The CNS communicates with peripheral body structures through pathways. These conduct either sensory nerve signals from or motor nerve signals to ; processing and integration occur along them. These pathways travel through the white matter of the spinal cord as they connect various CNS regions with spinal nerves. A pathway consists of a(n) (groups or bundles of axons that travel together in the CNS) and a(n) nucleus (a collection of neuron cell bodies located within the CNS).

receptors, effectors, tract

Explanation:

first is receptor because we have to sense the stimulus for our brain to send signal to certain parts or effectors to act on it. The third blank is tract because it serves the definition of tract which says  a tract major passage in the body, large bundle of nerve fibers, or other continuous elongated anatomical structure or region.

1. the energy lost to disorder metabolism     -entropy

2. related to or possessing motion potential     -kinetic

3. all of the chemical reactions in an organism required for maintenance of the processes of life entropy     -metabolism

4. possible; ability to go into action or perform work kinetic     -potential

5. the study of energy and its transformations thermodynamics     -thermodynamics