NBDE Tutorials

[Henna]

All subject related ( NDB1,NDB2, NBDE) info can be shared here.

This thread is exclusively for users who want to help others by explaining a certain topic of interest, post mnemonic's or questions ( please include answers too) and for deliberating academically informative information.

Please don't post unrelated links, websites ( use the "links of interest" for this) or any other messages including words of thanks and encouragement here.


( suggestions and opinions on how to improve and modify this thread are welcome)

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[mogembo]

Okay, I'll be the first to ask.

Which of the following represents the pH of a solution that has a 10 -5 (1/100000) M concentration of OH- ion?

A) 5
B) 7
C) 9
D)determinable only if pK is known
E) determinable only the base composition is known






Answer is (C)--9

Can somebody please explain me how to calculate this?

Thanks in advance

 

[elementz]

hi Mogambo!
here's the answer to your question:

The pH and pOH of a water solution at 25oC are related by the following equation.

pH + pOH = 14
(where 14 is the Kw, the equilibrium constant for the ionization of water)

so,

when they have given the concentration of OH- ion as (10) -5 M that means the pOH is 5 (since pH=negative log of H+ ion conc., same for pOH )
so, for your question the answer would be,
pH=14-5=9
(or) simply that the Concentration of H+ ion is (10) -9M

you can calculate either the pH or pOH using this .Hope that helps.
Good luck with your preparation.Hope Mogambo Khush hua....

 

[mogembo]

Thanks a lot! Mogembo....*bahut* khush hua

 

[Tightseal]

Hey all,
Does anyone know about the pharmacology questions for part 2 NDB exam that are compiled together as an when they have been asked in the past exams. I think UOP gives this out to there dental students.Does any one have it or knows how to get it.

Thanks

 

[nondentist]

OUTLINE OF REVIEW TOPICS FOR RESPIRATION

Ventilation and Lung Mechanics
1. Air flow between atmosphere and alveoli of lungs is proportional to the difference between atmospheric and alveolar pressures and inversely proportional to airway resistance: Flow = (Patm ? Palv)/R

2. Between breaths, Patm = Palv, no air is flowing, and the dimensions of the lungs and thoracic cage are stable as the result of opposing elastic forces.
a. Lungs are stretched and are attempting to recoil, whereas the chest wall is compressed and attempting to move outward.
b. This creates a subatmospheric intrapleural pressure and hence a transpulmonary pressure that opposes the force of elastic recoil.

3. During inspiration, contractions of diaphragm and inspiratory intercostal muscles increase volume of the thoracic cage.
a. This makes intrapleural pressure more subatmospheric, increases transpulmonary pressure, and causes the lungs to expand.
b. This expansion initially makes alveolar pressure subatmospheric, which creates the pressure difference between the atmosphere and alveoli to drive air flow into lungs.

4. During expiration, the inspiratory muscles cease contracting, allowing the elastic recoil of the chest wall and lungs to return them to their original between-breath size.
This initially compresses the alveolar air, raising alveolar pressure above atmospheric pressure and driving air out of the lungs.

5. Lung compliance is determined by the elastic connective tissue of the lungs and the surface tension of the fluid lining the alveoli. The surface tension is greatly reduced, and compliance increased, by surfactant, produced by cells of the alveoli.

6. Airway resistance determines how much air flows into the lungs at any given pressure difference between atmosphere and alveoli.
a. Major determinant of airway resistance is radii of airways.
b. Airway resistance is greatly increased during an asthma attack because of contraction of airway smooth muscle.

7. The vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation and
a. is the sum of resting tidal volume, inspiratory reserve volume, and the expiratory reserve volume.
b. The air remaining in the lungs is the residual volume.

8. Minute ventilation is the product of tidal volume and respiratory rate.
Alveolar ventilation = (tidal volume ? dead space volume) X (respiratory rate).
Tidal volume = amount of air inspired or expired during each breath.
Dead space = the portion of inspired air that fails to reach areas of gas exchange.

Exchange of Gases in Alveoli and Tissues
1. Exchange of gases in lungs and tissues is by diffusion, as a result of differences in partial pressures. Gases diffuse from a region of higher partial pressure to one of lower partial pressure.

2. In general adequate gas exchange depends on:
a. Thickness of membrane.
b. Surface area of membrane.
c. Solubility of the gas in the substance of the membrane.
d. Pressure difference between the two sides of the membrane.

3. At sea level, atmospheric air has a PO2 of 160 mmHg and a PCO2 near zero.

4. Average values in arterial blood: PO2 is 100 mmHg and PCO2 is 40 mmHg.

5. Hypoventilation
a. exists when there is an increase in the ratio of CO2 production to alveolar ventilation.
b. results in an increase in blood hydrogen ion concentration ([H+]) and a decrease in blood pH. This is called respiratory acidosis.

6. Hyperventilation
a. exists when there is a decrease in the ratio of CO2 production to alveolar ventilation.
b. results in a decrease in blood [H+] and an increase in blood pH. This is called respiratory alkalosis.

Transport of O2 in Blood
1. 98% of O2 is transported bound to hemoglobin and 2% dissolved in blood.

2. At saturation, hemoglobin binds to 4 O2 molecules.

3. The major determinant of the degree to which hemoglobin is saturated with O2 is the blood PO2.
a. Almost 100% saturated at a PO2 of 100 mmHg. The fact that saturation is 90% complete at a PO2 of 60 mmHg permits relatively normal uptake of O2 by the blood even when alveolar PO2 is moderately reduced.
b. Hemoglobin is 75% saturated at the normal systemic venous PO2 of 40 mmHg. Thus only 25% of the O2 has dissociated from hemoglobin and entered the tissues.

Transport of CO2 and Hydrogen Ion in Blood
1. The majority of the CO2 in the blood combines with water to form carbonic acid (H2CO3) (catalyzed by the enzyme carbonic anhydrase), which then dissociates to bicarbonate (HCO3) and H+. Thus the majority of CO2 is carried in the blood as HCO3.

2. H+ generated from carbonic acid is transported in the blood bound to hemoglobin.

Control of Respiration
1. Breathing depends upon cyclical inspiratory muscle excitation by the nerves to the diaphragm and intercostal muscles. This neural activity is triggered by the medullary inspiratory neurons.

2. Inputs to the medullary inspiratory neurons for the involuntary control of ventilation are from
a. peripheral chemoreceptors- the carotid and aortic bodies- and
b. central chemoreceptors.
c. lung stretch receptors.

3. Ventilation is reflexly stimulated by
a. decrease in arterial PO2, mediated by the peripheral chemoreceptors, but only when the decrease is large.
b. even a slight increase in arterial PCO2, mediated via both the peripheral and central chemoreceptors. The stimulus for this reflex is not the increased PCO2 itself, but the concomitant increased [H+] in arterial blood and brain extracellular fluid.
c. an increase in arterial [H+] resulting from causes other than an increase in PCO2 (metabolic acidosis), mediated via the peripheral chemoreceptors. The result of this reflex is to restore [H+] toward normal by lowering PCO2.

4. Ventilation is reflexly inhibited by an increase in arterial PO2, by a decrease in arterial PCO2 or [H+] and by activation of lung stretch receptors.

 

[Cutie Pie]

Hello CANDLES, thanks for telling everyone.If u come to know abt these papers please let us know by posting u r reply here. Thanks once again.

 

[Ashamurali]

Hi,
Could anyone tell me what preparations we are supposed to do for the California bench tests?Amalgam class 2,inlay,onlay,3/4crown,7/8crown,full crown..Is there anything else?

 

[gpg]

Now you will need only two things to master DAO:

1)The decks....I have been refering the 2001 version.So that will be good enough.

