Voltage clamp is an experiment that looks at the change in voltage of a membrane due thousands of channels opening and closing. Macro analysis. 

Patch clamp allows researchers to isolate a single channel and analyze its function. 

Cell attached recording- Normal patch clamp in which one channel is isolated while in tact to the whole cell so ion movement can be studies in terms of one channel.

Whole cell recordings- These are when the patch clamp is attached then suction breaks the membrane at the pipette to make the cytoplasm continuous with the pipette. Allows for recordings of whole cell potentials. 

Inside out recording- Allows you to change the medium to which the interior of the cell membrane is exposed. 

Outside out recording- ideal for studying the effect of signalling on a channel. 

Patch clamping allowed researchers to prove that hodgekin and Huxely were correct in their description of an action potential. 

Na is immediately allowed into the cell following depolarization followed by the slower opening of potassium channels that allow flow outward to re-establish the resting membrane potential. 

What is tetrodotoxin?

What is saxitoxin?

What do scorpions use to paralyze their prey with?

Most well known channel toxin. Produced by puffer fish and select other animals. Obstructs the Na channels responsible for action potentials. 

Saxitoxin is a chemical homologue to tetrodotoxin that is produced by dinoflagellates. 

They use a mix of peptide toxins that affect ion channels. Of which includes alpha toxins that slow inactivation of Na channels. This prolongs action potentials and confuses the senses of the prey. 

What to beta toxins do?

What does batrachotoxin do?

What toxins block potassim channels?

Beta toxins allow the sodium channels to open at a lower potential. 

This chemical both lowers the threshold and prolongs the open period of sodium channels. 

Dendrotoxin, apamin, and charybdotoxin block channels. 

What advantages do oocytes have in experimentation?

The gene product needs to be expressed efficiently. 

You need to be able to study the channel with methods such as patch clamping. 

should be readily available, have few endogenous channels and be large enough to inject DNA and mRNA with ease. 

Active transporters

ATPase pumps

Transmembrane proteins that actively move ions into or out of cells against their concentration gradients. Their source of energy may be ATP or the electrochemical gradients of various ions. 

membrane pumps that use the hydrolysis of ATP to translocate ions against their electrochemical gradients. 

CACNA genes

co-transporters

electrogenic

These genes code for voltage dependent calcium channels. 

active transporters that use the energy from ionic gradients to carry multiple ions across the membrane in the same direction. 

capable of generating an electrical current; usually applied to membrane transporters that create electrical currents while translocating ions. 

ion exhangers

Ion selectivity

membrane transporters that exchange intracellular and extracellular ions against their concentration gradient by using the electrochemical gradient of other ions as an energy source.

Ion channels are primarily selective in that they will only allow one type of ion to pass through the channel.  

ligand-gated ion channels

macroscopic currents vs microscopic currents

ion channels that respond to chemical signals rather than changes in membrane potential generated by ionic gradients. The term covers a large group of neurotransmitter receptors that combine receptor and ion channel functions into a single molecule. 

Currents resulting from the influx of ions through a mass number of channels. ~thousands.

Currents resulting fromt he influx through a single channel.  

pore

pore loop

SCN genes. 

structural feature of an ion channel that allows ions to diffuse through the channel.

an extracellular domain of amino acids, found in certain ion channels, that lines the channel pore and allows only certain ions to pass.

 Code for sodium channels. 

selectivity filter

voltage sensor

voltage-gated

voltage-gated ion channels. 

part of a membrane protein that senses the membrane potential

a membrane protein that is activated in response to the change in membrane potential. 

Ion channels that are activated by the change in membrane potential. 

Why did Hodgkin and Huxley surmise that neuronal membranes must have ion channels?

What properties did they think ion channels would have?

What did they not anticipate about the channels?

They thought this because of their experiments with voltage clamps in the squid giant axon. The squid 

1. high rate of ion movement

2. had to make use of electrochemical gradients. 

3. the channels had to be able to discriminate between sodium and potassium 

4. ion channels are voltage sensitive

They didn't suspect that the current resulting from depolarization was the result of an aggragation of single channels opening. 

Compare the responses of voltage-gated sodium and potassium channels to depolarization. 

How would you expect these channel properties to affect the shape, duration and frequency of action potentials?

Upon depolarization voltage gated sodium channel open. This opening allows sodium to rush in then the channel deactivates at positive membrane potential. 

Potassium channels open slowly to allow sodium to rush in. This repolarizes the membrane potential so another stimuli can be generated. 

What is meant by the statement that ion channels and active transporters have comlementary function?

What must all active transporters be able to do?

Ion channels and active transporters are complimentary because they could not function without each other. An ion channel needs a concentration gradient to work while an active transporter reset's this gradient. 

Active transporters must be able to utilize energy to move an ion against its concentration gradient. 

ATPase pumps: Utilize the hydrolysis of ATP to move ions against their concentration gradient. 

Ion exchangers: Swap an ion moving down its concentration gradient for one moving up its concentration gradient. One in while one goes out. 

Co-Transporters: One out while one goes in. 

