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First semester > PSL-Week 2 > Flashcards

PSL-Week 2 Flashcards

1
Q

True or false, receptor determine the effect and not the transmitter?

A

True

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2
Q

What are the two types of receptores?

A

ionotropic which directly opens channels and metabotropic which initiate a metabolic cascade to activate enzymes

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3
Q

What do the ionotropic effects result in?

A

ligand binding and opening an ion channels is known as ionotropic effect and ligand binding will result in Post synaptic potential which remains as long as transmitter is present

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4
Q

What are the two types of Post synaptic potentials?

A

EPSP= excitatpry post synaptic potential which cause depolarization
IPSP= inhibitory post synaptic potential which cause hyperpolarization

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5
Q

What is an example of ionotropic receptor?

A

nicotinic receptor for acetylcholine where when acetylcholine binds the receptor it causes an EPSP and cation channels open

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6
Q

What are the ligands that can bind ionotropic receptores?

A

acetylcholine, glutamate, GABA, and glycine

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7
Q

How are metabotropic effect different from ionotropic?

A

the metabotropic receptor will activate an enzyme, usually the G protein, when it is bound by ligand

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8
Q

Which effect cause a faster change in MP when wanting to infleunce an ion channel by ligand binding?

A

ionotropic effect will result in faster EPSP or IPSP than metabotropic because in metabotropic the change has to go through series of enzyme activity before influencing teh ion channels

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9
Q

What is teh metabolic receptor for noradrenaline and how does that ligand binding causes changes?

A

B- adrenoreceptor is the metabolic receptor for noradrenaline and binding of this receptor will activate adenylyl cyclase via the G-protein and increase the proiduction of cAMP
cAMP then activate kinase to phosphrylate teh Ca channels and increase Ca channels influx which is improtant for heart muscle and contractility

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10
Q

What are beta blockers and what are their effects?

A

beta blockers are ligand that block interaction btw the B-adrenoreceptor and noradrenaline which decreases the influx of Ca and decreases contractility, this can be helpful for people with high heart rate

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11
Q

What are some examples of ligands for metabolic receptores?

A

acetylcholine, peptides like ADH, catecholamines liek noradrenaline, serotonin, and purines

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12
Q

What is difference between AP and PSP?

A

PSP is a graded potential and it is found in inexitable membranes where the they don’t have a high Na voltage gated channels

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13
Q

Do PSP also exhibit saltatory conduction?

A

PSP exhibit passive conduction across the membrane to get to teh trigger zone

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14
Q

What are the two types of summations that can occur?

A

Spatial summations and Temporal summations

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14
Q

Why are PSP summations possible?

A

because the tissues are poorer conductors and they will loss current as you go through membrane to reach the trigger zone and some stimuli aren’t strong enough to cause PSP so they can be added to get the PSP

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15
Q

What si one requirment for spatial summation to occur?

A

the individual EPSP has to overlap in time to reach teh trigger zone at teh same time and cause the EPSP, where the individual EPSP gets added and then fire one PSP

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16
Q

What distinguish temporal summation from spatial summation?

A

spatial need a minimum of 10-30 synchronous EPSP while temporal only need few active synapses but eah generate EPSP at high frequency

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17
Q

What distinguish temporal summation from spatial?

A

temporal summation depend on timing, where as long as the next EPSP arrives before the previous ones dies out, then it can add to it and keep building onto each other, each g=one getting the potential closer to threshold step by step until they pass the threshold

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18
Q

How does the location of the IPSP give them the ability to shunt the depolarizing EPSP currents by preventing them from reaching the trigger zone?

A

IPSP are located right in the midddle between the trigger zone and EPSP and they involve teh opening of Cl ions so when membrane is depolarized, their signal will open the Cl ion channels and bring the MP back to -70 mV which prevents exitation and that si how it exhibit its inhibitory effect

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19
Q

Where are the IPSP located and how does that benefit them?

A

located on teh soma to completly block signal coming from EPSP

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20
Q

What is spike train?

A

it is when powerful input is translated into continous steam of AP

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21
Q

How can spike train be generated?

A

need to hyperpolarzie after each AP to restore the Na channels to reopen them for next AP and generate teh spike train

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22
Q

How can teh depolarization block be overcomes to generate many AP inspike train?

A

as soon s the membrane has been depolarized, immediatly depolarize below the threshold using K channels that open when membrane is repolarzing with leakage K channels so that the strong stimuli can generate another AP

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23
Q

What si receptor potential?

