Neurons and Nerve CellsEx: child eats poisonous bean, which causes muscle cramps, eye constrictions, and seizures. Doctor recommends giving the child a poison to ease these problems1. What is happening to the child?- The childs neurotransmitters are:o Blockedo Lackingo Excessive 2. Why does the doctor recommend giving the child a poison?- The poison is a muscle relaxant- Relieves seizuresSeizures: tight, numerous muscle contractionsParalysis: limp, none or few muscles contract3. Is a calaber bean the solution?- Similar to a regular bean- Determines guilt in primitive societies- Treats a variety of medical disorders in modern medicineNEURON STRUCTURE:The central part of the neuron is the nucleus. This is the cell body. Leading into the nucleus are many dendrites, which receive electronic stimulation that passes information into the nucleus so the nucleus can process it. At the edge of the nucleus is a trigger zone, which fires out information. This information travels down the axon, which is covered in a myelin sheath (made by Schwann cells) that allows it to travel easier. The information may pass through the node of ramvier. At the end of the axon, the action potential passes through the synaptic gap and reaches the synaptic terminal on the synapse. This is where the muscle reaction takes place and the effects of the action potential are seen/felt/heard/whatever.Stimulus  dendrites  axon  synapse  dendrites  axon  synapse  muscleNeurons are specialized cell types.- Cell body w/ nucleus- Dendrites receive impulses- Axon sends away impulses- Myelin sheath is produced by Schwann cells to speed transmission- Synapse connects the processCentral Nervous System: brain and spinal chordPeripheral Nervous System: nerves that connect muscles, organs to CNSAction Potential1. Resting potential- Positive outside, negative inside- Neurons contain negatively charged protons- High Na+ concentration outside of neuron- High K+ concentration inside of neuron- Na+/K+ pump is always working (3K+ for every 2Na+  an active process using ATP)2. Depolarization- Brief change in electron polarity across the axon membrane- Na+ channels open and Na+ enters the axon (passive process – no energy required)- The inside is now positive, the outside is now negative3. Peak depolarization- Na+ channels have closed- The process reaches its highest voltage difference – (+3.5mV)- K+ channels open and K+ leaves the cell (passive process – no energy required)So basically, at resting potential there is a high amount of Na+ outside the axon and a high amount of K+ inside the axon. A pump is working to keep both of these levels stable. During depolarization, there is a brief switch in polarity. The inside of the axon becomes positive from Na+ molecules entering it, and the ouside becomes negative because the Na+ left. This is a passive process. During peak polarization, the K+ molecules leave the axon after the Na+ channels have closed. This is also a passive process.Paralysis is stopped when:- Na+ gates remain open and action potential cannot return to resting potential- Na+ gates stay closed because “- K+ gates stay open because “If the process is interrupted and stopped in any way, paralysis will occur. Neurons are a tight web of communication through an organism and if this communication is stopped in any way, the entire process will stop and become paralyzed.Diffusion of Neurotransmitters 1. The action potential travels over the axon to the synaptic terminations of the presynaptic cell.2. Depolarization causes influx, moves vesicales with neurotransmitters into synaptic space3. Vesicles with neurotransmitters fuse with the presynaptic membrane4. EXOCYTOSIS: Neurotransmitters are released in synaptic space5. Neurotransmitters bind to receptor proteins postsynaptic space, opening Na channelsThe human brain has ~100 types of neurotransmitters. Acetylcholine is most commonly excited.After neurotransmitters are released in a synapes, reuptake occurs and it is removed and reused for the next impulse.WHEN TOXINS INTERFERE PARALYSIS EVERYTHING CAUSES PARALYSISParalysis of the emotionsHowever, when a chemical similar to acetylcholine is released into the synaptic space, this will result in seizures because new action potentials are being fired and they introduce new muscle spasms.Secretion via Excocytosis (step four of diffusion of NT)Muscle relaxants relieve seizures, different drugs/toxins affect the synaptic transmission.- Physostigmine  blocks breakdown of neurotransmitters which leads to more action potentials- Atropine  blocks receptors from neurotransmitters leading to fewer action