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20

There are instances of insect muscle growth in response to increased use. The flight muscles of the tsetse fly (Glossina morsitans) have been observed to grow at a faster rate when subjected to enforced exercise (Anderson and Finlayson, 1976). Also larger mandibular adductor muscles (which power the feeding apparatus), and associated head capsule have been ...


10

A recent paper called 'Genetic Influences in Sport and Physical Performance'[1] states: "Muscle fibre type determination is complex. Whilst initial composition is likely to be strongly influenced by genetic factors, training has significant effects on fibre shifts." They also go onto say that: "However, the role of genetic variation in determining ...


8

Good question that got me waist-deep in PubMed. It appears that the directionality of myosin motors is due to the angle at which the actin-binding catalytic domain is attached to the neck region. This review by Vale and Milligan, 2000, sums up the "unzippering" of the neck region that contributes the force for the movement (a video from the review adapted ...


8

The pressure that you apply when you push during a bowel movement derives from an increase in the pressure of the abdomino-pelvic cavity. You generate this pressure by closing the glottis (the opening to the lungs) and contracting the anteriolateral abdominal muscles (i.e., the external oblique, internal oblique, and transversus abdominus). This reduces ...


7

It seems that you are asking about activity significantly above basal metabolic rate. If aerobic conditions are maintained (and with appropriate training), muscles can operate more or less continuously for very long durations, days to weeks. In non-humans: Godwits have been recorded flying over 7000 miles (>11000 km) without stopping for 9 days Arctic ...


7

I speak only for the U.S. regulations: the calorie labels on wrappers refer to the energy released when burned. Sometimes these are inaccurate. Many dieticians recommend calculating the calories based on weights of protein, carbohydrates and fats in the serving: 4 kcal in each gram of protein and carbohydrate and 9 kcal in each gram of fat in your food. ...


7

The quick and simple answer: Cramps of a hypokalemic origin are much more common than those of a hyponatremic origin because the Na-K pump is more effective at moving potassium in comparison to sodium. At the onset of a muscle contraction, the presence of calcium triggers the opening of the Na-K channels in the membrane. Potassium is a calcium inhibitor, so ...


7

If you dissect striated muscle out of most-any organism, the actual contractile apparatus works over a wide range of temperatures. So that's at the single-muscle-fiber scale. The muscle itself continues to work at all (thawed) temperatures below body temperature -- the problem comes with its regulation. The shivering response -- a centrally controlled ...


6

Well, if we look in very basic detail at how muscle contraction works within a myofibril of the sarcomere: N.b. this isn't on a loop and only plays through seven times The red lines represent actin filaments whilst the blue lines represent myosin filaments. During muscle contraction the filaments move over each other: As shown in the above ...


6

The dynamic-dominance hypothesis of handedness states that the essential factor that distinguishes dominant from nondominant arm performance is the facility governing the control of limb dynamics. Sainburg (1) writes that It should be noted that dominant arm advantages do not apply to all tasks, or all aspects of tasks. Healey et al. (1986) examined an ...


6

The blood comes from the body's reservoirs: spleen (mostly erythrocytes) [1] liver [2] veins (probably the most important blood resevoir as they contain 50-60 % of the volume) [3] In pathological situations, if hypovolemia occurs, blood can also come from: splachnic vascular bed [5] But what attracts the blood into the muscle? The phenomenon is ...


5

Older papers initially presumed that it was part of a mechanism called "catch" in invertebrates like molluscs which is a "sustained contraction." However, paramyosin was also found in insects. There is a very detailed review on invertebrate muscle from 2008 that you should read through (or, you know, search through) points out that recent evidence has ...


5

There is not a linear relationship between the size of a muscle and its power. The cat weighs significantly less, but the decline in muscle power is not identical. If he weighs 20x less than you, but his muscle generate 1/5 as much force, he will still be able to jump way higher than you.


5

I would argue that the orbiculares do have antagonists. To some extent, levator palpebrae superiorus antagonizes orbicularis oculi, and zygomaticus major/minor as well as risorius antagonize orbicularis oris. I can think of three muscle that don't have obvious antagonists: Stapedius Tensor tympani Articularis genu 1 and 2 essentially perform the same ...


5

The "back of your mind" is correct: "if the muscle gets bigger, it's simply because individual cells get bigger." Growth of muscle can occur in three ways: by an increase in muscle cell numbers by an increase in muscle fiber diameter by an increase in fiber length. However, growth in cell numbers is limited to the prenatal and immediately postnatal ...


