The longest cell in the human body is _____________
A) Muscle cell
B) Nerve cell
C) Lung cell
D) Blood cell

Hint: They help in controlling the brain and coordination of other parts of the body. They send and receive the signals from the brain to perform various functions. They are excitable and specialized cells.

Complete Answer:
- In the human body, the nerve cell is the longest cell. Nerve cells are also called neurons that are found in the nervous system. They can be up to 3 feet long.
- Nerve cells are only present in animals. Nerve cell is an excitable and specialized cell of the nervous tissue which helps in proper functioning of the brain and coordination of other parts of the body.
- Neurons are divided into 3 types: Sensory neurons (stimuli response), motor response (receive signals) and interneurons (connects one neuron to another neuron).
- Nerve cells consist of dendrites, soma and axon. In dendrites, signals received via soma then signals send down the axon.

Thus, the correct answer is option B i.e., Nerve cell.

Additional information:
- Muscle cells contain thin and thick filaments like actin and myosin. Their main function is to provide motion and force. Muscle cells can contract and relax.
- Their length is up to 30cm. Lung cells protect against infection which include air-borne diseases, cancer etc. Lung cell consists of the epithelial cells.
- Blood cells help in the transport of the oxygen.

Note: The longest cell is the nerve cell which helps in maintaining the balance and coordination of the various parts of the body. They transmit information and nerve impulses via three components: dendrites, soma, axon. Nerve cells are 3 feet long.