Hypodermic needles frighten Janice. As she awaits a flu shot, Janice's nervous system is probably going into overdrive as she is imagining with terror what the injection is going to feel like.

Sympathetic Nervous System

Explanation:

Sympathetic nervous system is a division of the nervous system that capacities to deliver limited changes, (for example, perspiring as a reaction to an expansion in temperature) and reflex modifications of the cardiovascular systemUnder states of pressure, the whole Sympathetic nervous system is initiated, delivering a quick broad reaction called the battle or flight reaction This reaction is described by the arrival of enormous amounts of epinephrine from the adrenal organ, an expansion in pulse, an expansion in heart yield, skeletal muscle vasodilation, cutaneous and gastrointestinal vasoconstriction, pupillary widening, bronchial enlargement, and piloerection. The general impact is to set up the person for inevitable risk

What did one cell say to his sister cell that stepped on his toe?

Mitosis!