NEURONS, SYNAPSES & NERVE IMPULSES

1. NEURONS, SYNAPSES & NERVE IMPULSES MARIO ANDRES CRUZ NATALIA GONZALEZ LUIS FERNANDO VELAZQUEZ MEN 1

2. NEURONS • A neuron is a nerve cell that is the basic building block of the nervous system. • Neurons are similar to other cells in the human body in a number of ways, but neurons are specialized to transmit information throughout the body. • These highly specialized nerve cells are responsible for communicating information in: • chemical • electrical forms • There are several different types of neurons responsible for different tasks in the human body.

3. TYPES OF NEURONS

4. TYPES OF NEURONS

5. TYPES OF NEURONS

6. NEURON STRUCTURE DENDRITES Treelike extensions at the beginning of a neuron that help increase the surface area of the cell body and are covered with synapses. These tiny protrusions receive information from other neurons and transmit electrical stimulation to the soma.

7. NEURON STRUCTURE • SOMA • Where the signals from the dendrites are joined and passed on. • These two structures serve to maintain the cell and keep the neuron functional. • The support structures of the cell include: • Mitochondria: provides energy for the cell. • Golgi apparatus: packages products created by the cell and secretes them outside the cell wall.

8. NEURON STRUCTURE AXON HILLOCK It’s located at the end of the soma and controls the firing of the neuron. If the total strength of the signal exceeds the threshold limit of the axon hillock, the structure will fire a signal (known as an action potential) down the axon.

9. NEURON STRUCTURE AXON It’s the elongated fiber that extends from the cell body to the terminal endings and transmits the neural signal. The larger the axon, the faster it transmits information. Some axons are covered with a fatty substance called myelinthat acts as an insulator. These myelinated axons transmit information much faster than other neurons.

10. NEURON STRUCTURE TERMINAL BUTTONS These are located at the end of the neuron and are responsible for sending the signal on to other neurons. At the end of the terminal button is a gap known as a synapse. Neurotransmitters are used to carry the signal across the synapse to other neurons.

11. NEURON STRUCTURE

12. ACTION POTENTIAL • In order for neurons to communicate, they need to transmit information both: • within the neuron • from one neuron to the next. This process utilizes electrical signals and chemical messengers. • The dendrites of neurons receive information from sensory receptors or other neurons. This information is then passed down to the cell body and on to the axon. • Once the information has arrived at the axon, it travels down the length of the axon in the form of an electrical signal known as an action potential.

13. NEUROTRANSMITTERS

14. SYNAPSE Once an electrical impulse has reached the end of an axon, the information must be transmitted across the synaptic gap to the dendrites of the adjoining neuron. In some cases, the electrical signal can almost instantaneously bridge the gap between the neurons and continue along its path. In other cases, neurotransmitters are needed to send the information from one neuron to the next. Neurotransmitters are chemical messengers that are released from the axon terminals to cross the synaptic gap and reach the receptor sites of other neurons. In a process known as reuptake, these neurotransmitters attach to the receptor site and are reabsorbed by the neuron to be reused.

15. MESSAGE TRANSMISSION

16. SOURCES What is a Neuron? http://psychology.about.com/od/biopsychology/f/neuron01.htm Structure of a Neuron. http://psychology.about.com/od/biopsychology/ss/neuronanat_6.htm Great Pacific Media. Neuron Synapse http://www.youtube.com/watch?v=LT3VKAr4roo