Post by drbanks on Sept 12, 2017 8:22:28 GMT -5
Why are some peppers hot?
The "why" is believed to be an evolutionary response. Mammals are susceptible to the heat of peppers, so other than crazy humans and my former cat Hank (who loved his Vindaloo), they'll avoid eating pepper pods. Birds, on the other hand, are immune to the effects. Thus, they can eat the pods and... um... transport the seeds far, far away, where they can propagate the species. Apparently, mammals aren't so good about this.
What makes them hot?
A class of alkaloid chemicals called "Capsaicin," which was named after the pepper's genus of "Capsicum."
This stuff binds hard to your nerve cells at "Vanilloid Receptors" on nerve trunks called "C-fibers" (we'll get to that). These particular nerve receptors are also what senses heat and abrasion, which is why capsaicin feels "hot." it doesn't do any actual physical damage (directly) to your nerve or skin or anything else for that matter, other than simulating sometimes intense heat. An indirect effect is that your body will often react to what it thinks is actual physical damage and cause inflammation in the affected area (redness, swelling, in an attempt to insulate neighboring tissue, I suppose).
What's interesting is that capsaicin is "hydrophobic" meaning that it doesn't mix with water. This is why drinking water does little to help (at best) and just spreads it around like oil on water (at worst). On the other hand, it mixes well with fats, which is why yogurt and milk work better to get it off your tongue.
It also appears to bind to these receptors for a long time, which makes it extra special fun, and the C-Fiber nerve cells are not myelinated. Nerve Myelination greatly speeds up the conduction of a nerve impulse and is necessary for things like motor neurons so you can move your limbs quickly and accurately. But an unmyelinated sensory neuron can take a while, maybe seconds or more, to conduct their message to your brain, which is why the heat may take a while to "build up" and be noticed.
There are two more interesting side effects to this process (in addition to the possibility of inflammation).
The first is that by continually hammering these receptors, causing the nerve cell to fire continuously, it's possible/probable that before long, that nerve cell will run out of "I hurt" neurotransmitter, effectively reducing or eliminating its ability to signal pain until the little factories in the cell can generate more. This is why capsaicin can be used as a pain reliever. Yes, it burns when you rub it on, but after a while, those nerves are all used up (for a while). It's like ripping the Band-Aid off quickly.
The second is that your body knows that you don't like pain, and once the pain nerves start screaming loudly enough, your body starts releasing natural opiods called "endorphins" to tell them to shut the eff up.
Endorphins work by making that nerve cell's "GABA Receptors" (Gamma-Amino-Butyric Acid) much more sensitive. These are the same receptors that real opiods, alcohol or valium bind to, and inhibit the functioning of that nerve cell. In effect, it shuts them down. But, this endorphin release isn't really targeted to anywhere in particular, which means it puts a big damper on your whole nervous system, which includes your brain. The results con run from light headedness, dizziness, drunkenness, or just being stoned.
What does it mean to "build up a tolerance"?
What it means is very similar to being addicted to something. Nerve cells are not a static thing. Over the course of your life, nerve cells make and break connections with other nerve cells, and can strengthen or weaken those connections. Which can be a lot like spending a lot of time around someone.
If your friend talks a lot, over time, you'll probably get in the habit of paying less attention. There's just so much to process. If another friend doesn't talk very much, you'll eventually be more responsive to the rare occasion where something is said. Basically, it's adjusting your response/attention to that person to be appropriate for their level of talking.
Nerve cells work the same way. If a nerve cell is continually trying to communicate with another nerve cell, over time that other nerve cell will start ignoring it, by reducing the number of neuroreceptors linking them. This is why your response to a mind altering drug (alcohol or heroin, etc) can have a lesser effect over time if you abuse that drug. This is also why some neuroleptic drugs like antidepressants can take as much as a month to "kick in": because we're waiting for that habituation process to happen. Works the same for capsaicin: Abuse it, and over time, it takes a bigger "hit" to have the same effect.
And like any other drug, go cold turkey long enough for your neuroreceptors to repopulate, and you lose your tolerance.
