What does total available graphics memory mean ?

Hi every one

first im sorry if this is not the right place to ask y question :/ 

but i hope you can help me to know the answer, 

firs this is my laptops specs .. 

HP Pavilion 15 

Windows 8.1 - 64-bit 

Intel(R) Core(TM) i7-4500U CPU @ 1.80GHz 

System Memory : 8GB 

Graphics device 1 : NVIDIA GeForce GT 740M ( 2GB Dedicated ) 

Graphics device 2 : Intel(R) HD Graphics Family 

Current Resolution : 1366 x 768 

Refresh Rate : 60 

Total available graphics memory : 4096MB 

Dedicated video memory: 2048MB DDR3 

Shared system memory :2048MB 

ok, i know that dedicated video memory is the memory of the Nvidia Geforce itself, 

and the shared system memory is the memory shared from the RAM of my laptop 

to the "Intel(R) Graphic Card (tell me if im wrong about this point ) 

so my answer is , is it mean that if im playing a high game graphics with high graphic settings 

and the game needs more than 2GB , is it mean that there will be memory available 

Up to 4096 MB since my total available Graphics memory is 4096MB ? 

or only my 2GB of NVIDIA GeForce GT 740M will be available to me ? 

thank you a lot and i will appreciate any information :)