#sarcomeric

[birdyverdie]

I'm the most worried about my Anatomy Exam, cuz it's the most memorization. but out of the 6 topics I need to know, I'm only uncertain about 2 of them, which I think are pretty good odds.

[castielsbees]

the manacled brainrot is hitting SO hard today and normally i’d be revelling in it but i have so much studying for anatomy to do i can’t be having my brain occupied like this 😭

[penciltopbear]

College is so wild man. Talked to a girl today who told me she did all of her math homework with chat gpt and didn't believe in evolution. And she said she didn't know what a neurotransmitter was literally two days after we took a test about neurons

[simonh]

Dystrophin Abnormalities in Neuormuscular Disease by National Library of Medicine Via Flickr: Series Title(s): NIH director's Wednesday afternoon lecture series Contributor(s): Kunkel, Louis M. National Institutes of Health (U.S.) Publication: [Bethesda, Md. : National Institutes of Health, 1990] Language(s): English Format: Still image Subject(s): Neuromuscular Diseases, Dystrophin Genre(s): Posters Abstract: Predominantly gray poster with red and white lettering announcing a lecture given Nov. 1990 by Louis M. Kunkel, Ph.D., prof. of genetics at Harvard Medical School. Visual image is an abstraction of the myosin and actin filaments of a sarcomere, depicted with yellow and gray rods. The first iteration shows the rods in a close formation, as in a normal, contracted muscle; they become separated by greater distances in the iterations below. All text near bottom of poster. Extent: 1 photomechanical print (poster) : 72 x 43 cm. Technique: color NLM Unique ID: 101449377 NLM Image ID: A030719 Permanent Link: resource.nlm.nih.gov/101449377

[aspensmonster]

It's giving sarcomere:

[deadbirdlife]

Transparent mouse breakthrough!!

Ou et al. found that applying a food dye (tartrazine) to the skin of live, hairless mice turned the skin temporarily/reversibly transparent!

The dye molecule absorbs in the near ultraviolet and blue region of the light spectrum, and changes the refractive properties of the aqueous (water-containing) portion of the skin to match the lipid (fat) portion of the skin, such that the refractive index in the red part of the spectrum is increased without increasing absorption. This essentially allows not-blue (mostly red) light waves to pass through the skin with minimal scattering, hit muscles, organs, and other internal structures, and pass back through the skin to our eyes, allowing us to see "inside" the mice. They tested this in three regions on the mice: in the abdomen to view fluorescent protein–labeled enteric neurons to track gut motility, in the scalp to visualize cerebral blood vessels, and in the hind limb to visualize individual sarcomeres (microscopic muscle units).

Initial safety tests seem promising, although further experiments are needed to fully explore how safe it is to dump that much dye into the skin.

Note: this doesn't mean we'll be able to do this to humans, exactly; human skin is much thicker than mouse skin, and we have far thicker fat between our skin/muscles/abdominal walls/organs, which will interfere with penetration. However, if safety tests bear out...this could have really cool implications for small animal veterinary medicine, biomedical research, microscopy, and any other settings where noninvasive internal imaging of small, thin-skinned animals is needed.

Article: Zihao Ou et al., Achieving optical transparency in live animals with absorbing molecules. Science 385 , eadm6869 (2024). DOI: 10.1126/science.adm6869

[luisterine]

Absolutely beautiful shot of striated skeletal muscle tissue. Honestly one of the most beautiful tissues to look at. The multinucleated muscle cells and the striation caused by the sarcomeres makes for a really visually unique histological cut.

[beeffizz]

Prof said both of his sons are dyslexic.... you gotta wonder.....

White knuckling the lab table clenching my jaw biting my tongue because the anatomy and physiology professor can't pronounce the terms correctly

[justkidneying]

Rigor Mortis

This is the stiffening of the muscles of a person after death, which happens due to the depletion of ATP (energy) in the cells. It can happen within a few hours after death and persists up to a few days. After that, the corpse will relax as it continues to decompose.

To understand the mechanism of this phenomenon, we have to first examine how muscle contraction works, what glycolysis is, and how these two systems interact.

How do muscles contract? The contractile unit of a muscle is called a sarcomere. This composed of a lot of segments (like a caterpillar). In each segment there are two main types of fibers: actin and myosin. Myosin is a thick filament that sits in the middle of the segment, where a bunch are stacked on top of each other. In between these fibers are thin actin filaments that attach to the ends of each segment. Basically, you can imagine these two types of fibers like you have slotted two combs together. For each segment, there are two rows of actin on each end, and one row of myosin in the middle.

