Discuss:Some wrong answers in (part 1)1N relesed exam?

[kelvinsng]

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126). difference mandibular and maxillar premolars?
Ans: C
mandibular premolars have crowns tilted to the facial.

I thought it's jut reverse. googled the evidence:
Woelfel's dental anatomy:http://books.google.com/books?id=iVGbPei7gZ4C&pg=PT525&lpg=PT525&dq=mandibular+premolars+tilt+to+the+facial&source=bl&ots=Zf_uDcZIXu&sig=2iYyhAqvH4WCA_SGb2jVzNMDk8w&hl=en&ei=n3n8S4ufDIa69QTAoJ2kBg&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBMQ6AEwAA#v=onepage&q=mandibular%20premolars%20tilt%20to%20the%20facial&f=false
2) 41. A should be the answer instend of C.

Am I right? lets discuss it.

 

[ddsaspi]

anyone knows the ans for this q?
cryps of Lieberkuhn are in what layer of small intestine?? I think muscularis externa but not sure
thanks

Hey cusp, these crypts are a part of the epithelium of small and large bowel, they open at the base of each villus , where new epithelial cells are produced

 

[pb2007]

Hey cusp, these crypts are a part of the epithelium of small and large bowel, they open at the base of each villus , where new epithelial cells are produced

jst wanted to add sum more info ,its part of muscularis mucosa
http://en.wikipedia.org/wiki/Muscularis_mucosa
u can also check diagram plate 266 in netter's atlas.

 

[life easy]

I thought of logic and answered total serum calcium(a) , but why ionized calcium? Please explain, exam in 12 days

Alkalosis--->more bicarbonate ions in the blood--->binds to free calcium ions to form precipitated calcium bicarbonate(means it doesn't disolve in the blood)-->free calcium ions decrease.

 

[life easy]

Even I thought that, But two answer keys have given like max canine, so which to go with finally

ur answer is rite lathe ,it should be mandibular canine only.

 

[life easy]

Hey all please clear me in this question

Sesory organ concerned with maintanence of muscle tone?
Golgi tendon or muscle spindle

I thought muscle tone means tension, so thought answe would be golgi tendon, but the key says muscle spindle.

@cuspofcarebelli
From what is written above, which part of NEPHRON, it means the fluid in which part of the nephron is most HYPEROSMOTIC?
after all the salts and glucose are reabsorbed the remaining is in the tubules , since the water is present till the ascending limb of Loop of Henle ( as it is impermeable) so all the water is finally reabsorbed in the DCT and Collecting duct, so the fluid in this segment would be most hyperosmotic.
Please correct me if I am wrong.

 

[prez_al]

I thought of logic and answered total serum calcium(a) , but why ionized calcium? Please explain, exam in 12 days

According to wikipedia, alkalosis causes alkylation of albumin which increases Ca++ binding ability therefore reducing the amount of available ionized Ca++ for nerve function.

 

[life easy]

Hey If ph is 7.4, Pka is 6.4, How is Unprotonated to protanated ratio be 10?

Ph= Pka(D-/DA)
so D-/DA = PH/Pka
= 7.4/6.4
= 1.1
So how is the answer 10.

Please aswer

 

[prez_al]

Hey If ph is 7.4, Pka is 6.4, How is Unprotonated to protanated ratio be 10?

Ph= Pka(D-/DA)
so D-/DA = PH/Pka
= 7.4/6.4
= 1.1
So how is the answer 10.

Please aswer

The answer is 10 is because the equation is a log equation. the acid-base equation is pH = pka + log (A-/HA)

7.4 = 6.4 + log (A-/HA)
1 = log (A-/HA) --> you have to convert the log scale
10^1 = A-/HA
Therefore you have 10 times more deprotonated than protonated at this pH.

 

[life easy]

1) Hey can anyone explain what is implantation metastasis?

2) and an old man with atrial fibrillation after MI develops right side paralysis and ischemia of left foot due to arterial emboli?

Please explain.....Thanks in advance!!!!!!!!!

 

[life easy]

Oohh ,Thank you so much, I completely forgot the log part
Thank you very much

The answer is 10 is because the equation is a log equation. the acid-base equation is pH = pka + log (A-/HA)

7.4 = 6.4 + log (A-/HA)
1 = log (A-/HA) --> you have to convert the log scale
10^1 = A-/HA
Therefore you have 10 times more deprotonated than protonated at this pH.