2)The ASDA reprints......the ones I have are till 1996


So lets start with the topic about which I did not know ANYTHING till I started studing for my boards.And I used to go crazy trying to figure them out.

Mandibular Movements

Now basically there are only 2 movements....
A)The Functional Mandibular Lateral Excursion.
B)Mandibular Protrusion.

But since the mandible is a bilateral joint,there are two sides to consider in the lateral movement.

1)the working side:this is the side to which the mandible is moving.

2)Non-working side:The other side.....thats the side from which the mandible is moving away from.

How do you determine which is the working side and the non-working side looking at the arrows on the text?

SIMPLE!

When the arrow is exactly horizontal......pointing towards the lingual on mandibular and buccal on the maxillary teeth it is a WORKING SIDE MOVEMENT!

Now I am sure all of you will be able to determine the side looking at the occlusal surfaces of the teeth shown.

So when there is a Horizontal arrow that is a working side movement of the same side.

1)Imagine a diagram showing the occlusal surfaces of the lower right posteriors.The arrow is exactly straight pointing towards the lingual,then the movement is a working side movement to the right side.

2)When the occlusal surfaces of the upper left posteriors is shown with the arrows pointing to the buccal, its a working side movement to the left.

As simple as that!

Now in case of the non-working side movements,the arrow is obliquely directed.

The Mandibular cusps move mesially and lingually and the Maxillary teeth move distally and facially.

So if u have the occlusal surfaces of the lower right posteriors with the arrow pointing distofacially its a non-working side movement to the right(see 1 above)

and similarly if you have the occlusal surfaces of the upper right posteriors with the arrow pointing to the mesiolingually its the non-working side movement to the left....see 2 above!

Remember the arrows do not depict the movement of the cusps shown.They indicate the direction the occluding cusps move in the respective movement

so in 1 even though u have the lower right teeth shown with the arrow pointing to the lingual, it does not mean that the lower teeth are moving lingually.It means that the occluding teeth, viz. the upper right teeth are moving lingually against the lower teeth.

The protrisive movement is very easy to understand, as there is no working and non-working side confusion here.

just remember the direction of the arrow on the respective teeth.....it will point anteriorly on the maxillary and posteriorly on the mandibular teeth.

VERY ZIMBLE.......as my mallu geography teacher would have said it.

so now I would like you all to get out your reprints first, read only the questions with the occlusal surfaces of teeth and arrows on them.....and try to solve them using this key which I have given.You all have to get them right.

a very simple way to do it is to make a chart in the following format

Direction of arrow on the working side as shown on following teeth:

1)maxillary 2)Mandibular

buccally lingually

and draw diagrams showing the movement and direction of movement of cusps.

do the same thing for the non working side....and put it up on the mirror......you will surely master this aspect within a week,unless you are bald....in which case you have to put it somewhere u will see it the most......

There is a lateral-protrusive movement, but I think there is only one question showing this movement so I will not include this here as it is very confusing and not too important.

hope I have not bored you all with this.

Please let me know what you feel about my tutorial, whether it has helped you in any way and whether you would like me to make any changes in the next one....

happy mandibular movements!

 

[gpg]

Well here we are with the next tutorial

we will have a look at the actual occlusion of our teeth,
mainly the posteriors:

lets start with the Maxillary cusps.

1)Buccal cusps:-

Maxillary buccal cusps occlude only with grooves and embrassures of
class counterpart or class counterpart and tooth distal to it.

A)The cusp of the canine lies in the facial embrassure b/w the
mandi canine and pre-molar.

It is unique in that it is the only tooth which overlaps teeth in
both the anterior and posterior segment.

How ever the TIP does not articulate with any tooth.

B)Ist Pre-molar:-

It occludes with the facial embrassure b/w mandi pre-molars.

C)IInd Pre-molar:-

It occludes with facial embrassure b/w 2nd PM and 1st molar.

