Block 1 Lecture 11 Flashcards
what happens in an electrical synapse
Conduct electricity between 2 cells, a change in voltage in one cell spreads to adjoining cell
what are some characteristics of electrical synpases
the gap is smaller than chemical synapse
very fast bidirectional movement
what are connexins
proteins that form gap junctions
what is the role of connexins in heart muscle
connexion 43 forms gap junctions that electrically couple neighboring cells to coordinate cardiac action potential
what happens in a chemical synapse
-presynaptic neuron secretes a chemical neurotransmitter into cleft between cells
-chemical selectivity activates receptors on postsynaptic cell surface
-receptor activation causes a change in the postsynaptic cell
(communication occurs in one direction)
what does the presynaptic cell do
makes and packages neurotransmitters, releases neurotransmitters
what does the postsynaptic cell do
makes and displays receptors, responds to neurotransmitter
what is the mechanism for a chemical synapse
- membrane potential depolarizes in presynaptic cell
- fusion of neurotransmitter containing vesicles into synaptic cleft
- Neurotransmitter binds to postsynaptic receptors
- change in open/close of ion channels in postsynaptic cell membrane
- change in membrane potential in post synaptic cell
- response may be inhibitory or excitatory
what would cause excitation
increasing Na+ channels
decreasing K+ channels
what does excitation cause
depolarization
what would cause inhibition
increasing K+ channel
what does inhibition cause
hyperpolarization
what type of receptors are channel receptors
ionotropic
what type of receptors are seven helix receptors
metabotropic
what is an ionotropic receptor
contains a neurotransmitter binding site and an ion channel