 

[life easy]

Hey,

1) In the lingual surface contour of max canine, do we find develpomental grooves,mesial and distal fossa? the answer says that it has both.,Can anyone explain

2) What is the most constant and valuable trait to differentiate between max first, second and third molars?
a) comparitive size of cusp of carabelli
b) relative position of distolingual groove
answer is b ? how ?????????????

Please explain fast guys......

 

[lathe]

1) Hey can anyone explain what is implantation metastasis?



from wiki
Implantation metastasis is defined as metastasising tumour that seeds into a wound or tissue; a significant number of viable malignant cells need to be implanted to the wound.

 

[ddsaspi]

1) Hey can anyone explain what is implantation metastasis?

2) and an old man with atrial fibrillation after MI develops right side paralysis and ischemia of left foot due to arterial emboli?

Please explain.....Thanks in advance!!!!!!!!!

this could be a possible expalanation to your Qn.
In cases of MI following complications can give rise to thrombo- emboli.

• LV aneurysm causing clot formation in the left ventricle (most common)
• Arrhythmia (usually atrial fibrillation) causing clot formation in the left atrium... this is what is happening here. following left atrial clot formation it has fair amount of chances of getting lodged in one of the arteries of the brain, in this case obstruction leading to the paralysis of the right side of body. subsequent left foot ischemia is probably coz of another embolus getting lodged in one of the larger branches of left femoral artery too.

• Cholesterol emboli due to cardiac catheterization or during CABG
• DVT/PE with systemic thromboembolism due to patent foramen ovale.

last one is a very common cause of thromboemboli because about 25-30 % of the population has a patent foramen Ovale.

hope it helps, looking forward to more inputs on the same in case anybody has more info to add!!!

 

[ddsaspi]

Hey all please clear me in this question

Sesory organ concerned with maintanence of muscle tone?
Golgi tendon or muscle spindle

I thought muscle tone means tension, so thought answe would be golgi tendon, but the key says muscle spindle.

As far as i understand golgi tendon organ is responsible for muscle tone. Muscle spindle responds to muscle stretch.

According to the anatomy of the receptors - ie. muscle spindles are in parallel w/ the muscle fibers - therefore they will be stretched when the muscle is stretched, but this doesn't tell the CNS anything about the tone of the muscle as a whole, only that the muscle is being lengthened.

GTO's are in series with muscle fibers, ie they will sense the sum of muscle tension in many fibers, and adjust tone accordingly. For example, if tone is increased greatly, they will cause reflex relaxation of the muscle - clasp-knife like but not so exaggerated reflex.

I think of tension as more or less equal to tone...but maybe in a certain context you could think about tone as the amount of contraction occurring at rest in the muscle, and tension as the amount of contraction occurring under load,


Eg. a brief case you are holding for a long time can no longer be held and you drop it..

i am also going by this , but can anyone elaborate more?

 

[life easy]

exactly, spindly doesnt give information on tone.....But this question is always confusing, each time my answer and the key will be opp.

As far as i understand golgi tendon organ is responsible for muscle tone. Muscle spindle responds to muscle stretch.

According to the anatomy of the receptors - ie. muscle spindles are in parallel w/ the muscle fibers - therefore they will be stretched when the muscle is stretched, but this doesn't tell the CNS anything about the tone of the muscle as a whole, only that the muscle is being lengthened.

GTO's are in series with muscle fibers, ie they will sense the sum of muscle tension in many fibers, and adjust tone accordingly. For example, if tone is increased greatly, they will cause reflex relaxation of the muscle - clasp-knife like but not so exaggerated reflex.

I think of tension as more or less equal to tone...but maybe in a certain context you could think about tone as the amount of contraction occurring at rest in the muscle, and tension as the amount of contraction occurring under load,


Eg. a brief case you are holding for a long time can no longer be held and you drop it..

i am also going by this , but can anyone elaborate more?

 

[life easy]

hey please help in these questions too

1. which bony changes predominate during tooth eruption?
a) apposition at surface of alv crest and apposition at socket fundus
b) resorption at alv crest and apposition at socket fundus.

Answer key says a, but I feel B,,, Pls explain


2. what is prefunctional eruptive stage of tooth?

3. In hyaline cartilage, chondrocytes are surrounded by capsule which is youngest layer of intercellular substance. How is this, pls explain.


Thanks you very much in advance

 

[life easy]

hey, here are some biochemistry-physiology questions, please try to explain which ever possible, exam on 22 please help

1. how pyrophosphatase is linked to calcification of bone?

