True:

high specificity for a particular ion

dictated by:

1) charge

2) configuration of the ion

True:

some are gated and some are ungated

False:

its an 'all-or-none' phenomenon

1) voltage gated ion channels

2) ligand gated ion channels

False:

the channels are just integral proteins

they are voltage gated ion channels b/c their molecular conformation* is controlled by the electrical gradient across the membrane (the number of ions across the membrane)

True:

there are Na voltage gated ion channels which only allow Na ions to pass through and there are K voltage gated ion chanels which only allow K ions to pass through - so this means that voltage gated ion  channels have high specificity - well we already know that b/c ion channels in general have high specificity and voltage gated ion channels is an example of diffusion

False:

only hydrophilic substances require membrane channels like ions (which require ion channels)

when will the Na voltage gated channel be kept closed?

when will it be opened?

Na voltage gated channel will be kept closed when there is a strong negative charge inside the cell

it will be opened when the negative charge inside the cell decreases to allow the flow of Na ions through the ion channel

False:

they are

False:

ligands are molecules that specifically to other molecules* (these could be protiens but not necessarily only protiens)

False:

ligands only bind to ligand gated channels

this is why these channels are called 'ligand gated channels'

so a neurotransmitter does not bind to a Na voltage gated channel but does bind to Na ligand gated channel

True:

voltage gated ion channels undergo conformational chganes based on the electrical gradient across the membrane

ligand gated channels undergo conformational changes when a ligand binds to the channel protein

it can open the channel

and

initiate an action potential

False:

diffusion in general (whether facilitated or not) does not require energy

False:

both have specificity for molecules

recall: ion channels are integral proteins for moving ions across the membrane - gated can be voltage gated or ligand gated and they are very specific

transporters are integral proteins for facilitating the movement of certain substance like glucose or amino acids across the membrane

False:

both ion channels and transporters are specific to molecules

there are only glucose transporters that will only transport glucose molecules across membrane etc

False:

transporters are examples of facilitated diffusion

True

just like ion channels

True

needs facilitated diffusion

False

they do

in simple diffusion, the diffusion rate depends on permeability, concentration and electrical gradient.  the diffusion does not reach a Tmax

in facilitated diffusion, the diffusion rate reaches a Tmax due to limited number of transporter molecules

False:

osmosis referse to the movement of water** (not solutes) across a semipermeable membrane that results from a difference in water concentrations - b/c there is a difference in water concentratoins, it means that one side of the membrane has more solutes* than the other and therefore more/less water respectively - so there ARE solutes involved in osmosis but they are not the ones that are moving across the semipermeable membrane, only water is!

False:

water requires channels called 'water channels'

like there are Na voltage gated channels and glucose transporters, water also requires its own channel called water channel

not sure if the water channel is a transporter or an ion channel!

False:

water is a solvent but it also runs from higher concentration to lower concentration

False:

it does not depend on the size at all

only depends on the number

False:

only 1

True:

b/c it dissociates

osmolarity is measured in osmoles so osmoles is a unit

osmoles is the number of dissolved particles

osmolarity is the number of osmoles of solute per liter of solution

False:

its per one liter of solution

False:

osmolarity of both ECF and ICF is 300 milliosmoles

T/F: seawater has a higher osmolarity than freshwater

give numbers

True:

seawater's osmolarity is 1000 milliosmoles

freshwater's osmolarity is 10 milliosmoles

both use integral proteins

both reach Tmax in diffusion rates

False:

active transport is needed b/c substances are moved against* their concentratin gradient

False:

primary and secondary active transports

no such thing as activated transports and inactivated transports

what are the general examples of primary active transport?

what are the general examples of secondary active transport?

Primary active transport:

1) Na/K pump

2) Ca pump

Secondary active transport:

1) Co-transport

2) Counter-transport systems

False:

both directly utilize ATP

recall that both are examples of primary active tranpsort and primary active transport is known for directly utilizing ATP

False:

they are integral proteins

Na/K pump is a primary active transport example and we know that active transports like facilitated diffusion uses integral proteins

T/F: Na/K pumps are very important and present in all cell membranes

why or why not important?

