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BY 409 Test I Part II
test I part II
228
Biology
Undergraduate 3
09/06/2009

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Cards

Term
T/F: ion diffusion channels are highly selective
Definition

True:

high specificity for a particular ion

Term
what is the ion channel specificity dictated by?
Definition

dictated by:

1) charge

2) configuration of the ion

Term
T/F: ion channels can be gated or ungated
Definition

True:

some are gated and some are ungated

Term
T/F: whether the ion gated channel will open or close depends on the number of solutes that are willing to cross the membrane
Definition

False:

its an 'all-or-none' phenomenon

Term
what are the different types of ion gated channels?
Definition

1) voltage gated ion channels

 

2) ligand gated ion channels

Term
T/F: voltage gated channels have charges on their channels
Definition

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)

Term
what is the molecular conformation of voltage gated ion channel controlled by?
Definition
it is controlled by the electrical gradient across the membrane
Term
T/F: there are separate voltage gated ion channels for each ion
Definition

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

Term
T/F: all substances require membrane channels
Definition

False:

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

Term

when will the Na voltage gated channel be kept closed?

when will it be opened?

Definition

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

Term
T/F: a hormone is a ligand
Definition
True
Term
T/F: neurotransmitters are not ligands
Definition

False:

they are

Term
T/F: ligands are molecules that speciifcally bind to proteins
Definition

False:

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

Term
what happens when a ligand binds to a membrane channel protein?
Definition
when a ligand binds to a channel protein, it causes a conformational change of that channel protein which will either open or close the gate of the channel
Term
T/F: ligands bind to voltage gated channels
Definition

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

Term
T/F: both voltage gated and ligand gated channel protiens undergo conformational changes
Definition

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

Term
what happens when acetylcholine binds to receptors on Na channel proteins?
Definition

it can open the channel

and

initiate an action potential

Term
T/F: facilitated diffusion requires ATP
Definition

False:

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

Term
what is another name for facilitated diffusion?
Definition
carrier-mediated diffusion
Term
T/F: while ion channels have specificity for molecules, transporters do not
Definition

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

Term
T/F: while ion channels are specific to molecules, transporters can carry any molecule as long as they are a certain size
Definition

False:

both ion channels and transporters are specific to molecules

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

Term
T/F: transporters are example of active transport
Definition

False:

transporters are examples of facilitated diffusion

Term
T/F: transporters are integral proteins only
Definition

True

just like ion channels

Term
T/F: glucose needs transporters
Definition

True

needs facilitated diffusion

Term
T/F: amino acids do not need facilitated diffusion
Definition

False

they do

Term
why does hormone insulin increase the number of transporters across the cell membrane?
Definition
by doing that, it increases the amount of glucose that can be transported across the cell membrane
Term
what is the difference between simple diffusion and facilitated diffusion?
Definition

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

Term
T/F: osmosis refers to the movement of solutes across semipermeable membrane that contains water
Definition

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!

Term
T/F: osmosis requires a semipermeable membrane
Definition
True
Term
T/F: there are no specific channels for water as water can pass through the semipermeable membrane
Definition

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!

Term
T/F: unlike solutes that run from higher concentration to lower concentration, water being a solvent runs from lower concentration to higher concentration
Definition

False:

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

Term
what causes a difference in water concentrations across a semipermeable membrane?
Definition
b/c there is a difference in solute concentrations
Term
T/F: osmotic pressure is the pressure applied to stop osmosis
Definition
True:
it is the amount of pressure requred to stop osmosis
Term
what is osmotic pressure determined by?
Definition
it is determined by the number of solute particles per volume (not the size, only the number)
Term
what is an osmole?
Definition
osmole is the number of solute particles dissolved
Term
T/F: osmole depends on the size of solute particle only
Definition

False:

it does not depend on the size at all

only depends on the number

Term
T/F: 1 gram molecular weight of glucose has 10 osmoles
Definition

False:

only 1

Term
T/F: one gram molecular weight of NaCl has 2 osmoles
Definition

True:

b/c it dissociates

Term
why does NaCl have twice as much of an osmotic effect as glucose even though they are both 1 gram molecular weight?
Definition
b/c NaCl is 2 osmoles and gluose is 1 osmole
Term
what is the difference between osmoles and osmolarity?
Definition

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

Term
T/F: osmolarity is the number of osmoles of solute per 10 liters of solution
Definition

False:

its per one liter of solution

 

