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3 main components of synapse are presynaptic ____, postsynaptic ___, and the ____ which is where the 2 meet
neuron, cell, synapic cleft
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Chemical msngrs of neurons
neurotransmitters
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5 steps of transmitting signal across a synapse
- 1. Action potential comes down axon
- 2. Action potential opens voltage-gated Ca+ channels
- 3. Ca+ enters presynaptic cell & triggers exocytosis of NT
- 4. NT diffused across synapse & binds to receptor on postsynaptic cell
- 5. Response in cell
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What causes synapic delay?
Time it takes for Ca+ to come into neuron & for NT to be released (NOT time that diffusion of NT across synaptic cleft takes, which is instantaneous)
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3 types chemical receptors at synapses
- Channel-linked receptors
- G protein-linked receptors (couple to either ion chanel or 2nd msgr system)
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Change in mem potential of the postynaptic cell in rsponse to receptor-NT binding, can be inhibitory or excitatory
Postynaptic Potential (PSP)
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Excitatory postsynaptic potential (EPSP) causes ____ (increase or decrease) in amt of pos chrgs in cell due to ___ ions ____ the cell, ie it causes _____
increase; lots Na+ entering; depolarization
(membrane potential is less negative)
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Inhibitory postsynaptic potential (IPSP) causes ____ ions to ____ cell , which causes ____ (increase or decrease) in amt of pos chrgs in cell; ie it causes ____
K+ or Cl-; leave; decrease; hyperpolarization
(cell gets more negative)
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Chlorine has a higher concentration ___ of cell when it's not at equilibrium, and if a NT opens Cl- channel, causing _____, the inside of the cell becomes more ____ as Cl- travels ___ cell
outside of cell, hyperpolarization, neg, into
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Potassium channel is closed by a
neurotransmitter, so closing that channel
causes positive charges to stay in the cell, which causes a less negative membrane potential, which means it is ____
excitatory
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When Cl- is at equilibrium a NT opening a Cl- channel doesn't change mem potential b/c Cl- will stabilize the membrane potential by going out or in based on the mvmt of the other ion in or out (counteracts it)
Membrane potential stabilization
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One axon branches out ot many
Divergence
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Multiple axons acting on one neuron
Convergence
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The summing of input from various synapses at the axon hillock of the postsynaptic neuron to determine whether the neuron will generate action potentials
Neural integration
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Temporal summation vs spatial summation
- temporal: take info from one synapse through time (ie back to back) to reach threshold
- spatial: info taken from multiple synapses at the same time to reach threshold
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When modulating neuron stimulates or inhibits activity (amt of NT released) of presynaptic neuron which causes effect on postsynaptic neuron or not
+ 2 types
- Presynaptic modulation
- Presynaptic facilitation
- Presynaptic inhibition
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Diff b/w axoaxonic, axodendritic, axosomatic synapses as far as what they affect
- Axoaxonic: Excite or inhibit a synapse
- Axodendritic & axosomatic: Excite or inhibit postynaptic neuron
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Most NTs are synthesized in cytosol of ___ ___, packaged into ___ ___, and then ___
axon terminal, secretory vesicles, excreted by exocytosis
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Most abundant NT in PNS but is also everywhere else
acetylcholine
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Synapse which utilizes acetylcholine
Cholinergic synapse
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Types of cholinergic receptors
- Nicotinic: channel-linked (only can open); skeletal muscle
- Muscarinic: G-protein linked
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3 types of biogenic amines which are derived from AAs
- Catecholamines: dopamine, norepinephrine, epinephrine
- Serotonin
- Histamine
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Receptors which are for epinephrine & norepinephrine only
Adrenergic receptors
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Type of adrenergic receptors which prefer norepinephrine to bind
Alpha 1, Alpha 2, Beta 1
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Type of adrenergic receptors which prefer epinephrine to bind
Beta 2
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