The Descending Control Mechanism Activates Once Noxious Stimuli

p.483 The cell bodies of primary-order neurons or pain-transmitting neurons reside in the dorsal root ganglia just lateral to the spine along the sensory pathways that penetrate the posterior part of the cord. The second order neurons are found in the dorsal horn (p.484) Most nociceptive information tranvels by means of ascending columns in the lateral spinothalamic tract (also called the anterolateral funiculus). The principal target for nociceptive afferents is the thalamus (the major relay station of sensory information in general) Third order neurons project to portions of the CNS involved in the processing and interpretation of pain, the chief areas being the reticular and limbic systems and cerebral cortex. (p 484)

Pain is not only defined as a sensation or a physical awareness, but also entails perception. Moreover, pain is an unpleasant and an uncomfortable emotion that is transferred to the brain by sensory neurons. There are various kinds of pain and how one perceives them is varied as well. Certain parts of the brain also play a key role in how one feels pain such as the parietal lobe, which is involved in interpreting pain while the hypothalamus is responsible for the response to pain one has. Although some believe pain is just a physical awareness and is in the body, pain is all in one’s mind because the perception of pain and the emotion that controls its intensity differs in individuals and when pain itself is administered to the body, the brain determines the emotions one attaches to each painful experience.

The cervical spinal nerve C3-5 innervate the phrenic nerve. These are the lower motor neurons.

Pain effects the body through the nerves. The phenomena of pain is conveyed from a peripheral part of the person, through afferent nerves to a part of the brain, similar to sight, touch, and hearing. These signals are then interpreted by the brain as pain (Murphy, 1981). The nerve cells used to relay pain messages to the brain are specific nerve cells called nociceptors. These nerves do not send messages until "the stimulus reaches noxious levels," (McClesky, 1992).

Pain is not just a symptom, but a specific problem that needs to be treated. Pain is a neurologic response to unpleasant stimuli. What is the gate control theory of pain? What are the classifications of pain? What are some ways to manage pain?

The binding could only occur in the receptors active site if the size, shape and charge of the morphine’s meet the requirement of the receptor. Once the match is identified, the following binding process would take place. The flat benzene ring in morphine would fit securely in the flat surface of the receptor’s active site to allow the rest of the molecule to fall in place easily. The adjacent carbon atoms would fit into a nearby groove, while the nitrogen atom would attach to the negatively charged group receptor, hence joining the two together. After the binding occurred, the morphine would be able to block the sending of the painful information from the pre-synaptic neuron on the nociceptor. This is because, it caused a reactionary changed in the cell which blocks its ability to produces the substance that causes the feeling of pain during and/or after an operation and injury.

The most commonly available exogenous opioids primarily work by “high jacking” μ receptor functionality. μ receptors can be found throughout our brain and spinal cord and control reward, euphoria, analgesia, breathing, and nausea. These receptors are designed to be activated by our endogenous opioids. Exogenous opioids, however, are far better at attaching themselves and activating these same receptors. The result is an overactivation of these receptors throughout the body.

which in turn inhibits the second order neurons that transmit the nociceptive signals to the

In the analgesic effect, opioids influence mostly the central nervous systems. The primary type of receptors

Average pain is processed by nociceptors via two sets of neural pathways. The ascending neural pathway is activated by painful stimuli like extreme temperature, pressure, and impact. The ascending pathway sends nociceptive signals to send neurotransmitters

Mechanism: Although the exact mechanism of action is not known, ketamine appears to be an agonist at CNS muscarinic acetylcholine-receptors and opiate-receptors. Ketamine

G. What type of peripheral receptors would be activated in a normal, intact limb to produce the sensations Sannu is experiencing in his “phantom limb”?

This research paper is a compilation of information gathered during lectures and through the web on the Nervous System and the Reward Pathway. This paper examines the structure of these systems, their discovery and the effects that drugs have on influencing these systems and how addictions are formed.

But because they have a longer half-life and can rapidly cross the blood brain barrier, they are the choice of users. (Doweiko, 2014) Amphetamines and stimulants in general excite the CNS through stimulation of norepinephrine (Momaya, Fawal, & Estes, 2015), a neurotransmitter that helps, in conjunction with epinephrine to respond to the ?fight or flight? reaction to stress (Parse, 2015). Stimulants cause the release of norepinephrine from storage in sympathetic nerve endings. It then leads to the increase of arousal, heart rate, respiratory rate, and blood pressure. (Momaya, Fawal, & Estes, 2015) When taken orally, the stimulant is absorbed through the lining of the small intestine. It then reaches the brain through the bloodstream and produces regional effects. That is, it will cause a neurotransmitter activity in one region, while shutting of another region. Stimulants also seem to have an effect to alter the dopamine neurotransmission system. (Doweiko, 2014) The system is instrumental for movement and plays a role in Parkinson?s Disease when shut off. It also involves our pleasure center (rewarding properties), thus which is why we reach a euphoric state with certain stimulants. (Dopamine Neurotransmitter, 2015) (Steinkellner, Freissmuth, Sitte, & Montgomery,

Drugs of abuse, such as cocaine, ecstasy, heroin and cannabis, are of natural or synthetic origin, which can alter the emotional state, perception, body functioning and behaviour of an individual. Drugs are known to work in the brain by activating certain brain circuits via different mechanisms, and stimulate or inhibit different neurons in the pathway. However, due to the effects of each drug being different, a drug will affect either different pathways and neurons in the brain to that of another, or through a different process, i.e. direct or indirect activity. This essay will discuss the different mechanisms of action that cocaine, ecstasy, heroin and