Why does heart stop in diastole when plasma potassium level rises?

Normally, potassium has a tendency to move outside the cells due to the concentration gradient.

As plasma potassium rises, this concentration gradient is reversed. 
So potassium will move into the cells. 

The cell's resting membrane potential is very sensitive to changes in extracellular potassium ion concentration.
Elevated potassium, or hyperkalemia, causes the resting electrical potential of the heart muscle cells to be lower than normal (less negative). 

Without this negative resting potential, cardiac cells cannot repolarize. 

That means all your cells are depolarized.
This inactivates sodium channels. 

Inactivated sodium channels means the cells can not fire. 
The heart can not contract. 
That's why, heart stops in diastole. 

Hope you understand :)

This is the mechanism of execution by lethal injection, sudden depolarization of the cell without the ability to repolarize.

Increased extracellular potassium is also seen in rhabdomyoloysis, tumor cell lysis, hemolysis etc.

Cool fact:
In ischemic tissue, potassium in the surrounding interstitium rises. 
Wanna know why?
Ischemic tissue does not receive oxygen.
So there is lack of ATP.
Na+ - K+ ATPase doesn't work
K+ leaves the cell and no one can pump it back in.
(Special thanks to a friend for explaining this fact to me ^_^ )

Another cool fact:
Increased extracellular calcium tend to stop the heart in systole (contracted).
This is known as calcium rigor.

That's all!

-IkaN

Cerebellum mnemonics

Hello everyone!
This post is for those having trouble remembering the cerebellum

I modified a mnemonic I got online :)
So if you have a little bit of anatomic imagination cerebellum should be a piece of cake for you!

Region: Hemisphere (lateral)
Principle input: Cerebrocerebellar
Function: Peripheral coordination and planning
How to remember: It’s location is around the periphery of cerebellum

Region: Flocculonodular lobe
Principle input: Vestibulocerebellar
Function: Ear, eye, balance, body co-ordination.
How to remember: Pops out to the edges, looks like bunny ears to me =P

Region: Vermis
Principle input: Spinocerebellar
Function: Axial equilibrium
How to remember: It is located in the axis of cerebellum
And looks like the spinal column

Also, the intermediate hemisphere influences the lower motor neurons via the rubrospinal and reticulospinal tracts

I think of climber plants and the fruit olive
And that's how the "climbing fibres" and "olivocerebellar tracts" come together xD

Superior Sends out
Superior cerebellar peduncle in the major outflow from the cerebellum

That's all the mnemonics I got
Feel free to add more in the comments ^__^

-IkaN

Spinal cord organization mnemonic

Hello, all my Pokemon and cat fans =P

Spinal cord organization mnemonic
“SAD MEW”

S - Sensory
A - Afferent
D - Dorsal

M - Motor
E - Efferent
V V - Ventral

"Sad mew" Spinal cord organization mnemonic

-IkaN

Cochlear nerve, pathway and mnemonic

It's time to finish off the cochlear part of the vestibulocochlear nerve! :)

It starts off from the organ of corti, central processes of the spiral ganglion forms the cocchlear nerve and they terminate into the cochlear nuclei

From the cochlear nucleus, most of the axons cross to the opposite side in the trapezoid body and terminate in the superior olivary nucleus

The axons arising from the superior olivary nucleus form the lateral leminiscus
and reach the inferior colliculus

The fourth neurons pass through the inferior brachium to reach the medial geniculate body

The axons of the fifth neurons form the auditory radiation which passes through the sublentiform part of the internal capsule to reach the auditory area in the temporal lobe

How am I ever gonna remember all this? @_@
Mnemonic! =D
SLIM
S = Superior olivary nucleus
L = Lateral leminiscus
I = Inferior colliculus
M = Medial geniculate body

I sorted out the whole pathway for you :P

Now, all you need to remember is that lesion in the cochlear part of the 8th nerve of the cochlear nucleus will cause a unilateral sensorineural hearing loss
Because fibres haven't crossed yet

