Question

If we cut our skin , it can regenerate but after a brain stoke or brain injury we can't replace neurons .why? What might be the evolutionary significance of this? (For 3 marks ques.)

Answer 1

The skin cells keep dividing, they die and give birth to new cells all the time, even when you’re not injured. After an injury, the skin makes a bunch of new cells and uses them to heal your wound.But neorons do not renew themselves. They do not divide at all. The brain cannot replenish dead neurons. The reason for this is neurons lack centrioles.Because centrioles function in cell division, the fact that neurons lack these organelles they cant divide.

From an evolutionary point of view, the reason for the lack of regenerative capacity for neurons is explained as below:

Our brain is evolved to process complex tasks at a higher pace than other living beings. The brain achieves this with help of the whole nervous system, which is based on interneuronal connections, so adding an extra neuron would mess up these connections and alter both the functionality and the “stored” information. New cells in the nervous system wouldn’t do any good.

Our evolution lead to a very complex system of interconnected neurons, each nerve cell has a specific place in our nervous system. Its job is all about taking a signal from one specific place to another one. Adding new nerve cells would mess up these very specific connections in a very complex system.