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utsfl:classroom:seminars:pba201h [2017/07/17 14:40] – mmccann | utsfl:classroom:seminars:pba201h [2023/12/01 09:10] (current) – [Primitive Streak & Twinning] mmccann | ||
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====== PBA201H: The Biology of Prenatal Human Development ====== | ====== PBA201H: The Biology of Prenatal Human Development ====== | ||
- | < | + | Video (15min cut of EHD documentary): |
+ | http:// | ||
+ | OR [[https:// | ||
- | * Intro: close your eyes, imagine that you're in a small, dark, enclosed place, and you can only communicate with the outside world with a small cord. | + | < |
- | * Not talking about being in the womb, but the Chilean miners crisis | + | |
- | * SLED | + | |
- | + | ||
- | + | ||
- | ===== Prenatal Development: | + | |
- | + | ||
- | * Timeline (FIXME visual) | + | |
- | * [[wp> | + | |
- | * [[wp> | + | |
- | * [[wp> | + | |
- | * [[wp>fetus]]: 8 weeks until birth | + | |
===== When does human life begin? ===== | ===== When does human life begin? ===== | ||
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==== Fertilization ==== | ==== Fertilization ==== | ||
* As we learned in [[PBA100Y]], | * As we learned in [[PBA100Y]], | ||
- | | + | |
- | * Sperm-egg fusion: A mature egg will leave the ovary and the sperm that travels through the Fallopian tube will fuse with the egg; the first sperm that fuses, uses the enzymes to crack through the outer layer (zona pellucida) of the egg and fuse with the inner membrane; then, there' | + | |
+ | > "This brand new embryo contains the original copy of a **new individual’s complete genetic code**. Gender, eye color, and other traits are determined at conception, also known as fertilization." | ||
+ | |||
+ | * **How does sperm-egg fusion | ||
+ | * | ||
< | < | ||
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- The genetic code of the zygote is unique--distinct from those of the mother and father. For instance, a pregnant woman could be pregnant with a male child. | - The genetic code of the zygote is unique--distinct from those of the mother and father. For instance, a pregnant woman could be pregnant with a male child. | ||
- Whole: | - Whole: | ||
- | * Some may ask what makes a single-celled zygote different from a single cell of, say, human skin. Both are living, human, diploid cells. However, one is a human //whole// while the other is a human //part//. Give each cell time, nutrition, and safety, then wait 9 months or 15 years...which one continues developing into a toddler, or a teenager? A skin cell will always remain a skin cell, while a zygote will continue human development into an embryo, fetus, newborn, toddler, etc. | + | * Some may ask what makes a single-celled zygote different from a single cell of, say, human skin. Both are living, human, diploid cells. However, one is a human //whole// while the other is a human //part//. Give each cell time, nutrition, and safety, then wait 9 months or 15 years...which one continues developing into a toddler, or a teenager? A skin cell will always remain a skin cell, while a zygote will continue human development into an embryo, fetus, newborn, toddler, etc. |
+ | * //Nothing is added// to the embryo from the time of fertilization except adequate nutrition and a proper environment, | ||
- Living: | - Living: | ||
- If something is growing, isn't it alive? | - If something is growing, isn't it alive? | ||
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- Human: | - Human: | ||
- If someone has human parents, aren't they human offspring? | - If someone has human parents, aren't they human offspring? | ||
- | * **Cellular | + | * **Cellular |
- | * While the zygote is a very young individual composed of only one cell, that one cell is substantively different from the sperm cell or egg cell. We can see this by considering the criteria science uses to distinguish between different cell types: cell composition and behavior. In other words, what the cell is made up of, and what it does. | + | * While the zygote is a very young individual composed of only one cell, that one cell is substantively different from the sperm cell or egg cell. We can see this by considering the criteria science uses to distinguish between different cell types: cell //composition// and //behavior//. In other words, what the cell is //made up of//, and what it //does//. |
* **Composition**: | * **Composition**: | ||
* **Behaviour**: | * **Behaviour**: | ||
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< | < | ||
- | Let's set aside for a moment the question of abortion, of whether or not it destroys a human life. Let's instead look at when we want to //create// a new human life. Imagine | + | Let's set aside for a moment the question of abortion, of whether or not it destroys a human life. Let's instead look at when we want to //create// a new human life. Imagine that a fertility specialist((FIXME terminology? |
- | Would you do in-vitro...implantation? | + | Would she do in-vitro...implantation? |
**Think about it:** Pregnancy is typically 9 months long. 9 months starting when? At fertilization! </ | **Think about it:** Pregnancy is typically 9 months long. 9 months starting when? At fertilization! </ | ||
+ | ===== Developmental Milestones ===== | ||
- | | + | ==== Developmental Timeline ==== |
- | * cardio-pulmonary death is the legally recognized point | + | |
- | * complete irreversible brain death (this specifically), | + | * The first eight weeks of a pre-born child' |
