mana taknya... drugs such as amphitamine & etc. will eventually cause level of neurotransmitters such as epinephrine, norepinephrine, and dopamine to rise. those neurotransmitters will then bind to α1, α2, β1, β2, and β3 adrenergic receptors present in our body.
by the activation of α2, β2, and β3 receptors, high level of energy sources such as glucose are made available by activation of several process such as lipolysis, gluconeogenesis, glycogenolysis, etc.
next, β2 receptor activation also leads to increase in skeletal muscle contractility, hence, the reason the drug addicts were able to run as fast as 'pelesit'. even the delivery of nutrients and oxygen to the muscles were made faster than usual. β1 receptor activation causes the heart to pump crazily, pushing and pushing the blood to our countless cells. activation of α1 receptor (which is widely distributed in blood vessels compared to heart) leads to vasoconstriction of majority of vessels causing blood pressure (and also blood flow) to go sky high while β2 receptor activation leads to vasodilation of vascular beds, therefore increasing the surface area for exchange of nutrients, oxygen, and other substances between vessels and organs and skeletal muscle. then, the blood volume is also being expanded by increase in renin secretion. you know very well renin-angiotensin-aldosterone system leads to water and sodium retention, contributing to increase in blood volume. there, the organs and skeletal muscle are being bathed lavishly with nutrients and oxygen delivered by blood.
eh, but i didn't explain how the increase in oxygen supply were made possible, did i? β2 receptor activation also leads to bronchodilation. therefore, less turbulent air flow and less resistance. kenapa mata drug addicts kuyu? can it be because of activation of α1 receptor which leads to dilation of pupil (by contraction of pupillary muscle of the eye)? mungkin mat dadah tu rasa silau bila pupil dia jadi besar sebab cahaya lagi banyak masuk mata daripada kadar yang normal, so kena kuyukan mata? but that might also explain the reason those drug addicts can disappear so fast even in the middle of the night.
so... for all these... why abusing drugs is bad for us? easy. i told you that β1 receptor activation makes our heart beats crazily, didn't i? although the size of our heart is just slightly smaller than our clenched fist, it consumes so much of oxygen, about 20-25% of our oxygen supply if i'm not mistaken (tak berapa ingat percentage smua ni). so, when the heart gets crazy, so does it's oxygen demand. the oxygen demand will increase so high and might be one of the factors why amphetamine usage is linked to increase in heart attack incidence. not to mention that our blood pressure will go sky high. our brain has very fine blood vessels supplying it. it's not able to tolerate such ridiculously high pressure of blood, therefore, cerebral hemorrhage is one of the consequence you'll have to face if you were to abuse drugs. for guys... your 'little brother' down there will shrink due to redistribution of blood supply hahaha~ apparently, in sympathetic nervous system activation, our body behave in such way that it thinks the penis is not an important organ to be involved in 'fight & flight' situation. mestilah... takkanlah tengah takut nak kena belasah, 'little brother' boleh menolong. LOL!!!! and there are many more terrible side effects of drug abuse, so... mung nok ke... tokse ke... ikut mung la. aku ghoyak awal-awal dah. mung gelenya sangat nok try tu, try ni, rasakanlah, rasakanlah (bercakap dengan loghat Kelantan ala Siam).
okay, okay, biar aku 'be frank' je lah... aku tengah nak cuba hafal distribution and action setiap adrenergic receptor sebenarnya, haha~ bosan baca? haha, too bad, it's my blog anyway.