Answer to Question 1
In reaction to the fight-or-flight response, the heart increases its rate of contraction. Blood pressure also spikes to circulate blood carrying oxygen and energy to the brain and large muscles of the body in preparation for action.
Answer to Question 2
With time and repetition, such as when an organism is subjected to chronic stressors, the systems at play begin to pay an increasing cost. This cost is known today as the allostatic load. The continual wear and tear and drawing of resources from the different systems of the body, including the immune system, can eventually propel the organism from the first (alarm) stage into Selye's second stage, which he called the resistance stage. Over a more extended time as the organism endures repeated exposure to stressors, the systems become so depleted that injury may result. Thus, the body experiences the final stage called the exhaustion stage where organ systems fail and possible death may ensue.
The circulatory system plays a central role in thermoregulation by the moth, Manduca sexta
Mutualisms, such as those that occur among plants and pollinators, generally involve large numbers o
Renal System
Endomembrane system
The Ventricular System of the Brain
Risk Factors for Cardiovascular Disease