Without many varieties of potassium channels there would not be as much flexability in the nervous system to send varying signals. These numerous channels vary largely in the duration it takes them to inactivate allowing for different action potential timings. 

List major stimulus types that can gate various kinds of ion channels. 

Ligand(chemical), electrical (voltage), stretch, heat, 

Acetylcholine

actin

auxilin

Neurotransmitter at motor neuron synapses in autonomic ganglia, and in variety of central synapses. Binds to either ligand gated ion channels (nicotinic receptors) or G-protein-coupled receptors (muscarinic receptors). 

filaments in the cytoskeleton that may aid synapsin in tethering vesicles in the reserve pool. 

serves as a co-factor that recruits Hsc70 to the coated vesicle to help remove the clathrin coat

Calcium/calmodulin-dependent protein kinase, type II

clathrin

connexons

connexins

synapsin  is phosphorylated by this protein in the mobilization of theses reserve pool vesicles. 

Most important protein for endocytotic budding of vesicles from the plasma membrane; its three-pronged "triskelia" attach to the vesicular membrane to be retrieved. 

Precisely aligned paired channels that connect electrical synapses together. 

each of these connexon's are composed of 6 proteins called connexins. 

co-transmitters

dynamin

end plate current

two or more types of neurotransmitters within a single synapse; may be packaged into separate populations of synaptic vesicles or co-localized within the same synaptic vesicles. 

causes the final pinching-off of membrane that completes the production of coated vesicles. 

a microscopic postsynaptic current resulting from the summed opening of many ion channels; produced by neurotransmitter release and binding at the motor end plate. 

end plate potential

end plate

excitatory postynaptic potentials

depolarization of the membrane potential of skeletal muscle fiber, caused by the action of the transmitter acetylcholine at the neuromuscular synapse. 

the complex postsynaptic specialization at the site of nerve contact on skeletal muscle fibers. 

neurotransmitter induced postsynaptic potential change that depolarizes the cell, and hence increases the likelihood of initiating an action potential

fast axonal transport

gap junction

G- protein coupled receptors

carries vesicles at rates up to 400 mm/day along microtubules, moved by proteins such as kinesin require ATP

a specialized intercellular contact formed by channels that directly connect the cytoplasm of two cells. 

a large family of neurotransmitter of hormone receptors, characterized by seven transmembrane domains; the binding of these receptors by agonists leads to the activation of intracellular g-proteins. 

Hsc70

inhibitory postsynaptic potentials

ionotropic receptors

Heat shock protein that plays a role in removing clathrin coats from vesicles. 

neurotransmitter induced postsynaptic potential change that tends to decrease the likelihood of a postsynaptic action potential

receptors in which the ligand binding site is an integral part of the receptor molecule. 

large dense-core vesicles

metabotropic receptors

miniature end plate potentials (MEPP)

NEM-sensitive fusion protein (NSF)

vesicles that contain neuropeptides, named for the electron dense appearance in the electron micrograph

also known as g-protein coupled receptors

Small, spontaneous depolarization of the membrane potential of skeletal muscle cells, caused by the release of a single quantum of acetylcholine

NSF is an ATPase that is involved in priming synaptic vesicles for fusion, regulate the assembly of other proteins called SNAREs

This is site directed mutations to the gene that you are analyzing. This in turn will change corresponding amino acids that can give you different structures that may be less functional, equally functional, or more functional. 

This could tell you information about the importance of various amino acids in the protein. 

What are the pros and cons of the electrical versus chemical synapse. 

Electrical synapses are bi-directional, faster, all or none response. Harder to be inhibited. No graded response. 

Acetlycholine

Where is it used?

How is it synthesized?

How is it removed from the synapse?

Functions at the neuromuscular juntions, the ganglia of the visceral motor system and at a variety of sites within the CNS. 

Made from acetyl CoA and choline. Catalyzed by the enzyme choline acetyltransferase. 

Broken down by the enzyme acetylcholinesterase, then choline is moved back into the pre-synaptic terminal. 

What are Catecholamines made from?

Where is the major dopamine area in the brain?

What is the role of dopamine?

Made from tyrosine

Corpus striatum

reward, motivation, and 

How many subunits do nicotinic acetylcholine receptors have?

Glutamate is 

A) the most commonly used neurotransmitter in the brain

B) neurotoxic at high concentrations

C) a nonessential amino acid

E) all of the above. 

postsynaptic

postsynaptic current

postsynaptic potential

referring to the component of a synapse specialized for transmitter reception

the current produced in a postsynaptic neuron by the binding of neurotransmitter released from a presynaptic neuron. 

the potential change produced in a postsynaptic nueron by the binding of neurotransmitter released from pre-

Reversal potential

slow axonal transport

small clear-core vesicles

Membrane potential of a postsynaptic neuron at which the action of a given neurotransmitter causes no net current flow. 

Enzymes that synthesis neurotransmitters are located in the presynaptic terminal and need to be transported to the nerve terminal cytoplasm

These are vesicles that contain small0molecule neurotransmitters. They appear clear in the elctron micrographs. 

