The functional units of the nervous system are the
a. axons.
c. nephrons.
b. dendrites.
d. neurons.
The correct answer and explanation is:
The correct answer is d. neurons.
Neurons are the functional units of the nervous system. They are specialized cells that transmit electrical impulses throughout the body, enabling communication between different parts of the nervous system. The structure of a neuron includes three main components: the cell body, dendrites, and axon.
- Dendrites are branch-like structures that receive signals from other neurons. These signals are typically in the form of neurotransmitters, which are chemical messengers that cross synapses (gaps between neurons) to transmit information.
- The cell body houses the nucleus of the neuron and is responsible for the metabolic functions of the cell. It integrates the signals received from the dendrites and determines whether to transmit an impulse along the axon.
- The axon is a long, slender extension that carries electrical impulses away from the cell body to other neurons, muscles, or glands. Some axons are covered in a fatty substance called myelin, which speeds up the transmission of signals.
The functional role of neurons is critical for everything from reflexes to complex cognitive processes. They transmit information rapidly and efficiently across long distances within the body. These cells form intricate networks that allow the nervous system to respond to internal and external stimuli, control movements, process sensory information, and support higher cognitive functions like thinking and memory.
Nephrons, mentioned in option (c), are the functional units of the kidneys and are unrelated to the nervous system. Similarly, while axons and dendrites are components of neurons, they are not considered the functional units themselves. Neurons as a whole carry out the tasks of the nervous system, making them the correct answer.