Week 3

Created by zamboni49 

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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)

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