Nervous System and Neurons

Lipofuscin is the name given to finely granular yellow-brown pigment granules composed of lipid containing residues of lysosomal digestion. Lipofuscin or lipochrome is a wear and tear pigment since the number of its granules within the neurons increases with age. These granules are end products of intracellular peroxidation and polymerisation of unsaturated fatty acids. The precise function of lipofuscin is unknown.

Fatigue is a state of awareness describing a range of afflictions usually associated with physical and/or mental weakness though varying from a general state of lethargy to a specific work induced burning sensation within one's muscles.

An axon is a long branching cell structure that is unique to nerve cells. Axons are responsible for carrying information from the nerve cells to all the other cells of the body. The axon carries nerve signals away from the soma and also carries some types of information back to it. Interference with signals as they travel through the axons has been identified as a cause of certain degenerative neurological disorders.

The axon hillock is a specialized domain of the neuronal cell body from which the axon originates. A nissl body also known as nissl or tigroid substance is a large granular body found in neurons, but it cannot be seen in the axon or axon hillock.

The channels are made up of glycoproteins. The ions cross through their channels by electrical potential. Through the channels, the ions which are mainly carried in physiological conditions are sodium, potassium, calcium and chlorine.

The axon is the long, threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.

A sensory receptor is a specialized nerve ending or cell that detects physical stimuli, such as pressure, temperature, or light, and converts them into electrical signals.

The neural network that processes dopamine is central to the brain's reward system, reinforcing behaviors that are perceived as pleasurable.

The cerebro-spinal system is another name for the central nervous system, which consists of the brain and the spinal cord.

The autonomic nervous system regulates involuntary bodily functions, including heart rate and blood vessel diameter, which control blood circulation.

The peripheral nervous system consists of all nerves outside the brain and spinal cord, connecting the central nervous system to the rest of the body.

When nerves overlap, the brain receives a summation of signals, which is interpreted as an increased intensity of the sensation.

The autonomic nervous system regulates involuntary physiological processes such as heart rate, digestion, and respiratory rate. Other options like the central nervous system are involved in processing information and controlling voluntary actions.

The somatic nervous system is typically responsible for voluntary movement. However, in many electrology curricula, the cerebro-spinal system (which includes the brain and spinal cord) is taught as the primary controller of voluntary activity. Given the options provided, D is the intended answer.

The nervous system is composed of the brain, the spinal cord, and the nerves that branch out throughout the body.