Now, on to how they actually are able to move. When you want a muscle to contract, some stuff happens so that Calcium is released onto the sarcomere. It binds to troponin on tropomyosin, which causes actin to change conformation and expose an active site. This site is where myosin and actin can cross-bridge. Part of the myosin called the head will bend during a "power stroke", and pull the actin filaments towards the middle of the segment. Each segment gets shorter, so the entire sarcomere does as well. On a large scale, this is muscle contraction.

How do muscles relax? Muscles relax when a molecule of ATP (what you use for energy) dislodges the myosin head from the active site of the actin. ATP will be hydrolyzed into ADP and phosphate, and stay attached to the myosin head as it reenters the cocked position, waiting for the active site to be revealed again.

How do we make ATP? Cells break down glucose to make ATP, as well as other molecules, which can be used to make a lot of ATP. One of these processes involves oxygen, which is why we have to breathe. Using oxygen allows us to make energy in the most efficient way possible.

What happens after death? After death, someone is no longer taking in oxygen. This means that they are no longer making a lot of ATP. But, cells can still use glycolysis and other mechanisms to make ATP for a few hours after death. Once the brain is no longer functioning however, shit starts to go sideways in the body, and conditions become unfavorable for cells. Once all glucose has been used and the body cools, cells can no longer make ATP. This means that there is no energy to detach myosin from actin, causing persistent muscle contraction (aka Rigor Mortis).

Can Rigor Mortis happen while someone is alive? No. Rigor mortis is Latin for stiffness of death, and only happens once someone has died. However, a condition similar to it can be seen from respiratory failure. In patients who do not have enough oxygen, the cells begin to die from hypoxia and ATP is depleted. This leads to muscle contraction in the extremities that spreads until brain death occurs and the person stops breathing entirely. This can be a shocking condition to witness, as the person is still alive and breathing (though unconscious), yet they have begun to stiffen. As long as the brain stem receives oxygen, it will continue to send the signal for respiration.

Conclusion: Death is generally described as the breakdown of a complex harness that keeps systems from reaching equilibrium. After death, things begin to reach a chemical and thermal equilibrium with the environment. Cells are no longer protected from outside forces and begin to break down. Enzymes also begin to break stuff down. Because of this, myosin is eventually broken enough that it will detach from actin and the muscles will relax as they continue to decompose.

Note: This is important in the meat industry, as Rigor Mortis makes meat tough. The refrigeration of carcasses causes Calcium and ATP to work together to cause extreme contraction, called "cold shortening." To fix this, carcasses are electrocuted, which causes contraction and relaxation of muscles. This is done until ATP is depleted.

[crystal963]

My professor is promising extra credit for the whole class if this reaches 2k notes, so likes and reblogs would be appreciate. :)

Transcript: Join me as I explain the structure of a sarcomere. A sarcomere is the smallest functional unit of a skeletal muscle. It consists of different anchors, thick filaments, and thin filaments. For parts where it’s only the thick filament, that is called the H zone, which is here. In the middle of it, we have the M line, which are the proteins that anchor thick filaments. When we’re talking about thin filaments,that is called the I band, which is on both sides, and the thing that anchors it is called the z disc. When we’re talking about the entire length of the thick filaments, that is called the A band. And that is pretty much all you need to know about the different parts of a sarcomere.

[ooppo]

Hello everyone. Tendons are connected to muscles, which consist of fascial, which consist of muscle fibers, which consist of myofibril. Those myofibril have a sarcoplasmic coating, and are surrounded by T-Tubules which act as pores for the presynaptic site for neurotransmitters coming from motor neurons. Myofibril consists of many sarcomeres, connected together by z-plates. These sarcomeres are made up of thick and thin filaments. The thick filaments are made of myosin, and the thin filaments are made of actin. In muscle contraction, ATP is used to unbind the myosin heads from the actin. It then breaks down ATP into ADP and P. The P leaves the site, causing ADP to have a reaction with the myosin head. The myosin head stands upright and connects with the actin before releasing the ADP. This cycle must repeat many times to have a noticeable muscle contraction.

[kickasstorrents]

Overall, I generally think a low-level of DOMS is good. Why? Because it means your muscle fibres can lay down more sarcomeres during the recovery process which very gradually (over months) help muscles grow in size and strength.

[shrimpleasthat77]

I finally arrived home and I finally finished this ficlet!! I wanted to do some hurt/comfort just because, well, it's my favorite genre. I may have written this a lil tipsy so if it's bad or ooc, blame it on the apple cider champagne.