True:

they are very important

they are present in all cell membranes

they are important for 2 reasons:

1) b/c in many cells, they are a major item in the energy budget

2) they help control cell volume osmotically

True:

Na/K pump is a primary active transport example and primary active trnapsort are known for directly utilizing ATP

False:

Na/K pump is composed of 2 proteins*

it has 3 binding sites for Na on the ICF side

it has 2 binding sites for K on the ECF side

it has an ATPase region

composed of 2 proteins

3 binding sites for Na on ICF side

2 binding sites for K on ECF side

once Na and K are bound to their respective regions, ATPase region cleaves ATP and uses that energy to cause a conformational change that transports Na out of the cell and K into the cell

many protiens are normally retained in the cell and these proteins act osmotically

without Na/K pump, the cell can swell and burst

Na/K compensates for the abundance of intracellular proteins by expelling 3 out for every 2 in

note: this is all about the inside of the cell

False:

there is 10,000 times more Ca outside the cell (ECF) than inside the cell (ICF)

False:

Ca ion gradient is maintained two ways:

1) Ca pumps on cell membrane Ca ions outside the cell (into ECF)

2) Ca pumps on cell organelles pump Ca ions inside the organelles

(eg. Ca ions stored in the sarcoplasmic reticulum in muscles)

False:

ATP is not directly utilized

ATP is only directly utilized in primary active transport

it is the 'coupled' movement of two substances across the cell membrane

for this reason, it is also called 'coupled transport' or 'cotransport'

False:

it does integral protein but it is not called transporter (this is used for facilitated diffusion); it uses an integral protien called 'cotransporter'

recall that it is a type of secondary active transport

in cotransport, the two substances that move across the cell membrane are moved in the same direction

the concentration of one ion is the driving force for the movement of another ion against its concentration gradient (but they are still moving in the same direction even if one is moving against its concentration gradient)

glucose/Na

amino acids/Na

in both cases, Na is moved inside the cell and its concentratio is the driving force for moving glucose/amino acids against their concentration gradient but both Na and glucose/amino acid are moving in the same direction

False:

they are abundant in epithelial cells* that line the intestines (small or large)

False:

its an example of counter transport system

False:

more than one thing is false here

it is counter transport system that are found in almost all cell membranes

Na/K pumps are found in all cell membranes

Ca pumps are not* found in all cell membranes

cotransport systems are not* found in all cell membranes - notes do not specify

Na moves inside the cell - down its concentration gradient

Ca moves out of the cell - against its concentration gradient (there are 10,000 times more Ca ions outside the cell than inside)

Na is the driving force

recall that in secondary active transport, movement of one ion is the driving force of the movement of the other ion against its concentration gradient

True

i will forget this one

False:

mainly moves ions across the pumps like Na/K pump and Ca pump

False:

All cells including muscle cells, brain cells, liver cells etc have electric potentials across the cell membrane

False:

membrane potentials occur across a cell membrane therefore they are due to ion concentrations between ICF and ECF (not just within the cell but between the inside of the cell and the outside of the cell)

False:

only some cells have the ability like neurons

1) presence of large negatively charged proteins retained within the cell geenrates a net negative charge in the ICF

2) Membrane ion pumps:

ex: Na/K pumps - 3 out for every 2 in

3) Diffusion of K and N through membrane channels: even at rest, small amounts of K and Na move through the diffusion channels and reach an equilibrium based on electrical and concentration gradient

False:

this is what results when 'equilibrium potentials' occur!

resting potential results from the combination of 'equilibrium potentials' of individual ions

False:

Yes, Na and K have the greatest effect on resting potential but K have more of an effect than Na

False:

Nernst equation is used to calculate the 'equilibrium potential' of individual ions across the membrane

True

the ICF is 70mv more negative than the ECF

False:

150mM/liter = ECF

15mM/liter = ICF

False:

150mM/liter = ICF

5mM/liter = ECF

True:

105mM/liter = ECF

10mM/liter = ICF

False:

2.4mM/liter = ECF

0.0001mM/liter = ICF

True:

so, during action potential, ICF is positive and ECF is negative but normally (when there is no AP), it is the other way around

False:

they only occur in neurons and muscle cells, NOT liver cells

False:

few milliseconds

False:

notes say nothing about muscle cells, only that in neurons, the entire AP occurs in only a few milliseconds

True:

this means that the membrane potential is 'moving' towards zero

False:

the second stage is where the membrane potential reaches a 'threshold potential' which is around -45mV to -55mV

False:

after the rapid depolarization stage, there is a rapid re-polarization stage

False:

the last stage is return to the resting potential

1) Some type of triggering event causes an initial 'depolarization' of the membrane potential (ie. the membrane potential moves toward zero potential)

2) the membrane potential reaches a threshold potential which is around -45mV to -55mV

3) rapid depolarization occurs and then an abrupt stop

4) rapid repolarizatio occurs - voltage returns to resting potential

5) hyperpolarization occurs - voltage becomes more negative than the resting potential

