Muscular system
This article needs more primary sources. (October 2016) |
Muscular system | |
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Details | |
Identifiers | |
Latin | systema musculare |
TA98 | A04.0.00.000 A04.6.02.001 A04.7.02.001 |
TA2 | 1975 |
FMA | 72954 |
Anatomical terminology |
The muscular system is an
Types
There are three distinct types of muscle: skeletal muscle, cardiac or heart muscle, and smooth (non-striated) muscle. Muscles provide strength, balance, posture, movement, and heat for the body to keep warm.[3]
There are approximately 640 muscles in an adult male human body.[4] A kind of elastic tissue makes up each muscle, which consists of thousands, or tens of thousands, of small muscle fibers. Each fiber comprises many tiny strands called fibrils, impulses from nerve cells control the contraction of each muscle fiber.
Skeletal
Skeletal muscle, is a type of
This process consumes large amounts of
There are approximately 639 skeletal muscles in the human body.
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Skeletal muscles, viewed from the front
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Skeletal muscles, viewed from the back
Cardiac
Heart muscle is striated muscle but is distinct from skeletal muscle because the
Smooth
Smooth muscle contraction is regulated by the autonomic
Physiology
Contraction
Skeletal muscles are organized into hundreds of motor units, each of which involves a motor neuron, attached by a series of thin finger-like structures called axon terminals. These attach to and control discrete bundles of muscle fibers. A coordinated and fine-tuned response to a specific circumstance will involve controlling the precise number of motor units used. While individual muscle units contract as a unit, the entire muscle can contract on a predetermined basis due to the structure of the motor unit. Motor unit coordination, balance, and control frequently come under the direction of the cerebellum of the brain. This allows for complex muscular coordination with little conscious effort, such as when one drives a car without thinking about the process.[5][7]
Tendon
A tendon is a piece of connective tissue that connects a muscle to a bone.[8] When a muscle intercept, it pulls against the skeleton to create movement. A tendon connects this muscle to a bone, making this function possible.
Aerobic and anaerobic muscle activity
At rest, the body produces the majority of its
During activity that is higher in intensity, with possible duration decreasing as intensity increases, ATP production can switch to anaerobic pathways, such as the use of the creatine phosphate and the phosphagen system or anaerobic glycolysis. Aerobic ATP production is biochemically much slower and can only be used for long-duration, low-intensity exercise, but produces no fatiguing waste products that can not be removed immediately from the sarcomere and the body, and it results in a much greater number of ATP molecules per fat or carbohydrate molecule. Aerobic training allows the oxygen delivery system to be more efficient, allowing aerobic metabolism to begin quicker. Anaerobic ATP production produces ATP much faster and allows near-maximal intensity exercise, but also produces significant amounts of lactic acid which render high-intensity exercise unsustainable for more than several minutes. The phosphagen system is also anaerobic. It allows for the highest levels of exercise intensity, but intramuscular stores of phosphocreatine are very limited and can only provide energy for exercises lasting up to ten seconds. Recovery is very quick, with full creatine stores regenerated within five minutes.[6][11]
Clinical significance
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Multiple diseases can affect the muscular system.
Muscular Dystrophy
Muscular dystrophy is a group of disorders associated with progressive muscle weakness and loss of muscle mass. These disorders are caused by mutations in a person’s genes.[12] The disease affects between 19.8 and 25.1 per 100,000 person-years globally.[13]
There are more than 30 types of muscular dystrophy. Depending on the type, muscular dystrophy can affect the patient's heart and lungs, and/or their ability to move, walk, and perform daily activities. The most common types include:
- Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)
- Myotonic dystrophy
- Limb-Girdle (LGMD)
- Facioscapulohumeral dystrophy (FSHD)
- Congenital dystrophy (CMD)
- Distal (DD)
- Oculopharyngeal dystrophy (OPMD)
- Emery-Dreifuss (EDMD)
See also
- Major systems of the human body
- Intramuscular coordination
References
- ^ OCLC 548651322.
- )
- ^ )
- ^ "THE MUSCULAR SYSTEM" (PDF). www.uc.edu.
- ^ )
- ^ )
- OCLC 473478856.
- ^ "Tendon vs. ligament: MedlinePlus Medical Encyclopedia Image". medlineplus.gov.
- OCLC 943860.
- PMID 18500953.
- PMID 1581850.
- ^ CDC (2022-11-21). "What is Muscular Dystrophy? | CDC". Centers for Disease Control and Prevention. Retrieved 2023-05-05.
- S2CID 2426923.
Further reading
- Cartee GD, Hepple RT, Bamman MM, Zierath JR (June 2016). "Exercise Promotes Healthy Aging of Skeletal Muscle". Cell Metabolism. 23 (6): 1034–1047. PMID 27304505.
- Murphy AC, Muldoon SF, Baker D, Lastowka A, Bennett B, Yang M, Bassett DS (January 2018). "Structure, function, and control of the human musculoskeletal network". PLOS Biology. 16 (1): e2002811. PMID 29346370.
External links
- "Muscle". Cleveland Clinic.
- Online Muscle Tutorial
- GetBody Smart Muscle system tutorials and quizzes
- MedBio.info Archived 2011-02-05 at the Wayback Machine Use and formation of ATP in muscle