Integrated nervous system

There is really only one, whole, integrated nervous system. However, for the purposes of understanding the effects of drugs and poisons on the system, we will subdivide it anatomically and functionally. Afferent nerves... 

Sir Charles Sherrington ( neuron , synapse , integrated nervous system) Lord Edgar Adrian (electrical p.d.-based... 

Animal behavior has been dehned by Odnm (1971) as the overt action an organism takes to adjnst to its environment so as to ensure its survival. A simpler definition is the dynamic interaction of an animal with its enviromnent (D Mello 1992). Another, more elaborate, one is, the outward expression of the net interaction between the sensory, motor arousal, and integrative components of the central and peripheral nervons systems (Norton 1977). The last dehnition spells out the important point that behavior represents the integrated function of the nervous system. Accordingly, disruption of the nervous system by neurotoxic chemicals may be expected to cause changes in behavior (see Klaasen 1996, pp. 466-467). 

Many tests have been devised to provide quantitative measures of behavioral disturbances caused by neurotoxic chemicals. Tests have been devised that assess the effects of chemicals on four behavioral functions (D Mello 1992). These are sensory, cognitive, motor, and affective functions. However, because the entire nervous system tends to work in an integrated way, these functions are not easily separable from one another. For example, the outcome of tests focused on sensory perception by rats may be influenced by effects of the test chemical on motor function. 

Such hydrogels have been suggested to be suitable for biotechnological applications (DNA delivery vehicles, cell encapsulation) [28]. Recently, amphiphilic dibock copolypeptide hydrogels of KigoL2o were used in an in vivo study where the hydrogels were injected into the mouse forebrain. Evaluation of samples displayed substantial tissue integration with little or no detectable toxicity in the central nervous system [148]. 

D. J., Jeffrey, P. Improving the in vitro prediction of in vivo centtal nervous system penetration Integrating permeability, P-glycoprotein efflux, and free fractions in blood and brain. 

Many different types of sensory receptors are located throughout the body. These receptors monitor the status of the internal environment or that of the surroundings. Sensory receptors are sensitive to specific types of stimuli and measure the value of a physiological variable. For example, arterial baroreceptors measure blood pressure and chemoreceptors measure the oxygen and carbon dioxide content of the blood. The information detected by these sensors then travels by way of afferent neuronal pathways to the central nervous system (CNS). The CNS is the integrative portion of the nervous system and consists of the (1) brain and the (2) spinal cord. 

Figure 1.1 Functional components of the nervous system. The sensory division of the peripheral nervous system is sensitive to changes in the internal and external environment. The information gathered by this component is transmitted to the CNS where it is processed, integrated, and interpreted. The CNS then determines the appropriate response to this input. This response is carried out by the transmission of nerve impulses in the motor division of the peripheral nervous system to the effector tissues.

The brain is the integrative portion of the nervous system that serves to receive, process, and store sensory information and then plan and orchestrate the appropriate motor response. It is divided into several anatomically and functionally distinct regions (see Table 6.2). The forebrain consists of the cerebrum, basal ganglia, thalamus, and hypothalamus. The midbrain, along with the pons and the medulla of the hindbrain, composes the functional region referred to as the brainstem. The cerebellum is also considered a component of the hindbrain but is functionally distinct from the brainstem. 

Figure 15.4 Effects of the autonomic nervous system on mean arterial pressure. The baroreceptors, chemoreceptors, and low-pressure receptors provide neural input to the vasomotor center in the brainstem. The vasomotor center integrates this input and determines the degree of discharge by the sympathetic and parasympathetic nervous systems to the cardiovascular system. Cardiac output and total peripheral resistance are adjusted so as to maintain mean arterial pressure within the normal range.

Dono, R. Fibroblast growth factors as regulators of central nervous system development and function. Am. J. Physiol. Regul. Integr. Comp. Physiol. 284 R867-R881, 2003. 

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