Sunday, October 22, 2017

Electrocardiogram


File:Ecg.png - Wikimedia Commons

P wave

  • Positive wave
  • Shape is up rounded deflection
  • Cause: Depolarisation of atrial musculature.
  • Duration: 0.1 sec
  • Intensity: 0.1-0.12 mV
  • Represents functional activity of atria.


Clinical Aspects:
  1. Mitral stenosis: left atrium is hypertrophied and P wave is larger and prolonged.
  2. Tricuspid stenosis: Right atrium is hypertrophied and P wave is taller but there is no change (normal) duration.
  3. Atrial fibrillation: P wave disappears and is replaced by fine irregular oscillations.
  4. Ectopic Pacemaker: (reverse) The impulses are sent from AV node to SA node.

QRS COMPLEX

  • Q wave is often absent.
  • Cause: Ventricular Depolarisation.
  • Duration: 0.08 sec ( less than P wave)
  • Intensity: 0.1 mV to 0.2 mV ( amplitude is more)
  • R wave is 1 mV
  • S wave is 0.4 mV
  • Total Intensity is 1.5 mV to 1.6 mV

Clinical Aspects
  1. Deep Q wave: more than 0.2 mV. This is seen Myocardial Infarction.
  2. Tall R wave: more than 0.1 mV. This is seen in ventricular hypertrophy.
  3. Low Voltage QRS Complex:  This is related to hormones and pericardial fluid. Hypothyroidism and Pericardial fluid around the heart.
  4. QRS COMPLEX: Prolonged in bundle branch block.

T wave

  • Cause: Ventricular Repolarization.
  • It’s positive wave because the direction of Ventricular repolarization is opposite to depolarization.
  • Duration: 0.27
  • Intensity: 0.3 mV

Clinical Aspects

  1. Flattened T wave: old age.
  2. Height increases: during exercise.
  3. Inverted T wave: this is seen in myocardial infarction.
  4. Tall and peaked T wave:  Hyperkalaemia.

U wave
  • Positive round wave
  • Repolarization of papillary muscled
  • Duration: 0.08 sec
  • Intensity: 0.2 mV
  • Rarely seen
  • Prominent in hypokalaemia.

P R interval

  • Onset of P wave to onset of QRS complex (PQ interval)
  • Represents AV conduction time.
  • Duration: 0.12 to 0.21 sec

Clinical Aspects

  1. Prolonged PR interval: AV conduction block.

J Point

  • The meeting point of QRS complex with ST segment.
  • It represents the end of Depolarisation and beginning of repolarization.
  • At this point, no current flows around heart.


I hope this helped you :))  Have a good day!

Saturday, October 21, 2017

Lesions of visual pathway

Visual pathway starting from retina consists of optic nerve , optic chiasma , optic tracts , lateral geniculate bodies , optic radiations and the visual cortex .
Courtesy :- Comprehensive Ophthalmology 6th edition ; AK Khurana ; Pg.314


Sl . no
Site of lesion
Type of lesion
1
Optic nerve
Complete blindness on ipsilateral side
2
Anterior Chiasma
Junctional scotoma
3
Central chiasma
Bitemporal hemianopia
4
Lateral chiasma
Binasal hemianopia
5
Optic tracts / LBG
Incongruous homonymous hemianopia
6
Part of optic radiations in temporal lobe
Superior quadrant hemianopia (pie in sky )
7
Part of optic radiations in parietal lobe
Inferior quadrant hemianopia (pie on floor )
8
Optic radiations
Complete homonymous hemianopia
9
Visual cortex sparing macula
Congruous homonymous hemianopia
10
Visual cortex , only macula
Congruous homonymous macular defect
11
Bilateral Visual cortex , only macula
Bilateral homonymous macular defect


`~ Pratheek Prabhu

Pneumococcal vaccines mnemonic for the USMLE

Hey!

So we already have a wonderful post written about these vaccines here.

I am just here to share the mnemonic! :)

Mentzer index mnemonic

Hello everyone!

Monday, October 16, 2017

Na-K ATPase and Donnan effect

Hello Awesomemites :D

In Previous post, I gave an overview on Gibbs Donnan equilibrium.
This is to clear the doubt that Could animal cells attain Gibbs Donnan equilibrium?