What is the role of SNAP-25?

What are SNAP's?

What are SNAREs?

located on the plasma membrane, this protein is involved in pulling the vesicle to the plasma membrane and fusing it. This involves the interaction between SNAP-25 and synaptobrevin. 

soluble NSF-attachment proteins, they are involved in priming synaptic vesicles for fusion. 

SNARE proteins are involved in vesicle priming and fusion. They include synaptobrevin, syntaxin, and SNAP-25. 

summation

Synapsin

the addition in space and time of sequential synaptic potentials to generate a larger than nomral postsnaptic response. 

A protein that reversibly binds to synaptic vesicles, may keep these vesicles tethered within the reserve pool by cross link vesicles to each other and to actin. 

Synaptic vesicle cycle

Synaptic vesicles

sequence of budding and fusion reactions that occurs in presynaptic terminals to maintain the supply of synaptic vesicles. 

spherical, membrane-bound organelles in presynaptic terminals that store neurotransmitter molecules.

synaptobrevin

synaptojanin

synaptotagmin

protein in the membrane of vesicles that is involved in the SNARE complex that helps priming and fusion of the vesicle to the plasma membrane 

protein important for vesicle uncoating/ budding

Found in the membrane of synaptic vesicles- binds calcium, allowing it to act as a calcium sensor triggering vesicle release. 

syntaxin

tripartite synapse

similar function to SNAP-25, help form the SNARE complex that allows for vesicle fusion. 

The concept of a three way junction involving the presynaptic terminal, the postsynaptic process, and neighboring glial cells. 

Why does the sodium potassium pump only make minor contributions to the neuron's resting potential?

What structural features of potassium channels account for ion selectivity, voltage sensitivity, and ion conductance? 

The pumps act much more slowly that ion channels, thus the current produced is very small. 

The narrowest part of the channel near the mouth constricts size so only potassium can fit through. Sodium cannot pass through because the walls of the channel are too far apart to stabalized the dehydrated sodium ion. 

Acetylcholinesterase 

adrenaline AKA epinephrine 

AMPA receptors... one type of ionotropic glutamate receptor

Enzyme in the synaptic cleft that clears the cleft of acetylcholine by hydrolysis into acetate and choline; choline is then moved back into the presynaptic cell

catecholamine hormone and neurotransmitter that binds to adrenergic G-protein-coupled receptors. 

glutamate-gated cation channels that allow the passage of Na and potassium. 

biogenic amines

catecholamines

glutamate - glutamine cycle

category of small-molecule neurotransmitters including the catecholamines, serotonin and histamine 

Molecules containing a catechol ring and an amino group; examples are the neurotransmitters epinephrine, norepinephrine, and dopamine. 

a metabolic cycle of glutamate release and resynthesis involving both neuronal and glial cells. 

histamine 

kainate receptors 

muscarinic acetylcholine receptors. 

A biogenic amine neurotransmitter derived from the amino acid histidine. 

a type of ionotropic glutamate receptors

A group of G-protein coupled acetylcholine receptors activated by the plant alkaloid muscarine. 

neuropeptides

nicotinic acetylcholine receptors. 

A general term describing a large number of peptides that function as neurotransmitters of neurohormones. 

Receptor on muscle cells, nicotine binds to these receptors. Wide variety of locations. Five subunits, the alpha  subunits bind to acetylcholine. These are ligand gated ion channels. 

NMDA receptors

Norepinephrine AKA noradrenaline

serotonin

a type of ionotropic glutamate receptors. 

catecholamine hormone and neurotransmitter that binds to alpha and beta adrenergic receptors, both of which are G-protein coupled receptors. 

A biogenic amine neurotransmitter derived from the amino acid tryptophan. 

GABA-precursor, rate-limiting enzyme of synthesis, mechanisms of removal. 

Glutamate

Acetylcholine

Dopamine

Norepinephrine

GABA- Glutamate, GAD(glutamic acid decarboxylase), sodium dependent co-transporters located in the glial cells

glutamine is the precursor, glutaminase is the limiting enzyme, and transporters remove it. 

ACh choline and acetyl CoA, CAT choline acetyltransferase, acetylcholinesterase. 

Tyrosine, tyrosine hydroxylase, transporters, 

Same as dopamine, 

ionotropic receptors combine the ligand binding function with the channel portion of the receptor in one unit. 

Metabotropic receptors eventually move ions through channels dependent on intervening metabolic steps. They do not have the ion channels as part of their structure insteadd they have an intracellular domain that indirectly affects channels through the activation of intermetiate molecules called G-proteins. 

What are the two major inhibitory molecules in the CNS

What are the three major types of ionotropic glutamate receptors

Why are Two of them important and which ones are those. 

GABA and glycine

AMPA receptors, NMDA receptros, and kainate receptros, all named after the agonists that activate receptors activation always produces EPSP's

These are important because most central synapses possess both AMPA and NMDA receptors, antagonist drugs that selectively block either AMPA NMDA receptros are often used to identify synaptic responses mediated by each receptor type