What is the name of the initial fusion mass after fertilisation?
Zygote
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What is a blastocyst?
A hollow ball of cells
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At what age does the embryo implant itself into the endometrium?
7 days
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What is the endometrium?
Lining of the wall of the uterus
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What happens if the embryo does not implant itself in the endometrium?
The embryo is not supplied with enough food and nutrients so the pregnancy does not continue
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What is the correlation between body mass and gestation?
Positive
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What is the result on the offspring of a longer gestation?
More advanced in their development
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Do all animals obey the correlation between body mass and gestation?
No
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What hormone does the embryo secrete?
hCG (human chorionic gonadotrophin)
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What does hCG do?
Stimulates the ovary to keep secreting progesterone to maintain the uterus lining and thickening to support embryo after implantation; maintains corpus luteum to continue progesterone production
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How long is progesterone secreted for?
3 months
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Why does the embryo not die when progesterone stops being secreted?
The placenta has developed and takes over role of secreting progesterone
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What other hormone does the placenta secrete?
Estrogen
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What does progesterone do in terms of childbirth?
Prevents uterine contractions and spontaneous abortion
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When does the level of progesterone start to fall?
In the last third of pregnancy and then more steeply towards the end
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What does the fall in progesterone allow the mother to secrete?
Oxytocin
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When estrogen levels rise, what does this cause?
An increase in the number of oxytocin receptors on the muscle in the uterus wall
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What do uterine contractions stimulate?
Secretion of oxytocin
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What happens when oxytocin binds to the receptors in the muscle of the uterus wall?
Causes muscle to contract and contractions get stronger and stronger
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What sort of feedback system is childbirth?
Positive
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What does the cervix do during contractions?
Relaxes and widens
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Before birth, what happens to the amniotic sac?
Bursts and fluid is released
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Do contractions stop immediately after birth?
No they continue until the placenta is expelled
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What is another word for placenta?
Afterbirth
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What is the ball of cells when it implants in the endometrium?
Blastocyst
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More specifically, which part of the embryo secretes hCG?
Placenta
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When does hCG start to be produced?
Shortly after implantation
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Why can hCG be detected in urine?
It is small enough to pass through the basement membrane of the glomerulus
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What type of antibodies detect hCG?
Monoclonal
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What else causes uterine contractions as well as progesterone and oxytocin?
Stretch of uterine wall due to fetus
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What does pressure of the fetal head on the cervix cause?
Nerve impulses to be sent to posterior pituitary gland to secrete oxytocin
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What is an altricial species?
Give birth to young that are helpless and incompletely developed
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What are precocial species?
Give birth to young that are quite well developed, with hair, open eyes and are mobile
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What are some overlaps between precocial and altricial species?
Cats. They are well developed and have fur but their eyes are closed
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How are human babies partly altricial?
Cannot regulate temperature and are helpless
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Why might we be outliers with a low mass but large gestation?
Our enlarged brains need longer period of growth in safety of uterus
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How does implantation occur?
When energy stores are used up and zona pellucida has broken down, blastocyst sinks into lining and develops finger-like projections which allow exchange
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Is the mother's blood confined to vessels when flowing around placental villi?
No it is in the intervillous space
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What is another name for childbirth?
Parturition
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What stops producing progesterone at the time of birth?
Placenta
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Other cards in this set
Card 2
Front
What is a blastocyst?
Back
A hollow ball of cells
Card 3
Front
At what age does the embryo implant itself into the endometrium?
Back
Card 4
Front
What is the endometrium?
Back
Card 5
Front
What happens if the embryo does not implant itself in the endometrium?
What you need to know about cramps during ovulation: how to deal with it?
Sometimes, during ovulation, women experience cramps. These cramps can be mild or severe and can range in intensity from a twinge to intense pain.
There are a few things you can do to deal with cramps during ovulation, including drinking fluids, taking ibuprofen or acetaminophen, and resting. If the cramps are severe, your doctor may recommend medication to relieve them. READ MORE HERE
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