Neurotranmission

1. Neurotranmission

2. This diagram shows the component parts of the neurotransmission process between electrical impulses.

3. An electrical impulse travels down the axon toward the presynaptic nerve terminals.

4. The vesicles containing neurotransmitter move toward the neuron cell membrane at the end of the axon. The vesicles fuse to the membrane and then release their contents (neurotransmitter molecules) into the synaptic cleft.

5. The neurotransmitter is in the synaptic cleft and binds to the receptor on the postsynaptic neuron’s membrane.

6. Neurotransmitter molecules are still bound to the receptors and an electrical signal passes along the postsynaptic neuron away from the neuron’s ending.

7. Neurotransmitter molecules are released from the receptors. Neurotransmitter molecules are taken back up into the presynaptic neuron through the transporter. Once inside the presynaptic neuron terminal, the neurotransmitter molecules are repackaged into vesicles.

8. Crossing the Divide How Neurons Talk to Eachother

9. Neurotransmission • Neurotransmission, or the communication between neurons, is both an electrical and chemical process. • Within a single neuron, information is conducted via electrical signaling • Communication between 2 neurons is a chemical process

10. Electrical signaling • When a neuron is stimulated, an electrical impulse, called an action potential, moves along the neuron’s axon or dendrite. • Action potentials enable signals to travel very rapidly along the neuron fiber. • Action potentials last less than 2 milliseconds (1 msec= 0.001 sec) and the fastest action potentials can travel the length of a football field in one second.

11. Electrical  Chemical Signal • Stimulation of a neuron generates an electrical signal (action potential) which will travel down the axon to the axon terminals. When the electrical signal reaches the end of the axon, it triggers a series of chemical changes in the neuron which initiate the release of neurotransmitters which will cross the synaptic space and bind to receptors on the post-synaptic neuron.

12. Chemical  Electrical Signal • The chemical binding of neurotransmitter and receptor initiates changes in the postsynaptic neuron that may generate an action potential in the postsynaptic neuron.

13. Lock and Key Mechanism • The interaction of a receptor and neurotransmitter can be thought of as a lock-and-key for regulating neuronal function. Just as a key fits only a specific lock, a neurotransmitter binds only to a specific receptor. • For example, the dopamine receptor binds the neurotransmitter dopamine, but does not bind other neurotransmitters such as serotonin  

14. Lock and Key Mechanism

15. Different Kinds of Neurotransmitters • Different neurotransmitters fulfill different functions in the brain. • Excitatory neurotransmitters act to stimulate the firing of a postsynaptic neuron • Inhibitory neurotransmitters block the changes that cause an action potential to be generated in the responding cell. • Each neuron generally synthesizes and releases a single type of neurotransmitter.