Questions tagged [muscles]

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

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17 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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5k views

Why is there smooth muscle in our bronchioles?

Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just ...
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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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1answer
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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69 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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1answer
72 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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114 views

Do animal muscles atrophy slower than humans?

Suppose I consider the silver back gorilla as an example. I cannot imagine ever seeing one in the wild intentionally doing something akin to weightlifting like humans solely for the purpose of ...
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86 views

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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1answer
56 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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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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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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1answer
42 views

Does alcohol really helps to get substances get faster into the bloodstream? [closed]

I saw the video where Arnold Schwarzenegger cooks some protein cocktail and adds Austrian Schnapps to the mix, saying that it's to make everything get faster to the blood. Is it true or some kind of a ...
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2answers
97 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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29 views

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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1answer
70 views

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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What mammals can rotate and move their ears the most?

I found out that rabbits can rotate their ears 270 degrees, and also move them up, down and independently. Are there any other mammals that can control their ears' position that well, or even better?
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118 views

What does the term 'glycogen mobilisation' mean?

I read that glycogen is a mobilised store of glucose: Glycogen is a readily mobilized storage form of glucose. It is a very large, branched polymer of glucose residues (Figure 21.1) that can be ...
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30 views

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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Why Can't Muscles Push When They Return To Their Original Length?

I understand that muscles can only contract and shorten and thus can only pull, but why can't a muscle push when it relaxes and returns to its initial length?
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133 views

What stops myosin during muscle relaxation?

I understand that when the muscle is relaxed tropomyosin blocks myosin binding sites on actin filaments thereby preventing muscle contraction. What I am concerned with however, is whether myosin ...
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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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100 views

Does ATP production increase with oxygen availability?

I'm not a biologist so pardon any ignorance on my part. I'm working on a speculative evolution project and I'm looking to understand how the partial pressure of oxygen effects the maximum aerobic ...
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3answers
1k views

Biological Neural Network Training for Babies [closed]

I am concerned by the fact that babies cant walk because the muscles in their limbs arent developed and tuned to give directional control, it takes years before babies gain mobility and dexterity. So ...
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19 views

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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1answer
53 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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33 views

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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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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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 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 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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1answer
31 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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24 views

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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1answer
28 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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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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1answer
39 views

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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1answer
77 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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248 views

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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1answer
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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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1answer
59 views

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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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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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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296 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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1answer
31 views

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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552 views

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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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
64 views

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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2answers
161 views

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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