Body questions

Located deep in the center of the brain, the pineal gland was once known as the “third eye.” The pineal gland produces melatonin, which helps maintain circadian rhythm and regulate reproductive hormones. Melatonin makes us sleepy.

The mandible is the largest, strongest and lowest bone in the human face. It forms the lower jaw and holds the lower teeth in place. The mandible is the only movable bone of the skull, not counting the ossicles of the middle ear.

The term laterality refers to the preference most humans show for one side of their body over the other. Examples include left-handedness/right-handedness and left/right-footedness. It may also refer to the primary use of the left or right hemisphere of the brain.

The amount of water in the human body ranges from 50-75%. The average adult human body is 50-65% water, averaging around 57-60%. The percentage of water in infants is much higher, typically around 75-78% water, dropping to 65% by one year of age.

In humans, mature red blood cells are flexible and oval biconcave discs. They lack a cell nucleus and most organelles, in order to accommodate maximum space for hemoglobin; they can be viewed as sacks of hemoglobin, with a plasma membrane as the sack. Approximately 2.4 million new erythrocytes are produced per second in human adults.

1.5 g of the epidermis falls out of the body daily. Exfoliated epidermis feed mites and other microorganisms.

Plasma, a component of blood, is an aqueous solution.

The number on the bottom eyelid is significantly lower - about 50-150.

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