Receiving Receptors » Of receptors

Receptor cells similar in structure

receptor — Mon, 30 Nov 2009 19:15:43 +0000

Scientists have always been eager to understand the structure and function of the sense organs. Research has been especially intense in the past few years, after the electron microscope came on the scene. This is understandable since the ordinary microscope only magnifies ten to fifteen hundred times, while the electron microscope has a magnification of twenty, forty, sixty, and even a hundred thousand times. Certainly, it has helped scientists to pry out quite a lot of interesting secrets.

They made the astonishing discovery that the receptor cells (the ones that perceive stimulation) in all the sense organs of all animals on the Earth are very similar in structure. Each of them has a tiny mobile hair, or flagellum. These flagella are also very similar in diflerent receptor cells. Each flagellum contains two central fibrils surrounded by a ring of nine pairs of motile fibrils. The structure of the flagellum rarely varies.

The flagella in a receptor cell play the same part as the antennae in radio sets, and are therefore called receptor antennae. Through these antennae we perceive the outside world. The antennae in the receptor cells of the eye, for example, respond to light energy, or photons. The antennae of the organ of smell perceive the energy of the molecules of odoriferous substances. The antennae of the auditory cells respond to the energy of sound waves, or sounds.

Sense organs

receptor — Sat, 28 Nov 2009 19:10:45 +0000

How many communication channels does an organism possess? In how many ways can it get information?

The receivers for gathering information, the receptors, are what we commonly call the sense organs. Scientists distinguish six sense organs which they consider the principal ones: those concerned with vision, hearing, equilibrium, taste, smell and skin sensibility.

As for the ‘non-principal’ senses, they are innumerable. The skin, for example, contains a great number of receptors. Some respond to a slight touch (these are responsible for the ’sense of touch’), others respond to a stronger impact and their stimulation is perceived as pain. A third type responds to cold, and a fourth is sensitive to warmth. These are but a few of the long list of skin receptors.

The internal organs also have many specific receptors. There are receptors to determine the quality of the food that enters the stomach, others to measure the blood pressure, and still others to test the amount of carbon dioxide dissolved in the blood. We are never even aware that they are functioning. The information being constantly sent to the brain from the internal organs does not penetrate our consciousness.

That flow of information

receptor — Sat, 28 Nov 2009 19:06:39 +0000

From morning till night, a continuous flow of information comes to our brain through innumerable communication channels. The acoustic nerve is made up of 30000 conductor fibres, while the optic nerve has even more, about 900000. The amount of information coming in every second from the hearing aid alone is equal to tens of thousands of bits per second, while the information sent in by the eye amounts to millions of bits in a single second!

The brain has to sort all this out, glean from it the important information and separate it from what is minor or of no relevance. For the human brain can digest no more than 50 bits in a second.

In the morning, before it wakes up, the brain gets down to work. It has to tune in its receivers to ensure the unfailing supply of important messages. This is no easy matter, for human and animal organisms have numerous diverse receivers, each perceiving only a definite kind of encoded information.