Animal cells could never attain equilibrium. Plasma membrane can't sustain hydrostatic pressure gradient without evolution of some means of avoiding Gibbs-Donnan equilibrium.
Why do we need some new means? Because we couldn't afford to have "Protein free cell or no protein containing cell".
So,
Na-K ATPase counteract Gibbs Donnan equilibration.
The bottom line effect of this is to make cell effectively impermeable to NaCl. Gibbs Donnan equilibrium do not reached and cell does not swell inspite of the presence of protein ion.
Hope you got it.
-Upasana Y. :)

Donnan Effect

Hello Awesomemites :D

I was reviewing my 1st year physiology notes then I found this topic.
Let us begin. :D

We know that ions move across the membrane depending on 2 gradients :-
1. Concentration gradient (No. Of ions)
2. Electrical gradient (Charge of ions)

 The net movement of ion  is decided by the Electrochemical gradient.

I will do some calculations below. Caution point is when I will talk about electrical neutrality, I consider charge of ions.

Donnan Effect  ON DISTRIBUTION OF IONS has three effects:-
1. Because of charged proteins in cells, there are more osmotically active particles in cells than outside.
So what does it means? Animal cells do not have cell wall. Osmosis would make them swell and eventually rupture.

How to prevent this?
This implies need for evolution of pump (Na-K ATPase) to maintain osmotic equilibrium between cells and interstitial fluid across cell membrane.

2. At equilibrium the distribution of the permanent ions across the membrane is assymetric, an ELECTRICAL difference exists across the membrane.

What does it means?
K+ moves along its concentration gradient (as it is free to move)  lead to electrical disequilibrium.

This disequilibrium influence K+ to move continuously. Chloride also move it's side to equilibrate with charge.

Eventually ion concentration would stabilise (in diagram 64=64)  and individual solute concentration would not change over time (means 6 Na+ 4 Cl- 10 K+ 3 prot4- inside)
Gibbs Donnan force are responsible for development of a membrane charge due to passive process.

3.Because there are more proteins in plasma than in interstitial fluid,there is Donnan effect on ion movement across the capillary wall.

What do you mean by Donnan equilibrium?





Have a great day.
-Upasana Y. :)



Sunday, October 15, 2017

Neuroendocrine tumours of the Stomach



Neuroendocrine tumours of the stomach are uncommon tumours with a benign behaviour usually- hence known commonly as "Carcinoids"

They are diagnosed by the usual histomorphology of small organoid nests or clusters of cells with salt pepper or stippled nuclear chromatin and synaptophysin or chromogranin positivity.

We divide them into 4 types

1. One develops in the background of reactive gastrin secreting cell hyperplasia in cases of pernicious anemia

2. The second type is a part of Zollinger Ellison syndrome

3. The third is independent of any syndromic association or association with pernicious anemia

4. The fourth type is classified based on the histomorphology- "Neuroendocrine Carcinoma"- showing mitosis, nuclear pleomorphism, hyperchromasia

The closest differential could be Gastrc Lymphoma-
1. Lymphomas would not usually have an organoid pattern, tend to grow sparing the crypts and tend to form lymphoepithelial clusters
2. They would not have synaptophysin or chromogranin positivity
3. They would stain for the relevant lymphoid markers according to the cell of their origin- B or T cell type.
4. Hormone or S. Gastrin levels would be useful

Friday, October 13, 2017

House MD - Neurocysticerosis

Well, the post is from Author's diary. So read it when you are free.

Story time.

"Roll no 33, tell me how is Neurocysticerocis formed?" Asked our microbiology professor and ordered me-roll no 34 to be ready with my answer for the same. This happened during my preliminary viva. Microbiology was my last viva. This was my last moment with vivas, after this, awaited the exotic diwali vacations!! ( Rather PLs)

Roll no 33 started answering the question. However, she was wrong. Sir interrupted her and said, "I need the mechanism, not life-cycle! ".

He turned towards me and asked the same.Till this time I was in a delusion that neurocysticerocis is formed because larvae get an access to systemic circulation and end up infecting the brain!!
I was more than wrong! I got a deduction in my marks obviously.

