Excitable Membranes and Action Potential Signaling

Flashcards for reviewing neuroscience lecture notes.

Benveniste Personal Mandatory Recitation

Scheduled weekly throughout the semester for quantitative analysis of Neuroscience Data through Simulations in CoLab Notebooks.

Objectives of Essentials in Neuroscience I and II

A major objective is to understand how we discover what is in the textbooks through experimentation and experimental design.

Essentials I focus

Basic building blocks of Electrical Signaling, Channels and their involvement in rapid electrical signaling in nerve cells, Short and long term changes in rapid signaling and Experiments on Memory.

Essentials II focus

Development in the Nervous System, Functional Circuitry in Different Parts of the Brain, and Emphasis and Practice on Quantitative Analysis with the aid of Python Programming.

Mechanics of the Action Potential

The balance between concentration gradients and charge gradients, Equilibrium Potentials and the Nernst Equation, Driving Force, Membrane Potential and how it is influenced by current flow, and Ohm’s Law.

Neuroscience Spans Atoms and Molecules

Atoms, molecules, ion movement, neurotransmitters and G-Proteins

Neuroscience Spans Cells

Neurons, Excitatory, Inhibitory and Specialized cells – Photoreceptors (rods and cones)

Neuroscience Spans Cell assemblies

Feedback Inhibition and Feed-forward Inhibition

Neuroscience Spans Systems

Visual System, Spinal Cord and Hippocampus

Neuroscience Spans Organisms

Assessing Long Term Memory, Morris Water Maze, Contextual Fear Paradigm, Learning, Habituation, Sensitization, Classical Conditioning, Goal Seeking, Addiction and Tolerance and Stress, anxiety and depression

Neuroscience Spans Groups/societies

Spans sociology and philosophy

Mechanism Needed for Nervous System

Signals can travel long distances in milliseconds

Signaling Needs to be Specialized

Sensory, Motor and None of the above (for processing in the brain)

Signaling Needs to be Directional

Receive inputs from our senses that are collated in our brains

Central Nervous System (CNS)

Brain and Spinal Cord

Peripheral Nervous System (PNS)

Sensory and Motor Nerves

Autonomic Nervous System

Control of Respiration, Circulation, Digestion and Thermoregulation

Sympathetic Systems

Mobilize the body for activity – “Fight or Flight”

Parasympathetic Systems

Energy Conservation – “Rest and Digest”

Directionality of the Nervous System Components

Dendrites mainly used for signal collection from other cells and Axons are used to transmit signals to other cells.

Glia

Mainly support cells, but can influence signaling

Cell soma (body)

Integrates signals coming from dendrites

Dendrites

Collects input signals at synapses usually located on dendritic spines

Synapse

Specialized junction for communication of signal from one neuron to another

Axon

Sends output signal once integrated information in the soma reaches a certain triggering threshold

What makes a membrane excitable?

There must be a source of potential energy such as creation of electro-chemical gradients

How do We Make and Maintain Unequal Ion Concentrations

Active Transport of the Sodium Potassium ATPase

Current

The movement of ions (more on this later).

Directionality of the nervous system

The components of the cells also have directional signaling.

Depolarization

Membrane potential becomes more positive.

Hyperpolarization

Membrane potential becomes more negative.

Current in Biology

Defined as the flow of positive charge.

Inward current

Flow of positive charge into a cell and is negative in amplitude on graphs.

Outward current

Flow of positive charge out of a cell and is positive in amplitude on graphs.

Equilibrium Potential

Equilibrium Potential, Es, is defined solely on the concentration of a particular ion on either side of the membrane regardless of whether channels are open or closed.

Reversal Potential

Reversal Potential, Vrev, is an operational definition for the membrane potential at which the current reverses for a particular channel type.