Oliguria or hypouresis (both names from roots meaning not enough urine) is the low output of urine. In humans, it is clinically classified as an output more than 80 ml/day but less than 400ml/day.
The alternative is to take US Dollars with you, and then change your money in Colombia, but if you do want to take cash then it's probably easiest to just buy Colombian pesos in the UK and take them. The alternative is to rely on using your bank card to withdraw money in Colombia. There is a decent network of cash machines in Colombia and they take most UK bank cards so there shouldn't be a problem with this, but many people do prefer to take a pre-paid currency card instead.
According to the Currency Encyclopedia, Venezuelan currency is called a Bolivar. Its nicknames are bolo(s) and luca(s) and signified by the currency code VEF and the currency symbol Bs. As of 2014, the current exchange rate of one Venezuelan Bolivar to one American Dollar is about 16 cents and the inverse rate is about $6. In addition, Venezuela's currency has the largest gain on Chile since one Venezuelan Bolivar equals 87 Chilean Pesos. As of January 2010, the Venezuelan government created a two-tiered exchange rate system whereby imports of non-essential items receive 4.3 Bolivars per dollar and 2.6 Bolivars per dollar for essential items. These rates are set and controlled by Venezuela's central bank. Learn more about Coins & Currency