Systolic of 140 and diastolic of 60 is a good sign of heart in general unless there is history of heart disease in the past or family history of heart diseases. Still at the age of 17 it is unlikely to have major heart problem. Coming to the worries of I'll health, anxiety and fear of ill health could be another reason for the feeling of bounding pulse u feel.
Next Steps
1. Make sure to be calm, do not worry too much. there is no point in anxiety as it will only make things worst, assuming there is a problem, which is unlikely in your case.
2. Heart rate if below 100, no breathing problems, eating healthy food, avoid smoking and supplement with exercise.
3. Again most important is point 1. ANXIETY MANAGEMENT.