Note Jan 26, 2025 PDF

PART 1B Notes KeyTerms Conductance the process of transmitting an electrical signal along the length of the neuron's axon Happens when action potential is fired Permeability the ability of a cell membrane to allow certain molecules to pass through it Ion channel A protein embedded i...

PART 1B Notes KeyTerms Conductance the process of transmitting an electrical signal along the length of the neuron's axon Happens when action potential is fired Permeability the ability of a cell membrane to allow certain molecules to pass through it Ion channel A protein embedded in a cell membrane that allows specific ions to pass through Responsible forthe transmission of electrical signals in the nervous system They are fast gatedselective Resting membrane potential The electrical charge difference across a neuron's membrane when it's not actively sending signals Caused an uneven distribution of ions inside by outside the cell Ion distribution charged ions Nat att is outside the cell while charged ions CT kt is inside the cell 70mV Action Potential electric impulse th travels down anaxon to send signals Depolarization sodiumions channel open causing a rapid in the membrane potential Repolarization potassium ion channe open causing a returnto thpeotehef.hn Hyperpolarization membrane potential becomes more negative than resting Action PotentialThreshold membrane potential level electric activity level that must be reached toinitiate an action potential All or Nothing  EPSP Excitatory Post synaptic Potential IPSP Inhibitory Continuous conduction slow propagation of action potential along an unmyelinated neuron Saltatory Propagation rapidtransmission of nerve impulses along a myelinated axon where action potential jumps from one node of ranvier to the next CONCEPTS What are Neurons Ramon y Cajal's use of the Golgi stain Cajal developed the neuron doctrine The golgi stain painted neurons black had to be very zoomed in for visibili He predicted the direction of info flow Morphology of a Stereotypical Neuron Stathygert farther 3 Eightbark axon collateral one major branch Intra cellular recording of resting action potentials To record the resting potential a finetipped glass pipette a microelectrod must be inserted into the cell's interior Section Summary European scientists in the 20th century discovered that neurons are discrete cells Stereotypical neurons have long axons that synapse on dendrites are electrically excitable use glutamate or GABA as their neurotransmitte  What mechanisms generate resting action potentials Ion Concentrations Sodium Calcium ions are more concentrated outside of neurons than insi whereas the reverse is true for potassium most organic anions Intracellular free calcium concentration is extremely low The Sodium Potassium Pump Changes in Membrane Voltage Ion Flow During Each ActionPotential slide Read n How do Action Potentials travel along Axons Action Potentials travel along axons because the massive influx of Nat ions at one location of the axonal membrane tends to trigger Nat influx at adjacent locations as long as those sites are not in the action potential's wake refractory Look at slide 14 Myelin sheath Swipe up fordef A myelinated axon at two points in time Initially Nat rushes in the axon at a node of Ranvier triggering a pressure wave of ions that travel down the axon At the next node of Ranvier the wave of currenttriggers another action potential Nat influx due to this second action potential triggers another wave of positive current which flows both the axon However current flow back up the axon does nottrigger another action potential at the first node be its now refractory burnt The conduction velocity of action potentials increases w axon diameter myelination How do Neurons Transmit Integrate Info How Do Neurons Differfrom one another I Read slides 30 41 for Neural Info Processing Q1 a.GE ertiii i'ciint thte is no such thingas a small or large AP Q2 Because of the refractory period After a partofthe neuronfires it need a shorttime to reset before it canfire again This prevents the signalfromgoing backward keeps it moving forward alon the axon toward the axon terminals Q3 Because the soma is closer tothe axon hillock signals weaken as they travel