Human eye of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock. The eye is not shaped like a perfect sphere, rather it is a fused two-piece unit, composed of the anterior segment and the posterior segment. The anterior segment is made up of the cornea, iris and lens. The cornea is transparent and more curved, and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 11.5 mm (0.3 in) in diameter, and 1/2 mm (500
History of beliefs about the human body that even in European cultures that attempt to adhere purely to what can be seen and touched, recognize that there is a more cosmic necessity to the body and connection to the physical and cosmological worlds. History of beliefs about the human body The human body has been subject of much debate. How people are defined, and what defined them – be it their anatomy or their energy or both – depends on culture and time. Culture not only defines how sex is perceived but also how gender is defined. Today gender, sex, and identity continue to be of much