The blood Pressure, salivation, pupil movement, etc. are all the involuntary movements. Which part of the brain is responsible for controlling these actions?

The hind prain is responsible for all the involuntary movement.

It provides connection between spinal chord and rest of the brain.

The medulla oblongata is part of the Hind brain that controls these involuntary actions.

Different regions in the medulla oblongata control different cativities. Reflex centers are responsible for reflexes such as swallowing, vomiting, sneezing and coughing, the cardiac center is responsible for the regulation of the heart rate, the vasomotor center is responsible for the regulation of blood pressure and respiratory center is responsible for the breathing activity.