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47 Cards in this Set

  • Front
  • Back
Bipolar Neurons
1 dendrite
Multipolar Neurons
Multiple dendrites
What is the direction of a neuron receiving an action potential?
Dendrites receive signals and axons carry action potentials away from the body.
What is the difference between a neuron and a nerve
Neuron: single cell

Nerve: A bundle of many different axons from different neurons
Order of neuron composition
Dendrites
Soma
Nucleus
Axon Hillock
Axon / Nodes of Ranvier
Myelin Sheath
Synaptic knobs
Resting membrane potential
-70mV
Interior of cell negatively charged due to loss of ions through both Na+/K+ channels and potassium leakage channels.
Two membrane proteins required to establish the resting membrane potential
Na+/K+ ATPase
Potassium Leakage channels
Na+/K+ ATPase
Pumps out 3 Na+
Pumps in 2 K+

By hydrolysis of 1 ATP, Primary active transport.
Result of Na+/K+ ATPase
Sodium gradient with high sodium outside the cell and a potassium gradient with high potassium inside the cell.
Leakage channels
Open 24/7
Mostly Potassium, very few sodium leakage channels.
Cell membrane is virtually impermeable to Sodium.
How are neuron and muscle cells different in regards to the way they use resting membrane potentials?
Neurons use resting membrane potentials to generate action potentials along the axon interiors, making the neuron polarized (negative on the outside and positive on the inside)
A wave of depolarization disturbing the plasma membrane potential along the axon is termed
Action potential
If the potassium leakage channels were blocked, what would happen to the membrane potential?
Reduce the membrane potential to generate action potentials
What would happen to the membrane potential is sodium ions were allowed to flow down their concentration gradient?
Sodium ions would flow into the cell and reduce the potential across the plasma membrane, making the interior less negative and even relatively positive if enough ions flow into the cell.
An electrochemical impulse is a way to describe
The neuronal action potential
What would cause the interior of a neuron to have a momentary positive charge?
Opening of the voltage-gated sodium channels
Opening of which channel allows repolarization of the neuron?
voltage-gated K+ channels open as voltage-gated Na+ channels inactivate at peak of depolarization
Myelin sheath + axon =
Schwann Cell
Nodes of ranvier are necessary for saltatory conduction because they allow for
depolarization between myelin
Where in the axon is there no membrane depolarization, no voltage-gated sodium channels?
Schwann Cells.
Function of the Myelin Sheath
Speeds up conduction of action potentials by forcing the action potential to "jump" from node to node.
The amount of energy consumed by the Na+/K+ ATPase is much less in myelinated axons? true or false
True dat
What is the equilibrium concentration gradient for Na+
+50mV
No net movement of ions
What is the equilibrium concentration gradient for K+
-90mV
Total resting potential of -70mV is a reflection of:
The differences in equilibrium concentrations for Na+ and K+ , and tje relative numbers of leakage channels for these two ions (more for K)
Difference between the Absolute and Relative Refractory Periods?
Absolute Refractory Period: A neuron will not fire another action potential no matter how strong a membrane depolarization is induced.

Relative Refractory Period: Neuron can be induced to transmit an action potential, but the depolarization required is greater than normal because the membrane is hyperpolarized.
The junction between the axon terminus of a neuron and either the dendrites, soma, or the axon of a second neuron is called?
Synapse baby
Is the junction between the axon terminus of a neuron and an organ called a synapse or what?
Oh yes it is
Two types of Synapses
Electrical
Chemical
When the cytoplasms of two cells are joined by gap junctions
Electrical Synapse
When the action potential between two cells spread from one cell directly to the other
Electrical Synapse
Which synapse type is common to find in propagation of action potentials in smooth muscle and heart cells?
Electrical Synapse
Type of Synapse: Found at the ends of axons where they meet their target cell, then the action potential is converted to a chemical signal
Chemical synapse
Skeletal cells use which synapse
Chemical
What does depolarization of presynaptic cells open?
Voltage-gated calcium channels
What causes the exocytosis of neurotransmitters stored in secretory vesicles in the presynaptic cleft?
Influx of Ca2+
Where are Ligand-gated ion channels located in the neuron?
They are the receptors on the postsynaptic membrane
How is the signal terminated in the postsynaptic neuron?
The neurotransmitter is degraded and/or removed to terminate the signal
What is the neurotransmitter at the neuromuscular junction?
Corresponding degrading enzyme?
Acetylcholine (ACh)

Degrading enzyme to terminate signal: Acetylcholinesterase (AChE)
GABA, Seratonin, Dopamine, Norepinephrine are all?
Neurotransmitters
A neurotransmitter that is termed "excitatory" does what to the postsynaptic membrane?
Depolarizes it
A neurotransmitter that is termed "inhibitory" does what to the postsynaptic membrane?
Hyperpolarizes it (or makes it more negative)
The neurotransmitters are determined excitatory/inhibitory only based on:
How the receptors on the postsynaptic membrane react to them
Removing a degradative enzyme that terminates the action potential does what?
Lets the depolarization act longer than it should with each action potential
ESPs
Excitatory Postsynaptic Potentials

Caused by excitatory neurotransmitters causing postsynaptic depolarization.
IPSPs
Inhibitory postsynaptic potentials
How can a presynaptic neuron increase the intensity of a signal it transmits?
Increase the frequency of the action potential