Nevertheless, I was happy with "The End of viva".
Well, I tried to find out the mechanism of neurocysticerocis in my free time but I was not able to find it in any of the books.

So, vivas were over and I was free. I started watching the remaining episodes of "House MD. After coming home, I realized that I forgot to install the remaining episodes of House MD :(

I had season 1, so I preferred re-watching it.
Season 1 - Episode 1 - Pilot.

Guess what!!!!?
I found my viva answer of neurocysticerocis in my favourite series. Dude how can I miss this?!

So House explain's neurocysticerocis as follows:

"In a typical case, if you don't cook pork well enough, you digest live tapeworm larvae. They have  got these little hooks, they grab on your bowel, live,  grow up and reproduce.Tapeworm can produce 20,000-30,000 eggs which go out in excretion but not all of them. Unlike the larvae, eggs can pass through the walls of intestine and enter the circulation. Obviously, blood goes everywhere. As long as, it's healthy, your immune system doesn't even know it’s existence. The worm builds a wall, uses its  secretions to shut down immune system and control fluid flow. It’s really very beautiful. As it dies, this parasite loses it's ability to control the immune system. Immune system wakes up, starts attacking the worm and everything starts swelling up."

After this episode I realized I am a big moron and I haven't watched House MD with my utmost dedication. So, I am
re-watching it now :D

Everybody lies!!

Good - bye!

--Demotional bloke.

Thursday, October 12, 2017

Quick Facts - Swimming associated Diseases.

Hello everybody!
Let's swim through microbiology today and review some swimming related diseases.

Swimming pool conjunctivitis -
Caused by : Adenovirus 3,7 and 14 (tends to occur in children's swimming camps)
                      Chlamydia Trachomatis.

Swimming pool Granuloma -
Caused by Mycobacterium Marinum.

Swimmer's Itch -
Caused by Schistosoma Mansoni.

Swimmer's Ear - Pseudomonas.

Swimming in contaminated water can also cause Primary Amoebic Meningoencephalitis by Naegleria Fowleri which is a free living ameba.

If you come across more eponymous swimming diseases do share.

Let's learn Together!
-Medha.

BRCA1 vs BRCA2 gene mutations and associated chromosomes (mnemonic)


BRCA1 gene mutation is located on choromosome 17 while BRCA2 gene mutation is located on chromosome 13, how to remember that?

BRCA2 :
- 1 and 3 in number 13 if joined together, they look like a breast 1+3 =>13
- this reminds me of its association with breast cancer.

BRCA1 is really famous:
-Another Famous mutation is P53 gene mutation which causes LI Fraumeni syndrome.
-Flip IL in LI Fraumeni and you get the number 17.
-Asssociate LI Fraumeni (p53) and  BRCA1 together since both are very famous => both are due to chromosome 17 mutations.

and that's it :)

-Murad

Wednesday, October 11, 2017

Tuesday, October 10, 2017

Quick Facts - Fried Egg Appearance!

Hello everybody!

So the next time you make your own fried egg add some medicine to it!

Here is a list of certain characteristic fried egg appearances that you may Come across:

Mycoplasma Pneumoniae colonies show fried egg colonies on Eaton agar.

Oligodendroglioma cells show a fried egg appearance.

Hairy cell leukemia cells on bone marrow biopsy.

Seminoma cells on light microscopy.

Parietal cells of the stomach due to acidophilic cytoplasm & large central nuclei also resemble fried egg appearance.

Let's learn Together!
Medha.

Quick Facts - Human Herpes Virus 6!

Hello everyone!

Here are some quick important facts for the Human herpes Virus 6 (HHV-6)

HHV-6 affects T cells binds to CD46.

It has two variants 6A and 6B

The 6B variant causes 6th disease  (easy to remember HHV-6 causes 6th disease)
also called as Roseola infantum or exanthema subitum in children.

Roseola infantum -The disease is characterized by high grade fever wherein Febrile seizures can be seen.
After the defervescence the Rash classically appears.
One important finding is Nagayama spots which are small reddish papular lesion seen on the soft palate.

In Older age grp causes Infectious Mononucleosis like disease.

If you have more facts on it, Do share!