D)Ist Molar:-

MB Cusp:MB groove of mandi 1st molar

DB CuspB groove of mandi 1st molar

Oblique Ridgeeve. Groove b/w DB and Distal cusp of mandi 1st Molar

E)IInd Molar:

MB Cusp:MB groove of mandi 2nd molar

DB Cusp:Embrassure b/w mandi 2nd and 3rd molar.

---------------------*----------------------

Lets now go on to the Lingual cusps:

These occlude with Fossae and Marginal Ridges of class counterpart or
class counterpart and tooth distal to it.

A)Ist Pre-Molaristal triangular fossa of mandi 1st PM.

B)IInd Pre-Molaristal triangular fossa of mandi 2nd PM

C)Ist Molar:

-ML Cusp:Central Fossa of mandi 1st molar

-DL Cuspistal Marginal Ridge of 1st molar and
Mesial Marginal Ridge of 2nd molar

D)IInd Molar:

-ML Cusp:Central Fossa of mandi 2nd molar

-DL Cuspistal Marginal Ridge of 2nd molar and
Mesial Marginal Ridge of 3rd molar

Imp Notes:

The TIPS do not occlude with any tooth.

Also it is the triangular ridge of the maxillary cusps which are resting in the sucli and embrassures of the mandibular teeth.....there are a couple of questions about this point too...

I think I have covered almost everything about the maxillary cusps.....the tut on mandibular cusps will be uploaded in a day or two....
__________________

 

[gpg]

OK ppl its occlusion time.....

this time we will be having a closer look at the mandibular cusps.....and where they leave their mark...

A)Buccal cusps:

They occlude into central/mesial/distal fossae of their class counterpart or onto the marginal ridges of their counterpart and the tooth mesial to it.

lets go tooth wise...

1)Ist Pre-molar: Mesial triangular fossa of maxillary 1st PM
and Distal Marginal Ridge of Canine

2)IInd Pre-molar: Mesial triangular fossa of 2nd PM

3)Ist Molar:

-MB cusp: Mesial marginal ridge of 1st molar
and Distal marginal ridge of 2nd PM

-DB cusp: Central fossa of 1st molar

-Distal cusp: Distal triangular fossa of 1st molar

4)IInd Molar:

-MB cusp: MMR of 2nd molar and DMR of 1st molar

-DB cusp: Central fossa of 2nd molar


___________________________________________

B)Lingual Cusps:

They occlude into the lingual embrassures between their class counterpart and tooth mesial to it or into the lingual grooves of their counterparts

1)Ist Pre-molar: The lingual cusp does NOT occlude
with any opposing tooth.

2)IInd Pre-molar: Lingual embrassure btween Maxillary Pre-molars

3)Ist Molar:

-ML cusp: Lingual embrassure between 2nd PM and 1st molar

-DL cusp: Lingual groove of 1st molar

4)IInd molar:

-ML cusp: Lingual embrassur between 1st and 2nd molar

-DL cusp: Lingual groove of 2nd molar

 

[Athene]

thanks...gpg.....

 

[toothfairy78]

hi gpg thanks a lot for ur tutorial its brilliant.i have a q ...what is the primary function of pulp?this is fromt he asda reprint of da paper 1977(question number30),its in packet a.now the choices are,innervation,provide multiple apical foramina etc.the answer is #1,the formation of DENTIN? now how can this be?i have wiht my othjer set of papers i have as well.they also have the same ans listed now i am thoroughly confused shouldnt that ebthe job of soemthign else?liek enameloblasts prod enamel etc whats pulp got to do wiht dentin formation could ull pls check&lemme know if ull have the same ans as well in ur papers?
dec1977 da paper q no30.plssssssssssssssssssssssssssssss help!

