How do bears hibernate?

To face the cold and food scarcity of the winter in the northern hemisphere, they take the team out of the field, spending time without drinking, eating, urinating and defecating. In the case of black bears, this period varies between…

Why do we yawn?

»> It is a signal, caused by an involuntary reflex, that the body needs sleep. Once yawning starts, it’s nearly impossible to stop. The person may close the mouth, but the muscles triggered by the reflex continue to contract. Humans…

Why does the nose run when we cry?

»> Because when we cry we produce more acetylcholine, a neurotransmitter that increases the amount of nasal secretion. When the tears roll, it is released by the parasympathetic nervous system and causes the nasal mucosa, the inner wall of the…