“Yakushi Kabuto” and “overworked” are almost synonymous. 

As established, Kabuto was one of the most critical pieces to the complex puzzle of Otogakure. He proudly wears this title, almost with a lilt of arrogance, if you ask any lower-ranking members. While he is proud of this, he is just a human at the end of the day. Any person, especially a young man like him, can only keep up with so much. While having more patience than Orochimaru, something he reminds the older man every chance he gets, it does wear thin. 

If his patience could be tangible, it would be comparable to a sarcomere. 

His entire week had been filled with meaningless, busy work, running around in circles for anyone who called his name fast enough. The bespectacled man had to stop a spat between Jiboro and Tayuya, reevaluate the stability for certain test subjects, find god knows how many misplaced items, and so on. Kabuto didn't have a moment to breathe before another person asked for his assistance. Sometimes, he wishes he could clone himself permanently to avoid being worn out by these requests. As he turned down one of the various candle-lit hallways, not walking with purpose this time, Kabuto finally tried to catch his breath. 

…breathing was much more challenging than he remembered. 

It felt like a lump was in his chest, growing more apparent as he thought about it. The silver-haired man didn't recall feeling this way earlier, nor when he first woke up. The more he obsessed about fulfilling more requests, the worse the tension got. Leaning against the wall, he tried his best to pull himself together the best he could. Kabuto slowly began to make progress after a brief moment, his mind slowly reorganizing itself. The bespectacled man would be back on track in

“Kabuto, there you are. I've been calling you for minutes on end-, no matter. Now that I have found you, I require a favor.” Orochimaru disgruntledly said, stepping near the younger man. 

“What would you even do without me, sir?” Is what he wanted to say in response, but the words wouldn’t leave his mouth. He could only gape at the older man like a fish plucked out of the water. The feeling in his chest was choking him now, making it increasingly difficult to breathe. Usually, this could be chalked up to the oppressive aura Orochimaru carries himself with, but Kabuto is far used to that now. All he could do was stare back at the serpentine man, making him even more stressed, which certainly wasn’t improving his condition. The older man did not like it when he wasn’t answered, especially for a request. He couldn’t track what was happening; minutes could have passed, maybe even hours. One moment, he was staring at Orochimaru, and the next, his gaze was fixed on the floor. Everything was spiraling so out of control that the younger man didn’t even register that he was being guided into a side room, the click of the door being barely audible. 

“Kabuto, look at me,” Orochimaru asked, tilting the other man’s chin up. “I should have known something was wrong when you didn’t have some sort of smart response.” 

“S- Siiir…” Kabuto could barely choke the title out. It was pathetic, honestly. He knew he could be better than this- 

“Drop the title. Now is not the time for that.” the snake frowned. “Take a moment to gather yourself.” 

The rigid command eased him slightly as he moved closer to the other man. He was guided into an embrace, smooth, thin hands running over the back of his head. Orochimaru’s long yet manicured nails lightly raked over his scalp, the repeated friction grounding him. His master smelled of incense and sweet rot, a poignant smell Kabuto had grown indifferent to. If anything, it calmed him just as much. A silence had settled between the two, a rare instance for them. Kabuto felt his senses returning to him as time passed, no longer as panicked. 

Orochimaru stopped these repeated motions, touching the younger man’s shoulders. “Now, what happened to you? It’s a tad rare to see you so distressed.” 

“I…” Kabuto found himself lost again. He could just say what was on his mind, but he wasn't entirely sure how the snake would react. After a moment of thought, he realized he was simply too worn out to care. “I’ve been running around in circles for everyone here without a break. I’ve lost track of what I was even doing beforehand.” 

A smile had worked its way on the other man’s face. “Ever so hard working, Kabuto. You act like you are still trying to prove something to me.” 

That was something he could never get used to, Orochimaru’s ability to read people like a book. “I would like to do right by you, Orochimaru. I’m sure you didn’t just blindly place your trust in me.” 

“Kabuto…you know I would not do this for anyone but you, correct? Did your brain get scrambled during your escapades?”

“You aren’t exactly known to be very comforting.” 

“I do not care about everyone else like I do you. It would be useful to keep that in mind.” 

“I’m aware, I promise. It’s an issue with me feeling inadequate, not you.” 

Orochimaru thought briefly, moving down to the bespectacled man’s wrist. “Say…why don’t you join me in my chambers? I have some papers I need assistance with.” 

“Taking advantage of my lowest moment to push paperwork onto me? You’re truly awful.” Despite his biting words, Kabuto was smiling. 

