Neuroscience & Cells
What is neuroscience?
The study of how the brain and nervous system affect mental processes and behavior.
What chemical messengers do neurons release?
Neurotransmitters.
Which two ions play important roles in neural signaling?
Sodium (Na⁺) and potassium (K⁺).
What happens when neurotransmitters cross the synapse?
They bind to receptor sites on the postsynaptic neuron.
What is reuptake?
The process through which neurotransmitters are recycled back into the presynaptic neuron.
What are neurons?
Cells in the nervous system that transmit information.
What is a synapse?
The connection formed when the axon bulb of one neuron comes close to the dendrite of another neuron.
What is resting potential, and what is its approximate value in mammals?
The electrical potential difference in a resting neuron, approximately −70 mV.
What is excitation?
When a neurotransmitter makes the inside of the postsynaptic cell more positive, making an action potential more likely.
What happens to neurotransmitters after they bind to receptor sites?
They are removed from the synapse; some are taken back up through reuptake.
What are glia cells?
Cells that provide important support functions for neurons and are involved in forming myelin.
What is the synaptic gap?
The measurable space between the presynaptic and postsynaptic neurons.
What is the threshold of excitation?
The membrane potential level at which a neuron generates an action potential, typically around −55 mV according to standard neuroscience. The slide appears to have omitted the minus sign.
What is inhibition?
When a neurotransmitter makes the inside of the postsynaptic cell more negative, making an action potential less likely.
How else can neurotransmitters be removed from the synapse?
Some are broken down by enzymes after they detach from receptor sites.
What is myelin?
A fatty, waxy substance that insulates portions of some neurons in the nervous system.
What is the presynaptic neuron?
The neuron sending the signal across the synapse.
What is an action potential?
An electrical signal generated by a neuron when its membrane potential reaches threshold.
Can a neuron receive excitatory and inhibitory signals simultaneously?
Yes. A neuron can receive both types of signals from many presynaptic neurons at the same time.
Why is inhibition necessary in the brain?
It regulates neural activity and balances excitation, helping prevent excessive neural firing.
What is the role of myelin in a neuron?
It insulates portions of the neuron. The slides identify insulation as its function.
What is the postsynaptic neuron?
The neuron receiving the signal across the synapse.
What are the all-or-none law and refractory period?
The all-or-none law means an action potential fires fully or not at all. The refractory period is a brief period as the axon returns to resting potential.
How does a neuron decide whether to fire an action potential?
It sums its excitatory and inhibitory inputs. If their combined effect brings the membrane potential to threshold, an action potential fires.
What might happen if the brain had only excitation, and how do the two types of input work together?
Without inhibition, neural activity could become excessive and poorly regulated. Excitatory and inhibitory inputs are summed together to determine whether the neuron reaches threshold and fires.