Classify the given items with the appropriate group.
Many dendrites extend
from the soma.
One branch of each of
these cells is in the CNS
and the other in the PNS.
Most motor neurons are
of this type.
A short process emerges
from the cell body and
branches like a T.
A single dendrite extends
from the soma.
Examples of these are
found in the retina and
nasal cavity.
Multipolar Neuron
Bipolar Neuron
Unipolar Neuron
The correct answer and explanation is:
Classification of Neurons:
- Multipolar Neuron
- Explanation: This type of neuron is characterized by multiple dendrites emerging from the soma (cell body) and one long axon. The majority of neurons in the central nervous system (CNS), particularly motor neurons, are multipolar. In these neurons, many dendrites extend from the soma to receive signals, while the axon sends signals to other neurons or muscles. The motor neurons that control muscle movements are typically multipolar, as they require numerous input sources to integrate information from various parts of the body.
- Example: Most motor neurons.
- Bipolar Neuron
- Explanation: Bipolar neurons have two extensions: one dendrite and one axon. These neurons are relatively rare and are primarily found in sensory organs. In bipolar neurons, one branch of the cell’s process is in the CNS, while the other is in the peripheral nervous system (PNS). These neurons play an essential role in sensory processes, as they help transmit signals from sensory receptors to the CNS.
- Example: Neurons found in the retina of the eye and in the nasal cavity (olfactory neurons).
- Unipolar Neuron
- Explanation: Unipolar neurons, also known as pseudounipolar neurons, have a single process extending from the cell body, which then branches into two parts: one part functioning as an axon and the other as a dendrite. This structure is typical for sensory neurons, particularly in the peripheral nervous system (PNS). Unipolar neurons are involved in the transmission of sensory information from the body to the CNS. The process emerges from the soma and splits, with one branch extending toward the sensory receptors and the other toward the spinal cord or brain.
- Example: Sensory neurons in the dorsal root ganglia.
Summary of Classification:
- Multipolar Neuron: Characterized by multiple dendrites and one axon; primarily motor neurons in the CNS.
- Bipolar Neuron: Characterized by one dendrite and one axon; sensory neurons in the retina and olfactory system.
- Unipolar Neuron: Single process emerging from the soma, branching into a dendrite and axon; sensory neurons in the PNS.