Complete #1, 2. 3,4. 6, 7, 8, 9. 10 |?ptfor #1.2.7, 8( pg(2pts) pts) pt for each

Question

Complete #1, 2. 3,4. 6, 7, 8, 9. 10 |?ptfor #1.2.7, 8( pg(2pts) pts) pt for each blank #3-9 2 pts Complete #3, Sa, 5b, So Name Section NI 12 REVIE W Check Your Understanding Critical Thinking and Application Questions 1 You are examining a neuronal dendrite? How can you tell? process and you find that it generates action potentials. ls this an axon or a 12 2 You are examining another neuron, and find that it has two processes, both of which generate action potentials What is the structural class of this neuron? How did you come to this conclusion? 3 A damaged axon in the PNS may be able to regenerate only if the cell body is intact. Why do you think that the cell body must be intact for regeneration to occur? (Hint: Think about the function of the organelles and other structures located in the cell body.) ductioto the Neruous SustemUNIT 12 331

Explanation / Answer

1.

Since there is generation of action potential, the neuronal process is Axon. Axon can be differentiated from Dendrites, in that axons are long, thin cylindrical projection that often joins the cell body at a cone shaped elevation called Axon hillock. The action potential is generated at this axon hillock whose initial segment is referred to as Trigger zone.

On the otherhand, Dendrites (which means little trees) are the receiving or input portions of neuron and can be distinguished by their short, tapering, and highly branched form. Dendrites cytoplasm contains Nissl bodies, mitochondria and other organelles. Axons contain mitochondria, microtubules, neurofibrils but lack rough endoplasmic reticulum

2.

The structural classification of the neuron being observed is pseudounipolar neuron which are bipolar neurons in the embryo but later on fuse to become unipolar neurons where the axon is split into two branch of which one runs towards the periphery while other runs to the spinal cord. Sensory receptors involved in touch, pressure, pain or thermal stimuli are Pseudounipolar neurons.

Generation of action potentials in both the branches, absence of dendrites and lack of synaptic inputs on the cell body are the distinguishing features to come at this conclusion.

3.

Cell body also called as perikaryon or Soma contains a nucleus and a cytoplasm with organelles like lysosomes, mitochondria, Golgi complex, free ribosomes, and prominent clusters of rough endoplasmic reticulum called as Nissl bodies. Cytoskeleton includes neurofibrils and microtubules all of which are essential for cell repair. Hence, it should remain intact for regeneration.

Mechanism of repair in PNS:

Axons and dendrites which are associated with neurolemma in PNS can undergo repair if cell body is intact, Schwann cells are functional and scar tissue is not formed too fast. After 24-48 hrs of injury, the Nissl bodies break into fine granular masses by chromatolysis. By the 3rd -5th day, Wallerian degeneration of distal protion of axon and myelin sheath occurs. Macrophages clean up the debris by phagocytosis. RNA and protein synthesis occurs rebuilding and regenerating the axon.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.