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Skeletal muscle

Skeletal Muscles are those which attach to bones and have the main function of contracting to facilitate

movement of our skeletons. They are also sometimes known as striated muscles due to their appearance. The

cause of this 'stripy' appearance is the bands of Actin and Myosin which form the Sarcomere, found within theMyofibrils.

Skeletal muscles are also sometimes called voluntary muscles, because we have direct control over them

through nervous impulses from our brains sending messages to the muscle. Contractions can vary to produce

powerful, fast movements or small precision actions. Skeletal muscles also have the ability to stretch or contract

and still return to their original shape.

Skeletal muscle fibre type

ot all fibres within Skeletal muscles are the same. !ifferent fibre types contract at different speeds, are suited

to different types of activity and vary in colour depending on their Myoglobin "an o#ygen carrying protein$ content.

%tot rangka adalah mereka yang melekat pada tulang dan mempunyai fungsi utama kontrak untuk memudahkan

pergerakan rangka kita.

Mereka &uga kadangkadang dikenali sebagai otot Striated kerana penampilan mereka.

  (unca ini rupa 'stripy' adalah band Actin dan Myosin yang membentuk Sarcomere, mendapati dalam Myofibrils.

%tot rangka &uga kadangkadang dipanggil otot sukarela, kerana kita mempunyai kawalan langsung ke atas

mereka melalui impuls saraf dari otak kita menghantar mese& kepada otot.

  (engecutan boleh berbe)abe)a untuk menghasilkan, pergerakan pantas yang kuat atau tindakan ketepatan

kecil.

%tot rangka &uga mempunyai keupayaan untuk meregangkan atau kontrak dan masih kembali kepada bentuk

asalnya.

*angka &enis serat otot.

Tidak semua serat dalam otot rangka adalah sama. +enis gentian yang berbe)a kontrak pada kela&uan yang

berbe)a, yang sesuai untuk pelbagai &enis aktiviti dan berbe)a dalam warna bergantung kepada myoglobin

mereka "protein oksigen men&alankan$ kandungan.

Smooth muscle

Smooth muscle is also sometimes known as nvoluntary muscle due to our inability to control its movements, or

-nstriated as it does not have the stripy appearance of Skeletal muscle. Smooth muscle is found in the walls of

hollow organs such as the Stomach, %esophagus, ronchi and in the walls of blood vessels. This muscle type is

stimulated by involuntary neurogenic impulses and has slow, rhythmical contractions used in controlling internal

organs, for e#ample, moving food along the %esophagus or contricting blood vessels during /asoconstriction.

Cardiac muscle (heart muscle)

This type of muscle is found solely in the walls of the heart. t has similarities with skeletal muscles in that it is

striated and with smooth muscles in that its contractions are not under conscious control. 0owever this type of

muscle is highly specialised. t is under the control of the autonomic nervous system, however, even without anervous imput contractions can occur due to cells called pacemaker cells. Cardiac muscle is highly resistant to

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fatigue due to the presence of a large number of mitochondria, myoglobin and a good blood supply allowing

continuous aerobic metabolism.

Se&enis tisu otot yang hanya terdapat di dalam hati dan dibe)akan daripada keduadua bentuk otot, otot licin

"yang bergerak organorgan dalaman, seperti usus, dan kapal, seperti dinding arteri$ dan otot rangka "yang

kuasa sendi$. %tot &antung bertanggung&awab untuk mengepam darah ke seluruh badan.

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Skeletal muscles also become less elastic. Aging skeletal muscles develop increasing amounts of fibrous

connective tissue, a process called fibrosis. Fibrosis makes muscle less flexible so that movement and

circulation are restricted.

Tolerance for exertion decreases. A lower tolerance for exercise results partly from the tendency to

fatigue rapidly and partly from the reduced ability to eliminate heat generated during muscular

contraction. Plus, the ability to recover from muscular inury decreases.

!etween the ages of "# and $%, overall lean body mass decreases primarily due to reduced skeletal

muscle mass. This loss is called sarcopenia and occurs as the number and si&e of muscle fibers

progressively decrease.

'espite age(related reductions in muscle strength, muscle functional ability is similar in older and

younger adults. )sually, healthy elderly persons can easily climb stairs, rise from a s*uatting position,walk along a straight line, hop on either foot, and perform typical activities of daily living.

Otot rangka juga menjadi kurang elastik. Penuaan otot rangka dibangunkan

meningkatkan jumlah tisu penghubung berserabut, proses ang dipanggil

!brosis. "ibrosis membuat otot kurang #eksibel supaa pergerakan dan

peredaran adalah terhad.

 $oleransi untuk melakukan senaman berkurangan. % toleransi rendah untuk hasil

senaman sebahagian daripada kecenderungan untuk keletihan dengan cepat

dan sebahagian dari keupaaan dikurangkan untuk menghilangkan haba ang

dihasilkan semasa penguncupan otot. Plus, keupaaan untuk pulih daripada

kecederaan otot berkurangan.

%ntara ang berumur di antara &0 dan '(, keseluruhan jisim badan tanpa lemak

berkurangan terutamana disebabkan oleh pengurangan jisim otot rangka.

)erugian ini dipanggil sarcopenia dan berlaku sebagai bilangan dan sai* gentian

otot secara progresi+ berkurangan.

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alaupun pengurangan ang berkaitan dengan usia dalam kekuatan otot,

keupaaan +ungsi otot adalah sama di kalangan orang deasa ang lebih tua

dan lebih muda. iasana, orang tua sihat boleh mendaki tangga, meningkat

daripada kedudukan mencangkung, berjalan di sepanjang garis lurus, melompat

dengan berjalan kaki sama ada, dan melakukan aktiiti biasa kehidupan harian.