-Let's Learn Together!
Medha

USMLE Step 3: CCS Inflammatory bowel disease checklist

These are just my notes / checklist from the UW case 3. This post will not make sense to you if you are not preparing for CCS.

How to remember Sulfasalazine is associated with low sperm count

Hello!

I keep forgetting that sulfasalzine is the IBD drug associated with oligospermia... Sooo mnemonic.

Sunday, October 8, 2017

High tHcy associated with mortality from acute stroke!

Hey Awesomites

Various prospective studies in the past years have concluded that high levels of total Homocysteine ( tHcy ) are an independent risk factor for increased mortality from ischemic stroke, after adjustment of confounding factors!

This association is only significant in the large vessel atherosclerosis stroke subtype, and is relatively not significant in small vessel occlusion subtype.

The question that now arises is - Do elevated plasma tHcy levels cause more serious strokes or is it that more serious strokes result in higher tHcy levels?

Studies have found that elevated tHcy levels induce oxidative injury to vascular endothelial cells and impair the production of NO, thus increasing the arterial pressure and risk of stroke.
Also, tHcy enhances platelet adhesion to endothelial cells, promotes the growth of vascular smooth muscles, and is associated with higher levels of prothrombotic factors such as Beta- thromboglobulin, tissue plasminogen activator, and factor VII C.

Whether the more serious strokes increase  levels of tHcy and the changes in the levels before and after the acute episode needs further studies for clarification.

Note : High tHcy is not a cause of stroke and is not associated with stroke severity. Patients in the highest tHcy quartile ( >18.6 umol/L ) with Acute ischemic stroke  in large vessels of brain are in increased risk of Long - term mortality.

Therapy to control and lower tHcy levels with vitamin B supplements has been shown to reduce the risk of stroke and other acute cardiovascular events.
Metabolic B12 deficiency is present in 30% of vascular patients over the age of 70 years, while higher doses of B12 are required in elderly people than younger ones.
However, renal function tests should be done before starting the supplementation because high doses of cyanocobalamine increase cyanide levels in patients with renal impairment ( GFR <50 ml/min ).

Source  )
That's all
- Jaskunwar Singh

Heme Synthesis Mnemonic

Hello Everyone!

Lets discuss heme synthesis today.  Here's the Pathway:


That's all,
Thankyou
 -Chai

Saturday, October 7, 2017

Post - intubation Cardiac Arrest : possible mechanisms

Hey Awesomites

Early post - intubation Cardiac Arrest ( within 10 minutes ) is a serious major complication of emergency intratracheal intubation associated with high in - hospital mortality, and occurs with approximately 2% frequency in the ED.

Various retrospective and case- control studies have been well designed to establish the connection and factors associated in the causation. One of the studies by Heffner et al. found that a higher pre - intubation shock index ( PISI ), that is defined as heart rate divided by systolic BP, and a higher weight of the patient are independently associated with post - intubation CA.

Systolic hypotension ( BP less than 90 mmHg ) is independently associated with post - intubation CA.

Emergency intubation can cause hypotension potentially as a consequence of actual intubation acting as a sympatholytic stimulus, mechanical ventilation ( positive pressure ventilation with subsequent fall in venous return ), and/ or the induction agents used.

Also important to note is that the association between pre - intubation hypotension and post - intubation progressive decline in BP and subsequently pulseless electrical activity arrest raises the question of whether treatment of hypotension before intubating by fluid resuscitation and vasopressors can decrease the rate of post - intubation CA.

That's all
- Jaskunwar Singh

Tuesday, October 3, 2017

Fact of the day : Easier approach shot to the pouch of Douglas

Hey Awesomites

The posterior fornix of the vagina is separated from the peritoneal cavity by a single layer of peritoneum and the posterior vaginal wall. Therefore, vaginal approach from its posterior aspect for evacuation of pus in the pouch of Douglas can be done without much difficulty.

On the other hand, approach to uterovesical pouch ( anterior relation ) is much more difficult from the vaginal route and consists of a series of steps :
- Incise the vagina
- separate bladder from cervix
- Traverse the vesicocervical space ( till the uterovesical fold of peritoneum is reached )

This difference is due to the normal physiological position of the uterus that is anteverted and anteflexed; the direction of external os being downwards and backwards.


