Biology Questions

The skul contains the bones like Occipital bone, Frontal bone, Mandible, Temporal bone, Parietal bone. The mandible, or jaw bone, is the only movable bone of the skull, forming the temporomandibular joint with the temporal bone. The lower teeth are rooted into the mandible while the upper teeth are rooted in the two maxillae.

The hormone adrenaline also called epinephrine is known as a stress hormone. In emotional upsets( like fear, anger etc.) this hormone is poured into the blood and it accelerates heart beat. The hormone acetylcholine decelerates heartbeat rate.

High frequency sound attacks the tympanic memberance and makes it defective. 120 decibels is too high a pitch to be heard and therefore it impairs the hearing ability.