- | * fertilization is when we first //gain// that coordinating functioning | + | * The embryonic period |
- | === Implantation === | + | |
+ | > "Most significant **developmental milestones** occur long before birth **during the first eight weeks following conception** when most body parts and all body systems appear and begin to function. The main divisions of the body, such as the head, chest, abdomen and pelvis, and arms and legs are established by about four weeks after conception. Eight weeks after conception, except | ||
+ | |||
+ | * Within the embryonic period, there are further subdivisions depending on the embryo' | ||
+ | * At fertilization, | ||
+ | * By day 3, the embryo is spherically-shaped and consists | ||
+ | * Between 4 and 5 days after fertilization, the embryo | ||
+ | |||
+ | ==== Implantation | ||
FIXME condense | FIXME condense | ||
- | * Implantation starts at the end of the first week after fertilization, | + | * Implantation starts at the end of the first week after fertilization, |
* Admittedly, most pregnancy tests will only read positive after implantation; | * Admittedly, most pregnancy tests will only read positive after implantation; | ||
* But the fact that a pregnancy test doesn’t come back positive pre-implantation doesn’t mean life isn’t there—it just means the test's ability to detect that life isn’t there. | * But the fact that a pregnancy test doesn’t come back positive pre-implantation doesn’t mean life isn’t there—it just means the test's ability to detect that life isn’t there. | ||
* Take, for example, the commonly used hCG pregnancy test, one which looks for Human Chorionic Gonadotropin in a woman’s urine. hCG is a hormone that is secreted by the developing placenta, and this occurs at implantation. | * Take, for example, the commonly used hCG pregnancy test, one which looks for Human Chorionic Gonadotropin in a woman’s urine. hCG is a hormone that is secreted by the developing placenta, and this occurs at implantation. | ||
* The release of hCG indicates the presence of the pre-born child, but it doesn’t mean she didn’t exist prior to that. We know this intuitively, | * The release of hCG indicates the presence of the pre-born child, but it doesn’t mean she didn’t exist prior to that. We know this intuitively, | ||
- | |||
- | |||
* Likewise, one’s offspring first exists at fertilization even if we don’t discover her existence until implantation. | * Likewise, one’s offspring first exists at fertilization even if we don’t discover her existence until implantation. | ||
- | === Primitive Streak & Twinning === | + | ==== Primitive Streak & Twinning |
* At approximatly 14 days after fertilization((https:// | * At approximatly 14 days after fertilization((https:// | ||
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* Just because some humans have the ability to split into two, doesn’t mean that prior to the split one human didn’t exist. | * Just because some humans have the ability to split into two, doesn’t mean that prior to the split one human didn’t exist. | ||
* Take the case of the flatworm.((" | * Take the case of the flatworm.((" | ||
- | * Likewise, even though in rare situations one human splits into two, one human existed before that split happened, and the beginning of that one human still was at fertilization. | + | * Likewise, even though in rare situations one human splits into two, one human existed before that split happened, and the beginning of that one human was still at fertilization. |
- | ===== Developmental Milestones ===== | + | ERI Video on this: https://www.instagram.com/reel/ |
- | + | ||
- | > "Most significant developmental milestones occur **long before birth during the first eight weeks following conception** when most body parts and all body systems appear and begin to function. The main divisions of the body, such as the head, chest, abdomen and pelvis, and arms and legs are established by about four weeks after conception. Eight weeks after conception, except for the small size, the developing human’s overall appearance and many internal structures closely resemble the newborn." | + | |
==== Heartbeat ==== | ==== Heartbeat ==== | ||
- | The embryo' | + | * The embryo' |
+ | |||
+ | {{ : | ||
+ | |||
+ | **Embed** video in actual CCBR website (can embed EHD videos w/o permission): | ||
==== Brain ==== | ==== Brain ==== | ||
- | A pre-born child' | + | * A pre-born child' |
< | < | ||
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An abortion advocate may argue that a pre-born child is not a living human being until she has detectable brain activity. How do we know that pre-born children are still human beings, even before brain activity begins? | An abortion advocate may argue that a pre-born child is not a living human being until she has detectable brain activity. How do we know that pre-born children are still human beings, even before brain activity begins? | ||
- | Imagine that in one petri dish is an amoeba, a single-celled organism, and in another petri dish is the single-celled human zygote. They are both living, single-celled organisms. Given time, nutrition, and safety, will the amoeba ever have brain activity? No--because of //what// it is--an amoeba. It is not in the nature of an amoeba to develop a brain. In contrast, if the zygote is given time, nutrition, and safety, will she ever have brain activity? Yes. Why? Because of what she is: a human being. Why does she not have brain activity yet? Because she is too young to yet develop that function. Discriminating against her for a developmental feature that is directly reflected in her age would be [[https:// | + | {{: |
