Hearing

Many arthropods and nearly all vertebrates have acoustical organs and so can hear sounds. For example, humans and other land-dwelling mammals have a pair of distinctive ears. Small organs, flush with the body surface, serve comparable functions in insects and amphibians. Such organs are located on the front legs of crickets and near the hind legs of grasshoppers.

Hearing starts with acoustical receptors, which are vibration-sensitive mechanoreceptors. A vibration is a wavelike form of mechanical energy. For example, clapping produces waves of compressed air. Each time hands clap together, molecules are forced outward, so a low-pressure state is created in the region they vacated. The pressure variations can be depicted as a wave form, and the amplitude of its peaks corresponds to loudness. They frequency of a sound is the number of wave cycles per second. Each cycle extends fro the start of one wave peak to the start of the next. The more cycles per second, the higher the frequency, and the higher the perceived pitch of the sound.

When sound waves arrive at an acoustical organ, they encounter a membrane and make it vibrate. In invertebrates, vibrations directly stimulate mechanoreceptors attached to the membrane. In vertebrates, the membrane vibrations cause a fluid inside the ear to be displaced. The fluid movement causes mechanoreceptors to bend. With enough deformation, action potentials are produced. They travel along an auditory nerve leading from the receptors to the brain.

The introduction to this chapter described the sense of hearing that is associated with echolocation. Although we cannot hear them, the extremely high frequency waves (ultrasound waves) produced by an echolocating bat are not weak. They have been measured at 100 decibels which is in the same range as thunder or a freight train racing past.

Bear in mind, bats are not the only echolocating animals. Dolphins and whales also emit ultrasounds, which travel through their marine environments. By perceiving frequency variations in the echoes, all of these mammals also can pinpoint the distance and direction of movement of one another and of predators or pray.

Cloaning

In 1996 scientists in Scotland cloned a sheep, which they named Dolly. They did this by taking a body cell from an adult sheep and using its DNA to make an exact copy f that sheep. In the future cloning could allow scientists to produce tailor-made body organs for transplant patients, or create whole herds of cows or sheep that produce useful drugs in their milk. The technique could also be used to enable infertile couples to have a child who would be a clone of one of them.

1953 – Francis Crick and James Watson discover the structure of DNA

1973 – Stanley Cohen and Herbert Boyer carry out first Genetic Engineering with bacteria

1986 – Human Genome project set up to list sequence of entire human genome

1990 – First trials for ‘Gene Therapy’

1996 – Dolly, a cloned sheep, created by Roslin Institute Scotland

2000 – First draft of human genome published.

D4 syndrome

D4 syndrome is commonly known as middle back pain. The patients affected by this syndrome have pain between neck and the lumbar region (Lower back). Initially the pain occurs in the central position of the back, then gradually spreads to the lateral portion (side) of the chest. In some cases the pain may even be felt in the centre of chest causing breathing difficulty.

Reason: While driving we tend to berid a little forward coupled with this when the vehicle jolts in a pit it forces out body to bend downwards causing the posterior back ligament to stretch and lose its elasticity. The inter vertebral disc can also slip posteriorly (back wards) and it compresses the spinal cord causing pain. Whenever normal positioning of the bone is disturbed out body tends to deposit osteophytes (bone forming cells). This deposition of osteophytes compresses the nerves which branch from the spinal cord causing radiating pains in the chest. If this osteophytes compress the respiratory nerves, the patient will get some breathing problem. Problem similar to above can also be caused by wrong posture.

Bending forward creates angulation in the 4th thoracic vertebra (middle back) resulting pain in scapula region. Thus it is called D4 syndrome.

Treatment: In combined therapy, homoeopathic medicines, machines like shortwave diathermy ultrasound and special manipulation techniques are used. In physiotherapy ultrasound and shortwave diathermy are the effective treatment to remove the osteophytes. The vibration from the ultrasound and the electromagetic waves from the shortwave diathermy remove the osteophytes.

In addition, by effective manipulation we can rearrange the vertebrae to normal alignment. To maintain the normal positioning of the vertebrae the patient should do muscle strengthening exercises regularly. In these cases, traction treatment is not effective. Homeopathic medicines like Kali carb, pulsatilla, Cal Carb. Rhus tox can reduce the pain and inflammation immediately. They prevent the recurrence also.