Pari Talks

  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 ...

Chikungunya P.K.Ghatak,MD No. 57 An ethnic group known as Mokode who live along the banks of Ruvuma River in Uganda and Mozambique call Chikungunya in their language, a bend over posture from bone pain. A viral infection acquired from mosquito bites produces fever, skin rashes and painful arthritis. The patients assume bend over posture to minimize pain and resist movements of joints. Chikungunya virus (CHIKV) has jumped from the wild animals to humans like so many other viruses have. The virus infects humans from bites of Aedes aegypti and Aedes albopictus mosquitos. That makes CHIVK in the arthropod virus group and because it produces arthritis, it also belongs to the Semliki forest antigenic Alphaviridae group. CHIKV is a small spherical 70nm in diameter virus and has an envelope made of a double lipid layer, the materials for the envelope are stolen from the host and the virus makes infected cells reproduce viral particles, like all other viruses. The first endemic of Chikungunya i...

  MagLev Trains: P.K.Ghatak,MD No: 56 The common properties of magnets – similar poles of magnets repel, and opposite poles attract each other are utilized very ingeniously in superfast trains - Maglev Trains. The train is lifted up from the tract (Levitation), movement forwards and backwards (Linear Acceleration) and keep the train steady on the tract (Guidance). These three properties are achieved in Maglev Trains by cleverly employing permanent magnets and electromagnets. Levitation: The human quest for levitation is mentioned in a story of Buddha. Buddha came upon a group of ascetics, while he was waiting for the boatmen to ferry him across the river, he saw the ascetics were meditating. One of the ascetics recognized Buddha and invited him for some religious discourses. Buddha asked him what he was trying to achieve by meditation. The ascetic said, “to walk across the river on water”. To that Buddha invited them to join him on the boat in crossing the river and advised him to ...