Electrical properties of neurons

Posynaptic Potentials

• Chemical inut from other cells causes electrical charge

  • If big enough, AP is generted and conducted

Action Potential

• Electrical signal, all or none

Resting potentail

• Negative electrical charge

• -50 to -80mv

  • Due to ions on either side of cellular membrane

Na+, Cl-, Ca2+

• Too many outside of cell

• Inside cell, few

K+ and Proteins

Few outside

• alot of inside

Ion channels

• Proteins that span the membrane and allow ions to pass through from one side to another

Diffusion

• Concentrates > Less concentrated

Electrostatic

• Magnet, opposites attract, similar push away

Sodium/Potassium Pump

• 2 K+ ions for every 3 Na+, and one molecules of ATP

  • Constantly active

Hyperpolarization

• Neurons become negative

Depolarization

• Become more positie

Ionotropic Receptors

• Ions channel that oppen when NT bind to them

• IN postsynaptic membrane

  • Turn chemical to electrica

Nicotinic Acetylcholine Receptor

An Examle of Ionotropic receptor

Excitatory postsynaptic potential (EPSP)

• ionotropic Receptors

• Allow positvely charged ions into neuron

  • Causes breid local depolirization

Inhibitory Postsynaptic potential ISP

• Ionotropic Receptor

  • Allows negatively charged ions \

    • Causes brief local hyperpolarization.

Spatial Summation

• Close PSPs occur in space the more likely

Temporal summation

• Psps occur in time, more lileky the sum together

Voltage Gated sodium channels

• Opens to allow Na+ ions tinto the axon

• Initial rapid depolarization or rising phase of the action

Voltage gated potassium channels

• Open due to a depolarization (rising phase)

• Causes hyperpolarization( falling phase)

  • K+

Refractory Period

• Voltage gated sodiu, channels will not open again

Nodes of Ravier

• Generate action potential

  • Gaps in myelin

Saltatory conduction

• AP jumps from node to node

Myelin Damage

• Unable to provide insulation

• Na+ becomes less efeccient

  • SLowing AP or even eliminating it

Drug with caine

• Acts as local anesthetic

Tetrdotoxin

• Same as caine drugs but too toxic

Voltage Gated Calcium Channels

• Opens in axon terminal that allow Ca2+ in response to depolarization caused by AP

• Calcium detected and vesicle ruptures and ejects NT