BIOL 240W 1st Edition Lecture 29Outline of Last LectureI. OvulationII. MenstruationIII. EstrogenIV. ConceptionV. Ovulation (Tuesday)VI. Follicular PhaseOutline of Current LectureI. NeuronsII. Nervous SystemCurrent LectureI. Neurons (nerve cells)a. Generate and carry electric impulses call action potentialsb. Can be long/short (nerve cells in brain are short, or over three feet long in other places of the body)c. Cell body contains nucleus, organelles, etc.d. Short structures called dendrites branch off from cell bodye. Folds in cell membranes create a large surface area for a neural circuitf. Axon, which carries action potentials, are long structures, which branch into small terminalsi. Synaptic knobs are the ends of axon branches. They are also called terminals or pre-synaptic terminalsii. Membranes do not touch, but connections still exist with other neurons called synapse (not a physical connection)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.II. Nervous systema. Large complex circuits of neurons, especially in the braini. 500 trillion connections (synapses) between neurons in the brainb. Pre-synaptic neuron communicates with post-synaptic neuron by releasing neurotransmitter into the synapsei. Chemical messenger getting pushed out of a cellii. Physics1. Voltage/potential (separation of charge)2. Current (flow/movement of charged particles)3. Resistance resists the flow of charged particles (mess up current)4. All apply to cell membranesc. Charges exist inside and outside the cell, separated by a membranei. When all ions are at equilibrium, the cell is at its resting membrane potentialii. Differences of sodium and potassium concentrations inside and outside the cell creates a gradient iii. Facilitates a flow inside/outside the cell down a concentration gradient (diffusion; does not require ATP)1. Example: if more sodium exists outside the cell and the protein channel opens, sodium will enter the cell, causing the inside of the cell to become more positive. This results in depolarization, because the charges become less separated (loss of voltage)a. Depolarization is the process of bringing the charge/potential closer to 02. Repolarization is increasing the separation of charge/voltage3. If the potassium channel opens, potassium will diffuse down its concentration gradient outside of the cell. However, more potassium ions leaving the cell causes the cell to become more negative, increasingthe separation of charge. The cell is more polar than before. This is called hyperpolarization. The process of going back to resting membranevoltage after hyperpolarization is still repolarization.4. Resistance is created by closing protein channels so the ions cannot
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