Powerpoints 4 & 5 Flashcards
What are the classes of proteins found at post-synaptic sites?
Scaffolding proteins, signal transduction proteins, receptors
What are the classes of proteins found at pre-synaptic sites?
-Proteins that help vesicles release neurotransmitter (release machinery)
-Vesicles are not proteins (they are sacs of membrane) but they have proteins sticking out of them
-Proteins that pump neurotransmitter or parts of neurotransmitter back into cells
-Calcium channels (you need calcium to release neurotransmitter)
Nerve cells generate different types of electrical signals due to?
1) Differences in concentrations of specific ions (Anions/Cations) across the nerve cell membrane
2) Membranes are selectively permeable to different ions
What is Ohm’s Law?
Relationship between current, voltage, and conductance
What is potential (V)?
Electrical potential (potential per unit charge); The work needed to force charge between two points. Measured in Volts
What is current (I)?
net flow of charge (ions); charge per unit time; measured in Amps.
What is resistance (R)?
degree to which a material opposes current (Ohms); how much charge flow is impeded
What is conductance (g)?
degree to which material allows current; ease of flow of current (Siemans)
Same thing, different views!
Ohm’s Law equation
V=IR
Increasing the voltage results in
Increased current
Decreasing resistance (or increasing conductance) does what to the current?
Increases
Extracellular recordings are:
Recording from the extracellular environment near a cell of interest
Intracellular recordings are:
Recording from inside a cell of interest, piercing the membrane with an electrode
What are patch clamp recordings?
Recording from the membrane of a cell of interest
What tools are used to measure electrical signaling in neurons?
-Intracellular microelectrode (actually poke the cell and measure the inside; listen in to the chatter)
-Glass tubing with a very fine opening (1 um diameter) filled with a conductor (salt) and there is a wire (conductive core)
-Conductive core connected to a voltmeter (ei. Oscilloscope)
-Reference electrode
-Record transmembrane voltage
Resting membrane potential has a reading of ?
-40 to -90 mV
Membrane potential goes positive?
-DEPOLARIZED
If Membrane potential goes negative?
-HYPERPOLARIZTION
What are receptor potentials?
(due to activation of sensory neurons for example by external stimuli): transient changes are the first step in generating sensations
What are synaptic potentials?
(between two neurons) EPSPs and IPSPs
What are action potentials?
travel along long axons; boost signals; long range transmission
How do neurons overcome not being good “electrical wires?” (Not good conductor, too long, leaky (lots of channels))
Booster system, Electrical signals produced by this system are ACTION POTENTIALS
The Action Potential is a change from ____ to ____
negative, positive
How long does an action potential take?
Brief approx. 1 ms
True or False? Amplitude of the AP is independent of the magnitude used to evoke it
True
True or False? Bigger stimulation leads to bigger action potentials
False
True or False? Action Potentials are all- or none
True
True or False? With bigger stimulation, you can get multiple APs (increase frequency) but they will be different amplitudes
False, With bigger stimulation, you can get multiple APs (increase frequency) but they will be the same amplitude
Passive conduction ____ over distance
decays
Active conduction is ___ over distance
constant
How does Stimulus increase affect different types of electrical signals?
Stimulus Increase
-APs increase in frequency, NOT in amplitude
However….
-Receptor potentials, graded in proportion to the magnitude of the sensory stimulus
-Synaptic potentials, amplitudes vary according to number of synapses activated EPSPs and IPSPs
EPSP does what to the neuron ?
Depolarizes neuron
IPSP does what to neuron ?
hyperpolarizes neuron
Signals from other neurons?
produced by NT release at synapse
Active transport and passive ion channels are responsible for what
ionic movements across membranes
Active transporters do what
Actively move selected ions against concentration gradient, create ion concentration gradients
What do ion channels allow?
Allow ions to diffuse down concentration gradient (OSMOSIS), selectively permeable to certain ions
What is the movement of an ion
Electricity, movement of charge
Neural function involves which 4 ions, all electrical events are based on movement of these ions in/out of the neuron
K, Na, Ca, Cl
Ion channels are classified based on what
Ion selectivity, switch
What are Voltage-gated channels important for?
important for action potential
What are Ligand-gated channels important for ?
important for EPSPs
What are stretch/pressure-gated channels important for ?
sensory neurons
What are leak channels important for?
important for resting membrane potential
True or False? Ion channels and transporters work against each other
True
Transporters actively maintain _____ inside and _____ positive outside against concentration gradient
Negative, positive
Ion channels allow osmosis to occur ______ concentration gradient
down
Functional antagonism between ion channels and transporters help to generate
-Resting membrane potentials
-Synaptic potentials/receptor potentials
-Action potentials