Term
T/F: osmolarity of ECF is 100 milliosmoles while the osmolariaty of ICF is 1000 milliosmoles
Definition

False:

osmolarity of both ECF and ICF is 300 milliosmoles

Term

T/F: seawater has a higher osmolarity than freshwater

give numbers

Definition

True:

seawater's osmolarity is 1000 milliosmoles

freshwater's osmolarity is 10 milliosmoles

Term
what is common between active transport and facilitated diffusion?
Definition

both use integral proteins

both reach Tmax in diffusion rates

Term
T/F: active transports are needed b/c some molecules need to be activated in order to be moved
Definition

False:

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

Term
why does active transport utilize ATP?
Definition
b/c substances are moved against their concentration gradient
Term
T/F: the two basic types of active transports are activated tranposrts and inactivated transports
Definition

False:

primary and secondary active transports

no such thing as activated transports and inactivated transports

Term

what are the general examples of primary active transport?

 

what are the general examples of secondary active transport?

Definition

Primary active transport:

1) Na/K pump

2) Ca pump

 

Secondary active transport:

1) Co-transport

2) Counter-transport systems

Term
T/F: while Na/K pump directly utilizes ATP, Ca pump indirectly utilizes ATP
Definition

False:

both directly utilize ATP

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

Term
T/F: Na/K pumps are not integral proteins
Definition

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

Term

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

why or why not important?

Definition

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

Term
T/F: Na/K pump directly utilizes ATP
Definition

True:

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

Term
T/F: Na/K pump is composed of a protein that has 2 binding sites and an ATPase region
Definition

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

Term
explain the structure of the Na/K pump:
Definition

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

Term
what are the binding sites called on Na/K pump?
Definition
the binding sites for Na and K are called receptors
Term
how does Na/K pump help maintain cell volume osmotically?
Definition

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

Term
T/F: there is 1,000 times more Ca outside the cell than inside the cell
Definition

False:

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

Term
why is there a much greater concentration of Ca ions outside the cell than inside?
Definition
b/c Ca ions act as intracellular signals in the ICF (eg. Ca ions initiate contractions of muscle cells; Ca ions initiate release of neurotransmitters in neurons)
Term
T/F: Ca ion graident is maintained across the cell membrane b/c 3 Ca ions are pumped for every 2 pumped in
Definition

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)

Term
T/F: ATP is directly utilized in secondary active transport
Definition

False:

ATP is not directly utilized

 

ATP is only directly utilized in primary active transport

Term
in general, what is secondary active tranposrt?
Definition

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

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

Term
how does secdonary active transport two substances across the cell membrane?
Definition
concentration of one ion is used as the driving force to transport a second substance against* its concentration gradient
Term
T/F: secondary active transport uses a specific integral protein called transporter protein
Definition

False:

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

Term
what happens in cotransport?
Definition

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)

Term
what are examples of cotransport?
Definition

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

Term
T/F: cotransport systems are abundant in squamous cells of the small intestines
Definition

False:

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

Term
T/F: Na/Ca is an example of cotransport system
Definition

False:

its an example of counter transport system

Term
T/F: cotransport systems occur in all the cell membranes like Na/K pump and Ca pump
Definition

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

Term
in Na/Ca counter transport system, which ion moves inside the cell and which is moved out?
Definition

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)

Term
since Na is moved inside the cell and Ca is moved outside the cell in Na/Ca counter transport system, which ion concentration is the driving force?
Definition

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

Term
why is the calcium moved out of the cell in Na/Ca counter transpor tsystem?
Definition
it helps maintain low levesl of Ca in the ICF
Term
T/F: substances that move against their concentartion graidnet in the counter transport system can also be moved by other pumps by the primary active transport system
Definition

True

i will forget this one

Term
T/F: primary active transport mainly moves proteins across the pumps
Definition

False:

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

Term
T/F: while neurons have electric potentials across the cell membrane, muscle cells do not
Definition

False:

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

Term
define membrane potential:
Definition
membrane potential is referred to the separation of charges across the cell membrane (charges between ICF and ECF)
Term
T/F: membrane potentials are due to ion concentation in the cell
Definition

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)

Term
T/F: all cells have a slightly negative charge inside the cell relative to the outside
Definition
true
Term
T/F: all cells have the ability to generate changes in their membrane potential (ie. electrical impulses or action potential)
Definition

False:

only some cells have the ability like neurons

Term
what causes the difference in ion concentrations across the cell membrane?
Definition

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

Term
define resting potential:
Definition
resting potential is the membrane potential where the cell is at 'rest' and not undergoing rapid changes in ion concentration
Term
T/F: resting potential results from a distribution of a specific ion across a membrane when that ion is at 'equilibrium' between the diffusion gradient and electrical gradient
Definition

False:

this is what results when 'equilibrium potentials' occur!

