Consciousness Nervous system

The human body has more than 600 muscles. The body s movement is performed by muscle contractions, which are stimulated by the nervous system. This system links muscle tissue to the spinal cord and brain. The network of nerve cells which carries the brain s signals directs the flow of muscular energy. Most muscular activity occurs beyond the range of the conscious mind. The body, working through the neuromuscular network, manages... 

CNS DEPRESSANT Substanccs, e.g. anaesthetics and narcotics, which depress the activity of the central nervous system. Symptoms following exposure include headache, dizziness, loss of consciousness, respiratory or cardiac depression, death. 

Autonomic nervous system. The portion of the nervous system outside of the brain and spinal cord that is responsible for monitoring and controlling the digestive system, cardiovascular system, and other organs that are not under direct conscious control. 

Ethanol is classified for medical purposes as a central nervous system (CNS) depressant. Its effects—that is, being drunk—resemble the human response to anesthetics. There is an initial excitability and increase in sociable behavior, but this results from depression of inhibition rather than from stimulation. At a blood alcohol concentration of 0.1% to 0.3%, motor coordination is affected, accompanied by loss of balance, slurred speech, and amnesia. When blood alcohol concentration rises to 0.3% to 0.4%, nausea and loss of consciousness occur. Above 0.6%, spontaneous respiration and cardiovascular regulation are affected, ultimately leading to death. The LD50 of ethanol is 10.6 g/kg (Chapter 1 Focus On). 

Children are affected by methyl parathion in the same manner as adults. Exposure to high levels of methyl parathion, even for short periods, may result in changes in the nervous system, leading to headaches, dizziness, confusion, blurred vision, difficulty breathing, vomiting, diarrhea, loss of consciousness, and death (see also Section 1.5 for a more complete description of how methyl parathion affects human health). It is not known whether children are more sensitive to the effects of methyl parathion than adults. There is some indication that young rats may be more sensitive than adults to nervous system effects. 

Methods of detection, metabolism, and pathophysiology of the brevetoxins, PbTx-2 and PbTx-3, are summarized. Infrared spectroscopy and innovative chromatographic techniques were examined as methods for detection and structural analysis. Toxicokinetic and metabolic studies for in vivo and in vitro systems demonstrated hepatic metabolism and biliary excretion. An in vivo model of brevetoxin intoxication was developed in conscious tethered rats. Intravenous administration of toxin resulted in a precipitous decrease in body temperature and respiratory rate, as well as signs suggesting central nervous system involvement. A polyclonal antiserum against the brevetoxin polyether backbone was prepared a radioimmunoassay was developed with a sub-nanogram detection limit. This antiserum, when administered prophylactically, protected rats against the toxic effects of brevetoxin. 

The symptoms produced by respiratory alkalosis result from increased irritability of the central and peripheral nervous systems. These include light-headedness, altered consciousness, distal extremity paresthesias, circumoral paresthesia, cramps, carpopedal spasms, and syncope. Various supraventricular and ventricular cardiac arrhythmias may occur in extreme cases, particularly in critically ill patients. An additional finding in many patients with severe respiratory alkalosis is hypophosphatemia, reflecting a shift of phosphate from the extracellular space into the cells. Chronic respiratory alkalosis is generally asymptomatic. 

Central nervous system disorder resulting in a decreased level of consciousness (see section on cognitive impairment)... 

Glasgow Coma Scale (GCS) A scale for evaluating level of consciousness after central nervous system injury (evaluates eye opening and verbal and motor responsiveness). 

An analgesic drug acts on the nervous system to suppress or eliminate pain without causing loss of consciousness. As such, an ideal analgesic would exhibit the following qualities ... 

The autonomic nervous system (ANS), also known as the visceral or involuntary nervous system, functions below the level of consciousness. Because it innervates cardiac muscle, smooth muscle, and various endocrine and exocrine glands, this nervous system influences the activity of most of the organ systems in the body. Therefore, it is evident that the ANS makes an important contribution to the maintenance of homeostasis. Regulation of blood pressure gastrointestinal responses to food contraction of the urinary bladder focusing of the eyes and thermoregulation are just a few of the many... 

