Moved

The sarcoplasmic reticulum is a unique intracellular membrane structure that is found in the skeletal muscle cells. Its function is vital to the contraction and relaxation of muscles. The sarcoplasmic reticulum is made up of stacks of convoluting membrane that forms an enclosed environment in the muscle cells. The main function of the sarcoplasmic reticulum is to act as storage for calcium ions in the enclosed environment that it forms. Calcium pumps in the membrane of the sarcoplasmic reticulum facilitate the influx and outflow of the calcium ions. This regulation of calcium ions is vital because calcium ions take part in the process of moving the actin and myosin filaments in the muscle cells. This essay plans to explain and elaborate about the structure and function of the sacroplasmic reticulum, in particular looking at the semi permeable properties of its membrane, as well as the calcium ion protein pumps in the membrane.

The sarcoplasmic reticulum in the muscle cells forms a large network of lateral cisternae that surround the myofibrils. Traverse tubules made up by invaginations of the plasma membrane are often found beside the sarcoplasmic reticulum. The semi permeable nature of the sarcoplasmic reticulum means that it is a membrane that allows only certain molecules and ions to pass through. Like the plasma membrane, the sarcoplasmic membrane is also made up of a fluid phospholipid bilayer with proteins embedded all over the layer. The common features of the lipid molecules are that they are amphiphatic, meaning that they have a hydrophobic non polar end and a hydrophilic polar end. Due to these properties, the phospholipids molecules aggregate together in aqueous solution to from a continuous, fluid lipid bilayer (1). The hydrophilic phosphate heads are able to form favourable hydrogen bonds or electrostatic interactions when exposed to water whilst the hydrophobic fatty acid tails of each molecules form hydrophobic interactions with each other, away from the water. The molecules cluster together so as to minimize the free energy and thus such arrangements form spontaneously in aqueous environments such as the human body because they are energetically favourable (1).

The lipid bilayer membrane is semi permeable, and forms the enclosed environment of the sarcoplasmic reticulum. unscrambledthoughts.wordpress.com Being a continuous, enclosed layer, large molecules such as proteins, glucose, urea, are unable to pass through the membrane freely by diffusion. The region of high hydrophobicity in the membrane also prevents charged molecules or ions to pass through the membrane freely.

However, the sarcoplasmic reticulum allows the movement of calcium ions to pass through. How does this happen? Although the membrane is mainly impermeable, it consists of transport proteins that are found throughout the whole membrane. They allow the movement of essential molecules such as ions to pass through the membrane. A transport protein found on the sacroplasmic reticulum is the ATP dependent calcium pump (6). With the structure and properties of the sacroplasmic reticulum membrane already written, now the attention turns to the transport protein, in particularly to the structure, how it interacts with the surrounding molecules in the membrane, and how it regulates the transport of calcium ions.

Portrait of a summer thief

So what are you going to steal this time?

hehz.

before whom I stand...

he was a man like us...

Just 4 words that baffle.

Am I heartless? Do I lack compassion?

What does my heart beat for? I know what it is.... and if that is the case then....
it was my fault. I don't blame myself for it anymore...

Rising up to the occasion.

Prayer and science seems like an antithesis in itself...

Grace.

7end

It's Friday and it really has been a long week. Weekend war ahead... Plenty of work to catch up on though. I haven't kicked a ball in 5 weeks because of work and many other reasons... Yeah at the rate this is going, I think I have to really hang up my boots and find some other way to exercise. Well maybe swimming or running? haha who knows. I am waiting for the match against Hobson's Bay. My final match? haha perhaps.. It is pretty exciting to play a proper match... and even more exhilarating to put that ball into the opponent's net...

The silent and the cool. It's funny how I'm racking my brains to think of a character who's silent and cool. The world always admires the loudest, wittiest, the most eloquent and fluent. Maybe silent and cool characters only appear in anime.... Where one person's actions or facial expression or even a single smile means much more than any of the words he says. Characters who don't speak a lot, but when they talk, its probably something that will be quotable in ages to come... Then again, I hardly think such characters ever exist.

I like the character Aizen Sosuke from Bleach. Don't ask me why... but I like antagonists or supporting characters. Main characters or fan favourites are just so.... boring sometimes. Yes yes i know he's cold, calculative and manipulative but I have a liking for silently intelligent characters. Misunderstood characters as well, because silent people are most of the time misunderstood. Characters with depth, that are not what they appear to be... that sense of enigma and mystery yadda yadda yadda... I can go on... haha

time to take a nap. haha

To clarify

The earlier stages of PP syndrome, like stage 1 and stage 2 is tragic... and something I would identify myself with. hahahaha but the later stages of PP syndrome, like stage 3.... well I wouldn't really want to advance into that stage, because it garners a very disapproving look from someone.... hahahaha (:

I bore myself..

You Are An INTJ

The Scientist You have a head for ideas - and you are good at improving systems. Logical and strategic, you prefer for everything in your life to be organized. You tend to be a bit skeptical. You're both critical of yourself and of others. Independent and stubborn, you tend to only befriend those who are a lot like you. You would make an excellent scientist, engineer, or programmer.

What's Your Personality Type?

I Wonder

There are so many paths in life we take. The million of possibilities and decisions that affect our future in one way or another.

I muse and wonder what if I sticked to my music lessons. If I continued pursuing playing basketball seriously, or just what if I stayed in the island, what if I was serious in my faith during my time in army....

Well life isnt about dwelling on regrets. Second guessing is just tiring. Be thankful for what I have now, and the path I'm walking now.

More one-liners

Sometimes when I listen to 'Santa Monica', I just long for that perfect getaway. Longing for that one day where I can just care about nothing... It's like something so elusive.

It's there I sit and wonder what am i doing here...

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If i could have one dance with you, I'd play a song that'd last forever

I wished I had time to panic for the exams.

In the middle

Half asleep, thinking of whether to put my head on the library desk or to continue reading those dreaded journal articles. Abit out of it? That would be an understatement.

Milano is a funny place. It starts at the lobby, with the strange fountain statue. A sculpture of a naked woman who has a small flow of water coming out of her strangely obscene hair...

Then there's always the 3 white CIA agents every morning at 730. The 'flyboys'... complete with shades, shirt , tie and earpiece...

It's funny how you meet weird people in the lift... or the weird conversations that they strike up with you. It's always quite interesting when the lift stops and you wonder who might just be coming in to share that lift ride with you.

Elizabeth Street is dodgy. Adult shops, the backpackers, pubs, shops selling bollywood movies etc etc. A group of Indians always hang out at Elizabeth St... Big group of guys just unnerve me. It brings back the memories of street gangs. Aggression and strength in numbers. My friends alway tell me: Never get into a fight with indian gangsters. It's always a fight to the death, they say.

Well I could go on and on about random things I see everyday, but then again, I think I observe too much and never take any action... It's a scientist thing (: