Transduction and synapses Flashcards
what triggers action potentials?
depolarisation to threshold
what triggers graded potentials?
stimulus, neurotransmitter
does the size of action potentials change with the size of the stimulus?
no
does the size of graded potentials change with the size of the stimulus?
yes
where are action potentials located?
voltage gated channels
where are graded potentials located?
receptors and post-synapse
what is transduction at nerve endings?
conversion of stimulus energy to electrical energy through ion channels
what is a pacinian corpuscle?
mechanoreceptor at nerve endings
how does a pacinian corpuscle convert mechanical stimulus into electrical energy
stimulus distorts distorts the ion channels in the nerve ending causing depolarisation
what is a synapse?
relay station between nerves (pre- and post- synaptic nerves)
synapses are said to have plasticity, what does this mean?
means they can change for example if a nerve is damaged, then there can be “rewiring”
name this nerve
pre-synaptic nerve
name this structure
synaptic vesicles
name this channel
chemically gated protein channel
name this nerve
post-synaptic nerve
name this space
synaptic cleft
name this channel
Ca2+ channel
what happens when an action potential arrives at a synapse from a pre-synaptic nerve
Depolarisation causes Ca2+ channels to open, Ca2+ enters pre-synaptic nerve ending
Vesicles fuse with membrane and release neurotransmitter into synaptic cleft
Neurotransmitter diffuses across synaptic cleft and binds to channels on post-synaptic nerve
what is temporal summation?
an action potential arrives shortly after another one, their graded potentials are added together to generate an AP in post-synaptic nerve. If acting alone they wouldn’t reach threshold.
what is spatial summation?
multiple pre-synaptic nerves synapse at one post-synaptic nerve, two graded potentials added together to generate an AP. If acting alone wouldn’t reach threshold.
what is post-synaptic inhibition?
Inhibitory neurotransmitters cause inhibitory post-synaptic potentials through hyperpolarisation
name an example of an inhibitory neurotransmitter and how it works
GABA - opens K+ and Cl- channels to hyperpolarise post-synaptic membrane
what is pre-synaptic inhibition
Inhibitory nerve synapses with excitatory nerve before it synapses with post-synaptic nerve -> axo-axonal synapse
Results in decreased neurotransmitter released from excitatory presynaptic neurone
