To warm up before a run, david begins by completing quad and hurdler's stretches. which of these accurately evaluates his choice of warm-up activities?

a. these activities are appropriate because they prepare muscles for intense movement.
b. these activities are not appropriate because the muscles stretched are not warm yet.
c. these activities are appropriate because they make the leg muscles more flexible.
d. these activities are not appropriate because they stretch muscles not used in the exercise.

True or false. mucous membranes secrete mucus that traps pathogens.

How could natural selection best be used to explain the evolution of the white fur of arctic fox

A35-year-old woman comes to the ed complaining of chest pressure. she has had such episodes intermittently over the last 5 years, usually when sleeping, but over the last year she has had more frequent severe symptoms that are occasionally associated with severe migraine headaches. the pain is midsternal and is described as pressure that extends as a band around her chest. the ed physician is initially dubious that the pain is cardiac in origin, because the woman has no coronary disease risk factors. an ecg, however, shows 2mm st-segment elevation and inverted t waves in leads v1 through v5 and 1mm st-segment depression in leads ii, iii, and avf. before the cardiologist arrives in the ed, the patient's ecg has returned to normal. this repeat normal ecg is obtained after the administration of aspirin, nitroglycerin, morphine, and oxygen. which of the following is most likely for these findings? - diffuse intimal thickening with focal areas of atherosclerotic narrowing - intermittent thrombus formation and lysis in the left anterior descending artery - intermittent thrombus formation and lysis in the right coronary artery - plaque rupture and thrombus formation in the left anterior descending artery - transiently increased coronary vascular tone in the right coronary artery