The Nerve Cell PDF

THE NERVE CELL NERVE CELL The basic unit of the nervous system is the nerve cell. Nerve cell are also called the neurons. The main function of nerve cells is to receive, process, and transmit information. These cells receive signals from different sensory organs or other neurons, process this in...

THE NERVE CELL NERVE CELL The basic unit of the nervous system is the nerve cell. Nerve cell are also called the neurons. The main function of nerve cells is to receive, process, and transmit information. These cells receive signals from different sensory organs or other neurons, process this information, and then transmit signals to target cells, such as other neurons, muscles, or other organs. There are billions of neurons in the body. Some exist alone and others are joined together to form organs like the brain and spinal cord. There are 12 to 14 billions of neurons in one part of the brain alone. A neuron has a cell body containing the nucleus. Projecting out from the cell body are root-like structures. These are the dendrites and axons. Dendrites - carry impulses towards the cell body. A cell may have as many as 200 dendrites carrying impulses toward the cell body. A single dendrite can be over one meter long. Axons - carry impulses away from the cell body. Axons THE NERVE CELL CLASSIFICATION OF NEURON 1. Sensory or affective neuron – carry impulses from the sense organs to the brain and spinal cord. 2. Motor or effective neuron – carry impulses from the brain and spinal cord to the muscles. 3. Associative neuron – located in the CNS, they analyze or interpret the data or impulses. IMPULSES A wave of electrical chemical changes across the neuron that generates the action potential in response to a stimulus. It is an electrical current that travels along dendrites or axons. NERVE IMPULSE A nerve impulse is a combination of an electrical charge and chemical reaction. A nerve impulse is not a flow of electricity, but an electrochemical signal moving along neuron. A nerve impulse cannot jump from one neutron to another. When a nerve impulse comes to an end of an axon, it produces the chemical, called neurotransmitter, to be released. The chemical crosses the space between neurons called synapse and stimulates the nerve impulse to start in the next dendrite. The nervous system is assisted by five sense organs – the eyes, ears, nose, tongue, and skin. These sense organs are constantly receiving information from the environment and sending messages to the brain. These aid in the survival of human beings. A stimulus (plural: stimuli) is any factor in the environment that may trigger a nerve impulse. A response is reaction to a stimulus. A stimulus is received by the body and a response is made. An organism must be able to respond to a stimulus in order to survive. Messages do not travel in both directions along the same neuron. Only the axon of the neuron releases neurotransmitter that cross the space between neurons. Reaction time is the length of time between application of THANK YOU :]]