Final Exam Flashcards
What are the parts of the neuron?
dendrites: receives signals from other cells
Axons: transfers signals to other cells and organs
Cell Body: organizes and keeps the cell functional
What are parts of the synapse?
- presynaptic membrane/ neuron: neuron that sends the message
- postsynaptic membrane/neuron: neuron that receives the message. it is enriched in NT receptors and signaling and scaffold molecules.
- synaptic cleft: A gap that separates the presynaptic terminal of a neuron from its postsynaptic target cell.
- synaptic vesicles: localized at the presynaptic terminal; it’s filled with neurotransmitters and upon stimulation fuses with the plasma membrane to release NT into the synaptic cleft
- receptor sites:
What is a membrane action potential?
an elementary unit of nerve impulses that axons use to convey information across long distances. Also called a spike.
What are refractory periods? what is going on with the ions during those?
- a time window after an action potential during which another action potential cannot be initiated.
- delayed activation of K+ channels and the inactivation of Na+ channels
What is myelin?
allows electrical impulses to transmit quickly and efficiently along the nerve cells.
What is Ach receptors?
Receptor for Ach
G proteins vs. ionotropic receptors?
- While ionotropic receptors are typically ligand-gated ion channels, through which ions pass in response to a neurotransmitter, metabotropic receptors require G proteins and second messengers to indirectly modulate ionic activity in neurons.
What are the different types of gradients? What do they do?
- chemical gradient: a concentration difference of a solute over 2 sides of a membrane, which contributes to the direction and magnitude of solute movement across the membrane. If the solute is not charged, the gradient alone determines the movement direction: from higher to lower concentration.
- electrical gradient: Electrical potential difference between 2 sides of a membrane; it promotes movement of a charged solute toward the side with the opposite charge.
- electrochemical gradient: a combination of chemical and electrical gradients; it determines the direction and magnitude of movement of a charged solute across a membrane.
What are some toxins we talked about?
- tetrodotoxin (TTX): blocks voltage-gated Na+ channels of many animal species. It is used to silence neuronal firing.
- tetraethylammonium (TEA): blocks voltage-gated K+ channels.
They were used for the existence of ion channels selectively permeable to specific ions.
What are the necessary steps for using a transmitter? How do you define a neurotransmitter? How do you explore its function?
- Action potential from the axon –> depolarization of the presynaptic terminal —> opening of voltage-gated Ca2+ channels —> Ca2+ entry into the presynaptic terminal –> fusion of synaptic vesicles with presynaptic plasma membrane –> NT release
- Molecules stored in synaptic vesicles in presynaptic terminals, released into the synaptic cleft and activate ionotropic and metabotropic receptors on postsynaptic target cells.
- carry messages from one neuron to another - through ‘carrying messages’.
Ionotropic receptors (ligand-gated channels) and metabotropic receptors (also called G-protein coupled receptors)
How does the synapse work?
At the synapse, the firing of an action potential in one neuron—the presynaptic, or sending, neuron—causes the transmission of a signal to another neuron—the postsynaptic, or receiving, neuron—making the postsynaptic neuron either more or less likely to fire its own action potential.
What is the neurotransmitter cycle from start to finish? How are they stored? How are they released? How are they dealt with after that?
- They are stored in synaptic vesicles.
- They are released when the synaptic vesicles fuse with the presynaptic membrane.
- Different ways to get NT out of the cleft: (1) Enzymatic destruction (ex. Achtylcholine) (2) Reuptake (ex. Serotonin) (3) Diffuse away (4) Glial cells
What are the AMPA and NMDA receptors important for? What is necessary for them? How do they operate?
- AMPA is mostly involved in Na+ coming but sometimes other positive ions move through. When glutamate binds to the AMPA receptor, Na+ will go into the cell and cause it to depolarize.
-NMDA receptor: normally has a Mg2+ block on it. At rest, the NMDA receptor might bind to glutamate but if that cell isn’t depolarized enough, the Mg2+ will still be stuck there. It needs to bind glutamate and glycine while the cell is depolarized, the receptor will open.
What are the 2 types of synaptic integration? (how to question)
- Spatial (in dendrites): the summation of postsynaptic potentials produced by synchronous activation of synapses located at different spatial locations on the postsynaptic neuron. (different locations at the same time).
- Temporal (in dendrites): The summation of postsynaptic potentials produced by activation of synapses within a finite time window. (closely timed inputs at same location).
What are the presynaptic influences/modulations? what happens in a presynaptic input that increases or decreases the likelihood of a synapse being active?
-This potential is influenced by the excitatory presynaptic potential (EPSP) and the inhibitory presynaptic potential (IPSP).
- At several excitatory and inhibitory synapses, neuronal activity can trigger enduring increases or decreases in neurotransmitter release, thereby producing long-term potentiation (LTP) or long-term depression (LTD) of synaptic strength, respectively.
sensory potential vs. action potential vs. resting potential?
- Membrane potentials that can change in continuous values, as opposed to the all-or-none property of action potentials
- Action potential: unit of nerve impulses that axons use to convey information across long distances.
- Resting potential: The membrane potential of a neuron at rest which is typically between -50 to -80 mV relative to the extracellular fluid.
