What ions are important in the action potential Na Cl and K When the cell is at rest which ions are most highly concentrated inside of the cell K and which ones are most highly concentrated outside of the cell Cl and K Understand the forces working on the ions electrical gradient and concentration gradient Electrical gradient ions flow to areas of opposite charge Positive to negative negative to positive Concentration gradient ions flow from high areas of concentration to low concentration What is a voltage gated channel Where are they Voltage gated channel A class of ion channels that open and close in response to change in the electrical potential across the plasma membrane of the cell They are located in the Nodes of Ranvier Understand the steps of the action potential and how one leads to the next How is an action potential started and propagated What ion enters first Thru what type of channel does it enter What forces drive it inside Why does that channel close What channel opens next What ion moves thru that What forces drive that ion Etc etc The action potential starts when the voltage gated Na channels open and Na enters the cell and then the voltage gated Na channels close the VGKCs open and K exits the cell the cell becomes hyperpolarized and then the refractory period happens Terms to know and understand with regard to neurophysiology polarized depolarization hyperpolarization repolarization resting potential threshold Polarized Different inside vs outside Depolarization less negative than 70 as cells becomes less negative it is depolarized Hyperpolarization more negative than 70 as cell becomes more negative it is hyperpolarized Repolarization the membrane potential to a negative value after the depolarization phase of an action potential has just previously changed the membrane potential to a positive value Resting potential difference in voltage across the membrane of a cell Threshold The critical level of depolarization that must be achieved to trigger an action potential is called the threshold With regard to those last 2 terms What voltage is resting potential What voltage is threshold Where must threshold be reached for an action potential to occur Resting potential 70mV Threshold 50mV What is the sodium potassium pump What does it do What purpose does it serve Sodium potassium pump pumps sodium out of cells while pumping potassium into cells What is the purpose of myelin What happens at the nodes of Ranvier What is saltatory conduction Myelin is material that forms a layer the myelin sheath usually around only the axon of a neuron It is essential for the proper functioning of the nervous system The main purpose of a myelin layer or sheath is to increase the speed at which impulses propagate along the myelinated fiber The action potential travels from one location in the cell to another but ion flow across the membrane occurs only at the nodes of Ranvier As a result the action potential signal jumps along the axon from node to node rather than propagating smoothly as they do in axons that lack a myelin sheath The clustering of voltage gated sodium and potassium ion channels at the nodes permits this behavior Saltatory conduction is defined as an action potential moving in discrete jumps down a myelinated axon What does it mean that an action potential is all or none Either there is an action potential or there s not one What is heritability how do we study it what are twin and adoption studies what do their results tell us and what are the problems with studying it Estimate of how much of the variance in a characteristic within a population is due to differences in heredity genes What are examples of environmental influences on traits with otherwise high heritability Mice on elevated plus maze What is a sex linked gene Understand the heritability of sex linked genes What is a sex limited gene What are examples of each sex linked and sex limited Sex linked gene is a gene that usually is seen in one sex or the other Like red green colored blindness that gene is most likely to be on the Y chromosome so it s most likely going to effect the guy Sex limited gene is present in both sexes but has an effect only mostly in one sex An example would be like genes for chest hair men breast size women the genes are usually turned on under influences of sex hormones What is the multiplier effect slide 30 Genes predispose you to behaviors and to different treatment by others Genes or prenatal influences increase tendency environment facilitates it What started out as potentially small effect of genes ends up having a huge behavioral result leading to an overestimation of heritability Terms to know and understand DNA RNA gene chromosome transcription translation homozygous heterozygous dominant recessive DNA is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses RNA is a ubiquitous family of large biological molecules that perform multiple vital roles in the coding decoding regulation and expression of genes Gene is a molecular unit of heredity of a living organism Chromosome A chromosome is an organized structure of DNA protein and RNA found in cells We have 46 chromosomes 22 paired autosomal chromosomes plus 2 sex chromosomes XX female XY male What is evolution What types of traits move on to the next generation What is natural selection What are adaptive characteristics Similarities that we see between species suggests a common ancestor Differences between species allow us to question what pressures may have caused certain animals to develop certain traits Only the traits that help you survive in your environment move on to the next generation Natural selection is the process by which inherited traits that confer a selective advantage increase an animal s likelihood to survive and reproduce become more prevalent in a population Adaptive characteristics How does genetic variability occur Mixing of DNA recombination Random mutations Of even a single nucleotide Usually disadvantageous A T mutation in Ob Ob mouse Duplications or deletions Could contribute to schizophrenia for example Trinucleotide repeats important in diseases like Huntington s disease What is epigenetics Why does this new field of research blur the line between environment and genetics Epigenetics is changes in phenotype appearance or gene expression caused by mechanisms other than changes in the underlying DNA sequence DNA is
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