 

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

Term
T/F: Na and K have the greatest effect on resting potential with Na having a more of an effect than K
Definition

False:

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

Term
T/F: Nernst equation is used to calculate the resting potential of individual ions across the membrane
Definition

False:

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

Term
Permeability of a particular ion across the cell membrane determines what in terms of resting potential of a cell?
Definition
Permeability of a particular ion across the cell membrane determines how much its (the ion's) 'equilibrium potential' contributes to the overall resting potential of the cell membrane
Term
Why does K have the greatest effect on the resting potential?
Definition
b/c it has the highest permeability across the cell membrane when the cell is at rest
Term
T/F: in a typical cell, the resting potential is -70mV
Definition
true
Term
T/F: -70mV is the voltage of the ICF
Definition

True

the ICF is 70mv more negative than the ECF

Term
T/F: Na ion concentration is 150 mM/liter in ECF and 5mM/liter in ICF
Definition

False:

150mM/liter = ECF

15mM/liter = ICF

Term
T/F: K ion concentration is 5mM/liter in ECF and 1500mM/liter in ICF
Definition

False:

150mM/liter = ICF

5mM/liter = ECF

Term
T/F: Cl ion concentratio is 105mM/liter in ECF and 10mM/liter in ICF
Definition

True:

105mM/liter = ECF

10mM/liter = ICF

Term
T/F: Ca ion concentration is 24mM/liter in ECF and 0.0001mM/liter in ICF
Definition

False:

2.4mM/liter = ECF

0.0001mM/liter = ICF

Term
T/F: action potential is a complete reversal of the membrane potentials
Definition

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

Term
T/F: AP occur in both neurons and liver cells
Definition

False:

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

Term
T/F: in a neuron, the entire AP occurs in only a few microseconds
Definition

False:

few milliseconds

Term
T/F: in a muscle cell, the entire AP occurs in only a few milliseconds
Definition

False:

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

Term
AP is a complete reversal of membrane potential but what causes it?
Definition
AP is caused by rapid changes in membrane permeability
Term
T/F: the first stage of an action potential is when some triggering event causes an initial depolarization of the membrane potential
Definition

True:

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

Term
T/F: the second stage of action potential is a rapid depolarization phase
Definition

False:

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

Term
what is the 3rd stage of AP?
Definition
the third stage is the rapid depolarization after the threshold potential is reached and then an abrupt stop
Term
T/F: after the rapid depolarization stage, there is a rapid hyperpolarization stage
Definition

False:

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

Term
T/F: During the repolarization phase, the membrane potential moves back toward the threshold potential
Definition
False: the membrane potential moves back toward the resting potential
Term
what happens during the hyperpolarization stage?
Definition
the voltage becomes more negative than the resting potential
Term
T/F: the last stage of AP is the membrane potential going back to threshold potential
Definition

False:

the last stage is return to the resting potential

Term
Summarize the stages of an AP:
Definition

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

Term
T/F: the channels through which ions move during action potential are ligand gated channels
Definition

False:

they are voltage gated channels

Term

what does the activation gate do?

what does the inactivation gate do?

which voltage gated ion channel is each gate related to?

Definition

activation gate opens the channel

 

inactivation gate closes the channel

 

they are both found on the Na voltage gated channel

Term
T/F: activation gate is located on the Na voltage gated channel and inactivation gate is located on a different Na voltage gated channel
Definition

False:

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

Term

what is the activation gate doing at resting potential?

what is the inactivation gate doing at resting potential?