 

[dentaldoc]

hi gpg thanks a lot for ur tutorial its brilliant.i have a q ...what is the primary function of pulp?this is fromt he asda reprint of da paper 1977(question number30),its in packet a.now the choices are,innervation,provide multiple apical foramina etc.the answer is #1,the formation of DENTIN? now how can this be?i have wiht my othjer set of papers i have as well.they also have the same ans listed now i am thoroughly confused shouldnt that ebthe job of soemthign else?liek enameloblasts prod enamel etc whats pulp got to do wiht dentin formation could ull pls check&lemme know if ull have the same ans as well in ur papers?
dec1977 da paper q no30.plssssssssssssssssssssssssssssss help!

The pulp has in it, the odontoblast which produces dentin as long as the tooth is vital! So that's why it is listed as it's primary function.

Hope this helps.

 

[neha]

hi everyone,
I am confused with glomerular filtration rate,plasma clearance rate n substances which determine them.like is it creatinine or PAH or inulin which is used for determining the GFR.And also what products are reobsorbed n secreted by the tubules,it would be really helpfull if anyone can really help me with this
Thanks

 

[resagoyal]

need advice fcor these question
In ideal Occlusion the lingual cusp of max second premolar contacts
1 the distal fossa of ,mandibular second premolar
2 distal marginal ridge of mandibular first molar
3 mesial marginal ridge of mandibular first molar

largest incisal or occlusal embrasure is located between which of the following teeth
1 max lateral and canine
2 max canine and first premolar

in cervical cross section, the root of a mandibular canine is described as
1 triangular
2 roughly conical
3 flattened in a mesiodistal direction
4 broader mesiodistally on the lingual than on the facial

 

[dentaldoc]

need advice fcor these question
In ideal Occlusion the lingual cusp of max second premolar contacts
1 the distal fossa of ,mandibular second premolar
2 distal marginal ridge of mandibular first molar
3 mesial marginal ridge of mandibular first molar

largest incisal or occlusal embrasure is located between which of the following teeth
1 max lateral and canine
2 max canine and first premolar

in cervical cross section, the root of a mandibular canine is described as
1 triangular
2 roughly conical
3 flattened in a mesiodistal direction
4 broader mesiodistally on the lingual than on the facial

The answers: 1, 1, 3.
correct me if I am wrong

 

[dentaldoc]

hi everyone,
I am confused with glomerular filtration rate,plasma clearance rate n substances which determine them.like is it creatinine or PAH or inulin which is used for determining the GFR.And also what products are reobsorbed n secreted by the tubules,it would be really helpfull if anyone can really help me with this
Thanks

Ok, here is what I think,

Inulin is used for determining the GFR (Plama clearence of inulin indicates GFR)
Serun creatinine & assessment of blood urea nitrogen(BUN) also helps to determine kidney function. These tests primarily evaluate GF by assessing GFR.

Inulin is filtered but not secreted or reabsorbed by the kidney tubules.
PAH is filtered & secreted.
Creatinine is filtered & secreted(small amount) but not reabsorbed.

Hope this helps

 

[resagoyal]

don't u think the incisal embrasure should be the largest in between the canine and the PM and don't u think the the lingual cusp should fall in the distal fossa of the mandibular second molar

 

[neha]

Thanks dentaldoc.I will remember them now hopefully

 

[dentaldoc]

don't u think the incisal embrasure should be the largest in between the canine and the PM and don't u think the the lingual cusp should fall in the distal fossa of the mandibular second molar

I think incisal embrasure will be the largest in between the canine and the PM if it's in the case of mandibular teeth.

the lingual cusp of maxilary second PM should fall in the distal fossa of the mandibular second PM.

 

[G.P]

Do we need to use any text books for pharmacology other than the decks and the reprints.I find them inadequate as compared to what i had studied in the B.D.S. course .If so ,which texts should be used.Kindly let me know.

 

[neha]

Hi,
Which primary tooth bears least resemblance to any other tooth primary or permanent?

Is it the primary mandibular first molar or primary maxillary first molar.

 

[dentaldoc]

Hi,
Which primary tooth bears least resemblance to any other tooth primary or permanent?

Is it the primary mandibular first molar or primary maxillary first molar.

