The 5 Senses

uman Experience is effected by both internal and external stimuli and are able to distinguish among the many different types of stimuli by means of a highly developed system of sense organs.Sensory occurs when sense organs absorb energy from a physical stimulus from the environment and the sensory receptors convert this energy into neural impulses and the which gets carried to the brain for processing..One part of the nervous systems controls the body's relationship to the environment(somatic)and another part controls the body's internal organs(Autonomic)These is called the Peripheral Nervous system that falls under the Central nervous system.Our body collects information and stimuli via the senses using the sense organs.The most familiar organs are the Eyes,Ears,Nose,Skin and Taste buds which represents each of the five senses(Sight,Hearing,Smell,Taste and Touch)Human's Sensory systems represent an integration

of the functions of the Peripheral Nervous System and the Central Nervous System.The sensory division of the Peripheral Nervous System gathers information about the Body's internal conditions(Autonomic) and external(Somatic) environment.Sensory Systems translate light,sound,temperature and other aspects of the Environment to electrical signals and transmit these signals,in the form of action potentials,to the Central Nervous System(CNS),where they are interpreted!The Brain and Spinal cord composes our Central Nervous system that acts as a clearing house.Each sensory organs are packed with sensory receptors that can respond to stimuli by producing nerve impulses in a Sensory neuron.A neuron is a cedll specialized to conduct electrochemical impulses called nerve impulses or action potentials.All neurons outside the central nervous system (and many within it) conduct impulses along hairlike cytoplasmic extensions, the nerve fibers or axons.(See diagram,Motor neuron with omitted axons)

The axons connecting your spinal cord to your foot can be as much as 1 m long (although only a few micrometers in diameter)Axons grow out of the cell body, which houses the nucleus as well as other organelles such as the endoplasmic reticulum. The length of some axons is so great that it is difficult to see how the cell body can control them. Nevertheless, there is a steady transport of materials (e.g., vesicles, mitochondria) from the cell body along the entire length of the axon. This flow is driven by kinesins moving along the many microtubules in the cytoplasm within the axon.In many neurons, nerve impulses are generated in short branched fibers called dendrites and also in the cell body. The impulses are then conducted along the axon, which usually branches several times close to its end.Many axons are covered with a glistening fatty sheath, the myelin sheath. It is the greatly-expanded plasma membrane of an accessory cell, the Schwann cell. Schwann cells are spaced at regular intervals along the axon. Their plasma membrane is wrapped around and around the axon forming the myelin sheath.Where the sheath of one Schwann cell meets that of the next, the axon is unprotected. This region, the node of Ranvier, plays an important part in the propagation of the nerve impulse.There are million of neurons in the body that does not receive impulses from other neurons.There are 3major neurons types;1)Motor neurons(responsible for muscles and glands),2)Interneurons(found in Spinal cord and brain which acts as a medium between sensory neurons and itself) and lastly the sensory neurons which are the mentioned sensory receptors that reacts directly to stimulation from the environment.Examples of stimulation include;Light,sound,motion,chemical,pressure,pain or temperature changes.Once these receptors are stimulated they transform one form of energy from the environment(eg;Light,sound)into another form of energy(action potential)that can be transmitted to other neurons.These action potentials reach the Central Nervous System.There are many kinds of receptors and they can be categorized on the basis of the types of stimuli they respond to,for eg;Mechanoreceptors(responds to movement,tension,pressure),Photoreceptors(rods and cones-respond to variations in light),chemoreceptors(responds to chemicals),Thermoreceptors(responds to temperature changes),Pain