Neurons Flashcards
(22 cards)
What do neurons perform inside the brain?
Neurons perform computations inside the brain that we call thought.
What do dendrites do?
Dendrites receive nerve impulses from other neurons.
What is the function of axons?
Axons transmit nerve impulses and carry the action potential.
What does the cell body contain?
The cell body contains the nucleus, and is responsable for the maintenance and metabolism of the cell. It can also receive information and
What is the myelin sheath composed of, and what is the difference between a mylenated and unmyelinated axon?
The myelin sheath is part protein, part fat. If an axon is myelinated, it shows up as white matter; unmyelinated axons are grey matter. Myelinated axons makes the nerve impulse travel much faster.
What do axon terminals do?
Axon terminals secrete neurotransmitters into the synapse.
Where do motor neurons begin and what are they responsible for?
Motor neurons begin in the central nervous system, exit through the spinal cord, and end on muscle fibre. They are responsible for movement
Where do sensory neurons begin and what do they convey?
Sensory neurons begin at sense organs (e.g., retina, skin, tongue) and convey information to the brain via the spinal cord.
What is the role of interneurons?
Interneurons are interposed between other neurons and do much of the computation in the brain that we call thought.
What is the function of Glial cells?
Glial cells make up 90% of the brain, act as guidewires for growing neurons. Later in development, they provide scaffolding for mature neurons, and assist in repair processes when the neuron is damaged.
What is the resting potential of a neuron?
In the resting state, the inside of an axon is negative with respect to the surface by about -70 millivolts.
What happens when the excitatory threshold is reached?
An action potential occurs when a pulse exceeds the excitatory threshold (about -55 millivolts). This causes the inside of the neuron to swing positive relative to the outside.
How does an action potential travel down the axon?
The action potential travels down the axon like a Mexican wave until it reaches the terminal buttons.
What is the role of sodium ions (Na+) in resting potential?
Resting potential depends on positive sodium ions (Na+) on the outside of the cell membrane.
What occurs when a pulse is applied to a neuron?
In-going channels open, Na+ ions pour into the cell, reversing the voltage difference.
What is the synapse?
The synapse is the small gap between neurons where one neuron meets another.
What makes the action potenital fire in the next neuron, and what are the technical terms for firing/ not firing?
The transmission is governed by the release of neurotransmitters, and if the neuron doesn’t fire, this is called inhibition, whereas the neuron firing is called exicitation.
What is the lock and key model in relation to neurotransmitters?
Neurotransmitter molecules will only affect the postsynaptic membrane if the molecule’s shape fits into certain synaptic receptors.
What happens to neurotransmitters in the synapse?
Neurotransmitters are inactivated by ‘clean-up’ enzymes or are reused in synaptic reuptake.
What are the 3 ways drugs can affect the synapse?
Drugs can stimulate or inhibit neurotransmitter release on the presynaptic membrane, stimulate or block postsynaptic receptor molecules on the postsynaptic membrane, or inhibit neurotransmitter reuptake
What are the roles of a sodium pump and ion channels?
Sodium pumps keep Na+ out, and ion channels let charged ions out and in
Where do neurotransmitters do from one neuron to the other?
The presynaptic neuron sends the neurotransmitters to the postsynaptic neurons dendrites.