2. How is the venous return reduced during forced expiration with the glottis closed?

3. Does collagen cross-links increase or decrease with aging, Answer says it increases. How?

4.How does phosphate excretion and ammonia excretion provide best information on the acid elimination by kidneys?

5. Which enzyme is absent in mammalian muscle? options has both glucokinase and glucose 6 phosphatase. Which to choose? ( liver only glucokinase, all other tissues has hexokinase)

 

[ddsaspi]

exactly, spindly doesnt give information on tone.....But this question is always confusing, each time my answer and the key will be opp.

I am with you, i researched the internet for this , BRS n Kaplan, but in all asda papers it says muscle spindles , so we have to go with it. I hope someday i get an explanation for this answer i can understand..

i'll try finding these answers too, which you just posted.

One of them about collagen crosslinks is due to UV radiations crosslinking increases. since we know that new collagen synthsis dec. with inc. in age, and the fibers content & density inc. therefore the crosslinks happen in the available collagen fibers

 

[Rafdaman15]

This is how i went about this question. Tone deals with the contraction of muscles. Contraction deals the the shortening and lengthening of muscle. According to Okeson, "from a functional stand point, the muscle spindle acts as a length-monitoring system." I believe it revolves around the fact that stretching of muscle spindles causes firing of group I and II afferent nerve endings.

 

[Rafdaman15]

during forced expiration, with the glottis closed, there is an increase in intrathorasic pressure. This causes the decrease in venous return and thus a decrease in CO and arterial pressure. When ur body notices this the baroreceptor reflex fires up and counteracts by increasing sympathetic flow to the heart which increases CO so you wont die. This process is called The Valsalva maneuver and its an example of a baroreceptor mechanism. hope this helps

 

[teethie]

hi,

hey, here are some biochemistry-physiology questions, please try to explain which ever possible, exam on 22 please help

1
5. Which enzyme is absent in mammalian muscle? options has both lucokinase and glucose 6 phosphatase. Which to choose? ( liver only glucokinase, all other tissues has hexokinase)

muscle does not possess glucose 6-phosphatase so it does not export glucose released from its glycogen stores, but rather uses it as a fuel to power muscle contraction.

 

[ddsaspi]

hey, here are some biochemistry-physiology questions, please try to explain which ever possible, exam on 22 please help

1. how pyrophosphatase is linked to calcification of bone?
pyrophosphatase is an enzyme which splits PPi(pyrophosphate) into 2 Pi's so they are available during absorption in the bone.

2. How is the venous return reduced during forced expiration with the glottis closed? as explained above, mech. of valsava maneuver

3. Does collagen cross-links increase or decrease with aging, Answer says it increases. How? explained earlier

4.How does phosphate excretion and ammonia excretion provide best information on the acid elimination by kidneys?
Usually the H+ secretion occurs in the PCT, and is excreted hence, most along with HCO3- ion in form of bicarbonate, second being combined with NH3 to form NH4+ ion, and the 3rd mechanism , being excreted with HPO4- to form H2PO4.

(kidney produces NH3 which is subsequently excreted in urine normally).

5. Which enzyme is absent in mammalian muscle? options has both glucokinase and glucose 6 phosphatase. Which to choose? ( liver only glucokinase, all other tissues has hexokinase)

Glucose-6-phosphatase is specifically absent in muscle so it can't breakdown available Glycogen, instead use it for energy requirement c/ in the muscle.

hope this helps

 

[life easy]

Ya but muscle doesnt has glucokinase as well. This is what confused me......

hi,



muscle does not possess glucose 6-phosphatase so it does not export glucose released from its glycogen stores, but rather uses it as a fuel to power muscle contraction.

 

[life easy]

ya okeson says that..... Thank you very much

This is how i went about this question. Tone deals with the contraction of muscles. Contraction deals the the shortening and lengthening of muscle. According to Okeson, "from a functional stand point, the muscle spindle acts as a length-monitoring system." I believe it revolves around the fact that stretching of muscle spindles causes firing of group I and II afferent nerve endings.

 

[life easy]

Terrific... Thank you very much

during forced expiration, with the glottis closed, there is an increase in intrathorasic pressure. This causes the decrease in venous return and thus a decrease in CO and arterial pressure. When ur body notices this the baroreceptor reflex fires up and counteracts by increasing sympathetic flow to the heart which increases CO so you wont die. This process is called The Valsalva maneuver and its an example of a baroreceptor mechanism. hope this helps

 

[life easy]

Hey your answers are great.....Awesome wish you all good

hope this helps

 

[life easy]

Hey some more doubts...Please try to explain at least some....

