Serotonin 血清张力 is a chemical that carries messages between nerve cells in the brain and throughout your body. Serotonin plays a key role in such body functions as mood, sleep, digestion, nausea, wound healing, bone health, blood clotting and sexual desire. Serotonin levels that are too low or too high can cause physical and psychological health problems. Serotonin ([ˌsɛrəˈtoʊnɪn, ˌsɪərə-], also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter with a wide range of functions in both the central nervous system (CNS) and also peripheral tissues. It is involved in mood, cognition, reward, learning, memory, and physiological processes such as vomiting and vasoconstriction. In the CNS, serotonin regulates mood, appetite, and sleep. Most of the body's serotonin—about 90%—is synthesized 合成 in the gastrointestinal tract by enterochromaffin cells, where it regulates intestinal movements. It is also produced in smaller amounts in the brainstem's raphe nuclei, the skin's Merkel cells, pulmonary neuroendocrine cells, and taste receptor cells of the tongue. Once secreted, serotonin is taken up by platelets in the blood, which release it during clotting to promote vasoconstriction and platelet aggregation. Around 8% of the body's serotonin is stored in platelets, and 1–2% is found in the CNS. Serotonin acts as both a vasoconstrictor and vasodilator depending on concentration and context, influencing hemostasis and blood pressure regulation. It plays a role in stimulating myenteric neurons and enhancing gastrointestinal motility through uptake and release cycles in platelets and surrounding tissue. Biochemically, serotonin is an indoleamine synthesized from tryptophan and metabolized primarily in the liver to 5-hydroxyindoleacetic acid (5-HIAA). Serotonin is targeted by several classes of antidepressants, including selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine reuptake inhibitors (SNRIs), which block reabsorption in the synapse to elevate its levels. It is found in nearly all bilateral animals, including insects, spiders and worms, and also occurs in fungi and plants. In plants and insect venom, it serves a defensive function by inducing pain. Serotonin released by pathogenic amoebae may cause diarrhea in the human gut, while its presence in seeds and fruits is thought to stimulate digestion and facilitate seed dispersal.
Serotonin, also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter. It also acts as a hormone. As a neurotransmitter, serotonin carries messages between nerve cells in your brain (your central nervous system) and throughout your body (your peripheral nervous system). These chemical messages tell your body how to work. Serotonin plays several roles in your body, including influencing learning, memory, happiness as well as regulating body temperature, sleep, sexual behavior and hunger. Lack of enough serotonin is thought to play a role in depression, anxiety, mania and other health conditions. Most of the serotonin found in your body is in your gut (intestines). About 90% of serotonin is found in the cells lining your gastrointestinal tract. It's released into your blood circulation and absorbed by platelets. Only about 10% is produced in your brain. Serotonin is made from the essential amino acid tryptophan. An essential amino acid means it can't be made by your body. It has to be obtained from the foods you eat.
Dopamine is a neurotransmitter (chemical messenger) that works in your brain. It helps your nerve cells send messages to each other. Dopamine is made by cells deep in your brain and acts on cells in other parts of your brain. It is also made in other parts of your body, where it acts as a hormone. What is the role of dopamine? Dopamine acts on your brain to give you feelings of pleasure and satisfaction when you do something enjoyable. Dopamine and addiction: Dopamine is released in your brain when you achieve something or do something fun. The good feeling that dopamine gives you after pleasant experiences, including eating nice food, having sex, winning a game and earning money, can also happen after drinking alcohol and using illicit drugs. It's natural to want to feel more of this dopamine 'reward'. This is how dopamine is involved in reinforcing addictive behaviours. In addiction you might continue to drink, use drugs or gamble to try and get the good feeling again, even if doing so is not healthy. What happens if I have too much or too little dopamine? Dopamine is involved in many different body functions. It works with other systems and other neurotransmitters, not on its own. So, there are a lot of possible problems related to a dopamine imbalance. They can include both physical symptoms and psychological symptoms. Having too much dopamine may be linked to being aggressive and having trouble controlling your impulses. If you have low levels of dopamine, you may feel less motivated and excited about things in your life. Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. It is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical, L-DOPA, which is synthesized in the brain and kidneys. Dopamine is also synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. The brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior. The anticipation of most types of rewards increases the level of dopamine in the brain, and many addictive drugs increase dopamine release or block its reuptake into neurons following release. Other brain dopamine pathways are involved in motor control and in controlling the release of various hormones. These pathways and cell groups form a dopamine system which is neuromodulatory. In popular culture and media, dopamine is often portrayed as the main chemical of pleasure, but the current opinion in pharmacology is that dopamine instead confers motivational salience(salient [ˈseɪliənt] 明显的, 显而易见的 a salient fact, issue, or feature is one that is especially noticeable or relevant. The salient facts about something or qualities of something are the most important things about them: She began to summarize the salient features/points of the proposal. The article presented the salient facts of the dispute clearly and concisely. The report covered all the salient points of the case. He read the salient facts quickly. Chronic fatigue is also one of the salient features of depression. ...the salience of social reforms. valiant [væliənt] 勇敢的, 不懈的 A valiant action is very brave and determined, though it may lead to failure or defeat. very brave or bravely determined, especially when things are difficult or the situation gives no cause for hope: The company has made a valiant effort/attempt in the last two years to make itself more efficient. Despite valiant efforts by the finance minister, inflation rose to 36%. ...a valiant attempt to keep the business going. He suffered further heart attacks and strokes, all of which he fought valiantly. reticent 少言寡语的, 不怎么说话的, 谨言慎行的 unwilling to speak about your thoughts or feelings. Someone who is reticent does not tell people about things. She is so reticent about her achievements. As a reticent sort, the England defender was reluctant to hog the limelight. Pearl didn't mind his reticence; in fact she liked it. He is very reticent about his past. Most of the students were reticent about answering questions. ); in other words, dopamine signals the perceived motivational prominence (i.e., the desirability or aversiveness) of an outcome, which in turn propels the organism's behavior toward or away from achieving that outcome. Outside the central nervous system, dopamine functions primarily as a local paracrine messenger. In blood vessels, it inhibits norepinephrine release and acts as a vasodilator; in the kidneys, it increases sodium excretion and urine output; in the pancreas, it reduces insulin production; in the digestive system, it reduces gastrointestinal motility and protects intestinal mucosa; and in the immune system, it reduces the activity of lymphocytes. With the exception of the blood vessels, dopamine in each of these peripheral systems is synthesized locally and exerts its effects near the cells that release it. Several important diseases of the nervous system are associated with dysfunctions of the dopamine system, and some of the key medications used to treat them work by altering the effects of dopamine. Parkinson's disease, a degenerative condition causing tremor and motor impairment, is caused by a loss of dopamine-secreting neurons in an area of the midbrain called the substantia nigra. Its metabolic precursor L-DOPA can be manufactured; Levodopa, a pure form of L-DOPA, is the most widely used treatment for Parkinson's. There is evidence that schizophrenia involves altered levels of dopamine activity, and most antipsychotic drugs used to treat this are dopamine antagonists which reduce dopamine activity.[10] Similar dopamine antagonist drugs are also some of the most effective anti-nausea agents. Restless legs syndrome and attention deficit hyperactivity disorder (ADHD) are associated with decreased dopamine activity. Dopaminergic stimulants can be addictive in high doses, but some are used at lower doses to treat ADHD. Dopamine itself is available as a manufactured medication for intravenous injection. It is useful in the treatment of severe heart failure or cardiogenic shock. In newborn babies it may be used for hypotension and septic shock.
Dopamine VS serotonin: Dopamine and serotonin are both neurotransmitters. This means they are chemical message carriers between nerve cells in the brain as well as to and from other areas of your body. Both are also considered the “happy hormones,” as they both play a role in positive mood and emotion. Serotonin is associated with happiness, focus and calmness. Dopamine is associated with rewards and motivation. Dopamine and serotonin also share involvement in some mental health conditions, including depression and mood disorders. Dopamine and serotonin also have some distinct functions. Dopamine controls body movements and coordination. Serotonin helps regulate digestive functions including bowel function and appetite. Dopamine causes a feeling of hunger while serotonin suppresses that feeling. Dopamine is mostly stored in your brain while serotonin is found mostly in your gut. Sometimes these neurotransmitters work together to stay in a careful chemical balance in your body. Sometimes an imbalance leads to an overproduction of the other neurotransmitter. Having too much or too little of either can cause physical and psychological symptoms.