Pri Man 1st molar.

 

[prets]

All subject related ( NDB1,NDB2, NBDE) info can be shared here.

This thread is exclusively for users who want to help others by explaining a certain topic of interest, post mnemonic's or questions ( please include answers too) and for deliberating academically informative information.

Please don't post unrelated links, websites ( use the "links of interest" for this) or any other messages including words of thanks and encouragement here.


( suggestions and opinions on how to improve and modify this thread are welcome)

hi there, i am new to us and i am preparing for my nbd part 1 pls tell me where can i get the decks for both 1 an2 , if possible second hand. thanks for helping.

 

[elementz]

hi there, i am new to us and i am preparing for my nbd part 1 pls tell me where can i get the decks for both 1 an2 , if possible second hand. thanks for helping.

Dear Prets,
Welcome to SDN!
Regarding decks you can check out thw sales forum on SDN.Other than that you can try finding stuff on www.ebay.com.
All the best.

 

[drniralp]

hi guys i m giving my part i in august and i just came across this thread since i didnot have a computer couldnot much access to this site anyway i just went through the tutorials of gpg i thought it was awesome but i had one doubt regarding the movements of cusps during non-working movements for eg
in an ideal intercuspal position, when the mandible makes a right lateral excursion, mesiolingual cusp of permanent maxillary right first molar opposes the
1. sulcus bet mesiofacial and distofacial cusps of mandi first molar
2 sulcus bet distofacial and distal cusps of mandi first molar
3. embrassure bet mandi first molar and mandi second pre molar
4. sulcis bet lingual cusps of mandi first molar
5. embrassure bet mandi first and second molar
i m very confused regarding such movement like when maxi or mandi teeth move in lateral movements which cusps which contact or pass bet which teeth , which is the best way to determine such things.
any help is appreciated i m very confused. :

 

[pinktooth]

The ideal way would be to get a plaster model to practice but the best way(I use it!!) is to make movt and check in your mouth....don't worry about the stares to get

 

[dentistdreamer]

Does anyone want to sell used NBDE Part I material? I would like to pay for it. I am living in Columbus, OH. So people living in the same place are preferred. My e-mail is [email protected]. thanks!

 

[vinny]

hi
am new to this discussions.have a small doubt and need clearance reg...
please help me out guys...

in hematology,a shift to the left infers an increase in circulating immature neutrophils...

what does this mean

 

[treasure]

I was reading DA decks & this card is driving me crazy......
If anyone would care to explain the following it would be wonderful.....

In a workjing side movemnet, the mesiobuccal cusp of maxillary first molar passes thro the lingual groove of the mandi first molar.

Ina a working side movement, the mesiobuccal cusp of maxi second molar passes thro' the facial groove of mandi sec molar.

Ina a working side movement, the oblique ridge of max first molar passes thro distobuccal sulcus of mandi first molar.

Could someone please elaborate why the above is true......!!!!!!
Treasure!!!

 

[Silve]

have a question. I am not sure what are the materials needed for aprt 2. So let me list the ones I know and let me know if I miss something.
1.Dental decks-2001( COULD YOU TELL ME WHICH YEARS IS THE LATEST 2004 IS THERE??)
2.question papers booklets.
3.Sample Case Studies booklet.
4.Kaplan notes.( COULD YOU TELL ME WHICH YEARS IS THE LATEST 2004 IS THERE??)
5.Sample Case Studies booklet.
6.Color pathology booklet

PLEASE LET ME KNOW IF I MISS SOMETHING HERE. ALSO WHICH YEARS OF DECKS AND KAPLAN ARE THE LATEST???

thanks guys
ss

 

[kiwiboy]

Hi everyone

I am about to do NBDE part 2. Very confused with so called un-official released questions a friend gave it to me.Anyone know how reliable they are & how high yeild they are? I have alot of controversies in the answers as well.

kiwiboy

 

