Human Nervous System

To solve the problem, we need to identify the nerves that carry impulses from sense organs to the brain or spinal cord.

1. Understanding the Types of Nerves:
- Dendrites: These are part of the neuron that receive signals from other neurons but do not carry impulses from sense organs to the brain or spinal cord.
- Afferent nerves: These are sensory nerves that carry impulses from sense organs to the brain or spinal cord. They are also called sensory nerves.
- Motor nerves: These nerves carry impulses from the brain or spinal cord to muscles and glands to produce an action.
- Efferent nerves: These nerves carry impulses away from the brain or spinal cord to the muscles or glands.

2. Identifying the Correct Answer:
The nerves that carry impulses from sense organs to the brain or spinal cord are called **Afferent nerves**.

Final Answer:
The correct answer is option (B): Afferent nerves.

To solve this problem, we need to know the number of cranial nerves in humans.

1. Cranial Nerves in Humans:
Humans have 12 pairs of cranial nerves, which originate directly from the brain and are responsible for functions such as sensory input, motor control, and autonomic functions. These nerves are numbered I to XII.

2. Evaluating the Options:
(A) 10 pairs – Incorrect (Humans have 12 pairs, not 10.)
(B) 15 pairs – Incorrect (There are 12 pairs of cranial nerves.)
(C) 12 pairs – Correct ✅ (This is the correct number of cranial nerve pairs in humans.)
(D) 13 pairs – Incorrect (Humans have 12 pairs, not 13.)

Final Answer:
The correct option is (C) 12 pairs.

1. Structural and Functional Unit of Nervous System:
The structural and functional unit of the nervous system is the Neuron.

2. Explanation:
A neuron is responsible for transmitting electrical signals in the nervous system. It consists of three main parts: the cell body, dendrites, and axon, which help in the reception and transmission of signals.

Final Answer:
The structural and functional unit of the nervous system is .