Cam gears:
Provide the means of driving the cams from the timing belt or chain.
Conrod:
Connects the crank to the pistons
Headers/Extractors:
The exhaust manifold, the exhaust gases to flow away from the engine via this. Headers for a V6 pictures (one pipe per cylinder, 3 cylinders per side). Connects to the turbo in turbo charged vehicles.
Injectors:
The ECU/fuel management system pulse the injectors when they need to fire fuel into the combustion chamber. Fuel pressure is fairly constant behind the injectors so when they are pulsed open fuel is injected.
Bleed valve:
A boost control device used in turbo charged vehicles. You can use one to modify the intake manifold pressure required to activate the turbos wastegate. Manual bleed valves are quite primitive.