Opioid receptors are receptor sites that respond to naturally occurring peptides: The endorphins and the enkephalins. These receptor sites are found in the CNS, on nerves in the periphery, and on cells in the gastrointestinal (GI) tract. In the brainstem, opioid receptors help to control blood pressure, pupil diameter, GI secretions, and the chemoreceptor trigger zone (CTZ) that regulates nausea and vomiting, cough, and respiration. In the spinal cord and thalamus, these receptors help to integrate and relate incoming information about pain. The endorphins and enkephalins normally modulate the pain information coming into the brain. Endorphins are released during stress to block the sensation of pain. Professional athletes may be injured during an important game and have no sensation of pain or injury because their stress reaction is highly activated, and the endorphins are blocking pain transmission into the brain. In the hypothalamus, stimulation of the opioid receptors may interrelate the endocrine and neural responses to pain. In the limbic system the receptors incorporate emotional aspects of pain and response to pain. At peripheral nerve sites, they may block the release of neurotransmitters that are related to pain and inflammation.
Many factors play a role in the patient’s perception of pain. Past experience has a big impact on how pain is perceived. Having experienced pain in the past a patient may fear the intensity it could reach and the overall impact of that pain. Learned response to pain also plays a large role. Children learn the accepted response to painful stimuli when growing up. Some children are taught to ignore pain and deal with it without showing emotion. Some children learn that reacting to pain can lead to much-wanted attention. The environmental setting in which the pain occurs also has an influence on perception and response to pain. A parent may not be willing to admit pain when the children are present, feeling that the role of the parent is to be strong. If you cut your finger when you are alone, you may perceive pain and react loudly. If you cut your finger when you are surrounded by young children, you may show no reaction and just go on with your activities. These varied influences on pain perception and response often make it very difficult to effectively evaluate and manage pain.
Accurately assessing pain can lead to effective pain management. Because so many factors play a role in pain perception and it is very subjective, assessment has to depend on the patient’s report of pain. Health care providers often use a scale system to evaluate a patient’s pain. Patients may be asked to rank their pain on a scale from 0 to 10, with 0 being no pain and 10 being the worst possible pain. Some pain scales use drawings of faces and ask the patient to pick the face that most reflects the pain they feel. Numerous methods, both nonpharmacological and pharmacological, may be used to manage pain. Nonpharmacological treatments can include warmth, massage, positioning, acupuncture, or meditation. Pharmacological methods often include the use of nonsteroidal anti-inflammatory drugs or acetaminophen (Chapter 15) for tissue-related pain or atypical antipsychotics or other CNS depressants for the treatment of neurogenic pain. These methods can be used individually or in combination. The goal is to achieve maximum pain relief.
One major method of pain management involves the use of narcotics. The narcotics, or opioids, were first derived from the opium plant. Although most narcotics are now synthetically prepared, their chemical structure resembles that of the original plant alkaloids. All drugs in this class are similar, in that they occupy specific opioid receptors in the CNS. Their actions in the body are related to the stimulation of the various opioid receptors that they occupy.
★Vocabulary★ receptor site – 受体位点
peptide – n. 肽
endorphin – n. 内啡肽
enkephalin – n. 脑啡肽
brainstem – n. 脑干
chemoreceptor trigger zone – 化学感受器触发区
activate – v. 激活，活化
interrelate – v. 使相关联
perception – n. 感知
subjective – a. 主观的
pain scale – 疼痛量表
nonpharmacological – a. 非药理性的
neurogenic – a. 神经（源）性的
derive – v. 衍生
synthetic – a. 合成的
resemble – v. 相似，类似，象
alkaloid – n. 生物碱
1. Christine Ann is about to take her NCLEX examination next week and is currently reviewing the concept of pain. Which scientific rationale would indicate that she understands the topic?
A. Pain is an objective sign of a more serious problem
B. Pain sensation is affected by a client’s anticipation of pain
C. Intractable pain may be relieved by treatment
D. Psychological factors rarely contribute to a client’s pain perception
2. When evaluating a client’s adaptation to pain, which behavior indicates appropriate adaptation?
A. The client distracts himself during pain episodes.
B. The client denies the existence of any pain.
C. The client reports no need for family support.
D. The client reports pain reduction with decreased activity.
奥医教育“在线自测”正式上线，复习练习、效果检验，奥医NCLEX-RN/ISPN题库一站完成。
答案 Answers
1. B. Pain sensation is affected by a client’s anticipation of pain Rationale: Phases of pain experience include the anticipation of pain. Fear and anxiety affect a person’s response to sensation and typically intensify the pain. Intractable pain is moderate to severe pain that cannot be relieved by any known treatment. Pain is a subjective sensation that cannot be quantified by anyone except the person experiencing it. Psychological factors contribute to a client’s pain perception. In many cases, pain results from emotions, such as hostility, guilt, or depression.
2. A. The client distracts himself during pain episodes. Rationale: Distraction is an appropriate method of reducing pain. Denying the existence of any pain is inappropriate and not indicative of coping. Exclusion of family members and other sources of support represents a maladaptive response. Range-of-motion exercises and at least mild activity, not decreased activity, can help reduce pain and are important to prevent complications of immobility.
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