What Is A Neuron


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What Is A Neuron

  1. 1. What Is a Neuron<br />Univeristy of Saint Thomas<br />
  2. 2. A neuron is a cell in the body that is specialized to carry messages. <br />The process by which a neuron carries messages from one part of the brain to another is through what is called an electrochemical process. <br />The electro part happens in the neuron itself. <br />The chemical part happens at a junction between two neurons called the synapse.<br />All About the Neuron<br />
  3. 3. There are about 100 billion neurons in the human brain. <br />These neurons have many shapes and come in many sizes. <br />Their job is to allow you to think and behave.<br />For example, solving a math problem in your head and raising your hand in class to answer the teacher’s question are both activities that are controlled and coordinated by your brain through the behavior of neurons.<br />All About the Neuron<br />
  4. 4. Neurons are like other body cells<br />they have a cell membrane<br />a nucleus that contains DNA<br />some working parts of the cell known as organelles, <br />they carry on protein synthesis and energy production.<br />All About the Neuron<br />
  5. 5. Neurons are different from other body cells:<br />they have an irregular shape<br />they have specialized extensions called dendrites and axons<br />they communicate with each other through the electrochemical process<br />they have some other specialized structures (such as the synapse) <br />They use chemicals for communication called neurotransmitters.<br />All About the Neuron<br />
  6. 6. All About the Neuron<br />What a real neuron looks like<br />
  7. 7. All About the Neuron<br />Drawing of a neuron<br />
  8. 8. In the drawing of the neuron above you can see the cell body or soma and the nucleus containing the DNA. <br />These are parts of the neuron also found in other cells. <br />You will also see dendrites, the axon, myelin, the nodes of Ranvier, and the presynaptic terminals. <br />These are parts that are special to neurons.<br />All About the Neuron<br />
  9. 9. A dendrite is a structure of the neuron that brings information to the cell body from another neuron. <br />It has a rough surface, with little bumps called dendritic spines that increase the surface area of the dendrite so it can receive more information from the neighboring neuron. <br />Usually there are many dendrites on each cell, and dendrites don’t have myelin as the axon does. <br />Dendritesusually branch nearer to the cell body than does the axon.<br />All About the Neuron<br />
  10. 10. An axon carries information away from the cell body to the dendrites of a neighboring neuron or to another body structure such as a muscle. <br />Axonshave smooth surfaces and no spines like dendrites have. <br />Most neurons have only one axon, and the axon branches further from the body than the dendrite does.<br />All About the Neuron<br />
  11. 11. Myelin is a fatty substance that covers some axons. <br />If an axon has myelin, the information it sends can travel faster than if the axon does not have myelin. <br />Myelin is produced by support cells in the nervous system called glia. <br />There are breaks at various points in the myelin that surrounds the axon, and these breaks are called nodes of Ranvier. <br />As an electrical signal, called an action potential, travels down the axon, the action potential “jumps” from node to node. <br />This jumping allows the signal to travel much faster than it would be able to if it had to travel along an axon without myelin. <br />This type of movement by an action potential along an axon with myelin is called saltatory conduction.<br />All About the Neuron<br />
  12. 12. All About the Neuron<br />Axon with myelin and the nodes of Ranvier<br />
  13. 13. Glia are the support cells of the nervous system. <br />Gliado not carry information over a long distance as neurons do. <br />Gliaare smaller than neurons, but there are many more of them, so they occupy about as much space in the brain as do neurons.<br />All About the Neuron<br />
  14. 14. There are several types of glia. <br />One type, called astrocytes, wrap around the presynaptic terminals and take up chemicals released by axons. <br />They later release these chemicals back to the axons so the chemicals can be reused. <br />Astrocytesalso remove waste material created when neurons die (acting like little garbage men in the brain) and they also help control the amount of blood flow to specific brain areas.<br />All About the Neuron<br />
  15. 15. Microglia are another type of glia that also remove waste material and viruses, fungi, and other unwanted organisms in the brain. <br />These glia function as part of the body’s immune system.<br />All About the Neuron<br />
  16. 16. Oligodendrocytes occur in the brain and spinal cord and build the myelin sheath that surrounds these structures. <br />They make saltatory conduction possible. <br />Schwann cells are another type of glia that have the same function as oligodendrocytes, but in the periphery of the body.<br />All About the Neuron<br />
  17. 17. Radial gliaare a type of astrocyte that guide the migration of neurons and the growth of the neuron’s axons and dendrites during an infant’s development before birth.<br />All About the Neuron<br />
  18. 18. All About the Neuron<br />Some types of glia: astrocytes (left) and oligodendrocyteand the myelin sheath (right).<br />