6) membrane potential returns to resting potential

False:

they are voltage gated channels

what does the activation gate do?

what does the inactivation gate do?

which voltage gated ion channel is each gate related to?

activation gate opens the channel

inactivation gate closes the channel

they are both found on the Na voltage gated channel

False:

both activation and inactivation gate are located in Na voltage gated channels

what is the activation gate doing at resting potential?

what is the inactivation gate doing at resting potential?

activation gate is closed

inactivation gate is opened

False:

activation gate does open at threshold potential but inactivation does not close at threshold potential

however, the inactivation gate IS triggered at the threshold potential

False:

they are closed

in the notes, it says that the inactivation gate is open at resting potential

T/F: initial influx of Na ions causes a positive feedback

explain what happens

True:

The more influx of Na ions, the more positive the membrane potential becomes causing even more Na voltage gated channels to open

False:

the inactivation gate closes slowly but once its closed, Na influx is stopped

False:

they dont open but they are 'activated' at the threshold potential

they actually open approximately at the time when Na inactivation gates have closed

activation gate of Na voltage gated channel opens

inactivation gate of Na voltage gated channel is triggered to close

activation gate of K voltage gated channel is activated to open

False:

K voltage gated channel is responsible for repolarization phase of AP

False:

once AP has occurred, the membrane potential does reach resting potential but the charges in the ICF and ECF are changed - the concentrations in the ICF and ECF are not as they were when the cell was at rest

they come into play once AP has occurred and the membrane potential is back to resting potential

Na/K pumps will restore the charges in the ICF and ECF now

T/F: cells cannot shoot another AP after it has just repolarized even if its after just a few milliseconds

why or why not?

False:

once an AP has occurred, cells can shoot another AP after a few milliseconds

this is possible b/c during a single AP, only about 1 out of every 100,000 K ions actually leave the cell

recall that during AP, there is a reversal of ion charges in ICF and ECF so if all 100,000 K ions had left the ICF to go into ECF during that particlar AP, another AP cannot occur soon after the first one b/c there are no K ions left in the ICF that can go into ECF but since only 1 out of every 100,000 K ions leave the cell, there is a lot more K ions left in ICF - point is that only a very small concentration of K ions leave the cell during AP and very small conncetration of Na ions enter the cell during each AP

False:

refractory perid is the period during and immediately after an action potential (not depolarization) during which it is difficult or impossible to depolarize cell a second time

absolute refractory peirod is the period during action potential during which cell cannot be depolarized a second time

relative refractory period is the period during action potential during which cell can be depolarized a second time but it takes a stronger than normal triggering stimulus

False:

all the Na inactivation gates are closed so depolarization cannot occur hence no AP

False:

it takes one millisecond before they reopen

False:

some inactivation gates are closed and some are open (not activation gates)

True:

refractory periods occur b/c inactivation gates are closed

False:

lasts a few milliseconds

it is the closing of inactivation gate in absolute refractory period that lasts approximately one milisecond

False:

having refractory periods prevents the spreading of AP in all directions

AP can spread in all directions along membrane from initial depolarization but refractory periods prevent the spread of AP back over areas that have already been depolarized so normally, AP only go in one direction

1) tetrodotoxin (TTX)

2) saxitoxin (STX)

3) ciguatera toxin (CTX)

Saxitoxin and Ciguatera toxin are produced by certain algae (ie. dinoflagellates) while tetrotoxin is not

tetrotoxin is found in the internal organs of puffer fish

False:

in Japan

1) found in internal organisms of puffer fish

2) found in the skin of some salamanders

which toxin is related to red tides?

Saxitoxin

saxitoxin is also produced in algal blooms which causes red tides (can cause massive fish deaths)

False:

saxitoxin can become concentrated in shellfish that feed on algae

True:

b/c the shellfish have saxitoxin in them since they fed on algae

False:

it is a non-protein substance

False:

produced by algae

False:

1000

True:

field agents were given saxitoxin suicide pills in case they were captured

False:

ciguatera can become concentrated in fishes via the food chain

ciguatera is produced by certain algae (ie. dinoflagellates)

ciguatera toxin

ciguatera toxin can be prevalent in certain marine carnivorous fishes

False:

ciguatera toxin is prevalent in certain marine carnivorous fishes

marine carnivorous fishes = barracuda

False:

example of procaine is novacaine

there is no example of tetracaine

1) procaine (ie. novacaine)

2) lidocaine (ie. xylocaine)

