In response to a change in body position from horizontal to vertical blood circulation system develops reflectory pressor reaction. Which of the following is its compulsory component?

Answer options

1. Systemic dilatation of the arterial resistive vessels
2. Increase in the heart rate
3. Systemic constriction of the venous vessels
4. Decrease in the circulating blood volume
5. Weakening of the pumbing ability of heart