E. Signal intensity1. Stimulus – determines the number of graded potentials that gives the number of action potentials2. Frequency= # of impulses = [neurotransmitters]3. Qualities of stimulusa) Type- Nerve energyb) Location- hardwired line connection from the source of the stimulus to the brainc) Intensity- impulse frequency (the accumulation of neurotransmittersd) Duration- Impulse (conduction of an impulse tells us strength and how long its been there)4. Signal speeda) Axon diameter- small diameter has negative charges near the surface and the center- positive charges attracted to both, causing loss of voltage stimulus to open the Na Voltage channels(1) Small diameter is slower due to its higher resistance of conduction ***people often get this wrong, it has nothing to do with surface area(a) Have too many negative charges taken off the membrane that the positive charge is attracted to, making the signal move slowerb) Myelin- hydrophobic lipid protein that insulates the axon created SALTATORY CONDUCTION.(1) Nodes have a resting potential and then there is a lipoprotein (myelin) around some of the axon and this area is neutral, and it can race through this neutral area to the resting area with the negative charges(2) In salutatory conduction, are reaching further distances in less time. ** Not leap froging, no jumping involvedF. Cell to cell communication1. Synapse- physical connection of neuron to an effector (effector= another neuron or different organ)2. Neuron- always pre-synaptic membrane – the one that is releasing the neurotransmitter3. Effector- post synaptic membrane or the responder to that neurotransmitter that must then have the receptor for that neurotransmitter that allows for activation4. Chemical synapse- most of the nervous system operates on this, when a neurotransmitter is released by exocytosis and binds to a chemical ligand gated channel and allows the release of Calcium into the cell5. Electrical synapse- do not perform exocytosis and often there isn’t a neurotransmitter involved, instead there is protein channel for calcium that allows it to flow through V. FAST6. Pre-synaptic potential- [neurotransmitter] to impulse ratio, if impulse frequency is high, the amount of neurotransmitter will be large7. Post synaptic potential- [neurotransmitter] to receptor ratio8. Digestion of Neurotransmitter- end of the transmittion – determines the effector response (if you are quickly removing the signal, then the effector response is limited)a) Enzymatic digestion- an enzyme usually on the post-synaptic membrane that is digesting that compound into an inactive compound that is taken into the cell and often reused and reactivated chemicallyb) reuptake- grabs the neurotransmitter and brings it back into the cell and store it into a vesicle againG. Neurotransmitter signals (need to know name, family (chemical composition), what they do, location (PNS, CNS, etc.), clinical relevance) – can only excite or inhibit the receptor1. acetylcholinea) Family name: Cholenergic family- only possesses acetylcholine(1) Chantix- drug that is used for antismoking and taken off the drug market due to many suicide attempts(2) Muscarinic- slow action drug, involves a second messenger- mainly found in the peripheral nervous system(3) Atropine- poisonous plant –antagonist for muscarinic receptors (inhibits signaling)- often used to relax digestive crampingb) wide distribution throughout the whole body (involved in vision, all types of skeletal muscle, and can excite or inhibit smooth muscle)(1) Does this through the cholinergic receptors= nicotinic receptors (Nicotine is an agonist for this)- fast Na channel, always excitatory – without nicotine, have withdrawal2. bioaminesa) Family name: Catecholamine (all made from tyrosine)b) Dopamine= seeking behavior drug, drives you to go get something to eat, drink etc.(1) very controlled coordinated motor behavior, involved in storing memory generally excitatory, and most are slow(2) Confined to CNS only- targets Substantia Nigra(3) Parkinson’s disease- happens in substantia nigra, treated by taking a series of drugs with a lot of dopamine or Deep Brain Stimulation- which places a wire in the substantia nigra that will immediately stop a seizure with an electrical impulsec) Norepinephrine- closely related to Dopamine, but faster, used with stress, fight or flight reflex(1) Always excitatory in the CNS(2) only neurotransmitter that can rapidly change blood pressure with the dilation of blood vessels(3) alpha and beta adrenergic receptors are of the slow varietyd) Serotonin- Tryptophan based bioamine- associated with depression, regulates moods, also tells your brain that you are full (some obesity may be due to serotonin process defect)(1) In the Central nervous system and Digestive system(2) Most serotonin are inhibitory(3) sSRI- (selective serotonin reuptake inhibitor) treats depression by helping the reuptake inhibitor, so that we are not over attentive(4) also known as 5HT- 5-hydroxyltryptophan(5) serotonin is released after eating so some obesity can be caused by the failure to release serotonine) GABA –made from glutamine, potent, fast acting inhibitor found in all conscious processes(1) Helps to coordinate movement in skeletal muscle, necessary stopping some signals from the eyes, induces sleep(2) Exclusively in the CNS(3) 2 receptors- GABA receptors 1 and 2 are Fast acting Cl- channels and K+ receptor channels that both hyperpolarize the cellf) Glutamate and Aspartate- improves memory, wakefulness, mood, motivation,(1) found in CNS as excitatory receptors(2) 2 kinds, both are Na+ channelsg) Glycine- in spinal cord and can lower pain threshold or pain relay in brain- not as much research has been done here3. Neuropeptides- determined by the peptide linkages small, less than 20 amino acids, some fewer than 10a) Opiodes- lower pain responses, natural and produced in the brain as endorphin and inheptinone-both are inhibitory to feel pain in the spinal cord(1) Endorphins- seen with strenuous exercise= runners high (when things are beginning to feel a lot easier after a little while of exercise)b) Substance P- first found with receptors in the spinal cord and exhibited pain, determinedpain stimulant(1) excitory response to pain, want to lower this often – also in gut and plays some role in controlling appetitec) Some Neropeptides not found directly in the brain, but are potent and effects the brains signaling some are:(1)