1 There are two types of glial cells in the nervous system: the large-bodied macroglia and the smaller microglia. 2  There are two classes of macroglia in the central nervous system: astrocytes and oligodendrocytes.
Exports directly contribute and imports directly reduce their nation's balance of trade (i.e. net exports). A trade surplus is positive net balance of trade, and a trade deficit is a negative net balance of trade.
Graphically, producer surplus is the shaded region just above the supply curve, but below the equilibrium price level. Key Terms. producer surplus: The amount that producers benefit by selling at a market price that is higher than the lowest price at which they would be willing to sell. Producer surplus is the difference between what price producers are willing and able to supply a good for and what price they actually receive from consumers. It is the extra money, benefit, and/or utility producers get from selling a product at a price that is higher than their minimum accepted price, as shown by the supply curve.