Understanding the Nervous System: Neurons, Neurotransmission, and Functions

1. The nervous system • NS: gathers and processes information, produces responses to stimuli, coordinates the workings of different cells • CNS (brain + spinal cord): receives, processes, interprets, and stores incoming sensory information (e.g. Taste, state of internal organs) • PNS: deals with input and output of CNS through sensory and motor neurons. Jette Hannibal - Inthinking

2. The nervous system • Millions of neurons in different sizes and shapes organized in a network for transmission of information. • Communication between neurons: electric conduction and chemical transmission • A large concentration of neurons in the brain and the spinal cord. 80% are found in the brain’s Cerebral cortex • Neurons: basic structural unit of NS Jette Hannibal - Inthinking

3. Structure of neurons • Cell body or nucleus (contains DNA) • Dendrites: information transmission • Axons: the cell body. • Terminal buttons: storage of neurotransmitters. • Synaptic gap: between dendrites and terminal buttons. Where neurotransmitters “pass” information from neuron to neuron. Jette Hannibal - Inthinking

4. Neuron Jette Hannibal - Inthinking

5. Neuronalcommunication • Within neurons: Action potential • Between neurons: Synaptic transmission of neurotransmitters Jette Hannibal - Inthinking

6. Action potential • Electro-chemical messages • AP occurs when a neuron sends information down an axon • AP caused by an exchange of Sodium and Potassium ions across the neural membrane Jette Hannibal - Inthinking

7. Neurotransmitters • Chemical messengers from neuron to neuron. • Messages may also travel from neurons to to muscles and organs in the body, such as lungs or the intestines. Jette Hannibal - Inthinking

8. Synaptic gap • Synaptic vesicles with neurotransmitters at one side of the gap (terminal buttons): pre-synaptic gap. Like “keys” • Receptor sites for neurotransmitters (like locks) at the other side of the gap: post-synaptic gap • 1/10000 of a second to travel across the synaptic gap Jette Hannibal - Inthinking

9. Brain, neurons, neurotransmitters – how it works http://www.youtube.com/watch?v=haNoq8UbSyc Jette Hannibal - Inthinking

10. Neurotransmitters • Produced in the terminal buttons and diffused across the synaptic gap to bind to receptor sites. • The neuron on the postsynaptic side of the gap more or less likely to fire as a result of synaptic transmission. • Psychoactive drugs can change properties of neurotransmitter release, neurotransmitter reuptake and the availability of receptor binding sites. Jette Hannibal - Inthinking

11. Neurotransmitter processes • Excitatory: increases the frequency of action potential • Inhibitory: decreases the frequency of action potential • De-activation: effect of neurotransmitter stopped (destroyed by special enzyme) • Re-uptake: reabsorbed by the terminal buttons. • Drugs can inhibit re-uptake so that the neurotransmitter remains longer in the synaptic gap Jette Hannibal - Inthinking

12. Brief intro to principles of neurotransmission • Click here to see how neurotransmission works. Jette Hannibal - Inthinking

13. Examples of neurotransmitters • Dopamine: (inhibitory) Controls arousal levels in the brain; vital for physical motivation (e.g. associated with craving in addiction) • Serotonin: (inhibitory) Controls mood and anxiety levels High levels of serotonin are associated with optimism. • Acetylcholine (ACh): (excitatory) Controls activity in the brain connected with attention, learning and memory • Noradrenaline: (excitatory) involved in mental arousal and elevated mood Jette Hannibal - Inthinking

14. Dopamine and serotonin Jette Hannibal - Inthinking

15. Stimulation of the reward center is linked to release of dopamine Rats will continuously press a lever that gives a small electrical stimulation to the pleasure center The reward pathway - dopamine Jette Hannibal - Inthinking