Difference Between Upper And Lower Motor Neurons

Difference Between Upper And Lower Motor Neurons

Question 1. State the difference between upper motor neuron and lower motor neuron lesions.
Answer:

Question 2. Functional unit of nervous system.
Answer:

Neuron:

• The neuron is made up of.

1. Nerve cell body/soma:

• It is irregular in shape.
• It constitutes of
  1. Cytoplasm called neuroplasm. It contains.
     1. Nucleus.
        • Large nucleus covers central part of the nerve cell body and has two or more nucleoli.
     2. Nissl granules/bodies.
        • They are composed by many thin, parallely arranged, membrane bounded cavities.
        • They are covered by minute particles containing RNA with proteins.
     3. Neurofibrils:
        • They are thread like structures consisting of microfilaments and microtubules.
     4. Mitochondria and golgi apparatus.
  2. Cell membrane – covers neuroplasm:

2. Dendrite:

• It is the branched process of the neuron.
• It transmits impulses towards nerve cell body.
• It contains nissl granules, mitochondira and neurofibrillae.

3. Axon:

• It originates from thickened area of the cell body called Avon Hillock.
• It is the longer process of the nerve cell.
• It conducts impulses away from the cell body
• The cytoplasmic fluid occupying the centre of the axon is called axoplasm.
• The cell membrane covering it is called axolemma.
• A short distance from its origin, the axon acquires myelin sheath.
• Axoplasm contains mitochondira, neurofibrils and axoplasmic vesicles but nissl bodies are absent.