If it is a bilateral senorineural hearing loss, the lesion is at higher levels such as the brainstem, thalamus or cortex
These patients will also have a decreased ability to localize a sound source


I'll add the mnemonic for the auditory tests here too

W, for Webers test, is a symmetrical alphabet ie made up of two V's
So it tests both ears simultaneously
Also, tuning fork is placed on the Vertex

R, for Rinnes test, is asymetrical
Tests only one ear
It's kinda stupid but works for me :)


That's all!
-IkaN

Vestibular nerve, pathway and mnemonic for the receptors

Hello everyone! We'll finish off the vestibulocochlear nerve today :)
It isn't as hard as it seems, trust me <3

Vestibular receptors are:

The macuLae of the utricLe and saccuLe
And what do they sense? Linear acceLeration

The Cristae of the semiCircular canal
And what does it sense? Circular movements (rotatory)

It's a no brainer really =D

Lipoproteins and apoproteins

Hey guys!
We have always had difficulty remembering lipoproteins and apoproteins and stuff.. And what makes it simpler? Mnemonics!

After you eat, dietary trigylcerides is transported via chylomicrons from the intestine to the adipose tissue.
VLDL carries endogenous triglycerides from the liver to the peripheral tissues.

Both triglyceride transporters contain apoB

Chylomicrons have micro
Micro means small
So they have a small number, that is, apoB 48

VLDL have the larger number, apoB 100

apoC II is a Cofactor for lipoprotein lipase
Which hydrolyzes the triglycerides into fatty acids and glycerol
LIpoprotein LIpase is activated by InsuLIn

apoE helps in rEmnant uptake by lEvEr (Liver =P )

Chylomicron (B48, C-II, E) > Chylomicron remnant (B48, E)
 
VLDL (B100, C-II, E) > IDL (B100, E) > LDL (B100)
VLDL loses apoC-II to become IDL
IDL loses apoE to become LDL
LDL will transport cholesterol to peripheral tissues

apoA-I Activates lcAt (LCAT)
Also, I looks like l
It's on HDL
Converts cholesterol to cholesterol esters
(LCAT transfers a polyunsaturated fatty acid from 2nd carbon of glycerol to cholesterol forming lysolecithin and cholesterol ester)

*phew* That was work!
Let's have a look at the deficiencies now =)

So what happens if you have apoB deficiency?
No triglycerides is incorporated into VLDL and chylomicrons
Serum triglycerides, cholesterol and phospholipids are low
Beta lipoprotein (LDL) is absent
Lipids and lipid-soluble vitamins (especially A and E) are poorly absorbed (steatorrhea)
Hemolytic anemia—lipid imbalance causes RBC membranes to pucker (acanthosis)

What happens in lipoprotein lipase deficiency?
Increased triglycerides in chylomicrons and VLDL!
(You can't breakdown triglycerides to fatty acid and glycerol for uptake)

What happens if you have a LDL receptor deficiency?
There will be and increased levels of LDL and cholesterol
(Because peripheral tissues can't take them without the LDL receptor)

What happens if you have LCAT deficiency?
You have increased unesterified cholesterol
(You can esterify the cholesterol you have)
You also have increased phoshatidyl choline which is a component of lecithin

That's all!
 Have an awesome week <3

-IkaN

Post is continued here

Southern, Northern, and Western blot mnemonic

Hello everyone!

The mnemonic to remember blotting techniques is "SNoW DRoP"

S -    Southern - DNA     - D
N -   Northern - RNA     - R
O -   Oooooo - Ooooo    - O
W -  Western - Protein   - P

Blotting techniques illustration and mnemonic :)

There's another simpler one for all those who can speak the language Hindi.. Southern in Hindi is Dakshin for DNA & Western in Hindi is Paschim for Protein!

Cool facts on blotting techniques that the mnemonic doesn't cover -

If you want to visualize DNA at replication level, you will use Southern blot. This will require a DNA probe attached to phosphate.