[shauda]

hi
am new to this discussions.have a small doubt and need clearance reg...
please help me out guys...

in hematology,a shift to the left infers an increase in circulating immature neutrophils...

what does this mean

hai vinny ,
I think I could explain u the concept .Let us consider the formation of granulocyte as an example.The steps involved in the formation are as follows:

myeloblast-promyelocyte-myelocyte-metamyelocyte-granulocyte

In the above case a shift to left means metamyelocyte , myelocyte &so on (reverse ) which are all immature cells(only granulocytes are mature cells)
Hence a shift to the left infers an increase in circulating immature cells.
Vinny hope I was able to clear ur doubt.

 

[sarita_s]

Please help me with this question

If a person has normal musculature but has difficulty swallowing, which nerves should be tested for function?
Vagus and Splanchnic Or
Vagus and Glossopharyngeal

Thank you
Sarita

 

[dramol]

hi guys i m giving my part i in august and i just came across this thread since i didnot have a computer couldnot much access to this site anyway i just went through the tutorials of gpg i thought it was awesome but i had one doubt regarding the movements of cusps during non-working movements for eg
in an ideal intercuspal position, when the mandible makes a right lateral excursion, mesiolingual cusp of permanent maxillary right first molar opposes the
1. sulcus bet mesiofacial and distofacial cusps of mandi first molar
2 sulcus bet distofacial and distal cusps of mandi first molar
3. embrassure bet mandi first molar and mandi second pre molar
4. sulcis bet lingual cusps of mandi first molar
5. embrassure bet mandi first and second molar
i m very confused regarding such movement like when maxi or mandi teeth move in lateral movements which cusps which contact or pass bet which teeth , which is the best way to determine such things.
any help is appreciated i m very confused. :

drniralp,
I think the answer for ur Q is -- 4 i.e sulci bet ling. cusps of mand 1 st molar.
Check it i ur own mouth

 

[smilein]

Could any body clarify my confusion reg. depolarisation & repolarisation,hyperpolarisation..
I'm a bit confused after refering to kp then decks
I would appreciate if any one could clear my in a most simplest way you could.

 

[skm_11]

Hi Smiley,
I will try to explain your doubt.
You know that the resting membrane potential is -70mv.This is caused because of the un equal distribution of charged atoms (ions) on either side of the cell membrane . It is little negative on the inside of the cell,hence the "minus" (-70).This will continue to be as long as the nerve is not disturbed or not stimulated.
The two major ions responsible for the membrane potential are Na+ and K+.There are gates in the nerve membrane namely the Na+ GATES and K+ GATES( Channels).There is a pump called as the "Na-K pump".The active transport of the ions across the cell membrane is because of this pump.This forces the Na ions out of the cell and K ions into the cell.There will more Na concentration outside the membrane and K concentration inside,because of this.
When the cell membrane is at rest,Na gates are closed .But when there is a stimulus,the Na channels are opened and all the Na ions come in rushing into the cell and there will be a sudden increase in the positive charge inside the cell and the membrane potential will go from -70mv to say +30 mv in few milliseconds.This is the DEPOLARISATION
Na channels open only briefly and close again.
Now K channels open (all of them) and since there is more concentration of K inside the cell,K goes out of the cell, bringing down the membrane potential to its original value .this is REPOLARISATION.
Even after the resting membrane potential is reached sometimes the K channels are open for longer periods and then more K ions go out ,this is HYPERPOLARISATION
Hope i didnt confuse u even more and i know my explanation is very lengthy..but.. hope it helps you.Good luck

 

[smilein]

