Questions tagged [muscles]

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

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20
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1answer
3k views

How did the largest/longest dinosaurs hold their head and necks up?

After seeing the images in the articles shown below, I am having a tough time understanding the mechanics of how these incredibly long and heavy necks can be supported outstretched like this. A rigid ...
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1answer
75 views

Why fingers in human fists get folded in absence of neural stimuli?

Background: I noticed that the fingers in our fist tend to get folded in absence of neural stimuli. The same thing happens in case of our hands and legs. Question: What is the mechanism behind this ...
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152 views

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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1answer
143 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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2answers
842 views

What chemical conversions are involved , and what's the name for the process, when the muscles use lactate as an energy source?

I understand that muscles do anaerobic metabolism, specifically, "lactic acid fermentation", which I understand produces lactate. I'm not asking about that process. What chemical conversions are ...
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0answers
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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0answers
1k 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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2answers
8k views

Why does it hurt the next day after doing significant exercise?

I think this is a fairly common observation that if one does some significant amount of exercise, he/she may feel alright for the rest of the day, but it generally hurts bad the next day. Why is this ...
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2answers
8k views

Are tendons and ligaments classified under the muscular or bone system?

Are tendons and ligaments classified under the muscular system or the bone system? Basically they are not bones or muscles and that's why I have doubt.
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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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85 views

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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1answer
148 views

Lengthening muscles not good from evolutional perspective? Why do we do it with explicit stretching?

Stretching has many advantages, among other things it helps us to be flexible in our movement (which is an advantage?!). But why do we need to actively stretch, it seems that the body wants to ...
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84 views

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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2answers
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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53 views

Bone fracture cause [closed]

I had bone fracture twice in the same arm. So I had first bone fracture in right forearm with 45 degree break on two bones, after 3 months of that fracture while I was climbing a slope I fell and I ...
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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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0answers
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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2answers
798 views

Are there genetic causes underlying the difference in circumference of the upper arm and foream?

Is there any genetic reason for the difference in size between the upper arm and lower arm (i.e., the forearm)? In most women, it seems that the upper arm is larger in circumference than the forearm. ...
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0answers
105 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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382 views

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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0answers
270 views

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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1answer
228 views

Why are successful human rock climbers so dissimilar to Hominidae primates who spend extended time periods climbing? [closed]

In rock climbing, the sport considers the Ape Index when evaluating the factors critical for success. However, the majority of successful climbers are lithe and slim with less than 8% body fat. As ...
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71 views

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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103 views

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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1answer
9k views

What is difference between High quality and low quality proteins [closed]

I have seen in news that some bodybuilder died of taking steroids; when I went through details I learned that "low quality proteins" contributed to their death. I have studied about linkages in ...
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377 views

How can skeletal muscles in the human body be modeled as levers? [closed]

From what I understand, human arms can be thought of as third class levers, so that the distance from your elbow to the place where the muscle attaches is effectively the distance to the fulcrum, so ...
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1answer
8k views

Location of t tubule in muscle

Why do mammalian skeletal muscles have t-tubules at the junction of the anisotropic and isotropic band, whereas non-mammalian muscles and cardiac muscles have it at Z-line? What could have been the ...
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1answer
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Are tergo-sternal muscles of cockroach involved in blood circulation?

Tergosternal muscles help in the blood circulation in a cockroach as well as in movement of the wings for flying. I came across a question that claims that these muscles are used in blood circulation ...
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Bending your little finger without bending ring finger

It is possible to bend each finger without bending any other, except one for most people. It is more difficult for the ring finger, but when I try to bend my little finger independently my ring finger ...
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1answer
594 views

What is the difference between a “semi-contracted” muscle and a “contracted” muscle?

I read on http://www.spine-health.com/glossary/muscle-tension: Muscle tension refers to the condition in which muscles of the body remain semi-contracted for an extended period. What is the ...
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399 views

What is the difference between muscle tension and muscle tightness?

Is there any difference between muscle tension and muscle tightness? I want to study the relation between forearm muscles tightness/tension and tendinopathy (specifically, medial and lateral ...
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117 views

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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108 views

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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1answer
3k views

8 abdominal muscles but 10 pack

Simple question, how is it possible that there are people who appear to have 10 pack abdominal muscles while the human body has only eight?
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1answer
124 views

What makes us “tired” in the gym that forces us to rest? [closed]

If I'm doing push ups or any other of gym exercise, I can do 10 in a row, but each one I do I feel more "tired", but if I rest for 5 minutes, I'm much "full of energy". Please explain me exactly what ...
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0answers
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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1answer
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) ...
2
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1answer
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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2answers
2k views

How do legs of tiny insects/spiders like mosquito/Opiliones work?

I think I understand how legs of humans work. We have bones to which muscles are attached. Muscles can only contract / relax. By the combination of many different muscles we can make complex movements:...
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1answer
81 views

How correlated are the lengths of tendons in different part of a human body?

How correlated are the lengths of tendons in different part of a human body? E.g., if the we consider two humans, A, and B. Human A has a patellar tendon of length 2 cm, and human B has a patellar ...
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0answers
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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0answers
58 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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2answers
26k views

What is the difference between endomysium and sarcolemma [closed]

They both are lining of muscles so how can we differentiate these two? Please answer in simple terms.
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1answer
119 views

What is the state of actin-myosin in my biceps after I have flexed my arm?

When I'm starting to flex my arm, the myosin and actin slide over each other in a ratchet like mechanism. When I've totally flexed my arm, are the actinomyosin left in this contracted state? Since ...
3
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1answer
293 views

How do sarcomeres coordinate contraction?

As can be seen from the figure if myosins from both sides apply equal force then how does muscle contract? And also how do actins resist tearing? Is there any kind of coordination between different ...
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1answer
1k views

Are glands in human made up of muscles?

I came across this idea while reading an excerpt of my textbook $-$ Muscles move eye lid , tongue, beat the heart, popel food through gut, discharge wastes, squeeze out secretion from the glands ...
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1answer
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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0answers
144 views

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?
2
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1answer
662 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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0answers
32 views

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?