Pari Talks

  The Dark Side of the Moon. P.K.Ghatak,MD Blog No.61. The moon is admired by poets and voyagers unmatched by others, even perhaps, those scientists engaged in their moon missions. In the old days the villagers and seafarers knew much more about the moon than recent science graduates. Most young men look moon with the same concerns as their mothers – they know she will be there for them when they need her and in between times, just benign neglect. This is not the worst; in the world literature there are instances where the dark spot on the moon is compared with slip of moral character of the beautiful girls and young women. It was not until the Soviet mission Luna 3 flew past the far side of the moon and photographed. It showed more rugged and have higher density of craters. The Apollo mission of the USA No. 8, 10, 11 13,16 and 17 of the USA flew by the far side of the moon and photographed this side. China came next. Her mission, Chage 4 landed on the far side of the...

  Pupil. P.K.Ghatak,MD No.60 The central aperture of the iris is the pupil. People who like talk and write British English call students as pupils. The pupils, by varying their sizes, control the amount of light that can enter the eye for us to see clearly. Pupil also serves as a passage for the aqueous humor to circulate from the posterior compartment to anterior compartment. At the periphery of the iris (No.5 in the diagram below) the aqueous humor is absorbed and goes back to the blood, Thus this process maintains the pressure of the eye ball and prevents damage to delicate structures of the retina. Aqueous humor supplies nutrients to the cornea and oxygen and nutrients to the lens. [ cristalino = lens. cuerpo ciliar = ciliary body. Canal de Schlemm = Schlemm canal, point where aqueous humor is drained from the eye back to the blood.] When light is shone in one eye, both pupils contact. This reflex action is known as direct contraction for the eye receiving the light and co...

Iris P.K.Ghatak, MD No.59 In a conversation, the word Iris generally refers to Irish, the people from Ireland. If the talk is around flowers, then Iris means a lovely delicate Iris flower. In biology the Iris is a part of the eyeball, a very delicate screen like structure which regulates the amount of light rays can enter through the center aperture, Pupil to the retina for vision. This screen is like the diaphragm of a single lens reflex camera; and both have many common features. In fact, the design of a camera is based on the eyes. Anatomical structure of human iris: The iris is thinnest at the periphery where it is attached to the ciliary muscles, and thick in the middle because the circular and radial muscle layers criss-cross in the middle of the iris The central aperture of the iris is the pupil of the eye. Contraction of circular muscles narrows the pupil and radial muscles enlarges size. Histology of iris. Structerally the iris consists oftwo distinct parts, anterior and poste...

  Cochlea P.K.Ghatak, MD No.58. Cochlea is a part of the inner ear. Cochlea houses the receptors of hearing, the Organ of Corti. Humans have a pair of cochleae, one in each ear, buried deep inside the toughest bone in the human body, the mastoid process. The two cochleae do not receive sound waves not simultaneously, but the side closer to the source of sound, a fraction of second earlier than the other side, but the brain synthesizes two sounds into one. Cochlea is a Greek word that means snails, the outer shells having coils. One coil is partially overlying the lower coil as it also tapers upwards. Human cochleae are tiny, measuring 10 mm long and make 2.75 or usually mentioned having 3 turns. It is also twisted on itself like a fishhook. If the coils are stretched out, it would be 30-35 mm long. When a sound wave hits any object, the object vibrates. If objects are heavy the vibration is less and may approach zero. To achieve that property, the cochlea is encased in a cavity of ...