What pathophysiological mechanisms could prpduce hypertension on some occasions and not at others just a few w -

Try to identify three things that could cause this.

Sympathetic overactivity is the most important factor as there will be excessive stimulation of sympathetic nervous system sp. in stressful conditions due to release of adrenaline. Also salt and water retention.

accelerated heart rate is most common cause of temporary elevation in blood pressure. fluid volume overload is second most common cause. and third would be emotional upheaval.