If you want to borrow a Bitcoin you have to be sure that you cant lose some money with it otherwise that will be sin to you and that is the baddest thing that will happen if you lose money. So you need also a bit luck if you want to earn more money with Bitcoin and patience is also important.
It's possible to get a loan if you can keep your account as a collateral but if you are in an emergency and need a huge amount, the only possibility is to get fiat from a bank else borrow money from a friend. Getting bitcoins in an emergency is not always possible unless you have a regular exchanger who can lend you funds anytime. You can try localbitcoins but there as well you will need to exchange money to get bitcoins...
What I can think of if emergencies come is that you will go approach someone who you really know and borrow to him direct.
Because borrowing for a collateral will take a long time and needs to be review just like localbitcoins. Borrow in fiat and exchange in bitcoin
if you need bitcoin.