Mostly, this just shows that I managed to stay awake in all those neuropsychopharmacology courses I took.
The "why" is believed to be an evolutionary response. Mammals are susceptible to the heat of peppers, so other than crazy humans and my former cat Hank (who loved his Vindaloo), they'll avoid eating pepper pods. Birds, on the other hand, are immune to the effects. Thus, they can eat the pods and... um... transport the seeds far, far away, where they can propagate the species. Apparently, mammals aren't so good about this.
What makes them hot?
A class of alkaloid chemicals called "Capsaicin," which was named after the pepper's genus of "Capsicum."
This stuff binds hard to your nerve cells at "Vanilloid Receptors" on nerve trunks called "C-fibers" (we'll get to that). These particular nerve receptors are also what senses heat and abrasion, which is why capsaicin feels "hot." it doesn't do any actual physical damage (directly) to your nerve or skin or anything else for that matter, other than simulating sometimes intense heat. An indirect effect is that your body will often react to what it thinks is actual physical damage and cause inflammation in the affected area (redness, swelling, in an attempt to insulate neighboring tissue, I suppose).
What's interesting is that capsaicin is "hydrophobic" meaning that it doesn't mix with water. This is why drinking water does little to help (at best) and just spreads it around like oil on water (at worst). On the other hand, it mixes well with fats, which is why yogurt and milk work better to get it off your tongue.
It also appears to bind to these receptors for a long time, which makes it extra special fun, and the C-Fiber nerve cells are not myelinated. Nerve Myelination greatly speeds up the conduction of a nerve impulse and is necessary for things like motor neurons so you can move your limbs quickly and accurately. But an unmyelinated sensory neuron can take a while, maybe seconds or more, to conduct their message to your brain, which is why the heat may take a while to "build up" and be noticed.
There are two more interesting side effects to this process (in addition to the possibility of inflammation).
The first is that by continually hammering these receptors, causing the nerve cell to fire continuously, it's possible/probable that before long, that nerve cell will run out of "I hurt" neurotransmitter, effectively reducing or eliminating its ability to signal pain until the little factories in the cell can generate more. This is why capsaicin can be used as a pain reliever. Yes, it burns when you rub it on, but after a while, those nerves are all used up (for a while). It's like ripping the Band-Aid off quickly.
The second is that your body knows that you don't like pain, and once the pain nerves start screaming loudly enough, your body starts releasing natural opiods called "endorphins" to tell them to shut the eff up.
Endorphins work by making that nerve cell's "GABA Receptors" (Gamma-Amino-Butyric Acid) much more sensitive. These are the same receptors that real opiods, alcohol or valium bind to, and inhibit the functioning of that nerve cell. In effect, it shuts them down. But, this endorphin release isn't really targeted to anywhere in particular, which means it puts a big damper on your whole nervous system, which includes your brain. The results con run from light headedness, dizziness, drunkenness, or just being stoned.
What does it mean to "build up a tolerance"?
What it means is very similar to being addicted to something. Nerve cells are not a static thing. Over the course of your life, nerve cells make and break connections with other nerve cells, and can strengthen or weaken those connections. Which can be a lot like spending a lot of time around someone.
If your friend talks a lot, over time, you'll probably get in the habit of paying less attention. There's just so much to process. If another friend doesn't talk very much, you'll eventually be more responsive to the rare occasion where something is said. Basically, it's adjusting your response/attention to that person to be appropriate for their level of talking.
Nerve cells work the same way. If a nerve cell is continually trying to communicate with another nerve cell, over time that other nerve cell will start ignoring it, by reducing the number of neuroreceptors linking them. This is why your response to a mind altering drug (alcohol or heroin, etc) can have a lesser effect over time if you abuse that drug. This is also why some neuroleptic drugs like antidepressants can take as much as a month to "kick in": because we're waiting for that habituation process to happen. Works the same for capsaicin: Abuse it, and over time, it takes a bigger "hit" to have the same effect.
And like any other drug, go cold turkey long enough for your neuroreceptors to repopulate, and you lose your tolerance.
Mostly, this just shows that I managed to stay awake in all those neuropsychopharmacology courses I took.