Recent comments in /f/askscience

jrob323 t1_j777gje wrote

Reply to comment by EndlessEmergency in How could a high-altitude surveillance balloon be captured? by aggasalk

The F-15s M61 cannon sprays 20mm shells at 4000-6000 rounds per minute and they travel at high velocity for miles. You'd have to be extremely careful about picking an unpopulated area to do this over. I doubt any air-to-air missiles would lock onto this thing (I'm certainly no expert). And as you pointed out, this thing is beyond an F-15s service ceiling, so it would be risky. A U2 or other recon aircraft could easily reach that altitude, but they have no weapons.

Maybe they're planning to get more aggressive/creative when it's over the Atlantic.

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Bad_DNA t1_j774otc wrote

Reply to why you DON'T develop resistance to some medications? by sadra-the-legend

Often, the meds are either interacting directly with the body systems as a substitute for missing/tiny titers of the natural active component, or act as an antagonist for the same, so metering/shutting down the target system. This isn't quite the same as other systems that can develop tolerances (thereby requiring higher doses for the same perceived effect). Honestly, we'd have to take this on a case-by-case basis as no blanket statement is correct. Nor does this function in a natural selection format like antibiotics with bacteria that either evolve of die, where plasmids xfered via sex confer resistance for survivors.

There are plenty of other metabolic considerations. Some drugs are useless in their taken form, and only modifications/metabolism in the gut biome or liver or elsewhere generate the active physiological daughter products.

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MEsyas t1_j770his wrote

Reply to Why do some allergies get worse over time and some better? And how does allergen desensitivity work without making the reaction worse? by DontDoDrugs316

Basically, your body sees the allergen as a pathogen and makes antibodies. The more exposure, the more antibodies.

In desensitisation, the allergen is given in very small amounts so that the antibodies don't react. And desensitization doesn't always work: I was one of the people for whom it failed miserably.

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Ech_01 t1_j76ntwz wrote

Reply to comment by jacknikedisamotracia in What causes the onset of puberty specifically? by Voomit

Well if you want more detail, while the fetus is in the placenta (a place where lots of estrogen is located), we get inhibition of the KDNy neurons. (see above)

After birth, the high [] of estrogen that came from the mother goes away, so the KDNy neurons start releasing Kiss peptide => stimulation of the GnRH-neuron => LH and FSH release => testosteron + estrogen production

LH stimulates the production of progesteron and other androgens which leads to a positive effect on this cycle.

After 3 months the GABA hormone concentration starts getting high enough to block the KDNy neuron activity => the LH and FSH production (and testosteron as well) stops from the age of 6months until the age of 10 years old, where leptine starts getting produced as well and we get a more positive feedback on the testosteron production.

Edit: something like this

I also wanna say many other hormones play a role, but to keep it simple I only mentioned the important ones.

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Ech_01 t1_j76mea4 wrote

Reply to What causes the onset of puberty specifically? by Voomit

GNRH release is regulated by KNDY-neurons (Kisspeptide-neurokinine B -dynorphine)

The KDNY neurons get stimulated by progesteron, we get release of Kisspeptide which stimulates the GNRH neuron and releases GNRH

GnRH then binds on the gonadotropic cells which causes the release of FSH and LHLH and FSH stimulate the production of testosteron and estrogen then inhibits the KDNy-neurons (negative feedback loop) so we don't get too much of GNRH release

Edit: I don't exactly know what causes this release in the first place, but studies have shown that leptine, a hormone secreted by fat cells in the human body, stimulate the KNDY-neurones which could lead to the start of the GnRH release.

During puberty (10-12yo) the child starts having lots of lipid cells which thus means more leptin secretion. This also means the "fatter" childeren get a faster puberty. It's a process called the gonadarche.

​

source: med student

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