Neurons• *Neurons are special cells that send messages through the nervous system.
Neurons• *There are five main parts of a neuron:1.Cell body2.Nucleus3.Dendrites4.Axon5.Myelin Sheath
Parts of Neuron• *Dendrites- receive signals from other neurons and send the signal to the cell• *Cell body- holds the nucleus and other organelles of the cell• *Axon- carries the nerve impulse from the cell to other neurons and muscles
Parts of Neuron• *Nucleus- Contains the DNA and controls the cell activities• *Myelin Sheath – wraps around the axon of some cells to cause the nerve impulse to move faster
Nerve Impulse• *A nerve impulse is when a neuron sends a signal to another neuron.• *There are three types of neurons: – *Sensory Neurons send impulses from the skin to the brain and spinal cord – *Motor Neurons carry signals from the brain to the muscles – *Interneurons carry nerves impulses to motor neurons or to the spinal cord and brain
Action Potential• *Another name for nerve impulse is an Action Potential.• The speed of an action potential changes.• *If the axon has a myelin sheath, the speed of the impulse is much faster.• *Neurons with myelin carry impulses of sharp pain• *Neurons without myelin carry impulses that cause dull, throbbing pain.