应激性是指在新陈代谢的基础上，生物体对外界刺激都能产生一定的反应。

植物的根能够向地生长，是植物对重力的刺激的反应。如果把植物放到失重环境，则根不会出现向下生长，而是向四面八方生长。

人在看到文本、图像时产生的各种反应也属于应激性。

应激性是一种个体有压力的行为，具象对形态理解都能产出一定的反应。

Irritability is an excitation response to stimuli. The term is used for both the physiological reaction to stimuli and for the pathological, abnormal or excessive sensitivity to stimuli. It is usually used to refer to anger or frustration. Irritability can be a growing response to the objective stimuli of hunger or thirst in animals or humans which then reaches some level of awareness of that need.