The concept of chemical neurotransmission originated in the 1920s with the classic experiments of Otto Loewi (which were themselves inspired by a dream), who demonstrated that by transferring the ventricular fluid of a stimulated frog heart onto an unstimulated frog heart he could reproduce the effects of a (parasympathetic) nerve stimulus on the unstimulated heart (Loewi Navratil, 1926). Subsequently, it was found that acetylcholine was the neurotransmitter released from these parasympathetic nerve fibers. As well as playing a critical role in synaptic transmission in the autonomic nervous system and at vertebrate neuromuscular junctions (Dale, 1935), acetylcholine plays a central role in the control of wakefulness and REM sleep. Some have even gone as far as to call acetylcholine a neurotransmitter correlate of consciousness (Perry et al., 1999). 

Murphy, D.J., Joran, M.E., and Grando, J.C., A non-invasive method for distinguishing central from peripheral nervous system effects of respiratory depressant drugs in conscious rats, General Pharmacol., 26, 569-575,1995. 

We understand many aspects of the anatomy, physiology, and biochemistry of the human nervous system. The central points are the subjects of this chapter. As we come to understand them, much of great interest will be revealed to us. We will get important insights into how the nervous system functions and, in disease, malfunctions. We will also begin to understand why many molecules are effective in treatment of mental health disorders or induce abnormal states of consciousness in people. 

The final principle, the conservation of signaling molecules over evolutionary time, has the greatest practical significance for understanding the science of mind. The structure of the human nervous system is a marvel of complexity. This is splendid in the sense that the complexity yields so much functionality. The complexity makes problems, however, for those who seek an understanding of the mind learning, memory, consciousness. 

As we move forward, it will prove helpful to get some basic aspects of the human nervous system in place. An enormous amount of work has gone into making associations between brain anatomy and function. Starting with the three main parts of the brain, we know that the cerebrum is the seat of consciousness. It is divided into two hemispheres, which are linked by the corpus callosum. In a very general sense, the left hemisphere is associated with intellectual and the right hemisphere with emotional responses. Within the cerebrum, one can associate a number of brain areas (the prefrontal, frontal, temporal, parietal, and occipital lobes, for example) with functions including vision and hearing. One can make crude maps in which function is mapped onto brain structure. 

Once the information is processed and yon (consciously or unconsciously) have decided what it means, yonr nervous system coordinates a response. This is the task of execution. The loop from sensation to processing to execution can occur at many levels. The simplest level is the reflex arc. As noted earlier, when your family doctor strikes your knee with a rubber hammer, the nerves at your knee sense the impact and transmit that information. This information is intercepted and processed well before it ever reaches your consciousness. A reflex center interprets the sensation as a possible threat and automatically executes a command to straighten your knee. The result is a reflex action that protects your leg from injury by kicking away the perceived threat. This sensation to processing to execution loop is completed without any involvement of yonr brain. 

Forming part of the peripheral nervous system is the autonomic nervous system which controls the glands and non-skeletal muscles that are not under conscious control. This control is provided by two parts of this system the sympathetic and parasympathetic divisions which, in general, bring about antagonistic responses. 

Now it seems to me that this must be how consciousness works within the brain, where matter and energy are in a more unbound and dynamic state than throughout the rest of nature. It is easy for consciousness to direct the electrical flow in the central nervous system (though we have no idea how this is done) it is less easy for it to move, not... 

I saw that there is an interphase between consciousness active in the world and consciousness active in the central nervous system, whose intermediary is the body. That interphase is language. To use language, consciousness informs the brain to inform the body to impart coherency to the random motion of the air molecules near but outside the body. This coherency is supplied by consciousness in the form of a word. None of the physical laws operating on the air molecules have been violated, because the coherent pattern of behavior of the molecules is due to an input of energy—an input of energy whose release was initiated by an act of conscious will. Will is not an item in the toolkit of scientific explanation. 

Ingestion of ethanol acts on the central nervous system. In moderate amounts, it affects Judgment and lowers inhibitions. Higher concentrations cause nausea and loss of consciousness. Even at higher concentrations, it interferes with spontaneous respiration and can be fatal. 

Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system. These are classified as follows ... 

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