The Neuron Flashcards
Afferent (sensory) neurons
inward: sends messages from organs and sensory receptors to brain and spinal cord
Efferent (motor) neurons
Outward: carries instructions from CNS (brain and spinal cord) to muscles, glands of body
Interneurons
Neurons between the ones of the brain and spinal cord that communicate and pass information between sensory input and motor output
Dendrites
receivers of signals from other neurons (conducts info towards cell body)
Cell body
receives incoming signals from dendrites and passes them on
Nucleus
carries out metabolic (life-sustaining) function, contains genetic material
Axon
passes out messages away from cell body, down the tail, to other neurons/muscles/glands
Myelin Sheath
white fatty coating (bubbles covering axon.) Purpose is to speed up neural impulses (signals)
Nodes of ranvier
gaps in between myelin sheath that also speeds up neural impulse
Synapse
junction between transmitting neurons and receiving neurons, releasing chemical signals
Axon terminals
Terminal branches of axon through which axons make synaptic contact with other nerve cells.
Synaptic cleft
The fluid-filled gaps between the transmitting neuron (axon) and receiving neuron (dendrite). Area that the synaptic vesicles (neurotransmitters) will cross to penetrate the dendrite through receptor sites.
Synaptic vesicles
Little circles stored in axon that house neurotransmitters. These will be released when electricity changes the permeability of the membrane and the vesicles fuse to the membrane so that they can cross the synaptic gap.
How do neurons communicate?
Comm. STARTS with electricity (impulse/action potential)
What changes the permeability of a cell membrane?
Electricity
Neurotransmitters
in synaptic vesicles until they are stimulated by action potential. They are a messenger of chemical substance between neurons.
Receptor sites
located on the receiving neuron. Neurotransmitters are lite a key that fits perfectly into these.
Glial cells (glial sounds like glue)
hold neurons together, smaller than them, half of brain volume, removes waste (dead neurons)
4 steps of communication
- At rest= negative (resting potential) 2. Stimulated = positive (action potential / electricity) 3. Fires positive ions 4. back at rest (-) once the electricity (+) has exited *neurons fire all or nothing at all.
Weak vs strong stimuli
weak= fewer neurons firing more slowly. strong= more neurons firing quickly
What happens after neurotransmitters enter the receptor
- one of two things happen: excitatory reaction (neurons fire) or inhibitory reaction (neurons do not fire). 2. The cell body creates more neurotransmitters. 3. The unused ones can be broken down & taken back in axon terminals, or reuptake.
Reuptake
unused neurotransmitters are taken back into axon terminals AS IS to be used IMMEDIATELY.
