Week 5 - Neurons Flashcards
What is an action potential?
A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.
What is an axon?
Part of the neuron that extends off the soma, splitting several times to connect with other neurons; main output of the neuron.
What is the cell membrane?
A bi-lipid layer of molecules that separates the cell from the surrounding extracellular fluid.
What is a dendrite?
Part of a neuron that extends away from the cell body and is the main input to the neuron.
What is diffusion?
The force on molecules to move from areas of high concentration to areas of low concentration.
What is electrostatic pressure?
The force on two ions with similar charge to repel each other; the force of two ions with opposite charge to attract one another.
What are excitatory postsynaptic potentials?
A depolarizing postsynaptic current that causes the membrane potential to become more positive and move towards the threshold of excitation.
What are inhibitory postsynaptic potentials?
A hyperpolarizing postsynaptic current that causes the membrane potential to become more negative and move away from the threshold of excitation.
What are ion channels?
Proteins that span the cell membrane, forming channels that specific ions can flow through between the intracellular and extracellular space.
What is an ionotropic receptor?
Ion channel that opens to allow ions to permeate the cell membrane under specific conditions, such as the presence of a neurotransmitter or a specific membrane potential.
What isa myelin sheath?
Substance around the axon of a neuron that serves as insulation to allow the action potential to conduct rapidly toward the terminal buttons.
What are neurotransmitters?
Chemical substances released by the presynaptic terminal button that acts on the postsynaptic cell.
What is the nucleus?
Collection of nerve cells found in the brain which typically serve a specific function.
What is the resting membrane potential?
The voltage inside the cell relative to the voltage outside the cell while the cell is a rest (~ -70mV).
What is the sodium-potassium pump?
An ion channel that uses the neuron’s energy (adenosine triphosphate, ATP) to pump three Na+ ions outside the cell in exchange for bringing two K+ ions inside the cell.
What is a soma?
Cell body of a neuron that contains the neucleus and genetic information, and directs protein synthesis.
What are spines?
Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.
What are synapses?
Junctions between the presynaptic terminal buttion of one neuron and the dendrite, axon, or soma of another postsynaptic neuron.
What is a synaptic gap?
Also known as the synaptic cleft; the small space between the presynaptic terminal button and the postsynaptic dendritic spine, axon, or soma.
What are synaptic vesicles?
Groups of neurotransmitters packaged together and located within the terminal button.
What is the terminal button?
The part of the end of the axon that form synapses with postsynaptic dendrite, axon, or soma.
What is the threshold of excitation?
Specific membrane potential that the neuron must reach to initiate an action potential.
What are the three main categories of neurons in the brain?
- Unipolar neurons
- Bipolar neurons
- Multipolar neurons
What are motor neurons?
Neurons that allow us to initiate movement and behaviour (allows us to interact with the world).
What are interneurons?
Neurons that that process the sensory input from our environment into meaningful representations, plan the appropriate behavioral response, and connect to the motor neurons to execute these behavioral plans.
