Chapter 2 Flashcards
components that make up the synapse
- threshold of excitation reached.
- ion channels open and AP initiated at axon hillock.
- signal moves down axon.
- signal reaches terminal buttons.
Sherrington’s 3 properties of reflexes
- ) reflexes are slower than conduction along an axon.
- ) several weak stimuli presented a slightly different times/locations produce a stronger reflex than a single stimulus does.
- ) when one set of muscles become excited, a different set becomes relaxed.
Synaptic Delay
- speed of conduction along an axon is 40 m/s.
- speed of conduction through a reflex arc is slower and more variable (15 m/s or less).
reflexes
automatic muscular responses to stimuli.
synapse
a specialized gap between neurons.
reflex arc
the circuit from sensory neuron to muscle response.
temporal summation
the combined effect of quickly repeated stimulation at a single synapse.
presynaptic neuron
neuron that delivers transmission.
postsynaptic neuron
neuron that receives transmission.
spatial summation
the combined effect of several nearly simultaneous stimulations at several synapses onto one neuron.
excitatory postsynaptic potential (EPSP)
graded depolarization that results from a flow of sodium ions into the neuron.
leg flexion reflex
a sensory neuron excites a second neuron, which in turn excites a motor neuron, which excites a muscle.
law of reciprocal innervation
explains how a muscle will relax when its opposite muscle is activated.
inhibitory postsynaptic potential (IPSP)
- temporary hyperpolarization
- opens the gates for K+ to leave the cell or for Cl- to enter the cell.
synaptic cleft
the space between the presynaptic and postsynaptic membrane.
synaptic vesicle
a small sphere found in the terminal buttons, contain molecules of a neurotransmitter.
release zone
interiour of the presynaptic membrane to which vesicles attach and release their neurotransmitter into the synaptic cleft.
postsynaptic density
portion of postsynaptic membrane where receptors are located for binding.
synapses can occur at 3 places
- ) axodendritic (on dendrites).
- ) axosomatic (on the soma).
- ) axoaxonic (on other axons, between two terminal buttons).
axoaxonic synapses do not contribute to __________, they control ______________ with presynpastic _________ and _________.
- neural integration
- amount of chemical released by axon terminals.
- inhibition and facilitation.
presynaptic inhibition
reduces the amount of neurotransmitter released by the postsynaptic terminal button.
presynaptic faciliation
increases the amount of neurotransmitter released by the postsynaptic terminal button.
steps for synaptic neural communication
- ) synthesis and release of neurotransmitter from presynaptic terminals.
- ) activation of postsynaptic receptors.
- ) postsynaptic potential (EPSP/IPSP).
- ) termination of postsynaptic potential.
Explain the synthesis and release of neurotransmitter
- synthesis in some/terminal buttons.
- Ca+ channels open.
- synaptic vesicle fuses with membrane.
- vesicles break open and release neurotransmitters into synaptic cleft.