1) How do reversal lines suggest cessation of osteoclastic activity?

2. In hard palate and gingiva , does the lamina propria attach directly to bone without intervening submucosa? This histology is always confusing.. Pls clear it

3) The subliminal fringe of a motor neuron pool is useful in explaining central facilitation. What is this all about.. I have no idea of this whole concept..pls help

4) what is selective cytotoxicity? How does it affect parasites more strongly than host cells.

5) what effect of hyperparathyroidism is attributed to oat cell carcinoma?

 

[ddsaspi]

Hey some more doubts...Please try to explain at least some....

1) How do reversal lines suggest cessation of osteoclastic activity?
Reversal lines are areas of dense remineralization where there were earlier resorption bays. As resorption occurs 'coz of osteoclasts hence they show cessation of this . active resorption is in resorption bays which house osteoclasts c/ in howship's lacunae.

2. In hard palate and gingiva , does the lamina propria attach directly to bone without intervening submucosa? This histology is always confusing.. Pls clear it.. yeah its correct. the is no submucosa on hard palate, it is attached to the periosteum directly.but for gingiva its specific to attached gingiva and free or marginal gingiva, the alveolar mucosa has lining mucosa hence it has the submucosa

3) The subliminal fringe of a motor neuron pool is useful in explaining central facilitation. What is this all about.. I have no idea of this whole concept..pls help
Has to do with central facilitation.

may be this will help.

http://books.google.com/books?id=M6...#v=onepage&q=subliminal fringe effect&f=false

4) what is selective cytotoxicity? How does it affect parasites more strongly than host cells.
Certain Fe chelators bind to parasite infected RBCs leading to their inactivation

5) what effect of hyperparathyroidism is attributed to oat cell carcinoma?
I guess the answer lies with oat cell carcinoma os the ovary where PTH is produced as ectopic hormone. while in the same Ca of lung it produces ADH / ACTH ectopically..

plz correct them if you have other options. good qns anyway

 

[goodteethgirl]

#102 on I-J, 1996- biochem section

it says major function of LDL is transport ...?

answer says cholesterol, cholesterol esters, and phospholipids FROM THE LIVER

another option was cholesterol and phospholipids from peripheral tissues- is this right answer instead? because accordingly to first aid book pg 263 of first edition has a chart for the major lipoproteins and in it it says LDL carries lipid FROM VLDL of extrahepatic tissues and carries LIPID TO LIVER

so how come answer in the question is from liver but the first aid book says that it caries cholesterol to liver? i looked it up online and it says LDL transport cholesterol "LDL (low density lipoprotein) is a substance that is used to transport cholesterol from the liver to tissues throughout the body." this matches up with the answer but not with first aid😱

I know HDL particles are thought to transport cholesterol back to the liver and that's why they're good cholesterol since they decrease the cholesterol swimming around in our system. So that's why LDL is bad cholesteroal because it does oppposite of hdl...right? i think either I'm getting something mixed up or the book or the test is wrong because it's not all matching up like it should😕....ppllleaseeee help! any help is much appreciated!! and good luck to everyone still studying

 

[ddsaspi]

#102 on I-J, 1996- biochem section

it says major function of LDL is transport ...?

answer says cholesterol, cholesterol esters, and phospholipids FROM THE LIVER

another option was cholesterol and phospholipids from peripheral tissues- is this right answer instead? because accordingly to first aid book pg 263 of first edition has a chart for the major lipoproteins and in it it says LDL carries lipid FROM VLDL of extrahepatic tissues and carries LIPID TO LIVER

so how come answer in the question is from liver but the first aid book says that it caries cholesterol to liver? i looked it up online and it says LDL transport cholesterol "LDL (low density lipoprotein) is a substance that is used to transport cholesterol from the liver to tissues throughout the body." this matches up with the answer but not with first aid😱

I know HDL particles are thought to transport cholesterol back to the liver and that's why they're good cholesterol since they decrease the cholesterol swimming around in our system. So that's why LDL is bad cholesteroal because it does oppposite of hdl...right? i think either I'm getting something mixed up or the book or the test is wrong because it's not all matching up like it should😕....ppllleaseeee help! any help is much appreciated!! and good luck to everyone still studying

Catch hold of concepts from a standard book like lipincott review or kaplan lecture notes. it explains is really well

 

[rakhi]

hey, gastro-lienal ligament or gastro splenic ligament is the correct answer. short gastric and left gasrto-epiploic vessels are branches of splenic artery .

