Questions tagged [muscles]

The contractile tissue of animals derived from the mesodermal layer of embryonic germ cells.

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Are there certain symmetric-pair muscles that are slightly bigger and NOT due to handedness?

Ok, hear me out, I was just thinking about an article in Nature I read in the past titled "Scrotal asymmetry in man and in ancient sculpture"$^{\dagger}$ and more recently an entire medical textbook ...
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Do cells in healing ligaments or tendons have deformation processes? If so, what are they?

I am trying to better understand how non-muscle tissue in the muscuoloskeletal system heals. Specifically, I am interested in how ligaments or tendons heal once torn. I read the following text: ...
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How is atrophied muscle different than normal muscle in a chemical or biological way?

I am a writer with a question for a story I'm working on. In it, the character suffers from muscle atrophy due to spinal damage. So that I can portray this accurately, what would cause this type of ...
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Partial muscle fibre contraction

I'm being taught that: a muscle fibre spans the entire length of the muscle, from the originating tendon to the inserting tendon. The question is, can a muscle fibre contract only partially? Say, if ...
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Are there specific theories as to what causes cold[-water] muscle cramps?

The field of what might cause cramps is quite contested with a lot of controversy around the heat/dehydration cramps, but I find it surprising that no specific theories appear to have been proposed (...
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How does isometric contraction work?

What exactly happens to myosin during isometric contraction? I suspect that either myosin heads just "freeze" in the middle of crossbridge cycle, or go through full crossbridge cycles repeatedly at ...
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869 views

Why do hand/fore-arm muscles “lock up” after very high-powered effort?

Inspired from Why does it hurt the next day after doing significant exercise? with its excellent answer: In climbing, you can put tremendous load on the hand/fore-arm muscles (specifically, flexor ...
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53 views

How does gold chloride stain neuromuscular junctions?

Gold chloride is used in muscle biopsies to stain the NMJ. What is the substrate that it binds to?
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148 views

How is recruitment of multiunit smooth muscle cells fine tuned if they are innervated by varicosities?

In my physiology textbook (Silverthorn) and on wikipedia it says that: Multiunit smooth muscle tissues innervate individual cells; as such, they allow for fine control and gradual responses, much ...
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What are the metabolic consequences of negative mechanical work in muscle contractions?

When a muscle contracts while it shortens (concentric), it consumes ATP I believe primarily due to cross-bridge shortening to remove the myosin head from it's attached state. However, when a muscle ...
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Acetylcholine and muscles- excitatory or inhibitory? (muscle atonia and myasthenia gravis)

I have heard that acetylcholine can be excitatory or inhibitory, but I am confused as to which it is when it comes to muscles. On the one hand, I believe that muscle atonia during REM sleep is ...
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191 views

What controls the feeling of discomfort/comfort before and after sleep?

I'm interested in which biological systems or hormones are involved in the following phenomenon: Before sleep it may be difficult to find a comfortable position, and muscular aches and pains are more ...
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Does constant pressure cause muscle atrophy, and if so, why?

I read on https://en.wikipedia.org/w/index.php?title=Gluteal_muscles&oldid=876760828#Clinical_significance: Sitting for long periods can lead to the gluteal muscles atrophying through constant ...
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How much energy can one muscle contraction deliver?

How much energy is available in a single muscle contraction? I'm guessing the correct units are J/kg, but I'm open to more correct units. I'm looking for work done, not total energy dissipated (not ...
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Exhaustion of skeletal muscle and ligaments

I read somewhere that while doing lifting back should be straight(means normal curve), so that erectors muscle in back do the work but it gets tired easily. Hence we form curve on our back like when ...
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seafood muscles - how do they work?

Today, first time in my life I ate seafood. It was a squid and a calamar. Note that I am biology layman, so please be merciful :( While dissecting my food I noticed that the tissues of those ...
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When a muscle contracts, does it store potential energy like a spring that is released upon relaxation?

A colleague of mine who mainly focuses on clinical chiropractic work claimed recently in a book he wrote that muscles in the pelvic floor have "elastic recoil." What he means by this is that a ...
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What do we mean when we say that a muscle fiber contracts strongly?

Sounds dumb but anyway, i heard that superfast fibers contract more strongly than fast twitch fibers. And i never thought of muscle contraction as something that has a magnitude (i thought of it as "1 ...
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Energy efficiency of muscles and animals as a whole

When human or animal do some work, they use energy from their food. What is known about overall efficiency of this process? Say a horse is turning a winch and does 10,000 kJ of work. How much more ...
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Does the speed of muscle contraction within a single sarcomere differ between people?

Of course the number of muscle cells can be different person to person. But within a single sarcomere, are we all the same? Would the frequency of the protein motor binding and release cycle ...
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How to contract sternocleidomastoid muscle by thought?

If I do not turn my head, how can I contract ( or tighten) the sternocleidomastoid muscle ( like we can intensely tighten muscle in limbs)?
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283 views

How does the ATPase stain for muscles revert on changing the pH?

Muscle sections are stained with ATPase to differentiate between types of fibres and to display the ckecerboard pattern. But it is done at two different pH. The staining is reversed at acidic/basic pH....
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60 views

Myoblasts Formation

Myoblasts arise from mesenchymal stem cells (MSCs), and are precursors to myocytes. In muscles, in the basement membrane, there are also present satellite cells which can divide to generate muscle ...
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In a sarcomere, during contraction, is chemical energy turned into elastic energy and then mechanical energy?

I'm familiar with the cross bridge cycle and how the sarcomere contracts, but I have two related questions. I’ve read that when the myosin head cocks, it’s similar to a spring-loaded mousetrap. But is ...
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91 views

How is the side-polarity of the myosin filament in myofibril maintained?

