Can I upgrade memory and graphics card in my laptop?

I have a Lenovo z500t touchscreen laptop (core i5, 4gb RAM, 1tb hard drive, Intel HD4000) but it runs pretty slow with some games, even on low resolution. I know I have a free slot for RAM but does it have to be the exact same size and model RAM that's in the other slot or can I (for example) get an 8gb ram to work alongside my 4gb? Also I would like to upgrade my graphics card but I understand some laptops come with them integrated and therefore can't be changed I'm not sure if mine is able to or not.

Unfortunately The ram, hard drive, and operating system is the only things you can upgrade on a laptop because the components are soldered to the motherboard.
If you add ram make sure it's the same type.

Ram sizes can be different, but the bus speed should be the same. Otherwise it will cause instability or the faster ram will automatically be downgraded to the speed of the slower ram. Of course the pins should match that of the motherboard also.

Graphics cards can't be replaced on laptops - due to the nature of them being soldered on as the previous person said. If you want to upgrade your graphics card, the manufacturer would have to replace motherboard + processor + graphics card. Which as you can guess would just be as expensive as buying a new laptop.

RAM can be upgraded by purchasing exact model of RAM chip found inside your laptop and inserting into empty slot

Graphics card can't be upgraded, since it's soldered to motherboard

You also need to find out the maximum memory for your laptop
your computer can take up to 16 GB using PC3-12800 1600Mhz DDR3 SDRAM So DIMM 204-pin Ram.