The correct option is (a).
Explanation
The neuron (nerve cell) is the fundamental structural and functional unit of the nervous system. It is specialized to detect, receive, and transmit information through electrical and chemical signals across the body.
Statement-wise Analysis
- Statement 1 is Correct: A neuron consists of a main part called the cell body (soma or cyton), which contains the nucleus and typical cell organelles suspended in the cytoplasm. This region is responsible for maintaining the cell and integrating incoming signals.
- Statement 2 is Incorrect: The axon is a single, long, cylindrical projection that extends from the cell body. Its primary function is to conduct nerve impulses away from the cell body to other neurons, muscles, or glands. Axons are a defining feature of human nerve cells.
- Statement 3 is Incorrect: Dendrites are short, branched fibers projecting from the cell body. Their function is to receive electrochemical signals from other neurons and transmit them towards the cell body. They are not responsible for secreting hormones; hormone secretion is generally the function of endocrine glands or specialized neurosecretory terminals at the end of axons.
Key Takeaway
A typical neuron comprises three distinct parts: dendrites (receive signals), the cell body (contains the nucleus), and the axon (transmits impulses away). Axons are present in human neurons.