Involved in the transport of substances within the neuron 7. essentially rough endoplasmic reticulum, important metabolically 8. impulse generator and transmitter Column B a. axon b. axon terminal c. axon hillock d. cell body e. chromatophilic substance f. dendrite g. myelin sheath h. neurofibril 5. Draw a “typical” multipolar neuron in the space below. Include and label the following structures on your diagram: cell body, nucleus, nucleolus, chromatophilic substance, dendrites, axon, myelin sheath, myelin sheath gaps, and axon terminals. 6. What substance is found in synaptic vesicles of the axon terminal? 7. What anatomical characteristic determines whether a particular neuron is classified as unipolar, bipolar, or multipolar? Make a simple line drawing of each type here. Unipolar neuron Bipolar neuron Multipolar neuron
The Correct Answer and Explanation is:
Matching Questions (Column A to Column B):
6. Involved in the transport of substances within the neuron
✅ h. neurofibril
Neurofibrils are part of the cytoskeleton, playing a role in intracellular transport and maintaining the neuron’s shape.
7. Essentially rough endoplasmic reticulum, important metabolically
✅ e. chromatophilic substance
Also known as Nissl bodies, these are clusters of rough ER and ribosomes involved in protein synthesis.
8. Impulse generator and transmitter
✅ a. axon
The axon conducts electrical impulses (action potentials) away from the cell body toward axon terminals.
Drawing of a Typical Multipolar Neuron
While I can’t draw directly here, a typical multipolar neuron should include and label the following:
- Cell body (soma): central part containing the nucleus and nucleolus
- Dendrites: short branches receiving incoming signals
- Chromatophilic substance: dark-staining rough ER in the soma
- Axon: long process transmitting impulses
- Myelin sheath: fatty insulation around the axon
- Myelin sheath gaps (Nodes of Ranvier): gaps between myelin segments
- Axon terminals: ends of the axon that communicate with other neurons or effectors
6. Substance Found in Synaptic Vesicles of the Axon Terminal
✅ Neurotransmitters
Common ones include acetylcholine, dopamine, serotonin, and glutamate. These chemicals transmit signals across synapses.
7. Anatomical Classification of Neurons
✅ Based on the number of processes extending from the cell body:
- Unipolar neuron: One process that branches into two; typical in sensory neurons of the PNS.
- Bipolar neuron: Two processes (one axon, one dendrite); found in sensory organs like the retina.
- Multipolar neuron: One axon and many dendrites; most common type in the CNS.
Explanation
Neurons are specialized cells in the nervous system that transmit electrical signals. Structurally, they have three main parts: the cell body, dendrites, and axon. The cell body contains the nucleus, nucleolus, and organelles like the chromatophilic substance, which is involved in protein synthesis. The dendrites receive signals, while the axon sends them away from the cell body toward other neurons or muscles.
Neurofibrils, part of the cytoskeleton, are important for maintaining cell shape and facilitating transport within the neuron. The axon is the primary conductor of action potentials and is insulated by the myelin sheath, which increases transmission speed. Gaps in the sheath, called Nodes of Ranvier, allow saltatory conduction—an efficient jumping of impulses between nodes.
The axon terminals house synaptic vesicles containing neurotransmitters, which are released to transmit signals across synapses.
Neurons are classified by the number of processes they extend from the soma:
- Unipolar neurons have one fused process and are mostly sensory neurons.
- Bipolar neurons have two processes and are found in sensory structures like the eyes and ears.
- Multipolar neurons, with one axon and multiple dendrites, are the most common type in the brain and spinal cord.
Understanding these structures and classifications is essential for grasping how the nervous system communicates and coordinates the body’s responses.