That's all
- Jaskunwar Singh


Basic modalities of Transitional Zone

Hey Awesomites

Squamocolumnar junction ( the transitional zone ) is a junction formed by merging of squamous epithelium of the vagina with the columnar epithelium of endocervix.

Squamous non keratinized epithelium lining the vaginal mucosa has three distinct layers -
- Basal layer of cuboidal cells
- Middle layer of prickle cells
- Superficial layer of cornified cells

Embryologically, the junction consists of columnar epithelium that spreads over the external os and only the basal and middle layer of squamous epithelium lining the vaginal mucosa.

After attaining puberty, hormonal effects of oestrogen and progesterone induce metaplastic changes in columnar epithelium. Therefore, the squamous epithelium comes in close vicinity to the external os.

During reproductive age, growth of uterus, hypertrophy of cervical cells and associated hormonal changes and in females exposed to DES in utero, the transitional zone extrudes well out of the external os.

Due to high cellular activity and sensitivity to certain irritants and mutagens, there is high risk of dysplastic changes in the squamocolumnar epithelium and eventually carcinoma cervix. So, scrapings for PAP smear are done without difficulty from this exposed area to screen the patients.

In menopausal women, the atrophy of cervix leads to in drawing of SCJ into the canal. Hence the junction is not easily accessible and this ill exposure is the reason for high rates of false negative findings in PAP smear in older women! Hormonal therapy in such patients improves the positivity of results.


That's all
Jaskunwar Singh

Types of tympanic membrane perforation

Hello Awesomites ! :D

There are different types of perforation of tympanic membrane. We name it on the basis of :-
1. Size of perforation
2. Site of perforation

So, let us begin.

ACCORDING TO SIZE OF PERFORATION,
1. Pinhole :- 1-2 mm in size.
2. Small :- Area involving one quadrant or <10% of pars tensa.
3. Medium :- Area involving 2-3 quadrant or 10-40% of pars tensa.
4. Subtotal :- Area involving the pars tensa >75% and does not involve the annulus.
5. Total :- A total perforation is present in tympanic membrane. Tympanic membrane is essentially absent and involve annulus also. 

ACCORDING TO SITE OF PERFORATION,
1. Anterior 
2.Posterior
3.Inferior
4.Central

OR,

1.Central :- A simple perforation in pars tensa with intact annulus. 
                   Perforation is surrounded all around by pars tensa.
2. Marginal :- Perforation in the pars tensa surrounded partly by pars tensa and partly by bone.
3. Attic :- Perforation in pars flaccida.

I found this topic very confusing in my exams.
I hope it helped. :D



Have a great day ahead.
-Upasana Y. :) 

Monday, October 2, 2017

Corpus Callosum - Let's connect

Hey Awesomites
Jas here
I am back :)

Let's talk about the largest connective pathway in the brain, the Corpus Callosum that is made up of more than 200 million nerve fibres, connecting our left brain to the right.

Friday, September 29, 2017

Rotator Cuff muscles and their actions (mnemonic)

To remember the actions of Rotator Cuff muscles ( Supraspinatus, Infraspinatus, Teres Minor and Subscapularis), just remember the following:

1- The mnemonic for the muscles is: SITS
2- We will start with ABDuction and finish with ADDuction
3- The vowels in English can be remembered by AEEIou ( shout to remember better :P )
4- Now just match letters from the 2 mnemonics in the same order they are written in
 as you can see in the table:

So S goes with A...I goes with E...T goes with E and the last S goes with I.

Never forget the action of Rotator Cuff muscles again :)

-Murad

Wednesday, September 27, 2017

Echinocandins: Mechanism of action, side effects and orgranisms affected (mnemonic)

To easily remember anything related to Echinocandins (eg: Caspofungin, Micafungin) , just think of the letters "C, A and N"  => CAN :D

=> EchinoCANdins.
=> Inhibit synthesis of B-gluCAN. 
=> Used in CANdida and a thing that CAN invade your body (invasive aspergillosis).
=> CAN make you flush ( due to histamine release).

-Murad

Tuesday, September 26, 2017

Joll's triangle in thyroidectomy

Hello friends,

This post is about the importance of Joll's triangle in thyroidectomy.