3) tetracaine

False:

they act on activation gates making them more difficult to open

False:

2 things are false:

1) local anesthestics decrease membrane* excitability (not muscles)

2) they decrease membrane excitability by increasing threshold voltage (not decreasing it)

1) soma = cell body

2) dendrites

3) axon

4) axon hillock

5) axon terminal

6) synapse

soma is the cell body of a neuron

1) functions as the center of metabolism

2) functions as the center of protein production

False:

only neuron

recall that soma is one of the parts of a neuron

True:

dendrite = synapse to cell body & axon

axon = cell body to synapse

False:

between a cell body and an axon

this is what causes the axon hillock to have the lowest threshold potentials

and

this is what causes most action potentials to occur at the axon hillock

True:

note: most do but not all

False:

they can receive impulses from synapses and/or dendrites

i think the dendrites are the dendrites from the same cell as the cell that has axon hillock

the synapse is clearly from a different neuron

True:

it says that axon terminals make contact with other cells at the synapse but it also says that the cell with which they make contact with are either dendrites or soma so technically, soma make contact with other cells at the syanpse :P

False:

axon terminals are small round or oval knobs at ends of axons (not axon hillocks)

T/F: axon terminals make more contacts with dendrites at the synapses than with cell bodies

give numbers

True:

80-95% with dendrites

5-20% with soma

False:

postsynaptic neuron can be dendrites or soma

False:

30-50 nanometers

False:

thousands of inputs

100 synapses

100 inputs = 100 synapses

1000 inputs = 1000 synapses

False:

at axon terminal

what happens when Ca ion channels are opened?

what does this lead to?

opening of Ca channels causes an influx of Ca ions into the axon terminal

this induces exocytosis of synaptic (ie. secretory) vesicles that contain neurotransmitters

True

dendrite of a postsynaptic neuron

can also bind to soma of a postsynatic neuron

binding of neurotransmitters to receptors can lead to a variety of events. 

where do these events take place?

what are the different events based on?

since the NT bind to receptors on postsynaptic neurons, clearly the events take place in the postsynaptic neurons

the different events are based on the type of synapse through which the NT diffuse across

True:

it can open ion channels by activating G proteins

binding of NT to receptors can cause one of three things:

1) it can directly open specific ligand gated channels

2) it can cause the opening of ion channels by the activation of G proteins (so this is indirectly opening channels)

3) it can produce second messengers such as cAMP

False:

1) they are membrane bound peripheral proteins

2) they act as intermediaries between receptor and ion channel (not NT)

False:

they are often regulated by G proteins

False:

they are membrane bound peripheral proteins

cAMP are second messengers

False:

long term potentiation of neurons is an exmaple

this is an example of a long-term effect of neurons by second messengers

the use of certain neurons makes them more excitable (easier to stimulate them)

False:

a synapse can either be excitatory or inhibitory but not both

Na = excitatory b/c brings membrance potential closer to threshold

K = inhibitory

Cl = inhibitory

False:

many factors in the ECF can have general effects on the synaptic transmissions

pH

specific drugs: caffeine, theophylline, theobromine

False:

increase in pH

pH of 7.8 to 8 = cerebral seizures

True

decrease in pH causes a decrease in excitability

this is a decrease in pH which causes a decrease in excitability

comatose = pH of 7

False:

1) caused by an increase in pH

2) the increase in pH in blood (not cells)

severe diabetic acidosis

comes from keto acids

in severe diabetic acidosis (ie. ketosis), lack of insulin causes fats to be metabolized for energy which produces fatty acids and some of these acids are keto acids

acidosis from keto acids can cause coma

False:

caused by a decrease in pH

comatose = pH of 7

its a collective name for drugs including caffeine, theophylline, and theobromine

these affect the excitability of synaptic transmissions

T/F: methylxanthines increase excitability of neurons

How?

True:

they increase excitability of neurons by blocking the degradation fo second messengers (ie. cAMP) thus enhancing the effects of certain NT

False:

not found in chocolate

found in coffee, tea, and some sodas

False:

theophylline is found in tea

__________ is found in chocolate

___________ is not found in cholocate

theobromine is found in chocolate

caffeine is not found in chocolate

T/F: theobromine can be toxic to some dogs and cats

why or why not?

False:

toxic to dogs and horses b/c they do not metabolize it efficiently

what affect do local anesthetics have on synapse tranmissions?

they decrease excitability of synapses by increasing the threshold potential of Na activation gates

this decreases excitability of neurons

False:

they act on Na activation gates (not inactivation gates)