RNA at transcription level can be visualized with Northern blot. This will require a DNA probe attached to phosphate too.

Remember: If you want to visualize protein at transcription level, you will go with Northern blot!

Proteins at translation level are just antigens (Whether they are cell membrane, cytoplasmic or secretory proteins!) Therefore, antibodies (not probes) are used to visualize proteins byWestern blot.

DNA binding proteins also known as transcription factors go to the nucleus and bind to DNA. They are proteins but they work at the DNA level. They are different than just regular antigens and therefore, we use DNA probe (not antibodies!) to visualize them. This is known as the South Western blot :)

That's all!

Hope you won't go, "Which direction was that again?" in the exam =P

-IkaN

Updated on 4th December, 2013: Hindi mnemonic & illustration.
Updated on 5th December, 2013: Cool facts that you may have not known.

Leukocyte adhesion deficiency mnemonic

Leukocyte adhesion deficiency mnemonic

Chemokines (chemoattractants) mnemonic

Here is something for chemoattractants..

Phagocytic cells are in blood vessels which is like street of city
Now they want to go in tissues which is like a dark forest

Somebody suggested phagocytic cells that if you want to go,
"Before (B4) going, make sure you can See five (C5a) clearly In Light (IL8) and form peptides (N-formyl peptides)"

So it is B4, C5a, IL8, N-formyl peptides.

-IkaN

HLA, MHC & CD T cell mnemonic

Hello everyone!

Time for another immmunology mnemonic =D

MHC class I:
CD8+ T-cells recognize MHC I.

It takes only 1 stroke of the pen to write “8″

The genes have only one alphabet. (HLA-A, HLA-B, HLA-C)

CD8 x MHC1 = 8

CD8+ are Cytotoxic T cells because "EighT" has T for "Toxic"

All cells have one nucleus, so all nucleated cells have class I MHC.

MHC I has one chain (alpha chain) & one microglobulin (Beta 2 microglobulin).

Interleukin 2 mnemonic

Another Interleukin mnemonic!
 
You're a T cell
& you see a second T cell looking just like you :O

You: "Woahh.. You're.. You are my friggin' clone!!"
Clone T cell: "Yeah.. IL - 2 made me"

That's all!

Shout out to Microbiology Made Easy for sharing the T lymphocyte comic character.. Thank you so much :)

-IkaN

Hematopoietic stem cell differentiation mnemonic

Do you know that lymphoid and myeloid cells come from the same precursor?
Yes! It is the multipotent stem cell which differentiates into either a lymphoid or a myeloid stem cell
So how they know what to differentiate into?
Interleukins tell em what to do!

IL-7 stimulates the differentiation of multipotent (pluripotent) hematopoietic stem cells into lymphoid progenitor cells
IL-3 stimulates the differentiation of multipotent (pluripotent) hematopoietic stem cells into myeloid progenitor cells

How do I remember that? @_@

Here's a mnemonic just for you :*

Hematopoietic stem cell differentiation mnemonic

That's all! ^________^

"Why can't you ever see what's in front of you.." ;)
-IkaN

Difference between viral and bacterial infection

Hello everyone! ^__^

How would you differentiate a viral infection from bacterial infection? @_@

Viral infections are widespread and involve a number of mucosae simultaneously or in quick succession

Bacterial infections are localized and cause site specific symptoms

A virus may produce clear or cloudy mucous

Discharge is watery

A bacterial illness typically causes colored phlegm (green, yellow, bloody or brown-tinged)

Discharge is thick

Viral infections usually clear up pretty quickly

They last for 2 - 10 days

Bacterial infections have a longer duration of illness

They last for more than 10 day

Viral infection may or may not cause a fever

A bacterial infection will cause fever

 

That's all!

All time pageview: It's over 9,000!!!

Guess we are viral too :P

(Viral - An image, video, advertisement, etc. that is circulated rapidly on the Internet)

-IkaN