Joll's triangle is used to identify external laryngeal nerve during thyroidectomy.

Boundaries of this triangle are :
Laterally: Upper pole of thyroid gland and superior thyroid vessels.
Superiorly: Attachment of strap muscles and deep investing layer of fascia to hyoid.
Medially: Midline of neck.
Floor: Cricothyroid muscle.

This triangle contains superior laryngeal nerve which gives rise to external laryngeal nerve.

Given below is the diagram of this triangle:

Mnemonics for Modified Jones Criteria

Modified Jones Criteria is used  for diagnosis of Acute Rheumatic Fever.

Mnemonic - "JONES CAFE PAL"

MAJOR CRITERIA :-
Joint involvement (polyarthritis)
O 'O' looks like a heart - myocarditis
Nodules subcutaneous
Erythema Marginatum
Sydenham Chorea

MINOR CRITERIA :-
CRP elevated
Arthalgia
Fever
ESR elevated

Prolong PR interval
Anamnesia of Rheumatism
L eukocytosis

Presence of  either
- 2 major criterias or
- 1 major criteria + 2 minor criteria

Is considered to diagnose patient positive.

Written by,
Pratheek Prabhu

SIADH vs Diabetes Insipidus, Osmolarity and Sodium levels in urine and serum in both (mnemonic)


Serum and urine findings in SIADH and  Diabetes Insipidus can really mess up our brains :S

A nice mnemonic to memorize SIADH is to recall the letters as  :
 "S"odium "I"s "A"lways "D"own "H"ere (by here: I mean serum) =>
so in SIADH:
=> low Na in serum
=> high Na in Urine & high Urine Osmolarity

Now ...just think of the opposite and you ll get Diabetes Insipidus
so in DI:
=> high Na in serum /high serum osmolarity
=> low Na in Urine

-Murad

Monday, September 25, 2017

Chronic Renal Failure : Indications for dialysis.

Hello guys!

In this post I am going to list down the Indications for dialysis in patients of Chronic Renal Failure.

Absolute Indications :
1. Volume overload not responding to medication.
2. Refractory hypertension.
3. Hyperkalemia unresponsive to medications.
4. Severe metabolic acidosis unresponsive to medications.
5. Uremic pericarditis
6. Neurological signs and symptoms of Uremia.
7. Plasma creatinine more than 1060 umol/l or BUN more than 36 mmol/l

Relative Indications :
1. Anorexia
2. Severe anemia unresponsive to erythropoietin.
3. Persistent severe pruritus.
4. Restless legs syndrome.

That's all.
Thank you

MD Mobarak Hussain (Maahii)

Some thalamic nuclei and their function (mnemonic)

Thalamic nuclei can really cause a headache if no mnemonics are used while studying them :O

The following mnemonics may be used to associate the nuclei with their functions:

1- Ventral Postero-Lateral nuclues  (VPL) => Very Painful Leg
This nucleus has input (pain, temperature, pressure, touch, vibration and proprioception) from Spinothalamic and dorsal columns/medial lemniscus ( Lower Limbs and Upper Limbs).

2- Ventral Postero-Medial nucleus (VPM) => Very Painful Mouth
This nucleus has input (face sensastion and taste) from trigeminal and gustatory pathway).

3- Lateral Geniculate Nucleus  (LGN) => Looking Good Naked :O
This nucleus has input (part of the visual pathway) from the optic nerve.

4- Medial Geniculate Nucleus (MGN) => Making Good Noise
This nucleus has input (part of the hearing pathway) from superior olive and inferior colliculus of tectum.

& that's it! :)

-Murad

Sunday, September 24, 2017

Relation between Type I, Type II errors and Null hypothesis (mnemonic)

Biostatistics can really be dry and hard to engulf sometimes. 

One of the things that always confused me was when to accept and when to reject the null hypothesis. 

Since  mnemonics are one of the best things ever, here you go:

Type ONE error:
You use a verb with ONE consonant => reJect => so you reJect Null hypothesis

Type TWO error:
You use a verb with TWO consonants => aCCept => so you aCCept Null hypothesis

& that's it! :)

-Murad
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