Definition

activation gate is closed

 

inactivation gate is opened

Term
T/F: activation gate opens and inactivation gate closes at threshold potential
Definition

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

Term
T/F: at resting potential, the voltage gated ion channels are open
Definition

False:

they are closed

 

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

Term
when does a 1000 fold increase in Na permeability occur?
Definition
this occurs when the activation gate of the Na voltage gated channel opens at the threshold potential
Term

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

explain what happens

Definition

True:

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

Term
T/F: the inactivation gate closes abruptly stopping the diffusion of Na ions across the Na voltage gated channel
Definition

False:

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

Term
___________ cannot reopen immediately after being closed.  It takes some time before it can reopen again
Definition
Inactivation gates
Term
Which ion is responsible for the depolarization phase of the AP?
Definition
Na ions
Term
T/F: activation gate of K voltage gated channels open at the threshold potential
Definition

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

 

 

Term
summarize what happens to all the gates in both Na and K voltage gated channels at the threhsold potential:
Definition

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

Term
T/F: like the inactivation gate of Na voltage gated channel, the K activation gate opens slowly
Definition
True
Term
T/F: K voltage gated channel is reponsible for the depolarization phase of AP
Definition

False:

K voltage gated channel is responsible for repolarization phase of AP

Term
till when does the K voltage gated channel remain open?
Definition
until the cell repolarizes
Term
When does hyperpolarization occur - in other words, what causes it?
Definition
it occurs when the K voltage gated channel remains open for several milliseconds after membrane potential has reached resting potential
Term
T/F: once the action potential has occurred, there is a restoration of the membrane potential (ie.resting potential has reached) and there is a restoration of the charges in the ECF and ICF
Definition

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

Term
when do Na/K pumps come into play?
Definition

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

Term
How have the ion concentrations changed after the AP?
Definition
Na moved into ICF during AP and K moved into ECF during AP so these need to be restored again
Term

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

why or why not?

Definition

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

Term
T/F: refractory period is a period after a cell has depolarized during which a cell cannot be depolarized again
Definition

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

Term
T/F: the term 'refractory' is derived from a Latin word that means 'stubborn'
Definition
True
Term
what is the difference between absolute refractory perid and relative refractory period?
Definition

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

Term
T/F: in absolute refractory period, all the K activation gates are closed
Definition

False:

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

Term
T/F: once Na inactivation gates have closed during repolarizatio stage, it takes approximately 10 milliseconds before they can reopen
Definition

False:

it takes one millisecond before they reopen

Term
which period overlaps the rapid depolarization and repolarization stages?
Definition
the period in which all the inactivation gates of Na channels are closed for approximately one millisecond
Term
T/F: in relative refractory period, some Na activationg gates are closed while others are not
Definition

False:

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

Term
T/F: activation gates have nothing to do with refractory periods
Definition

True:

refractory periods occur b/c inactivation gates are closed

Term
T/F: the fact that some inactivation gates of Na channels are open and others are not last approximately one millisecond
Definition

False:

lasts a few milliseconds

 

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

Term
T/F: because of refractory periods, AP can spread in all directions along membrane from initial location of depolarization
Definition

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

Term
which toxins do we need to know for the pharmacology of ion channels?
Definition

1) tetrodotoxin (TTX)

 

2) saxitoxin (STX)

 

3) ciguatera toxin (CTX)

Term
_________ and ________ block Na channels while ________ opens Na channels
Definition
tetrodotoxn and saxitoxin block Na channels while ciguatera toxin opens Na channels
Term
__________ and ________ are produced by certain algae while __________ is not
Definition

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

Term
_________ and ________ can cause respiratory paralysis while _________ does not
Definition
tetrotoxin and saxitoxin can cause respiratory paralysis while ciguatera does not
Term
T/F: Fugu is considered a delicacy in China
Definition

False:

in Japan

Term
T/F: about 50 deaths occur annually in Japan due to Fugu poisoning
Definition
True
Term
where is tetrotoxin found - in which animals?
Definition

1) found in internal organisms of puffer fish

 

2) found in the skin of some salamanders

Term
what is the purpose of tetrotoxin in the skin of some salamanders?
Definition
prevents predation
Term
what is saxitoxin associated with?
Definition
paralytic shellfish poisoning
Term
which ion channel toxin is a marine toxin poisoning?
Definition
ciguatera toxin
Term

which toxin is related to red tides?

