Among the long and varied list of neurotransmitters which reside in the human brain, I find endorphins and serotonin to be quite interesting. Having gone through the pain of child birth and Navy boot camp, I can say with certainty that I am thankful for endorphins. According to the text, endorphins are “pain-controlling chemicals in the body.” (Ciccarelli & White, 2015, p. 53) This means that when one gets injured, endorphins are released, and the person is alerted to the injury by pain. Endorphins also regulate pain by “inhibit[ing] the transmission of pain signals in the brain, and in the spinal cord they can inhibit the release of substance P.” (Ciccarelli & White, 2015, p. 115) This substance messages the brain to activate cells which cause even more alerts throughout the body to either increase or decrease pain accordingly. The origin of the word endorphin is “endogenous morphine” meaning that it is “the body’s natural version of morphine.” (Ciccarelli & White, 2015, p. 115) These particular neurotransmitters also have a role in pain disorders such as congenital insensitivity to pain with anhidrosis (CIPA), and phantom limb pain. In CIPA, the patient is unable to feel pain. This may sound quite appealing to thrill seekers, but in reality it is a nightmare. For example, the patient would not feel the excruciating pain of a broken limb which needs immediate medical care and simply go about their day oblivious to the critical problem. Additionally, those afflicted with CIPA “have an additional disruption in the body’s heat-cold sensing perspiration system,” (Ciccarelli & White, 2015, p. 114) called anhidrosis. Patients who suffer from phantom limb pain appear to have pain in the amputated or phantom limb. This disorder, however, is being reexamined as it may be due to “traumatic injury to the nerves during amputation” (Ephraim et al., 2005) rather than an endorphin disorder.
As mentioned before, serotonin is also a fascinating neurotransmitter. Like endorphins, serotonin also has a variety of functions. For example, it can have “either an excitatory or inhibitory effect.” (Ciccarelli & White, 2015, p. 52) Additionally, it affects sleep, mood, anxiety and appetite. For example, when serotonin levels are too high, a patient may be prescribed a selective serotonin reuptake inhibitor (SSRI) such as Prozac in order to regulate their depression. Another example of a serotonin imbalance occurs when the consumption of alcohol decreases serotonin levels within the brain. (Ciccarelli & White, 2015, p. 488) This may result in aggressive behavior as “alcohol acts to release inhibitions.” (Ciccarelli & White, 2015, p. 488) Additionally, serotonin is “associated with arousal and sleep regulation.” (Ciccarelli & White, 2015, p. 139) It works with melatonin, “a hormone secreted by the pineal gland,” (Ciccarelli & White, 2015, p. 138) to regulate circadian rhythms thereby regulating one’s sleep.