Hi Smiley,
I will try to explain your doubt.
You know that the resting membrane potential is -70mv.This is caused because of the un equal distribution of charged atoms (ions) on either side of the cell membrane . It is little negative on the inside of the cell,hence the "minus" (-70).This will continue to be as long as the nerve is not disturbed or not stimulated.
The two major ions responsible for the membrane potential are Na+ and K+.There are gates in the nerve membrane namely the Na+ GATES and K+ GATES( Channels).There is a pump called as the "Na-K pump".The active transport of the ions across the cell membrane is because of this pump.This forces the Na ions out of the cell and K ions into the cell.There will more Na concentration outside the membrane and K concentration inside,because of this.
When the cell membrane is at rest,Na gates are closed .But when there is a stimulus,the Na channels are opened and all the Na ions come in rushing into the cell and there will be a sudden increase in the positive charge inside the cell and the membrane potential will go from -70mv to say +30 mv in few milliseconds.This is the DEPOLARISATION
Na channels open only briefly and close again.
Now K channels open (all of t shem) and since there is more concentration of K inside the cell,K goes out of the cell, bringing down the membrane potential to its original value .this is REPOLARISATION.
Even after the resting membrane potential is reached sometimes the K channels are open for longer periods and then more K ions go out ,this is HYPERPOLARISATION
Hope i didnt confuse u even more and i know my explanation is very lengthy..but.. hope it helps you.Good luck

Hi skm,

Thanqs a loooot for ur patience in explaining my basic dout,confusing since my college.It's been cleared by you now.
your explanation is in a easy way ,re solved my confusion.
thaxz 4 all
GOOD LUCK 2 u too...

 

[dentb'lore]

Hi all
can ne one explain me,
about the FOUR HANDED DENTISTRY...

Thanks .

 

[gpg]

Four Handed Dentistry refers to the practise where the dentist is continously assisted by a chair side assistant.

The assistant is either sitting or standing on the other side of the chair and is mainly responsible for suction and handing out materials and instruments.

This is expected to save time and also prevent contamination of the dentists hands.

 

[Athene]

Four Handed Dentistry refers to the practise where the dentist is continously assisted by a chair side assistant.

The assistant is either sitting or standing on the other side of the chair and is mainly responsible for suction and handing out materials and instruments.

This is expected to save time and also prevent contamination of the dentists hands.

Hi...Thanks a lot.

 

[dentistz]

HI!
Am looking for Dental Decks & BRS for Pathology & Physiology (Second Hand).
Anybody interested in selling pls contact at
[email protected]
THANKS

 

[sonibun]

hi
I want your help to trace the site for Canadian dental schools which take international students.
waiting for reply
sonibun

 

[nimeshshingala]

hi
I want your help to trace the site for Canadian dental schools which take international students.
waiting for reply
sonibun

click here for american and canadian dental schools

 

[sonibun]

click here for american and canadian dental schools

hi
how r u ??how is ur prepartn for joining the school i got rejectn lettr from upenn and expectng same from boston.my sruggle is not over yet keep in touch i will have to give canadian exam no other option for me.Can u guide me for HARP in Canada.
with thanks and regards

 

[bhumika_201]

hi all
i have one question:-
what is the most common site for intraoral SCC?
LATERAL BORDERAND VENTRAL SURFACE OF THE TONGUE
FLOOR OF THE MOUTH
actually i m confused with the answer given in dental decks and kaplan
in kaplan it is written floor of the mouth and in dental decks its lateral border and ventral surface of tongue.
if anybody knows the exact answer plz help.
thanx and good luck

 

[rahmed]

hi all
i have one question:-
what is the most common site for intraoral SCC?
LATERAL BORDERAND VENTRAL SURFACE OF THE TONGUE
FLOOR OF THE MOUTH
actually i m confused with the answer given in dental decks and kaplan
in kaplan it is written floor of the mouth and in dental decks its lateral border and ventral surface of tongue.
if anybody knows the exact answer plz help.
thanx and good luck

The answer is

Tongue - Lateral Border & Ventral Surface ...Incidence 35%

Floor of the Mouth......Incidence 30%

rahmed

 

[fido!]

u r right sir! it is the ventral surface of the tongue.

 

[rahmed]

u r right sir! it is the ventral surface of the tongue.

Thanks

rahmed