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Questions tagged [muscles]

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

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Etymology of eccentric/concentric contractions

I was wondering if anyone knew why the terms eccentric and concentric were chosen to refer to lengthening and shortening muscle contractions? The basic etymology of the words are to do with ...
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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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When muscles contract is the process similar to how non-newtonian fluids react?

I'm trying to understand how muscles contraction/tension works but getting loss in on the cellular level. From my understanding, when muscle tissue need to contract, the cells are flooded with calcium?...
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How efficiently does the human body convert the energy stored in fat into kinetic energy?

I read that one gram fat contains 9 kcal energy. There are many tables around claiming that x type of exercise for t duration ...
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How many muscles work for a smile and how many when you are sad? [closed]

Muscles works in both cases but it’s seems difficult to understand that how they work
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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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Myoglobin in meat

When looking at the reason why some meat is white and the rest is red, I found out it is down to the levels of myoglobin as higher levels of myoglobin are found in "slow twitch" muscles. I have also ...
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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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Skeletal muscle has got many many peripheral nuclei. What does “peripheral” mean here?

Cardiac muscle has got a central nucleus similar to smooth muscle, but skeletal muscle you may recall has got many many peripheral nuclei. What does "peripheral" mean here?
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Do muscles and connective tissue have different types of pain receptors?

I assume that muscles have pain receptors ("nociceptors"?) that fire when the muscle is under excessive strain or even tears or becomes injured. I also assume that similar pain receptors exist for ...
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Difference between reciprocal inhibition and regular muscle movement?

I was looking into a condition I have, anterior pelvic tilt, quite a bit. I ran into a website describing part of the issue as reciprocal inhibition. This was my confusion: Reciprocal inhibition, ...
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Does only one interneuron or upper neuron innervate all lower motor neurons in a muscle?

After reading Kandel I am unclear on this point. I understand that the cell bodies of somatic lower motor neurons cluster in motor nuclei (motor pools) in the ventral horn of gray matter in the spinal ...
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Are there any small lumbar forward flexors?

I've been looking into the smaller muscles in the spine such as the intertransversarii, interspinales, and rotatores. To my understanding, they are capable of spine extension, rotation and lateral ...
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56 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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How can “muscle fullness” be achieved with electrolytes?

Muscle fullness or the "pump" is a common goal among physique or bodybuilding competitors. Carbohydrate-loading is one way they can look dense during competitions but electrolyte manipulation also is ...
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The role of calcium concentration in excitation-contraction coupling of skeletal vs cardiac muscle

Below is an illustration showing the intracellular concentrations of calcium ions during skeletal and cardial muscle contraction; and how they change over time. I understand why the shape of the ...
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Is the ACh receptor more permeable to sodium ions?

The AChR is permeable to sodium and potassium ions only and has a reversal potential of 0mV. However the Nernst potentials for sodium and potassium ions is ~ +60mV and -88mV respectively. Taking a ...
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Pictures of trigger point muscle fascia

Are there any pictures of an actual trigger point looks like? All I am able to find online are animations.
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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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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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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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What are the max angles of human eyeball rotation?

How much can our eyeballs rotate towards the nose, away from it, towards the top and bottom?
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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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Could the protein dystrophin be artificially synthesised?

Could the protein dystrophin be artificially synthesised and if so could patients with DMD (Duchenne Muscular Dystrophy) benefit from it? //Now I don't have much scientific background other than a ...
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How strong of an electric field is dangerous to adult humans?

Given that "a potential difference is introduced over the membrane, the associated electric field induces a conformational strong in the potassium channel" is required for our muscles to move, how ...
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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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Can acetylcholine leak away from the synapse and cause spasms?

I am currently studying Pharmacology and a question came to mind. We know that Acetylcholine is used as a neurotransmitter in the neuromuscular junction, both Sympathetic as Parasympathetic, but as I ...
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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 does use an action potential from innervation selectively modify tropomyosin over time?

Within a myofibril, the myofilaments move past one another to product muscle contraction if and only if the actin binding sites are exposed to the myosin by locally removing the tropomyosin by binding ...
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Muscle receptors: Juxtaglomerular renin secretion and atrial ANP secretion

I'm searching for the mechanism that allows juxtaglomerular cells to secrete renin or cardiac muscles to secrete ANP due to stretching or lack of stretching. The baroreceptors in the juxtaglomerular ...
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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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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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Muscle heat production during and after an effort

I noticed that I keep evacuating heat through sweat up to 15min after a running session, which gives me the impression that muscles keep producing heat even after the effort. It could be that muscle ...
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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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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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Understanding isotonic contraction of muscles

Could some one explain for me how the muscle shortens and keeps a constant tension (case of isotonic contraction). I'm very confused, I mean since the muscle gets shorter then there must be more ...
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What is the point in the Neuromuscular Junction?

Surely a direct connection (i.e. an electrical synapse) between motor neurone and the sarcolemma would allow for much faster neuromuscular transmission? It is my understanding that chemical synapses ...
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Function of Smooth Muscles in the skin

I understand that the overall function is voluntary movement, but is it the same in the skin? Is the main function in the skin movement or is there a greater function? Could anyone could provide this ...
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Do muscles move towards heat?

I was just wondering whether muscles move towards heat because my cousin had said it was true. Since she has a history in believing in myths I highly doubt it. I have tried googling this question but ...
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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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Under which circumstances does muscle hyperplasia happen in humans?

What circumstances allow humans to have muscle hyperplasia in the prenatal and immediately postnatal period that doesn't exist later? Is it about specific hormones that follow through our veins?
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Do eye's muscle share the same nerve?

When I try to rotate my eye, both of my eyes will rotate the same amount and in the same direction (obviously). I'm wondering if it is possible to control each eye separately. I've never seen anyone ...
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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 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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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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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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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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What underlying electrophysiological mechanism is measured in an EMG?

I'm wondering what exactly the electrophysiological mechanism underlying the EMG is. Is it the calcium ion release? I have heard that an EMG is always a bipole as charge cannot be created in the body, ...