Biological Olfaction - The Electronic Nose Artificial Olfaction Technology - page 78

odorants that share some chemical feature and cause similar patterns of neural
firing. Neurons that fire to the same odotope are usually located near each other.
It is hard to imagine how to build a system that could reproduce smell infor-
mation collected by human olfactory system. This is sometimes discussed in terms
of a multi-dimensional ''odour space,'' where each odor could be described by its
location along each dimension. It is clear that odors are comprised of chemicals,
but still it's under research. Understanding the odor space is a prerequisite to build
a system that can transmit messages from it.
Also, to a great extent, how to engineer a smell transmission system is only
partly a biological question. Transmitted pictures and transmitted sounds can be
coded because they activate our photoreceptors and auditory hair cells in the same
pattern that the original images and sounds would. We can build systems for
picture and sound because we understand the nature of the information sensory
systems decode, and we don't need a really deep understanding of the physiology
to do that.
3.6 Signal Transduction System
The cell senses extra cellular signals: -Hormones, pheromones, heat, cold, light,
osmotic pressure, concentration change of glucose, K + ,Ca 2+ or cAMP and compute
them in intercellular signals.
One of the main functions of neurons is to communicate with other neurons. An
individual neuron may receive information from many different sources. Its job is
to evaluate this information and ''make a decision'' as to whether to send out
information to all of its target neurons, or whether to remain silent. It is hard to
know where to begin describing the process of signaling in neural circuits, because
signaling in any individual neuron depends on its getting input from other neurons
that have been activated by the same processes that will consider in model neuron.
Signal Transduction—chain of events that converts the message ''this molecule is pres-
ent'' to a physiological response.
Key Steps in Signal Transduction:
• Release of the primary messenger
• Reception of the primary messenger
• Delivery of the message inside the cell by the second messenger
Electric signal in nerve: nerve cells or neurons make up the nervous system
(NS), one of the control systems of the body. The nervous system controls body's
muscular and glandular activities that are mostly directed towards maintaining
homeostasis. Neurons act rapidly for electrical and chemical signaling for com-
munication. Through chemical means neurons pass messages to muscles and
glands through intricate pathways from neuron to neuron. Nerve and muscle are