If myosin molecules are the properly oriented relative to their position in the the myosin filaments, the sarcomere is not functional. But how is the orientation of the myosin molecules determined? ...
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Why do workouts cause your muscles to feel heavy?

I know that muscle activity causes your muscles to build up lactic acid. Is this the specific reason that your muscles begin to feel heavy? How does this relate to the healing or inflammation process ...
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What are potential side effects of myostatin inhibitors?

Myostatin inhibitors, which are being developed to treat muscle wasting diseases like muscular dystrophy, are likely to be abused by athletes. What are the potential long-term side-effects of taking a ...
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614 views

When a muscle contracts, but not all the muscle fibers are activated, what happens to the remaining muscle fibers?

I understand how motor neurons work, but I would like clarification on what exactly is going on when a muscle contracts. For the sake of simplicity, let's just use the bicep as an example. If I do a ...
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ATP and Muscle Contraction

I have a question regarding how molecular interactions manifest in physical actions - such as hanging from a bar. To the best of my understanding, when it comes to the contraction of muscles, ATP is ...
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For each movement performed by both the gluteus minimus and medius, what percentage of the movement do the gluteus minimus and medius account for?

From what I read on Wikipedia, all functions of the gluteus minimus are mirrored by the gluteus medius. Additionally, the gluteus medius is larger than the gluteus minimus (see comparative images here)...
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Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it?

Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it? On How does muscle size relate to strength?, I read this answer from Moses (...
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Are there known counterexamples to Hennman's size principle for muscle unit recruitment?

It is known that generally muscle units are recruited from small to large, and that typically also means slow to fast twitch. This principle is called Hennman's size principle. I've seen many ...
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Contracting mouth muscles as reaction to taking in specific food items

When eating very specific food items, especially confectionery like (salty) liquorice, (it feels as if) the muscles of my mouth contract, right when it hits my tongue. Does anyone know why this ...
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What is official term for contraction induced muscle “vibration”?

I can activate my tensor tympani muscles at will, it makes me hear rumbling bass sound becose the muscles "shiver / "vibrate" when contracted. Also when I put cleched fist to my ear I can hear it too. ...
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Why proximal muscle weakness is seen earlier than distal muscle weakness in Dermatomyositis?

It is said that in dermatomyositis(DM) , proximal muscle weakness is seen earlier than distal muscle weakness. It is also said that , DM is due to damage to small blood vessels contributing to muscle ...
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49 views

does being battered build muscle?

My crude understanding of how people normally go about building muscle is something like this following 2 step process: 1) a person can lift weights (for example), which tears muscle and stimulates ...
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What was the first known organism to exhibit muscle growth based on activity?

Being able to grow bigger muscles to match an organism's personal habits seems like a pretty nifty feature since most organs grow to one specific size, aside from some stretching. Was this a feature ...
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examples of transitional fossils showing development of internal skeleton

What fossils exist that show the development of skeletons, and muscles attached to bones?
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How can myoglobin be responsible for the red color of meat if it is located in the cytoplasm?

How can myoglobin be responsible for the red color of meat if it is located in the cytoplasm, as the visible part of muscle cells is the membrane (at least as I believe)? Sources: https://en....
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28 views

Muscle involved in carrying load on head

I have seen people carrying heavy load on their head especially in 3rd world countries, does carrying on head any benefit or harm, which muscle get strengthen in doing it?
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Is an adaptation against impact of fall a factor in babies' bones' structure?

Obviously, babies' bones need to be flexible to get through the pelvic bone. But is that the only reason? Could it be that as babies aren't able to maintain stability, they need bones less prone to ...
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How is the Force of Contraction Applied to the Tendons by the Muscle's Individual Fibers?

Image and question have been updated for clarity! The image above is a side view of a semi-transparent skeletal muscle. The dark red lines represent individual fibers, the blue lines represent ...
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Why does lactate build up prevent a further increase in the speed of an athlete?

This question was triggered by an exam question that I was doing on the following paper (Q2 part (b)(i)): http://qualifications.pearson.com/content/dam/pdf/A%20Level/Biology/2013/Exam%20materials/...
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What is coffee effect on muscles ? On sport performances?

Since coffee is a vaso-restrictor does it have any impact on sport performances ? I mean does it go against natural way the body works (sending more blood to muscles due to the increasing needs) or ...
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What makes delayed onset muscle soreness stop occurring?

If someone lifts weights or takes a long jog after not doing it for a while, they can experience delayed onset muscle soreness (DOMS). However, when they return to the same exercise days afterwards, ...
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How do our muscles get tired?

I know one of the main reason why our muscles get tired is because there is too much lactic acid, but how does this lactic acid negatively affect the action of myosin on actin?
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Muscle contraction/extension percentage during normal ranges of motion

What is the typical percentage range/limits of extension/contraction during normal ranges of motions for muscles? Assuming a rest length in a typical relaxed state. I'm mostly interested in humans ...
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Are myosatellite cells myoblasts or do they differentiate into myoblasts?

Can satellite cells immediately fuse to a myotube/myofiber (meaning it is a myoblast already) or do they differentiate into a myoblast first and then fuse to myotubes/myofibers?
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Long-Term EMG studies

I am having trouble differentiating onset/offset of muscle activation. Is there anyone in the field has a specific way to set the threshold for both time and magnitude?
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How are muscle fibre size and oxygen consumption related?

Does anyone know of a paper which correlates the muscle fibre size to oxygen consumption in mammals? I am trying to find a correlation between muscle fibre type, size and (absolute and specific) ...