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Biology IB HL - 11.4 Sexual Reproduction Part 5

Biology25 CardsCreated about 1 month ago

This deck covers key concepts related to sexual reproduction in humans, focusing on hormonal regulation, pregnancy maintenance, and the role of the placenta.

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What is the effect of hCG in terms of maintaining pregnancy?

As a consequence of this, the corpus luteum survives and continues to produce both oestrogen and progesterone
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Key Terms

Term
Definition
What is the effect of hCG in terms of maintaining pregnancy?
As a consequence of this, the corpus luteum survives and continues to produce both oestrogen and progesterone
How does oestrogen maintain pregnancy?
Oestrogen inhibits FSH and LH production by the pituitary gland, preventing the release of more eggs from the ovaries
How does progesterone maintain pregnancy?
Progesterone also functions to maintain the endometrium (which is nourishing the embryo) and thicken the cervix
How long are the levels of hCG maintained for?
The levels of hCG are maintained for roughly 8 – 10 weeks while the placenta is being developed
How is pregnancy maintained once the blastocyst no longer secretes hCG?
After this time, the placenta becomes responsible for progesterone secretion and nourishing the embryo
What happens to the corpus luteum once the blastocyst no longer secretes hCG?
At this point the corpus luteum is no longer required and begins to degenerate as hCG levels drop
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Biology IB HL - 11.4 Sexual Reproduction Part 5
TermDefinition
What is the effect of hCG in terms of maintaining pregnancy?
As a consequence of this, the corpus luteum survives and continues to produce both oestrogen and progesterone
How does oestrogen maintain pregnancy?
Oestrogen inhibits FSH and LH production by the pituitary gland, preventing the release of more eggs from the ovaries
How does progesterone maintain pregnancy?
Progesterone also functions to maintain the endometrium (which is nourishing the embryo) and thicken the cervix
How long are the levels of hCG maintained for?
The levels of hCG are maintained for roughly 8 – 10 weeks while the placenta is being developed
How is pregnancy maintained once the blastocyst no longer secretes hCG?
After this time, the placenta becomes responsible for progesterone secretion and nourishing the embryo
What happens to the corpus luteum once the blastocyst no longer secretes hCG?
At this point the corpus luteum is no longer required and begins to degenerate as hCG levels drop
What is the v. general function of the placenta?
The placenta functions as the life support system for the foetus
What are the two key functions of the placenta?
It facilitates the exchange of materials between the mother and foetus It secretes hormones to maintain the pregnancy after the corpus luteum has degenerated
What is the general structure of the placenta?
The placenta is a disc-shaped structure that nourishes the developing foetus
What is the placenta formed from and what does it eventually invade?
It is formed from the development of the trophoblast upon implantation and eventually invades the uterine wall
What allows the maternal blood to pool?
Maternal blood pools via open ended arterioles into intervillous spaces within the placenta called lacunae
What is the role of the chorionic villi?
Chorionic villi extend into these pools of blood and mediate the exchange of materials between the foetus and the mother
How is exchanged material transported from mother to foetus?
Exchanged material is transported from the villi to the foetus via an umbilical cord, which connects the foetus to the placenta
What happens to the placenta after birth?
Upon birth, the placenta is expelled from the uterus with the infant – it is then separated from the infant by severing the umbilical cord (the point of separation becomes the belly button)
Where do the chorionic villi extend to allow for material exchange?
The chorionic villi extend into the intervillous space (lacuna) and exchange materials between the mother and foetus
What are chorionic villi lined by and why?
Chorionic villi are lined by microvilli to increase the available surface area for material exchange
What helps minimise diffusion distance in placental material exchange?
Foetal capillaries within the chorionic villi lie close to the surface to minimise diffusion distance from blood in the lacunae
What will diffuse FROM the lacunae INTO foetal capillaries?
Materials such as oxygen, nutrients, vitamins, antibodies and water will diffuse from the lacunae into foetal capillaries
What will diffuse FROM the lacunae INTO MATERNAL blood vessels?
Foetal waste (such as carbon dioxide, urea and hormones) will diffuse from the lacunae into the maternal blood vessels
What is the general hormonal role of the placenta?
The placenta takes over the hormonal role of the ovaries (at ~12 weeks) and begins producing estrogen and progesterone
What does estrogen stimulate? (placenta)
Estrogen stimulates the growth of uterine muscles (myometrium) and the development of the mammary glands
What does progesterone maintain? (placenta)
Progesterone maintains the endometrium, as well as reducing uterine contractions and potential maternal immune responses
When do progesterone and estrogen levels drop?
Both estrogen and progesterone levels drop near the time of birth
What is the process of childbirth called and by what mechanism does it occur by?
The process of childbirth is called parturition and occurs via positive feedback under hormonal control
What does positive feedback involve?
Positive feedback involves a response that reinforces the change detected (it functions to amplify the change)