Questions tagged [muscles]

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

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184 views

Does estrogen increase muscular growth in females?

Regarding humans it is said that most psychological effects caused in men by testosterone are caused in women by estrogens. There are many studies on that, particularly regarding temporary shifts of ...
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34 views

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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33 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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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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383 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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272 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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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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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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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?
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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?
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Why do, humans, like many birds,tend to stand on one leg (hut without lifting the other leg)? [closed]

I know, by observing people and from my own experience (you can try it yourself while standing, but not too consciously and in a loose way) that they, while standing, tend to do this on one leg. Just ...
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43 views

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) ...
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What Effect Does Skin Redness Have On Underlying Tissue?

When someone applies a rubefacient ( something that increases blood flow to the skin, turning it red), what effect does this have on the underlying tissue? Is blood supply increased radially from ...
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1answer
1k views

What causes muscle spasms?

What causes muscle spasms with muscles that are not in the heart ? Could it be some sort of stimulus overload that causes a massive contraction?
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154 views

How do BCAA's promote faster muscle recovery?

I am aware that ingesting Branched chain amino acids (BCAA's) prior, during, and after workouts has an effect on muscle recovery due to their difficulty of metabolism. However, how much more ...
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What's the max speed that humans could run? [duplicate]

Assuming humans could use all of their muscle strength at once, with no need of cooling or energy, how fast could we theoretically run?
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64 views

Hormones and body mass

I was wondering how some animals (bulls, elephants etc.) become so large by only eating grass or plant based material and why some humans can build large amounts of muscle and mass without a proper ...
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36 views

Prenatal hyperkinetic dysfunction and its effect on endurace

Do people with an hyperkinetic dysfuntion have a better endurance? Are they fitter in cause of their Dopamine-overdose or any other reason? I have a case, where someone does not do any sports, but ...
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927 views

Relationship between small and large fast-twitch motor units

When large fast-twitch motor units are temporarily fatigued, non-fatigue small motor units in the same muscle are impaired for small delicate tasks. Why? When impulses from the brain comes down, the ...
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1answer
62 views

Are (muscle) satellite cells the same as muscle stem cells?

In terms of muscle: are the terms 'satellite cell' and 'muscle stem cell' interchangeable? That is, are there muscle stem cells that are not satellite cells, or vice versa?
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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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97 views

Typical firing patterns of (some) motor neurons

Since it is not so easy to imagine and visualize the behaviour of the muscles in the fingers, hand, and arm of a violinist performing a fast and accentuated trill vs. a slow and soft vibrato, I try to ...
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318 views

What is the pathogenuc mechanism of brown pigment lipofuscin in muscle atrophy?

I think it is autophagy. Lysosomal degradation. Autophagocytosis. Example of the brown pigment (lipofuscin) here: I am not sure if autophagy is the right answer to the "pathogenic" mechanism of ...
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109 views

Why doesn't muscle strength depend on its length?

In case of tug of war the more people participate the more strength they represent. And in case of muscles - the longer it is, the greater the number of myosin heads bind to actin when muscles ...
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431 views

Similarity between a heart attack and a spasm

When someone is having a heart attack, could it be considered , in some situations, a spasm? Below, I have written how I believe the process may work. The heart is basically a muscle working ...
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232 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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13k views

Strongest muscle of Human Body

Which is the strongest muscle of human body ? Confusion b/w Masseter muscle (Muscle of Jaw) and Tongue and Muscle of Heart and Muscle of Uterus.
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636 views

if the load is removed from an eccentrically contracting muscle, will it start contracting concentrically?

Geometrically speaking, a muscle contraction should exert a force between the two attachment sites. However, the actual effect of the force on the overall geometry of the body near the point of ...
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What are the binding sites (or receptors) of cortisol?

I am in the process of a OCR GCSE Case Study, and my question is "Do the benefits of anabolic steroids outweigh the risks, which has an obvious conclusion. I need to know the scientific name, or a ...
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Our muscles give us the ability to move our arms but…? [closed]

I have a strange question, but let me tell you something first. If you think of this carefully, then you realize something, please try this right now: Contract your muscles only so that your arms ...
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585 views

Why rectus abdominis is not proximal muscle?

I am thinking this picture which shows proximal muscles. Why for instance pectoralis major, subclavius and rectus abdominalis are not included in proximal muscles?
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How do neurons send electric pulses even though they are surrounded by liquid which is mostly water?

I just thought about the fact that people move through electrical pulses traveling through neurons in the brain and muscles through the body. Here is what i know: the body is full of 97 or more, ...
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56 views

What is the difference between a myofibril and a myoblast? (In skeletal muscle)

I read that a muscle fibre (myofiber) is formed when myoblasts fuse. https://teaching.ncl.ac.uk/bms/wiki/index.php/Skeletal_muscle#:~:text=The%20multinucleate%20feature%20is%20established%20in%...
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What inhibits linkage between actin and myosin filaments

What is the mechanism behind the inhibition for cross-bridge linkage between actin and myosin filaments in the binding-tilting cycle? There are 2 possible ways that are in my mind: a. Tn-I (tropnin-I)...
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Are “tremors” and “ tetanic contractions” the same thing?

Do these two expressions have the same meaning? 1- Tetanic contractions in the skeletal muscles 2- Rythmic shaking of the hands (These two expressions are supposed to be two symptoms of Parkinson’s ...
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2answers
44 views

why do we tighten out muscles against cold?

When I'm in shower and I want to open the cold water on myself suddenly I make my muscles so tight before I open the water and that helps so much in being able to handle the shock. Why does tightening ...
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If hands are folded with both index fingers parallel, they will come closer and touch eventually?

I have a question out of curiosity. It is just something I found out/discovered: if I fold my hands into each and let my two index fingers (see picture) be in parallel then they will eventually come ...
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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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335 views

All or none phenomenon

Let's say that the threshold potential of a neuron is +40 mV to make a muscle twitch. Now suppose we have two signals of +20 mV. So, this signal will cause the twitch in muscle because it has reached ...
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What is seperating one muscle from another in body?

I have been learning about gross anatomy and have been watching a lot of dissection videos online and this question has me a bit confused. I know that the human body have about 600 muscles. I know the ...
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Why does bicep activate during dead hang?

Hanging from a bar causes my bicep to feel much harder than when simply holding my arm straight above my head relaxed, without a bar. This was slightly surprising to me: I used to assume that since ...
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Is protein intake required for the formation of new myosatellite cells?

Hypertrophy of muscle fibers requires an adequate (significant, really) intake of protein, but what about just forming new myosatellite cells as a response to a stress applied to the muscle? Does that ...
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Getting confused by neutralizer, fixator and stabilizer muscles

I know that neutralizers may also be classified as stabilizers because it is their ability to keep joints balanced that holds motion along a specific path. A fixator muscle is a stabilizer that acts ...
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Does Krebs cycle occur in fast glycolytic muscle fibres?

They have mitochondria. So they can have aerobic respiration. (?) Does Krebs cycle occur in their mitochondria?
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How do myosins cause myofibrils to be shortened?

I know that it is the binding and tilting of myosins on actins that cause the sarcomere to be shortened. But I am a little bit confused about the details. The structure of a sarcomere is made of ...
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Why is the Hill muscle model only applicable to isometric contractions?

From what I've read, Hill's muscle model provides a reasonable model of isometric contraction. However, there are other forms of contraction, such as concentric, eccentric, or isotonic contractions. ...