4

Muscle contarction is when the brain tell the body to move. the brain then starts an action potential down the motor neurons. The action potential moves down motor neuron and reached the terminal bouton. At the terminal bouton, it releases the neurotransmitter acetylcholine. Acetylcholine travels through myoneural junction and into myoneural cleft. ACH binds ...


4

That is highly unlikely. The article to which you linked specifically states: While watching other people exercise may increase your heart rate and have other physiological effects, nothing can replace the health benefits of getting off the couch. With proper nutrition, muscle is built through exercise by adding sarcomeres [to muscle cells which ...


4

A tissue can undergo two types of quantitative growth: hypertrophy - cells increase in size hyperplasia - cells increase in number There are tissues that grow as a result of one of the above processes and there are tissues that grow because both processes happen. A Google search for muscular growth yields as first result Muscle hypertrophy. And this is ...


3

The situation you are describing where muscles are situated on opposites sides of a joint and produce opposing movements is called "antagonism." Most joints are set up where one or more muscles on either sides will produce such movements (e.g., flexors vs. extensors). Here's a question about muscles without antagonists. When you contract all the muscles ...


3

For car crashes, it's a mixed bag: Better Better Worse Worse Basically, it looks like, if wearing a seat belt, slightly overweight is more likely to survive a car crash, but if no seat belts are worn they are at a disadvantage; the very obese are always more likely to die, however. Also, some of this was found only for males, not females.


3

This seems complicated, but I found a reference that might answer these questions (if its right). Sports physiology common wisdom is that human muscles regularly work in the range of 37C to 40C which is basically body temperature. Since the muscles generate quite a bit of heath when they function, they are usually not functioning in colder temperatures ...


3

There are a few studies around related to this. One particular study(1) suggests that: Neural drive is decreased following eccentric exercise leading to a reduction in muscle force. Alcohol may further reduce the already depressed neural drive. Alcohol also has been shown to affect the innate immune system by altering the activity of a number of ...


3

This is well-explained at the Wikipedia page on skeletal striated muscle. There are two principal ways to categorize muscle fibers: the type of myosin (fast or slow) present, and the degree of oxidative phosphorylation that the fiber undergoes. Skeletal muscle can thus be broken down into two broad categories: Type I and Type II. Type I fibers ...


3

How does extra blood come from to fill your muscles during exercise? Blood pumps (blood) and sucks (lymph). There are many pumps in our body thoracic pump smooth musculature respiratory pump which work together to provide the blood to the peripheral circulation. These pumps provide us Pulse, Vasomotor tone and Respiratory waves which when act together ...


3

By shin splints you probably mean the pain on the inner front side of the lower 2/3 parts of the shins? This is called medial tibial stress syndrome (MTSS). Causes, mechanism, prevention and treatment of shin splints are still poorly understood. From what I managed to find, custom-made cushion insoles are the only proven prevention that can help in some ...


3

From: http://www.acad.carleton.edu/curricular/BIOL/classes/bio126/Documents/Lab_5.pdf Glycerination disrupts the membranes of the muscle cells, ruptures mitochondria, and leaches out soluble constituents such as ATP and inorganic ions. However, glycerinated muscle retains the organized structural array of myosin thick filaments and actin thin filaments, ...


2

You can try Biomechanical models used in software frameworks such as OpenSim. Here is an example of a combined upper and lower body model in XML: ULB_Project.


2

Check out the muscle relaxant article on Wikipedia, it's pretty straight forward. In short, there are two main types: Neuromuscular blockers, than act at the junction between the neuron and the muscle; and spasmolytics/antispasmodics, which (mainly) act on the central nervous system to reduce excitation or increase inhibition. Most of the ones I've heard ...


2

You can find a concise answer here in a section from The Insects: Structure and Function by R. F. Chapman, eds. Stephen J. Simpson, Angela E. Douglas. 5th Edition. Cambridge University Press. In essence the source says that the muscle attachment to the cuticle is maintained during the moulting process, while the new cuticle is formed under the old cuticle. ...


2

You say "snout" but you might more specifically mean "muzzle" if you're focusing on the teeth aspect. Ram Manohar M hypothesizes some good reasons that make sense but for some other examples of snouts, here's a fun link that describes a few uses: Tapir: "nose and upper lip form a trunk he uses to grip, handy for grabbing and cleaning branches and plucking ...



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