</ | </ | ||
- | |||
==== Pain ==== | ==== Pain ==== | ||
- | |||
- | Determining precisely when the pre-born feel pain is largely dependent on technology to detect this. While it is an interesting topic, it has no bearing on the morality of abortion. After all, is it wrong to kill someone because she feels pain or because she’s human? | ||
{{ : | {{ : | ||
- | Consider [[http:// | ||
+ | * Determining precisely when the pre-born feel pain is largely dependent on technology to detect this. While it is an interesting topic, it has no bearing on the morality of abortion. After all, is it wrong to kill someone because she feels pain or because she’s human? | ||
- | To make the point even more simply: would it be permissible to kill a 3-year-old as long as we give him anaesthetic first? | + | * Consider [[http:// |
+ | * May we kill her because of her inability to feel pain? Why then may we kill the pre-born because they don't feel pain at certain points during pregnancy? | ||
+ | * To make the point even more simply: would it be permissible to kill a 3-year-old | ||
+ | |||
+ | FIXME Giving analgesics for fetal surgeries seems to be commonplace, | ||
+ | [[https:// | ||
+ | " | ||
==== Viability ==== | ==== Viability ==== | ||
+ | * The term " | ||
+ | |||
+ | > "By 21 to 22 weeks after fertilization, | ||
- | http://www.ehd.org/prenatal-summary.php | + | * Some will argue that a human being' |
+ | * Furthermore, | ||
+ | * Lastly, a pre-born child is always viable if in the right // | ||
+ | * FIXME confusing viability and vitality, the difference between being able to survive and being alive | ||
===== Common Objections ===== | ===== Common Objections ===== | ||
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**"A fetus is just a blob of tissue, just a clump of cells." | **"A fetus is just a blob of tissue, just a clump of cells." | ||
- | Terms like "blob of tissue", | + | * Terms like "blob of tissue", |
+ | * Although | ||
**"It doesn' | **"It doesn' | ||
- | {{ : | + | {{ : |
- | Pre-born children also look different from born children; a zygote looks different from a 10-week fetus, who looks different from a toddler, etc. But how would we expect a human being of that specific age to look? For instance, we would not expect a toddler to undergo the same body changes that a teenager undergoes during puberty. Pre-born children look exactly the way they are supposed to look for their age and level of development. | + | |
+ | * But how would we expect a human being of that specific age to look? For instance, we would not expect a toddler to undergo the same body changes that a teenager undergoes during puberty. Pre-born children look exactly the way they are supposed to look for their age and level of development. | ||
+ | * Richard Stith offers the following analogy((https:// | ||
- | Richard Stith offers the following analogy((https:// | + | **"So many embryos miscarry anyway, so what' |
- | **So many embryos miscarry anyway, so what's the big deal about abortion?** | + | |
- | + | * It is true that some children die naturally, | |
- | - high rate of miscarriage in 1st trimester | + | * As an analogy, if one person |
- | - miscarriage | + | |
- | - cause of death is different: one child dies naturally, | + | |
**"A fetus isn’t human, it’s just a parasite feeding off of a woman’s body!" | **"A fetus isn’t human, it’s just a parasite feeding off of a woman’s body!" | ||
- | While a fetus does require nutrients from her mother via the umbilical cord in order to survive, it is unscientific to call the fetus a parasite. By definition, a parasite must be of a **different species** than the host organism--for example, a flea on a dog. Since a fetus and her mother are of the same species – human, it doesn’t make sense to call her a parasite. | + | * While a fetus does require nutrients from her mother via the umbilical cord in order to survive, it is unscientific to call the fetus a parasite. By definition, a parasite must be of a **different species** than the host organism--for example, a flea on a dog. Since a fetus and her mother are of the same species – the human species -- it doesn’t make sense to call her a parasite. |
- | + | ||
- | "a tumour" | + | |
- | | + | **"An embryo is basically a tumour feeding off the mother' |
+ | * Some will compare a pre-born child to a tumour, since both are growing groups of cells. | ||
+ | * A tumour occurs when cells from a person' | ||
+ | * The human embryo, in contrast, has her own unique genetic code that differs from that of her mother. The cells of //her// body will proliferate in a controlled, coordinated manner (leading to the various developmental milestones listed above). | ||
+ | * Ultimately, this is an anti-science comparison that we can know intuitively to be untrue. If you have one friend who has just gotten a positive // | ||
+ | ===== Conclusion ===== | ||
- | FIXME condensed version of the rest of Oriyana' | + | Biology textbooks, embryology studies, and medical advancements continue to confirm what we already know: pre-born children are living human beings from fertilization onward. By advocating for the legal protection |
===== Other Links ===== | ===== Other Links ===== | ||
- | * Maybe introduce fetal origins (Annie Murphy Paul): [[https:// | + | |
+ | * https:// | ||
+ | * https:// | ||