 

Definition

Saxitoxin

 

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

Term
T/F: saxitoxin can become concentrated in puffer fish that feed on algae
Definition

False:

saxitoxin can become concentrated in shellfish that feed on algae

Term
T/F: eating shellfish can cause respiratory paralysis
Definition

True:

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

Term
T/F: saxitoxin is an amino acid
Definition

False:

it is a non-protein substance

Term
T/F: saxitoxin is one of the most toxin non-protein substance produced by the shellfsh
Definition

False:

produced by algae

Term
T/F: saxitoxin is 10000 times more toxic than sarin nerve gas
Definition

False:

1000

Term
T/F: saxitoxin is a chemical warfare used by UN
Definition
True
Term
T/F: saxitoxins were once used by CIA as suicide pills
Definition

True:

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

Term
which toxin can become concentrated in fishes via the food chain?
Definition
ciguatera toxin
Term
T/F: ciguatera can become concentrated in algae via the food chain
Definition

False:

ciguatera can become concentrated in fishes via the food chain

 

ciguatera is produced by certain algae (ie. dinoflagellates)

Term
which toxin is related to barracuda?
Definition

ciguatera toxin

 

ciguatera toxin can be prevalent in certain marine carnivorous fishes

Term
T/F: saxitoxin is prevalent in certain marine carnivorous fishes
Definition

False:

ciguatera toxin is prevalent in certain marine carnivorous fishes

 

marine carnivorous fishes = barracuda

Term
T/F: example of lidocain is xylocaine
Definition
True
Term
T/F: example of procaine is tetracaine
Definition

False:

example of procaine is novacaine

 

there is no example of tetracaine

Term
which local anesthetics do we have to know?
Definition

1) procaine (ie. novacaine)

 

2) lidocaine (ie. xylocaine)

 

3) tetracaine

Term
T/F: the local anesthetics act on the inactivation gates making them more difficult to open
Definition

False:

they act on activation gates making them more difficult to open

Term
T/F: local anesthetics decrease muscle excitability by decreasing the threshold voltage
Definition

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)

Term
what are the parts of a neuron?
Definition

1) soma = cell body

 

2) dendrites

 

3) axon

 

4) axon hillock

 

5) axon terminal

 

6) synapse

Term
T/F: soma is the center of protein production
Definition
True
Term
T/F: soma is the center of metabolism
Definition
True
Term
What are the functions of a soma?
Definition

soma is the cell body of a neuron

 

1) functions as the center of metabolism

 

2) functions as the center of protein production

Term
T/F: all cells have soma
Definition

False:

only neuron

 

recall that soma is one of the parts of a neuron

Term
_______ and _______ are fiber like structures
Definition
dendrites and axons
Term
T/F: while dendrites are short, axons can be very long
Definition
True
Term
T/F: while dendrites conduct impulses from synapses to cell bodies & axons, axons conduct impulses from cell bodies to synapses
Definition

True:

dendrite = synapse to cell body & axon

axon = cell body to synapse

Term
what is the longest an axon can be?
Definition
over a meter in length
Term
T/F: axon hillock is the connecting area between an axon and a dendrite
Definition

False:

between a cell body and an axon

Term
T/F: axon hillock has the lowest threshold potential in the entire neuron
Definition
True
Term
why is there an abundance of Na voltage gated channels at the axon hillock?
Definition

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

Term
T/F: most action potentials start at axon hillock
Definition

True:

note: most do but not all

Term
T/F: axon hillocks always receive impulses from synapses
Definition

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

Term
which part of the neuron has the ability to summate potentials conveyed from numerous synapses and/or dendrites?
Definition
axon hillock
Term
T/F: the soma makes contact with other cells at the synapse
Definition

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

Term
T/F: axon terminals are big oval knobs at ends of axon hillocks
Definition

False:

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

Term

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

give numbers

Definition

True:

80-95% with dendrites

5-20% with soma

Term
__________ contain synaptic vesicles with neurotransmitters
Definition
axon terminals
Term
T/F: all postsynaptic neurons that come into contact with presynaptic neurons are dendrites
Definition

False:

postsynaptic neuron can be dendrites or soma

Term
T/F: length of a synapse is about 30-35 nanometers
Definition

False:

30-50 nanometers

Term
define synapse:
Definition
synapse is a 30-50 nanometer cleft between axon terminal of presynaptic neuron and dendrite/soma of the postsynaptic neuron
Term
T/F: some neurons in the brain have the ability of receiving millions of inputs
Definition

False:

thousands of inputs

Term
How many synapses are found between presynaptic and postsynaptic neurons that receive 100 inputs?
Definition

100 synapses

 

100 inputs = 100 synapses

 

1000 inputs = 1000 synapses

Term
T/F: synapses normally operate in one direction - presynaptic to postsynaptic
Definition
True
Term
T/F: Ca ion channels are opened at axon hillocks
Definition

False:

at axon terminal

Term
what triggers the opening of Ca ion channels?
Definition
propagation of AP down the axon
Term

what happens when Ca ion channels are opened?

what does this lead to?

