Category: Science & Nature

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From Cell To Birth: Growth

Posted on by Jinavie

After implantation, the embryo quickly grows from a ball of cells into what will be a fully-formed baby. However, it first needs a way to feed: the placenta.
It is an organ that actively takes nutrients and oxygen from the mother’s blood, exchanging it for the embryo’s waste products. It is extremely effective in keeping the fetus alive and protects it from infections or the mother’s immune system.
The blood is carried by the umbilical cord, which plugs into the belly button. This cord is the lifeline throughout term, and disrupting the blood supply will lead to permanent brain damage or even death.

In the first 10 weeks, the blastocyst develops into a very primitive disk-like object that shares no resemblance to a person. It keeps growing and differentiating at a rapid rate (almost doubling in size per week) until it forms an embryo that is more familiar, roughly about week 6. Interestingly, a human embryo looks almost identical to embryos of rabbits, chickens, turtles and fish, showing how all animals shared a common ancestor in the course of evolution. At this stage, the embryo has features such as gills, a tail and a fish-like appearance.

After 10 weeks, the embryo has grown to about 5~8cm (almost 10~20 times the size at week 6), and is now called a fetus. It begins to properly grow organs, and resembles a miniature baby with primitive features.
It continues to grow for the next 30 weeks, continuously relying on the mother for nutrition and life support.

Many different factors contribute to premature birth and IUGR (intrauterine growth restriction), which leads to the birth of a small baby. This may result in less developed organs (especially the lungs) and may affect the health of the newborn throughout its life. There are also many poisons known to harm the development of the embryo/fetus, such as alcohol, nicotine, cocaine, heroin and much more. These should be avoided from a few weeks before conception onwards (even after birth while breastfeeding).

By about 38 weeks, the lungs (the last organs to fully mature) are ready and the fetus is upside down. It is ready to leave the womb, and thus sends a signal to the mother, known as labour. This is when the arduous process of childbirth begins.

(Full series here: https://jineralknowledge.com/tag/arkrepro/?order=asc)

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From Cell To Birth: Implantation

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When an egg is fertilised by the sperm, it is called a zygote. This zygote immediately starts to divide at an exponential rate, to achieve the feat of transforming from a single cell to a 3kg baby. The division and growth happens as the zygote slowly drifts towards the uterus, where it can secure itself.

30 hours after fertilisation, the zygote is now 2 cells.
72 hours, the zygote is now 16 cells.
96 hours, the zygote is now a ball of over 60 cells, and now called a morula.
108 hours, the morula has a cavity inside, and is called a blastocyst.
The blastocyst, essentially a shell of cells with a mass of cells at one point, hatches out of the zona pellucida as it is now much bigger.
To gain the massive amount of energy required for development, the zygote eats up simple sugars in the fallopian tube during its travel.

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As mentioned before, when pregnancy does not happen, the endometrium is shed and flushed out. To prevent this, the blastocyst secretes something called βhCG, keeping the corpus luteum alive, which secretes progesterone to maintain the endometrium. As the endometrium is the fertile “soil” where the embryo will grow, this is a vital step (βhCG is the hormone tested in a pregnancy test).
When the blastocyst reaches the uterus, it finds a safe spot on the endometrium, with the inner cell mass facing the wall. This is where implantation begins.

After clinging tightly to the endometrial cells, the blastocyst fuses some of its cells into a digging tool that can eat away at the endometrium. As it digests away the cells, the blastocyst slowly burrows in until it is completely embedded inside. Cells invade the hollowed space, firmly securing the blastocyst while destroying blood vessels and glands to release nutrients, securing a supply line. Now, it can start its rapid development into an embryo as it leeches away the mother’s nutrients.

A foreign body latching on to the host’s cells, digesting away tissue and leeching blood and nutrients – an embryo acts exactly like a parasite, to ensure that it can safely survive the 40-week gestation. In fact, an embryo can implant itself almost anywhere in the body, such as the fallopian tubes, ovaries or even the gut, as long as there is a secure blood supply. This is called an ectopic pregnancy, and can be an extremely dangerous scenario to both the mother and developing fetus.

