Questions tagged [muscles]

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

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29 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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Question on thick filaments

In this photo, I know that the arrows pointing towards the M-line of sarcomere on actin filaments are due to the power strokes of myosin heads. However, what I don't understand are the arrows on the ...
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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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what powers power strokes

I am wondering what really powers the myosin head to undergo the power stroke to push the actin filaments towards the M-line. I have 2 thoughts: when ATP in the myosin head gets hydrolyzed, the ...
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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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Why didn't more muscles evolve the endurance of heart muscle? [closed]

The heart is a muscle capable of both the quick contraction of white muscle cells, and also the endurance of red muscle cells. Why haven't more muscles in the body adapted the same combo of abilities? ...
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22 views

Pectoralis muscles as push muscles vs pull muscles

Pectoralis muscles are the adductors, flexors of arm in addition to medial rotators of arm. How does this action translate in to acting as helping in push ups or in bench press? I am having trouble ...
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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. ...
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28 views

Suspensory ligaments: why are they ligaments?

Don't ligaments connect bone to bone? In the eye for example, the suspensory ligaments connect the ciliary muscle to the lens, which obviously aren't bones. Is this just one of those instances where ...
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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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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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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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Humans best at long distance running: purely physiological or is it a function also of ability to pace?

I have read that although certainly other land animals are much faster over short distances, a human can run down any other animal over time, so that if a human is hunting like a gazelle, etc. ...
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Do people with higher body hair growth (eg. Women with hirutism) need more protein? [closed]

Hair is protein. Does that mean that the body of a woman with hirutism is using more than usual protein to make hair and thus she needs more for building and repairing muscles?
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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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Are changes in flexibility from stretching due to changes in the nerves or the muscles?

For many people, stretching repeatedly over a period of time improves their flexibility. I want to know whether this improvement commonly seen is due to a change in the nerves or the muscle’s material ...
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how has the fibrous skeleton contributed to the structure of the heart valves?

I'm a little bit (or a lot!) confused that how has the fibrous skeleton contributed to the structure of the heart valves? Since the fibrous skeleton takes part in the cardiac muscle, how does it help ...
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Why do flexor and extensor group of lower limb attach on opposite sides in forelimb of mammals?

The flexor and extensor group of the forearm attach on the medial and lateral condyle of the ulna respectively. What is the evolutionary explanation for that? Selected for to favour internal and ...
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Muscle fibers same width along entire muscle?

If muscle fibers run along the entire length of a muscle, and the muscle is wider at the middle than near the tendons (like many muscles are, biceps brachii for example), is the reason for the ...
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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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Does the fiber type profile of a muscle influence what kind of contraction it specializes in?

From what I understand, muscles have 4 types of fibers: I also know that there are 4 types of contractions: Concentric -- muscle gets shorter while it contracts Eccentric -- muscle gets longer ...
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Motor innervation sites across skeletal muscle

Along the length of a skeletal muscle, what are the general patterns for motor innervation? Are motor nerve endings confined to certain regions, or are they more distributed equally throughout the ...
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How does shortening a muscle over a long period of time impact its length?

I have read that repeatedly overstretching a muscle will cause it to lengthen. The idea is that, as the muscle is stretched more and more, the muscle tissue increases the number of sarcomeres, which ...
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Do multiple axons innervate a single skeletal muscle fiber?

The typical text-book illustration of innervation of muscle fibers shows branches at a single position along the fiber. Does any given muscle fiber have more axons that innervate it though, given that ...
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Are there any detrimental effects to long term electrical muscle stimulation?

I know that different types of electrical stimulation can be used in fields such as physical therapy to get muscles to contract. However, these electrical stimulation sessions are not prolonged and ...
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What percent of mucle growth is possible without steroids consumption?

I am interested to know, if someone does bodybuilding exercises with good rest, enough protein, high presure workout, etc, but without consuming any steroids, how much of muscle gorwth is possible for ...
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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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Does electrical muscle stimulation helps to loose weight?

At the risk of being blocked, I ask my question anyway. In this Wikipedia article much is written about electrical muscle stimulation. I can imagine it helps with developing your stomach muscles. You ...
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Does the body replace muscle cells in a regular rhythm?

Increase in muscle size seems to be primarily due to increase of the size of muscle cells and not growth in the number of cells. If a muscle cell dies, does the body replace it with a new one? If so, ...
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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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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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How does an electrical impulse spread in a muscle fiber spread from the motor end plate?

Does this impulse in skeletal muscle spread much in the same way it does in neurons, with an initial potential change that spreads to its immediate surroundings and is then re-amplified or is it the ...
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Why do red muscle fibres have more mitochondria than white muscle fibre but less ATP than White muscle fibres?

This is a question given in my Anatomy book and I am really confused because logically the substance which have more mitochondria should have more ATP as mitochondria is the power house of cell.But ...
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Why is there a mass limit on biological powered flight?

So, this is a thing I never fully understood. There are a lot of reasons for a flying creature to be limited in mass (though I'm unsure if I'm familiar with all of them), from energy consumption to ...
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Is there a minimum amount a muscle can move? And thus, gaps in our movement?

Lately I've been thinking about something, based on my knowledge my chain of reasoning works like this... When you want to move a muscle your brain sends an electrical nervous impulse along the chain ...
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Why does flicking a finger generate so much more force than extending it quickly?

Flicking a finger (holding it back with e.g. the thumb while building up "pressure" against the thumb, then releasing) is much more powerful than just uncurling the finger quickly. I tried to do the ...
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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 your finger muscles and tendons interconnected?

Are finger muscles and tendons interconnected? If they are interconnected, then if i exercise one finger will it train the other fingers since they are interconnected and share the same muscles in the ...
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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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What trajectory do action potentials take, from initial visual stimulus all the way to motor function?

Say we see a mosquito, and our brain tells us 'hey that's a mosquito, you should kill it.' Then we move our hands and slap/clap it. The initial visual stimulus is translated to an action potential ...
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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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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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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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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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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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What is a myotube?

If I understand correctly, the following images show the main components in a human skeletal muscle: From Life: The Science of Biology: From Human Physiology/The Muscular System in wikibooks: ...
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Where does the gluteus medius attach to the greater trochanter compared to the gluteus minimus attachment?

Where does the gluteus medius attach to the greater trochanter of the femur compared to the gluteus minimus attachment? Is it above, below, next to it, etc.? Ideally I'd like to know the distance as ...
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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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Mechanism of redirected blood

I've read several fitness articles mentioning redirected blood flow to muscles that are in use. However, they never mention how it works. Is it local and specific to the muscles in use? Or, for ...
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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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