Psyc 362 Class Notes for Exam 1 Chapter 2 2 3 15 Nerve Peripheral neural structure that contains a large number of Axons It can be both or just one motor or sensory Neuron internal structures organelles contained within cytoplasm Nucleus Endoplasmic reticulum in charge of protein production ribosomes aid in protein protection mitochondria golgi apparatus Membrane consists of lipid molecules defies outer boundaries of cell contained multitude of molecules that serve different functions receptors channels transporter etc Mitochondrial extracts energy from nutrients and creates ATP nucleus contains genetic materials in the form of chromosomes strands of DNA with associated proteins which carry genetic information which is composed of DNA long complex macromolecules of 2 interconnected neural strands and associated proteins neurotransmitters produced by neuron mostly in the soma and need to be transported down the cell Microtubules and neurofilaments are capable of such transportation down the axon Axoplasmic transport active process of propelling substances along microtubles long strands of bundles of protein filaments arranged around a hollow core that run the length of the axon enzyme molecule that controls a chemical rxn combining or breaking apart a molecule supporting cells CNS since neurons have high metabolic rates they use supporting cells to supply nutrients to sustain themselves Neuroglia provide physical support control nutrient flow and are involved in phagocytosis engulfing toxic debris to remove from environment 1 Astrocytes physical support removes debris becomes scar tissue and transports nutrients to neurons May reproduce if there is an injury in order to fill space 2 microglia phagocytosis and involvement in brain immune function 3 oligodendroglia physical support and form of myelin sheath around axons in brain CNS 4 Schwann cells form myelin for PNS myelin the layer around axon that specifically function to insulate the axon and accelerate the rate of action potential Is formed by Oligodendroglia in CNS and Schwann cells in PNS different formation method in these Blood Brain Barrier there is a semi permeable barrier between the CNS and neural tissue that is in part formed by cells in walls of the brains capillaries It makes it so not all substances in the blood can reach the brain which is necessary to keep certain toxins out There are different levels of passivity throughout the barrier Capillaries in body PNS have more open gaps s opposed to those in the brain CNS Communicaiton within neurons Action Potential nerve cells are specialized for communicating with electrochemical signals conduction Dendrites receive chemical message chemical messengers activate receptors on dendritic membrane and the receptors then activate the opening of ion channels which can alter membrane potential The result can be state of A P and is propagated down the membrane of the Axon and causes a release of neurotransmitters from the terminal buttons When the action potential reaches the terminal buttons the release of neurotransmitters may produce an effect on the membrane of adjacent cells connected by a synapse This effect can be inhibitory or excitatory Electrical changes in cell can be measured by taking different formes of charges or potential across the membrane Resting potential use giant squid axon in seawater in recording chamber to measure resting potential using glass microelectrode to be inserted into axon the voltage measures 70mV inside with respect to outside To maintain resting p the cell must work to maintain differences between inside and outside of cell in which the inside is more negative than the outside the wall neuronal membrane with a number of channels inbedded into it the players Ions Na K Cl proteins within the cell not ion are charged molecules cations are positive anions are negative Voltage dependent ion channels in the wall open or close depending on whether 70mV changes to maintain RMP resting membrane potential Na K pumps must be active Forces effecting change in charges Electrostatic pressure attractive and repulsive forces of charged particles Diffusion tries to even out the concentration of molecules inside and out of membrane relative ion concentration across the axon membrane is while resting is shown at rest K can leave cell causing the exterior of the cell membrane to be slightly higher in charge than the inside depolarizing makes the inside of the cell less negative which can generate an Action Potential Action Potential the stereotyped change in membrane potential if RMP moves past threshold membrane potential quickly moves to 40mV and then returns to resting The AP depends on ion movement across the membrane AP has an ionic basis as seen in picture above Na in upswing of spike both forces persuade and K out in response for downside of spike When membrane becomes depolarized and reached threshold voltage dependent ion channels open to allow ion movement and further changes of the membrane potetial down the axon 5 phases of AP 1 2 3 4 5 resting threshold rising Na channel opens and Na ions enter cell falling K channels open next so K can leave the cell producing hyperpolarization recovery