Questions tagged [muscles]

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

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110 views

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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163 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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53 views

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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744 views

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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194 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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10k views

Why we shiver/tremble/shake while performing some work which requires high accuracy?

Shivering when nervous or anxious is a common thing. But, shivering or trembling sometimes also occurs when we are performing a work which requires high accuracy. In such case, our whole body doesn't ...
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5k views

When contracting a muscle will the muscle spindle stretch or contract?

When you contract your muscle, will your muscle spindle stretch or contract? And why? I was always under the impression that it was contracting your muscle spindle, but now I am not sure.
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Can you build muscles from watching point of view videos of people weightlifting?

According to this, "new research has found that viewing other people exercise actually increases your heart rate and other physiological measures, just as if you were working out yourself". This got ...
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9k views

Mechanism of Myosin Head Bending in Cross Bridge Cycle Power Stroke Phase

What is the mechanism of bending of myosin head during the power stroke of the cross-bridge cycle of the muscle contraction? Does this have anything to do with the protein's 3-D structure i.e. folding ...
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364 views

Can the human body store protein?

I am interested to know if a human body can store protein. Absolutely for the bodybuilders, does it really matter if they divide their protein consumption during the day or eat all of it in one meal ...
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78 views

brain and fingers movement theorie

I heard somewhere that when we want to do a repetitive movement of one finger (ex the index) . Our brain (in a very crude way) sends a first message to move all the fingers, and then a second message ...
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58 views

Which of the response is faster? voice or hand action?

After taking certain stimuli and making the the decision to do certain action, which one response (output) (out of 2 possible output-ways, voice and hand-movement) would act faster? For example lets ...
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90 views

Why does hypocalcaemia cause increased muscle contraction?

Calcium is needed for muscle contraction, so how does hypocalcaemia cause increased sustained contraction?
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144 views

In myosin II are regulatory and essential light chains calcium binding proteins or sites of phosphorylation?

According to my medical physiology by Rhodes and Bell their description is as follows: the essential light chain is necessary for myosin stability, and the other chain called the regulatory light ...
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12k views

What is the difference between muscle fascicle and muscle bundle?

In the photo above (given by Bio teacher), the muscle bundle is shown to be as a bundle of fascicles, but in most web definitions I've seen, the two terms are used interchangeably. What is the correct ...
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339 views

How much mechanical stress can a skeletal muscle bear?

In the movie- Saw, for the last trap Bobby was told to insert metallic hooks into his pectoralis major muscle. In his fake story Bobby has raised himself successfully, but when he was "really" trapped,...
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255 views

advantages of shivering in cold environments

When we feel cold, our the muscle tries to generate heat by shivering and the brown adipose tissue tries to generate heat by non-shivering methods. The muscle generates heat but also spends energy on ...
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60 views

Need / consumption of magnesium

Does doing sports makes a human require more magnesium and – if any – how strong is this effect? Do athletes take magnesium supplements (e.g. pills of magnesium carbonate) because they build muscles ...
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1k views

How does motor nerve innervation determine type of muscle fibre?

Muscle fibres are of two types - type I and type II. They differ from each other in various properties. Even the underlying biochemical processes are different to suit their function (slow vs fast) ...
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2k views

What happens when our muscle tense? [closed]

Is the tensing of muscles equivalent to stretching them? I am trying to understand what tensing of the muscles means.
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188 views

Are gizzard muscles voluntary or involuntary?

I started raising chickens this year. They have amazing appetites, and I often wonder what eating is like for them. They have no teeth, so they don't chew their food as they eat it. They do seem to ...
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1k views

Why do some cells like myofibrils have multiple nuclei?

I see that myofibrils (muscle cells) contain not one, but multiple nuclei. Why is this so? Do all the nuclei participate in cell division?
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1answer
114 views

Kinesiology Tape Benefits

Recently, kinesiology tape has become popular, especially in CrossFit. I have also noted its' use in the NFL, and I want to say Tennis as well. What beneficial effects does this tape offer our bodies ...
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128 views

Why some muscles have more tendons than others?

Very interesting examples to me are Trapezius or Latissimus - they both have places with more tendons than muscles. Taking into account that now they contract weaker and slower with all these tendons, ...
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35 views

In a skeletal muscle contraction, what happens after ACh binds to the nicotinic iontropic receptors on sarcolemma?

Does the bound ACh becomes unbound and then gets hydrolysed by acetylcholinerase?
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109 views

Why is muscle force more dependent on cross-sectional area than on fiber length?

I was looking up why smaller animals are proportionally stronger than larger animals. The answer that comes back everytime is that muscle force depends on the number of muscle fibers, which is ...
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Is “muscular attachment” synonymous to tendon? (when talking about the insertion of glutei medius and minimus to greater trochanter of the femur)

I have read the following two terms in an MRI report (both points refer to the insertion of gluteus medius/minimus to greater trochanter of the femur): mild degeneration of the muscular attachment ...
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117 views

Are there biological ratchet cycles that are small in number?

I recently came across the strange factoid that all animals that can jump do so to roughly the same height (within an order of magnitude). The argument was that the work done by muscles in a single ...
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168 views

By What Mechanism Does Heat Cause Muscle Relaxation?

Heat is commonly used "loosen" muscles, but what exactly is happening to relax the muscle? It wouldn't make sense that increased blood flow alone would relax muscle.
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2k views

Is the Klein's bottle a good analogy to the relation between T-tubule and sarcolemma? [closed]

I am not quite seeing how the T-tubule and sarcolemma is connected. It says that the T-tubule is an "invagination" of the sarcolemma, which is sarcolemma folded from the inside to form a T-tubule Can ...
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81 views

Is there a difference in flying technique or anatomy between birds and bats which means bats don't need a large sternum?

I know that birds have a large sternum in order to anchor the wing muscles. Bats also have wings, but don't have the same large sternum. Is there a difference in either flying technique or anatomy ...
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Most optically transparent muscle phantom?

I am trying to use Schlieren imaging techniques to visualize how a sound wave propagates through muscle tissue. In the past, when needing to experiment with muscle we would use an agar based muscle ...
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32 views

Summation on muscles

I am learning myology and encountered 2 problems in tetanus and summation: Unfused tetanus is just a continual summation of twitches if I am not mistaken. However, is it a MUST for summation / ...
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78 views

What happens to eyeball when you push your eye muscles harder?

I have myopia and I read that the rays of light intersect before the retina. When I can not see clearly I can push somehow my eye muscles and can see a bit clearly. The object gets clear but moves ...
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Why do muscle spindles send impulses at a constant rate when the muscle is at rest?

According to my book, the sensory neuron around the muscle spindle is sending impulses at a constant rate, while the entire muscle itself is relaxated (at rest). So when the muscle stretches the ...
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1answer
74 views

Does loss of dopaminergic neurons totally eliminate voluntary muscular control?

Breathing is a function that is not only autonomic, but can also be temporarily overridden and placed under voluntary control. In fact, you are now breathing manually. Now, suppose that someone has ...
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42 views

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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31 views

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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43 views

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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63 views

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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51 views

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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Limit of muscle atrophy [closed]

I read that lack of action leads to muscle atrophy , I experienced same when I had a cast for hand fracture. So how far this atrophy go, who decides minimum size of muscle due to lack of activity, for ...
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48 views

The link between muscle mass and muscle strength and how to train for each [closed]

I'm getting into my fitness and am beginning to see an increase in muscle mass. However, I look at people like Bruce Lee, Elliott Hulse, Mohammad Ali and Wim Hof who are capable of incredible strength ...
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137 views

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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106 views

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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301 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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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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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? ...