BIOL 3800 1st Edition Lecture 3 Outline of Current Lecture I. PharmacologyA. Pharmacology is What Synapse?II. Proteins and TransmitterA. QuantalB. ProteinsC. TransmittersIII. Integration and Summation A. Integration and SummationIV. SynapsesA. Facilitation and Post-synaptic Potentiation Current LectureChapter 6 Part IIIV. Pharmacology. A. Pharmacology is What Synapse?1. It is specific to the neuromuscular junction. But since this is a cholinergic synapse it pretty much abides to all the synapses that use acetylcholine as a transmitter. 2. So we have cholinergic synapses, cholinergic is just a term that means acetylcholine 3. And yet we have nicotinic and muscarinic and they do have pharmacology meaning that the normal neuromuscular synapse at your muscles is essentially the fast direct synapse and it’s response to ACH acetylcholine and many other compounds and one of the first ones they found is nicotine. a. The efficacy is not as high as ACH but let’s not worry about that it does respond to nicotine. That’s why you feel a little more alert and more fidgety when you smoke. 4. The receptors are blocked by curare and it’s found in the skeletal muscles because it’s not found on cardiac muscles.5. Muscuranic synapses different they are linked by G proteins so they use slow indirect ACH still normal transmitter in body but now responds to muscarine and blocked by atropine. 6. That is a really interesting phenomenon where protein is changed and is pharmacologically different than what the fast and direct receptors look like. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.* So, if Dr. Gross asks … Muscarinic synapses linked by G proteins and therefore do not use ACH as transmitter? Answer is False. They use acetylcholineII. Proteins and TransmitterA. Quantal1. When they say quantal release just means bucket of transmitter will be released. Just means transmitter package is a vesicle don’t make it more complicatedB. Proteins1. Know that there are many different proteins that are associated with presynaptic membrane.2. We have v-snare and t-snare just to remind you that there are snare proteins on both the vesicle and near the membrane in the docking area. If you had to redesign it as an engineer you could probably make it simpler and make it work fairly well butthis is the way it has developed.C. Transmitters1. Now in terms of the transmitters we have talked about glycine (gly) the simplest amino acid, and it’s inhibitory certainly in spinal cord and maybe in brain stem the cortex does not use glycine as an inhibitory transmitter. 2. GABA is all over the nervous system Gamma Amino Butyric Acid. 3. Glutamate another amino acid is primary excitatory transmitter. Not so much the transmitter molecule it’s the receptor and the channel it activates but in most cases there is no example of glutamate being inhibitory. 4. With ACH it can be both excitatory and inhibitory. Should know structure in that if it has 5 proteins that are not covalently linked you require two ACH’s, common theme these alpha helical structures and happen to have in their side chains hydrophobic regions and consequently they insert themselves into membranes and that’s how it stays. VI. Integration and Summation A. Integration and Summation1. When you think of these two words, for purposes of this class we will keep the same. 2. The summation or integration that’s spatial means that synapses in close proximity all have influence on postsynaptic membrane potential and they will either add or subtract depending on if you have inhibitory or excitatory synapses. 3. Temporal integration means that at each synapse depending on how fast action potentials come in you get the release of transmitters and an EPSP and you know before the first one dies out the second one and third one can ride piggy back on those earlier ones and so you get a fairly large depolarization at a single synapse just from high frequency action potential arrival. 4. Spatial attenuation: attenuation is always turning things down. Spatial attenuation passive signals that decay exponentially and that happens across your neuron. 5. It is what happens at the axon hillock that determines what the cell says.6. So it is true that hundreds and thousands of signals can often be just soaked up in the dendrites if enough inhibitory and excitatory stuff arrives at the same time, but the axon hillock sits there and does nothing or very little or not enough to reach threshold. So that’s what you have going on in your head.7. Also the more depolarization the higher number of action potentials are produced and the frequency initially also is higher VII. SynapsesA. Facilitation and Post-synaptic potentiation 1. These are the two basic mechanisms people have identified. Simply is something happening at the synapse. 2. Little changes in potential second one is 20% bigger in amplitude than the second one. That has an influence how a particular action potential pathway is selected but it fades out very quickly. 3. Post-tetanic potentiation lasts for several minutes and even though there’s a depression there is certainly an increase in the postsynaptic potential. Important thing to remember is that after about a few seconds you have this increase that lastsabout 5-10 minutes so in the minute range. 4. Facilitation and Post-tetanic potentiation are synaptic mechanisms. They make possible the reverberation of action potential patterns and circuits it’s kind of like directing a train it goes left or right depending on how the switch is set. So it’s the same thing. So pattern reverberation turns into working memory in psychology. 5. Memory is not that well understood just beginning to emerge on a mechanistic level the psychologist have been talking about memory since Aristotle but the mechanisms are unknown and are just beginning to come into view.- Will not have notes about vision on test the retina is extremely complex and do being that we did not thoroughly go over it in class Dr. Gross has decided that it is better if we do not deal with