Definition

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

Term
T/F: neurotransmitters diffuse across the synapse and bind to receptors on dendrites
Definition

True

dendrite of a postsynaptic neuron

can also bind to soma of a postsynatic neuron

Term

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?

Definition

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

Term
T/F: binding of NT to a receptor can cause the opening of ion channels
Definition

True:

it can open ion channels by activating G proteins

Term
binding of NT to receptors can cause the production of _________ called __________.
Definition
binding of NT to receptors can produce second messengers called cAMP
Term
generally speaking, what are the effects of binding a NT to a receptor?
Definition

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

Term
T/F: G proteins are membrane bound integral proteins that act as intermediaries between neurotransmitters and ion channels
Definition

False:

1) they are membrane bound peripheral proteins

 

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

Term
T/F: second messengers are often regulated by neurotransmitters
Definition

False:

they are often regulated by G proteins

Term
what do second messengers function as?
Definition
they can have rapid and/or long term intracellular effects (meaning they have effects in the cells- postsynaptic cells)
Term
T/F: G proteins are second messengers
Definition

False:

they are membrane bound peripheral proteins

 

cAMP are second messengers

Term
T/F: long term potentials are an example of long-term effect on neurons by second messengers
Definition

False:

long term potentiation of neurons is an exmaple

Term
what is 'long term potentiation'?
Definition

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)

Term
what is the advantage of using second messengers rather than having a direct effect on ion channels?
Definition
advantage is that second messengers can 'amplify' the initial signal
Term
T/F: ion channel effects on postsynaptic neuron can be inhibitory or excitatory
Definition
True
Term
T/F: a synapse can be both excitatory and inhibitory
Definition

False:

a synapse can either be excitatory or inhibitory but not both

Term
what effect does Na have on synapse? K? Cl?
Definition

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

 

K = inhibitory

 

Cl = inhibitory

Term
what does synaptic transmission mean?
Definition
it means excitability of the synapse
Term
T/F: many factors in the ICF can have general effects on the synaptic transmissions
Definition

False:

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

Term
which factors affect synaptic transmissions?
Definition

pH

 

specific drugs: caffeine, theophylline, theobromine

Term
 increase in pH causes _________ in excitability
Definition
increase in pH causes an increase in excitability of synaptic transmissions
Term
how does pH affect syanptic transmissions?
Definition
pH alters the excitability of ion channels (eg Na channels)
Term
T/F: cerebral seizures are a result of decrase in pH
Definition

False:

increase in pH

pH of 7.8 to 8 = cerebral seizures

Term
T/F: severe diabetic acidosis is an example of a decrease in pH
Definition

True

decrease in pH causes a decrease in excitability

Term
what is comatose?
Definition

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

 

comatose = pH of 7

Term
T/F: hyperventilating is caused a decrease in pH in the cells
Definition

False:

1) caused by an increase in pH

 

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

Term
how is epilepsy related to pH and excitabilty?
Definition
an increase in pH (pH = 8) can cause people that are predisposed to epilepsy to precipitate a seizure by hyperventilating
Term
what is ketosis?
Definition

severe diabetic acidosis

 

comes from keto acids

Term
what happens in ketosis?
Definition

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

Term
T/F: coma is caused by an increase in pH
Definition

False:

caused by a decrease in pH

comatose = pH of 7

Term
what are methylxanthines?
Definition

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

 

these affect the excitability of synaptic transmissions

Term

T/F: methylxanthines increase excitability of neurons

How?

Definition

True:

 

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

Term
T/F: caffeine is found in all things sugary
Definition

False:

not found in chocolate

 

found in coffee, tea, and some sodas

Term
T/F: theobromine is found in tea
Definition

False:

theophylline is found in tea

Term

__________ is found in chocolate

___________ is not found in cholocate

Definition

theobromine is found in chocolate

caffeine is not found in chocolate

Term

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

why or why not?

Definition

False:

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

Term

what affect do local anesthetics have on synapse tranmissions?

 

Definition

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

this decreases excitability of neurons

Term
T/F: local anesthetics increase threshold potential by acting on Na inactivation gates thus decreasing excitabilty of neurons
Definition

False:

they act on Na activation gates (not inactivation gates)

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