(Full series here: https://jineralknowledge.com/tag/arkrepro/?order=asc)

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From Cell To Birth: Fertilisation

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Once the sperm enters the vagina, the real battle begins. The vagina is highly acidic, an environment in which sperm can only survive 2~3 hours. It is crucial for the sperm to enter the uterus through the cervix, but only 1% of the 200~300 million sperm make it through.

Even within the uterus, they must brace harsh conditions as they travel against gravity. After about 5 hours of intense swimming, the sperm reach the top of the uterus. Here they face a choice: go left or go right. Half the sperm make the wrong choice and head down the eggless fallopian tube and ultimately die. The rest navigate their way through the maze of folds in the fallopian tube, often getting lost or sticking to the wall thinking that it is an egg.

About 200 sperm finally make it to the egg, which sits in the ampulla of the fallopian tube. But as always, there is competition even at this final moment. Only one sperm can win the race, and the fastest one will ultimately produce a new life.

When the first sperm touches the egg, a series of chemical reactions occur, essentially “priming” the sperm. This causes it to start the acrosome reaction, where it releases a hoard of enzymes from its head, digesting away the covering shell (zona pellucida) of the egg. It then becomes supercharged, using all of its energy to drive itself inwards until it reaches the oocyte within. As soon as this happens, the tail breaks off, and one final chemical reaction as the calcium level spikes occurs to release more enzymes that prevent the acrosome reaction in other sperm. It also solidifies the zona, forming an impenetrable shield to prevent other sperm coming in (polyspermy can lead to a failed pregnancy).

The calcium spike that causes the above cortical reaction also triggers the egg to divide, so that it reaches the most mature stage. The winning sperm can then combine its nucleus with the oocyte, forming the 46 chromosomes that will set the genetic basis of the new zygote (first stage of a baby).

To reach the egg, the sperm must travel over 20cm – beating its tail over 20,000 times. The probability that a certain sperm will fertilise the egg is 1 in 500,000,000.
Life starts under a near-zero probability condition.


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From Cell To Birth: Sex

Posted on by Jinavie

The two copulatory organs are the penis and the vagina. Both are designed to maximise the chance of a new life being conceived.

The penis is normally flaccid, but when stimulated through touch or erotic images and thoughts, it can become stiffened to eight times its original size. Contrary to certain slang words, the penis contains no bones – it is merely a sponge.
When the brain signals the penis to become erect, the sponge is relaxed, letting blood flood in, filling it like a balloon. This combined with two muscles and the sheath enclosing the penis achieves the erection which is critical in sex.

The vagina is shaped to perfectly accommodate an erect penis, and receives the sperm that will eventually fertilise the egg. As sex involves the piston movement of the erect penis within the vagina, it is bound to suffer chafing. So nature developed Bartholin’s glands that produce a lubricant, smoothing the process.
The clitoris actually shares its origin with the penis, and thus swells when sexually excited. It is also extremely sensitive.

The goal of sex is simple – excite the penis enough for the man to achieve an orgasm (note that female orgasm is optional, but ideal, for conception). When a threshold is reached, the brain sends out strong signals to squeeze sperm out from the epididymis, and seminal fluid from the prostate and seminal vesicles. The combined fluid (semen) shoots through over half a metre of tube until it is ejaculated out.
The semen collects in the vagina, where the cervix laps up the semen and transports it into the uterus. From here, the sperm’s adventure begins, facing many troubles to conceive the egg at the end of the line.

(Full series here: https://jineralknowledge.com/tag/arkrepro/?order=asc)

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A Simple Task

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A plague struck the ancient Greek island of Delos. As the disease ravaged the island, the people went to the oracle at Apollo’s temple for help. This is what the oracle said:

Double the volume of the cube-shaped altar in Apollo’s temple

People considered this a simple task and made a new altar where each side was double the original length. However, instead of disappearing, the plague worsened and people were confused.

Reason being, given that the length of one side of a cube is a, the volume is a³; if one side is 2a, the volume becomes 8a³, or eight times the original volume. Therefore, to double the volume of a cube, the number ³√2 is required. The problem is, whether ³√2 can be found using only compass and straightedge construction (where only the two tools are used to solve a geometric problem).

This problem, also known as the Doubling the cube problem, is one of three geometric problems known to be unsolvable by compass and straightedge construction. In other words, without the help of other mathematical methods, the answer cannot be found.
However, the solution to the above story is very simple.