A

the change in MP due to reciept of signal from exterior sensory cue which causes depolarization of sesnory receptores and that potential is a graded potential

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24
Q

Where can we find the receptores that will sense that outside signal and what happens to them when they recieve that signal?

A

these receptores proteins are found in sensory cell membrane and they change their shape when they recieve the specific signal

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25
Q

Since the receptor proteins undergo a conformational change, what could that result in?

A

that will either directly open the ion channels that depolarize the membrane or cause enzyme activation via the G protein coupling that rpoduce second messenger which end up amplifying teh signal

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26
Q

What are teh stages of amplification?

A

G protein activating number of different enzymes and then each of those enzymes producing lots of secondary messenger

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27
Q

How does the specific receptors in our nose cause depolarization of memebrane that will reach the brain wehn it is boudn by specific odorant?

A

when the odorant bind the specific receptor, that will cause activation of the G protein which activates adenylyl cyclase and cause the production of cAMP and that cAMP directly binds the ion channels to let cations in and depolarize the membrane, this is in trigger zone and that graded potential will make its way to neuron in cell by amplifying the signal

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28
Q

What are the two catergories of the sensory cell transmission?

A

sensory cell may generate AP at spike generating zone
sensory cell may release vesicles when depolarized

29
Q

How does transmission of the signal using AP occur?

A

AP will be generated at the trigger zone and first patch of excitable membrane will generally be at branch point which means the receptor potential will ahve to travel and generate summation at branch point to reach threshold and get a AP

30
Q

How does transwmission of the signal through vesicles work?

A

the depolarizing current don’t have to produce its own AP, it will travel and depolarize the membrane to allow influx of Ca ions which trigger exocytosis of vesicles

31
Q

What is an example of signal transmission using vesicles?

A

taste receptor since the signal will travel and depolarize the membrane and cause exocytosis of vesicle

32
Q

What does adaptation mean?

A

MP decaying over time as the original voltage is not sustained and it’s dropped over time even if stimulus is constant

33
Q

What are the two types of adaptation?

A

slow adapting and rapid adapting

34
Q

What receptor is an example of slow adapting?

A

tonic receptores as they will fire rapidly when first activated and then slow to maintain their firing as long as stimulus is present and those receptores are baroreceptor and irritanat receptores

35
Q

What is an example of rapid adapting receptor?

A

phasic receptores as they fire when they first recieve the stimulus and then stop if stimulus stength remains constant and example of that is sense of smell

35
Q

How can new signal be created and precieved by receptor when new adaptation occured?

A

by increasing intensity of excitatory stimulus or removing the stimulus and allowing receptor to reset

36
Q

What is habutation?

A

response to successive stimuli at a time where repeated stimuli in succession will elicit weaker responses and the habituation depends on the cell as some will show larger degree than other

37
Q

What is the coding that occurs because of stimulus intensity?

A

it is the receptor potential that will vary directly in proportion with intensity of stimulus where greater stimulus means greater change in receptor potential but the impulse frequency will always be limited by refractory period

38
Q

After while, the stimulus intensity reaches a ceiling due to referactory period so what if more coding need to be done above this ceiling?

A

recruit more neurons

39
Q

What are the two strategies that post synaptic receptores use to code for strength of stimulus?

A

increase frequency of AP at excitable membrane and increase stimulus strength by recruiting additional receptor with higher threshold

40
Q

What is modality?

A

different types of stimulus

41
Q

How can we distinguish between different types of stimulus

A

Using Labeled line strategy where activity of one pathway means particular stimulus quality and nothing else

42
Q

What is population coding?

A

coding using ratio of activity from restricted number of different receptor types and specific stimulus is coded by ratio of activitu across the population of receptores and this is how multiple receptor function together to send CNS more information than would be possible

43
Q

What is receptive field

A

each sensory neuron is going to respond to particular areaand that is teh territory in which you could activate that neuron so it is always defined as in relation to given sensory neuron

44
Q

What is convergence in receptive field?

A

when many primary sensory neurons converge single on single secondary neuron that also causes their individual receptive fields to converge into one secondary receptive field

45
Q

What is the major function of the blood brain barrier?

A

to carefully regulate the extracellular fluid in neuronal environemnet by not changing the excitability of membrane and not having neurotransmitters floating around for no reason

46
Q

BBB can be though of as two folded entity, between what are these two folded entity?

