The heart pumps blood that carries oxygen and nutrients to the different parts of the body. to which organ system does the heart belong?

With the increasing scarcity of arable land,what type of foods are being manufactured recently to compensate for the production of natural food? what kinds of food have you been eating recently? ​

Origin of the universe of humankind of taoism​

When gretchen starts being chased by a dog, her brain sends a signal to her muscles to run. which neurons are at work?