Download Neurobiology Guide: Neurons, Action Potentials, Resting Potential, and Neurotransmission and more Study notes Biology in PDF only on Docsity! Neurobiology BACKGROUND GUIDE Neurobiology Background Guide This guide is to give you a background on neurobiology that will be discussed in a more advanced level in the Neurobiological Basis of Psychiatric Disorders Lecture. Please read over this guide before the lecture to facilitate a better understanding of the lecture materials. NEUROBIOLOGY (Below is an Axon, Can you identify the parts of a neuron?) Terms to Know: Action Potential/Resting Potential, Function/ Parts of a Neuron Neurobiology BACKGROUND GUIDE NEURONS ACTION POTENTIAL CONCEPTS 1) An action potential is a wave of electrical discharge that travels along the membrane of a cell. Action potentials are an essential feature of animal life, rapidly carrying information within and between tissues. 2) They also occur in some plants. Action potentials can be created by many types of cells, but are used most extensively by the nervous system for communication between neurons and for transmitting information from neurons to other body tissues such as muscles and glands. 3) Action potentials are not the same in all cell types and can even vary in their properties at different locations in the same cell. 4) For example, cardiac action potentials are significantly different from the action potentials in most neurons. NEURONS RESTING POTENTIAL CONCEPTS 1) The resting potential is what would be maintained were there no action potentials, synaptic potentials, or other changes to the membrane potential. In neurons the resting potential is approximately -70 mV (the negative sign signifies excess negative charge inside the cell relative to the outside). 2) The resting potential is mostly determined by the ion concentrations in the fluids on both sides of the cell membrane and the ion transport proteins in the cell membrane. 3) The term resting is somewhat misleading, for the cell must constantly do work to maintain the resting potential. 4) The establishment of this potential difference involves several factors, the most important of which are the transport of ions across the cell membrane and the selective permeability of the membrane to these ions. NEURONIC PROPOGATION 1) In un-myelinated axons, action potentials propagate as an interaction between passively spreading membrane depolarization and voltage-gated sodium channels. 2) When one patch of cell membrane is depolarized enough to open its voltage-gated sodium channels, sodium ions enter the cell by facilitated diffusion. 3) Once inside, positively-charged sodium ions "nudge" adjacent ions down the axon by electrostatic repulsion (analogous to the principle behind Newton's cradle) and attract negative ions away from the adjacent membrane. 4) As a result, a wave of positivity moves down the axon without any individual ion moving very far. Once the adjacent patch of membrane is depolarized, the voltage-gated sodium channels in that patch open, regenerating the cycle. 5) The process repeats itself down the length of the axon, with an action potential regenerated at each segment of membrane.