Find a new god.

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Man Versus Ant

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Human:
A mammal that ranges in size from about 1 to 2 metres.
Weighs between 30kg and 100kg. Females are pregnant for 9 months. 
Omnivorous diet. Population estimated around 7 billion.

Ant:
An insect that ranges in size from about 0.01 to 3 centimetres.
Weighs between 0.001mg and 1g. Can produce eggs endlessly given there is an ample sperm reservoir.
Omnivorous diet. Population estimated around 1 quintillion (1 billion times 1 billion).

(from The Encyclopaedia of Relative and Absolute Knowledge by Bernard Werber)

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Manhole

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Why are manholes round?

The reason is that a square or rectangle has a diagonal greater in length than a side, so it can fall through if misplaced. A circle has equal lengths at any angle and is perfectly symmetrical, thus will never fall through.

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Bat

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The most famous characteristics of a bat is its behaviour of hanging upside down. This strange behaviour actually greatly benefits a bat’s survival.  Because a bat’s wing is structurally different to a bird’s, it cannot generate enough flight to lift a bat off the ground directly. Therefore, bats leap off a high location to fly, so hanging from a high place allows them to fly off at any given moment. Also, living in a high place provides protection from predators.

A bat’s anatomy has heavily adapted to accommodate this behaviour. Thanks to its unique anatomical structure, a bat expends no energy while hanging. This is because they have talons that are designed to clench naturally when pulled by gravity, as the tendons tense. Thus, when hanging upside down, a bat can rest peacefully, and can even sleep in that posture as it requires no muscle action (all muscles relax in REM sleep).

As it is the norm to live upside down, a bat does everything in that manner. As stated above, a bat sleeps upside down, eats upside down, mate upside down, and even stay like that after death. There is only one time a bat stands upright: when it excretes waste. Even behaviour cannot overcome the power of gravity.

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Urban Paradox

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A few years ago, a theoretical physicist studied population growth in cities to find the mechanism of how cities operate. What he found was an astonishing law.
Wherever the city, as the population doubled in size, the average income, number of patents, number of educational and research facilities and other important numbers all increased around 15 percent. Although it is normal for such statistics to increase as a city grows, it is interesting to see that almost all of them increasing at a similar rate, despite being so different sometimes.
More fascinating is the fact that not only do the above “good” statistics increase equally, but so do crime rates, pollution, smog occurrence, stomach flu and AIDS prevalence all increase approximately 15 percent.
Therefore, a city can be seen as a double-edge sword that is both the source of fast growth, wealth and ideas, but also waste, pollution, stress and disease.

Biologically speaking, an organism has a tendency to have slower growth and pace of life as it gets larger. For instance, an elephant’s heart beats slower than a mouse, and its cells do less work on average too. However, a city exhibits a snowball effect where it grows faster as it gets larger. To achieve this extremely high rate of growth, it must consume an immense amount of resources, which ultimately ends up as large quantities of waste and pollution. Also, as people get busier, the overall “quality” of the society falls, leading to increased stress and disease prevalence.

If so, should we abandon our current productivity and live a slow, village life and ignore our potential as a species? Or should we continue our exponential growth at the cost of using up nature’s well-maintained resources like no tomorrow?

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Bamboo

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There is a bamboo forest on a desert island. How can you use these?

  • If you cut a section of bamboo so that one side is open, one side is closed, it becomes a cup.
  • If you cut a section of bamboo and split it lengthwise, it becomes a dish.
  • If you cut a section of bamboo and cut a wide hole in the side, it becomes a pot.
  • If you cut a section of bamboo and fit a large rock on one end, it becomes a hammer.
  • If you cut a branch of bamboo and craft it, it can be a spoon, fork or chopsticks.
  • If you take a stick of bamboo and tie a string and hook at the end, it becomes a fishing rod.
  • If you take a stick of bamboo and sharpen the end, it becomes a spear.
  • If you take many large bamboo and tie them together, you can make a house, a bed or a raft to escape in.

The most important rule of survival is application.

As an addendum, bamboo is a grass (the largest in the world), not a tree.
This is because its stalk has become hardened yet still hollow, making it look like a tree. However, it has segments, shallow roots and dies after flowering (which can take decades) that are features of grass.