OPTM4106 Action Potential 2024 PDF

OPTM4106 Action potential Dr. Jason Charng [email protected] Acknowledgement of country The University of Western Australia acknowledges that its campus is situated on Noongar land, and that Noongar people remain the spiritual and cultural c...

OPTM4106 Action potential Dr. Jason Charng [email protected] Acknowledgement of country The University of Western Australia acknowledges that its campus is situated on Noongar land, and that Noongar people remain the spiritual and cultural custodians of their land, and continue to practise their values, languages, beliefs and knowledge. Artist: Dr Richard Barry Walley OAM Objectives Action potential mechanisms Action potential Propagation of electrical signals along the axon Movement of ions N+ K+ Cl- -ve charged protein molecules https://www.cambridge.org/ Resting membrane potential > Neronsare naturally - - the action potentiala Negatively charged Resting potential is constant Net negative movement of in the absence of stimilation. ions across membrane -70mV in neurons - -45mV in photoreceptors means there are more"+ "Ton outside than inside the neuron. For every 3 Nat pumped out , 2 kt are pumped in https://pubmed.ncbi.nlm.nih.gov/21750765/ https://courses.lumenlearning.com/wm-biology2/chapter/resting-membrane-potential/  Steps involved in action potential Threshod potential is initiated by the neurotransmitters that released by the previous ascon terminal reaching the receptors on the due to large influx of dendrites of the O Nat next neuron. *. causes the opening of Nat channel. ↑ C https://www.zoology.ubc.ca/~gardner/chemical_synapses %20-%20postsynaptic.htm Neuron will only fire if the ↓. reached reached threshold potential is Threshold potential is not resulting depolarization of the neuron. : no https://content.byui.edu/file/a236934c-3c60-4fe9-90aa- d343b3e3a640/1/module5/readings/action_potential.html  the time Referes to which a intervel during The interval Propagation of action potential of time during a potential T cannot second action second action potential be initiated /f be initiated but require OO can must be One way traffic unidirectional - a greater stimulies than ↓ before. Retractory period are caused by the inactivation gate of sodium channels. Once inactivated , the sodium channels can not respond to another stimulies https://content.byui.edu/file/a236934c-3c60-4fe9-90aa-d343b3e3a640/1/module5/readings/refractory_periods.html http://pittmedneuro.com/actionpotentials.html  If the chance of postsynaptic potential occuring ↑ firing by making the · · the chance neuron neuron neuron by making the neuron more ( potential the next more depolarized a closer to the theshold in ④. hyperpolarized & away from theshold potentials. Photoreceptors Hyperpolarizes on stimulation Stimulation – decreased - glutamate release GRADED POTENTIAL: the hyperpolarization is related to intensity of the stimulus https://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/ReceptorPotential.html  Neurotransmitters & Ion Flow Excitatory postsynaptic potential (EPSP)- increases the chance of post synaptic action potential occurring in the next neuron. Inhibitory Postsynaptic Potentials (IPSP)-decreases the chance of post synaptic potential occurring in the next neuron. These subsynaptic currents may flow either inwards or outwards, so removing charge or adding charge to the whole postsynaptic membrane-according to whether the synapses are excitatory or inhibitory.  Neurotransmitters & Ion Flow The essential feature here is that the action of the neurotransmitter and the permeability of the subsynaptic membrane is only dependent on: – the sizes of the hydrated ions – their electric charge – not at all by the chemical properties of the ions. – The only thing changes in IPSP is that it causes reversal of the potential which means the target cell or neuron neurotransmitter causes no current flow of ions. Summary General overview of neuronal structure Information propagation along and between neurons Glial cells of the retina Major neurotransmitters of the retina