So what exactly should be the right answer for Q 41 in paper N?

is it gastro lienal as short gastric and left gasrto-epiploic vessels are branches of splenic artery or is it leino renal as according to wikipedia?

please make this clear.

Thanks

 

[teethie]

it is gastrolienal
for reference, check this.
http://education.yahoo.com/reference/gray/subjects/subject/154

So what exactly should be the right answer for Q 41 in paper N?

is it gastro lienal as short gastric and left gasrto-epiploic vessels are branches of splenic artery or is it leino renal as according to wikipedia?

please make this clear.

Thanks

 

[rakhi]

it is gastrolienal
for reference, check this.
http://education.yahoo.com/reference/gray/subjects/subject/154

Thanks teethie!!!🙂

 

[Svetlana]

Guys i m so confused and really getting nervous about all the mistakes in tests and books!!!
NBDE 1st aid,micro\path section, Q29
Rheumatic fever.Type of hypersensitivity.
AND THE ANSWER IS TYPE 3!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
and it is explained why!!!

How do you like it?
I dont know what book i should really trust to...

 

[teethie]

hi, there is no mistake in that question and answer. rheumatic fever is an inflammatory condition and not an infection, it is type 3 hypersenstivity. it is also given in pathology books.

see next post.

Guys i m so confused and really getting nervous about all the mistakes in tests and books!!!
NBDE 1st aid,micro\path section, Q29
Rheumatic fever.Type of hypersensitivity.
AND THE ANSWER IS TYPE 3!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
and it is explained why!!!

How do you like it?
I dont know what book i should really trust to...

 

[Svetlana]

hi, there is no mistake in that question and answer. rheumatic fever is an inflammatory condition and not an infection, it is type 3 hypersenstivity. it is also given in pathology books.

Ok.
I know its not infection.
I was sure that Post.strep sequelae are
Rheum.fever,which is type 2
Glomerulonephritis type 3.

Wiki says " This cross-reactivity is a Type II hypersensitivity reaction and is termed molecular mimicry"

??????????????????????????

 

[teethie]

yes svetlana, you are right. it is type 2 , a big mistake in first aid nbdepart1.
i have again checked in usmle first aid book which says it is type 2.

Ok.
I know its not infection.
I was sure that Post.strep sequelae are
Rheum.fever,which is type 2
Glomerulonephritis type 3.

Wiki says " This cross-reactivity is a Type II hypersensitivity reaction and is termed molecular mimicry"

??????????????????????????

 

[Svetlana]

yes svetlana, you are right. it is type 2 , a big mistake in first aid nbdepart1.
i have again checked in usmle first aid book which says it is type 2.

Thanks a lot,teethy!!!
I almost started to think that everything goes wrong in my head!)))

 

[Dental407]

Question 170 from L (pilot exam):

Lymphatic fluid from the area of infected tooth #32 will drain INITIALLY to which of the following nodes?

A. Buccal
B. Submental
C. Deep cervical
D. Submandibular
E. Superficial cervical

The answer says C but shouldn't it be submandibular initially which ultimately leads to deep cervical? Can someone please explain why the answer is C?

 

[bratdoc]

Question 170 from L (pilot exam):

Lymphatic fluid from the area of infected tooth #32 will drain INITIALLY to which of the following nodes?

A. Buccal
B. Submental
C. Deep cervical
D. Submandibular
E. Superficial cervical

The answer says C but shouldn't it be submandibular initially which ultimately leads to deep cervical? Can someone please explain why the answer is C?

The 3rd molars always drain directly into the deep cervial lymph nodes!

 

[Dental407]

The 3rd molars always drain directly into the deep cervial lymph nodes!

Does that mean for all the other mandibular and maxillary teeth (1st and second molars included) that they will drain to the submandibular nodes? Do you know if Decks says that 3rd molars go to deep cervical nodes? The reason I ask is because First Aid was saying submandibular.

I know mandibular incisors go to the submental nodes first.

Thanks for your help!

 

[teethie]

hi there,

pl see this thread, i have posted a reference there.

http://forums.studentdoctor.net/showthread.php?t=563458&page=26

Does that mean for all the other mandibular and maxillary teeth (1st and second molars included) that they will drain to the submandibular nodes? Do you know if Decks says that 3rd molars go to deep cervical nodes? The reason I ask is because First Aid was saying submandibular.
I know mandibular incisors go to the submental nodes first.

Thanks for your help!