chorionic) part of the placenta
Cleavage, a rapid series of ______________ without intervening growth, begins with the ________ and ends with a _________.
mitotic divisions, zygote, blastocyst
The blastocyst consists of the ___________ and an ____________
trophoblast, inner cell mass
Implantation is completed when the __________ is entirely surrounded by _____________, about ______ days after ovulation
blastocyst, endometrial tissue, 14
hCG released by the blastocyst maintains hormone production by the ___________, preventing menses. hCG levels decline after _________. Typically, the placenta is functional as an ____________ by the third month
corpus luteum, four months, endocrine organ
The placenta acts as the....
respiratory, nutritive, and excretory organ of the fetus and produces the hormones of pregnancy
Germ layer formation: Primary germ layers(3)
ectoderm, mesoderm and endoderm
Ectoderm forms the _____________ and the ____________ of the skin and its derivatives. The first event of organogenesis is _________, which produces the brain and spinal cord. By the _______, all major brain regions are formed
nervous system, epidermis, neurulation, eighth week
Endoderm forms the ________ of the digestive, respiratory and urogenital systems, and all associated ____________________. It becomes a continuous tube when the embryonic body undercuts and fuses ventrally
mucosa, glands (thyroid, parathyroids, thymus, liver, pancreas),
Mesoderm forms ...
all other organ systems and tissues
Mesoderm segregates early into ...
(1) a dorsal superior notochord, (2) paired somites that form the vertebrae, skeletal trunk muscles, and part of the dermis, and (3) paired masses of intermediate and lateral mesoderm.
The intermediate mesoderm forms the ...(2)
kidneys and gonads
The somatic layer of the lateral mesoderm forms ... (3)
the dermis of skin, parietal serosa, and bones and muscles of the limbs
the splanchnic layer of the mesoderm forms the ... (2)
cardiovascular system and the visceral serosae
The fetal cardiovascular system is formed in the...
embryonic period
The umbilical vein delivers _________ to the embryo; the paired umbilical arteries return oxygen-poor, waste-laden blood to the _______
nutrient- and oxygen-rich blood, placenta
The ductus venosus allows most of the blood to bypass _______; the foramen ovale and ductus arteriosus are pulmonary shunts
the liver
Metabolic Changes In Pregnant Mother: Total body water and blood volume ________ dramatically. Heart rate and blood pressure ____, resulting in __________ of cardiac output in the mother
increase, rise, enhancement
Parturition
birth
Fetal cells produce __________, which stimulates __________ production by the placenta. Both hormones stimulate contraction of uterine muscle. Increasing stress activates the __________, causing ________ release from the posterior pituitary; this sets up a positive feedback loop resulting in true labour
oxytocin, prostaglandin , hypothalamus, oxytocin,
Stages of Labour:The dilation stage is from...
the onset of rhythmic, strong contractions until the cervix is fully dilated. The head of the fetus rotates as it descends through the pelvic outlet.
Stages of Labour:The expulsion stage....
extends from full cervical dilation until birth of the infant.
Stages of Labour:The placental stage...
is the delivery of the afterbirth (the placenta and attached fetal membranes)
Colostrum
a premilk fluid, is a fat-poor fluid that contains more protein, vitamin A, and minerals than true milk. It is produced toward the end of pregnancy and for the first two to three days after birth.
True milk is produced around _____ in response to suckling, which stimulates the hypothalamus to prompt anterior pituitary release of ______ and posterior pituitary release of ________.
day 3, prolactin, oxytocin
________ stimulates milk production; _________ triggers milk let-down. Continued breast-feeding is required for continued milk production.
Prolactin, oxytocin
PREGNANCY-RELATED DISORDERS: Ectopic Pregnancy
alien location; most commonly Fallopian Tube or peritoneum (attached to exterior of an abdominopelvic organ); normally dies very early due to insufficient support structures/space
PREGNANCY-RELATED DISORDERS: Pre-Eclampsia/Toxaemia
pregnancy-induced hypertension, oedema and albuminuria in the mother; caused by immune attack by mother on the (foreign) placenta (this is usually prevented by HCG); can lead to foetal distress (␣or␣HR, cardiac arrhythmia, passage of meconium (foetal faeces);
Gestational Diabetes
type II diabetes mellitus (NIDDM) occurring for the first time in pregnancy
Gestational diabetes occurs in women who are pre- diabetic ie have fewer ____________ than normal (or reduced sensitivity) but not so low as to cause NIDDM when not pregnant; [in pregnancy _______ causes reduced sensitivity in insulin receptors which in these women tips them into full DM]
nsulin receptors, HCS
Medical Emergencies During Parturition: placental haemorrhage
commonly caused by the placenta coming away from the uterus before stage 3
Medical Emergencies During Parturition: breech delivery
baby not coming head first - shoulder, arm, feet first, due to failing to turn earlier in the pregnancy
HCG
used to diagnose pregnancy since only secreted (normally) when woman pregnant; can be tested in urine (screening test for diagnosing pregnancy) and blood (specialised for disorders, determination of dates etc)