If the Na+ voltage-gated channels in a muscle cell open, the Na (sodium) ions rush inside the muscle cell and makes the cell more positive as Na ions carry positive charge on it. Due to the entry of positively charged ions inside the cell, the cell becomes less negative and more positive. This is called depolarization of cell.
Answer:
The Amazon rainforest plays an important part in regulating the world's oxygen and carbon cycles. It produces roughly six percent of the world's oxygen and has long been thought to act as a carbon sink, meaning it readily absorbs large amounts of carbon dioxide from the atmosphere.