“Well, that’s not all; I’ll let you do it on my bed, and I shall stay by your side. Doesn’t sound so awful now, does it?” 

With that, Kabuto allowed himself to be led through the compound to his Master’s room. While it was just more work, it had at least meaning. If he could assist Orochimaru, he didn’t care. 

[crazybulkireland]

How Long Does It Take to Build Muscle?

The process of building strong body muscles cannot happen overnight. However, when you have been exercising regularly for weeks but still don't show results, what's wrong? Don't worry, muscle formation does not happen instantly. How long does it take for muscles to form? Come on, find out the answer below!

Know the Muscle Building Process Skeletal muscles consist of myofibrils and sarcomeres like threads that form muscle fibers and are the basic units of contraction. The muscle building process begins when you train your muscles to do new exercises. For example, doing weight training with barbells, a series of push-ups, or running on a treadmill. These exercises will stress the muscles, as well as create micro "damage" to muscle cells and muscle fibers. The muscle "damage" will then stimulate the body to form protein. Later, muscle cells become larger than before. Depending on the amount of muscle "damage" due to the exercise performed, muscle cells will grow larger and stronger from a matter of days to weeks. Therefore, most experts argue and suggest not to continuously do the same muscle exercises. Then, muscle formation is also influenced by hormones. Insulin Growth Factor (IGF)-1, especially Mecho-Growth Factor (MGF) and testosterone, are the two most vital mechanisms that drive muscle formation. Strength training helps release more testosterone, and makes muscle cell receptors more sensitive to testosterone released by the body. In the first weeks you start training or switch to a new type of sport, your muscles will need to adapt. Therefore, do not be surprised when you first do a new exercise such as push-ups, after which you will feel your arms shaking. However, do not worry because you will start to get used to it when you do the same exercise continuously. How long does it take for the body to become muscular? Most beginners will feel muscles starting to form and muscle strength increasing within eight weeks of starting a new exercise or sport. This increase in muscle mass will be seen more quickly in muscles that have less fat mass. As the training time increases, muscle mass will increase and provide additional weight of 0.5-1 kg / month. This can of course be achieved with the right exercise and diet too. This achievement is slightly different from athletes or bodybuilders who can gain weight, because muscle mass increases by 2-3 kg. Although athletes or bodybuilders appear to have proportional bodies, their weight is actually greater than it looks.

Read More : Food for Bulking: Building Muscle Becomes Easy and Fast

Signs of Increase Muscle Here are some signs that your muscles are developing: Muscles feel tight and hard Muscles thicken so that they are more visible or create muscle lines Muscle strength increases Weight increases but the body looks slimmer

Tips to Speed ​​Up the Muscle Building Process These methods can be done to speed up the muscle building process: Train Your Muscles at Least 2 Times a Week You don't need to increase or add to your training portion to maximize muscle building. As long as muscle building exercises are done 2-3 times a week.

Consume Enough Protein The protein you eat will be the protein needed for muscle building and its recovery process. You are advised to consume 25-35 grams of protein at breakfast, lunch, and dinner to maximize muscle building. Sources of protein can be obtained from nuts or chicken breast.

Vary Your Exercise Portions Every 4-6 weeks, you need to vary your training. You don't need to change the type of training, but simply change the number of repetition variations of the training, duration of the training, rest time, and so on. However, it is best to avoid training more than four times per week so that the muscles have time to recover. Building muscle is not easy and not instant. The process of building muscle can also vary depending on the condition or training of each person.

[er-cryptid]

Organization of Skeletal Muscle

Muscle -- blood vessels -- nerve fibers -- covered by epimysium

Fascicle -- bundle of muscle cells -- surrounded by perimysium

Muscle Fiber -- muscle cell -- surrounded by endomysium

Myofibril -- organelle -- complex

Sarcomere -- contractile unit

.

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[charmcoindied]

studying muscles is actually super fascinating because like... i'm taking handwritten notes on my ipad and i'm very aware of the movement of my hands the entire time i'm doing this. just continually looking from the online textbook to my hand holding my pencil and back again as my hands move over the screen and adjust the movement of the pencil to write words. and thinking about the hundreds of muscle fibers being activated not just in my hand, but in my wrist and arm as i write, and the thousands of sarcomeres contracting in those hundreds of muscle fibers almost instantaneously to move my hands and write my notes.

when you're studying biological processes it seems like time sort of slows down--the movement of actin against myosin takes a couple seconds, drawn out so it's easier to observe. it's easy to forget that this is happening a million billion times per second all over your body forever