A

one between blood vessels and interstitial fluid as fluid bathing neurons and other between blood vessels and CSF as fluid in ventricles

47
Q

True or false, there is free diffusion of chemicals between interestitial fluid and cerebrospinal fluid

A

true, it si almost as if there is no barrier

48
Q

What is cause of parkinson’s disease?

A

low levels of dopamine as the receptores are dead or damaged and injections of dopamine aren’t effective as they cannot cross the BBB so use the L-DOPA precursor that can cross BBB by amino acid transporter and then metabolize dopamine

49
Q

What is MSG and how does it relate to BBB?

A

it is mono-sodium glutamate which cannot cross the BBB and causes thirst and stiff neck but can activate glutamate receptores outside brain and peripheral nervous system

50
Q

How come BBB isn’t continous and some areas lack the BBB?

A

that is because some places have neurons that need to communicate freely with the blood stream like the pituitary gland that is directly related to hypothalamus so BBB is broken there to allow release of hormone or in circumventricular organs which has BBB broken si neurons can sense the specific chemical [ ]

51
Q

True or false, generally the BBB is broken in areas that interact with endocrine system or require sensitivity to metabolities

A

True

52
Q

Brain is chemically protected by BBB but how is physically protected?

A

by the skull and meningies and reticular formation

53
Q

What are the meninges and how do they protect the brain?

A

consist of 3 layered membrane lying between bone nad tissues of CNS and their role is to stabilize and protect the neural tissue from bruising against bone of skeleton

54
Q

What are the three layers of meninges?

A

Dura mater- tough membrane, sac containing brain and spinal cord
arachnoid membrane- delicate tissue
pia mater- on top of membrane and tethered to arachnoid by arachnoid trabeculae

55
Q

What is the subarachnoid space and how does it provide support?

A

space between arachnoid membrane and pia mater which is where brain floats to protect from meachnical stress

56
Q

What is reticular formation?

A

collection of loose nerve cells that deal with connecting brain to behaviour

57
Q

What does the subarachnoid space contain?

A

blood vessels, capillaries to brain tissue, BBB between capillaries and brain tissue

58
Q
A
59
Q

What is the difference between endothelial lining of blood vessels and that of endothelial cells in brain?

A

in blood vessels, they contain large gaps called fenestrations which allows molecules to pass while in brain, the junctions are induced by paracrine cells called pericytes and astocytes leaving no gap

60
Q

What are the ventricles and how are they connected between the two hemisphere?

A

ventricles are cavities deep in the brain and lateral ventricle is the one inside each hemisphere which is a paired structure wo it connects the ventricles

61
Q

Where does the CSF from central canal drain into?

A

CSF will move to outer parts of the brain and finally exit at top of the brain into large venous sinus

61
Q

What are arachnoid villi?

A

an out pouching of arachnoid tissue that stick out through dura mater into venous sinus and 1/2 of CSF drains into teh venous system

62
Q

How do the ventricles empty their CSF?

A

lateral ventricles empty into 3rd ventricle which is right in middle and then the 3rd ventricle communicate using aqueduct of sylvius with the 4th ventricle and then the fourth ventricle connect to the central canal

62
Q

What is CSF made from?

A

it is mostly made by choroid plexus and some produced by capillaries inside the brain

63
Q

What are choroid plexus?

A

mader up of epithelia cells connected by tight jucntions and is continously producing the CSF to circulate cleansing mechanism and it is a dense network of capillaries ballooning out into ventricular wall

63
Q

What are characteristics of cerebrospinal fluid?

A

it has same osmolarity and [Na] as blood biut reduced [k], [Ca], and [Mg]

63
Q

What are astrocytes>

A

are glial cells that provide bridge between neurons and blood vessels as it has one foot end around capillary and other foot end aroud neurons

63
Q

Why is a lumbar puncture useful?

A

is a diagnostic and therapeutic procedure that collect smaple of cerebrospinal fluid and presence of blood or proteins in it usually indicate infection as smaple of CSF is indicator of chemcial environment in brain

64
Q

How do astrocytes regulate local blood flow?

A

since they are already bridging th gap between BV and neurons, they cna signal BV when to dilate and constrict as when they detect increased signalling, they can send metabolic signal outward to BV and signal neuronal activity level
glutamate trigger Ca release within astrocytes and the Ca wave travel through astrocytes to trigger prostaglandin release at end foot and prostaglandin causes vasodilation which increase blood flow

64
Q

What are characteristics of astrocytes?

A

they are efficient at glycolysis and produce lactate as end product which is substrate for ATP production so it provides energy substrates for eurons and remove neurotransmitters

First semester (24 decks)

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