View
43
Download
0
Category
Preview:
DESCRIPTION
dasar dasar anatomi fisiologi
Citation preview
Anatomi sistem muskulo – skeletal manusia
Ns. Herlina,M.Kep.,Sp.Kep.An
PENDAHULUAN
• Sistem muskulo skeletal terdiri dari tulang sendi, oto dan struktur pendukung lainya : tendon, ligamen, fasia, dan bursae
• Pertumbuhan dan perkembangan struktur ini terjadi selama masa anak-anak dan remaja
• Pada usia 25 tahun pengerasan tulang telah lengkap
TULANG• 206 tulang membentuk kerangka orang dewasa (20%
dari massa tubuh) 80 tulang kerangka aksial 126 tulang kerangka apendikularis
• Kesehatan dan fungsi tulang sangat bergantung pada sistem tubuh yang lain
• Struktur tulangmemberi perlindungan terhadap organ vital (otak, jamtung, dan paru)
• Kerangka tulang merupakan kerangka yang sangat kuat untuk memyangga struktur tubuh dan otot yang melekat ke tulang memungkinkan tubuh bergerak
4
Bone Classification
• Bone Classification:
• tulang panjang• tulang pendek• Sesamoid Bones• Flat Bones• Irregular Bones• Wormian Bones (sutural)
(a) (e)
(b)
(c)
(d)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pembagian skeletal• Axial skeletonTd: kerangka tulang kepala dan leher, tengkorak,
kolumna vertebrae, tulang iga, tulang hioid sternum• Apendikular skeletonTd: 1. kerangka tulang lengan dan kaki 2. ekstrimitas atas : skapula, klavikula, humerus, ulna,
radial ; tangan (karpal, metakarpal, falang) 3. ekstrimitas bawah : tulang pelvik, femur, patela,
tibia, fibula; kaki : tarsal, metatarsal, falang
Classification of Bones on the Classification of Bones on the Basis of ShapeBasis of Shape
Slide 5.4cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.1
Tulang panjang
• Bentuknya silindris• Berukuran panjang seperti batang (doiafisis) • Tersusun atas tulang kompakta• Kedua ujungnya berbentuk bulat/episis tersusun
atas tulang kanselus• Tulang diafisis memiliki lapisan luar berupa tulang
kompakta yang mengelilingi sebuah rongga tengah yang disebut kanalmedula
• Kanal medula mengandung sumsum kuning.
• Sumsung kuning terdiri dari lemak dan pembuluh darah tetapi suplay atau eritrositnya tidak terlalu banyak
• Tulang epifise terdiri dari tulang spongiosa yangmengandung sumsung merah yang isinya sama dengansumsum kuning dandibungkus oleh selapis tipis tulang kompakta.
• Bagian luar tulang panjang dilapisi jaringan fibrosa kuat yg disebut periosteum.
• Lapisan ini kaya pembuluh darah yang menembus tulang
Tiga kelompok yang menyuplai tulang panjang
• Sejumlah arteri kecil menembus tulang kompakta untuk menyuplai kanal dan system harvesrs
• Banyak arteri yang lebih besar menembus tulang kompakta untuk menyuplai tulang spongiosa dan sumsum merah
• Satu atau dua arteri besar menyuplai kanal medula. Arteri ini disebutarteri nutrien yang kemudian masuk ke foramen nutrien
• Periosteum memberikan nutrisi tulang dibawahnya melalui pembuluh darah
• Jika periosteum robek maka tulang dibawahnya akan mati
• Periosteum berperan dalam pertambahan ketebalan tulang melalui kerja osteoblast
• Periosteum tidak ditemukan pada permukaan sendi. Fungsiperiosteum digantikan oleh tulang rawan hialin (tulang rawan sendi)
11
Parts of a Long Bone• Epiphysis
• Distal• Proximal
• Diaphysis• Metaphysis• Compact bone• Spongy bone• Articular cartilage• Periosteum• Endosteum• Medullary cavity• Trabeculae• Bone marrow
• Red marrow and yellow marrow
Femur
Periosteum
Yellow marrow
Medullary cavity
Space containingred marrow
Spongy bone
Compact bone
Articular cartilage
Epiphyseal plates
Proximalepiphysis
Distalepiphysis
Diaphysis
Endosteum
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tulang Pendek
• Bentuknya hampir sama dengan tulang panjang tetapi bagian distal lebih kecil daripada bagian tulang panjang,
• Bagian distal lebih kecil daripada bagian proksimal
• Berukuran pendek dan kecil
Tulang Pipih
• Contoh: sternum, kepala, skapula, panggul• Bentuknya gepeng• Berisis sel-sel pembentuk darah• Melindungi organ vital dan lunak di bawahnya• Terdiri dari 2lapisan tulang kompakta dan bagian
tengan terdapat lapisan spongiosa• Dilapisi periosteum yang dilewati oleh dua
kelompokpembuluh darah untukmenyuplay tulang kompaktadan tulang spongiosa
Tulang tak beraturan
• Contoh: tulang vertebrae, tulang telinga tengah• Mempunyai bentuk unik sesuai fungsinya• Terdiri dari tulang spongiosa yang dibungkus oleh
selapis tipis tulang kompakta• Diselubungi oleh periosteum seperti tulang pipih
keculai pada peermukaan sendinya• Periosteum tsb memberi dua kelompok pembuluh
darah untuk menyupali tulang kompakta danspongiosa
Tulang sesamoid
• Contoh: patela• Merupakan tulang kecil yang terletak di
sekitar tulang yang berdekatan dengan persendian
• Berkembang bersama tendon dan fasia
STRUKTUR TULANG
• Tulang tersusun oleh jaringan kompakta (kortikal) dan kanselus (trabekularatau spongiosa)
• Tulang kompaktasecaramakroskopis terlihatpadat tetapi secara mikroskopis terdiri dari sistem Havers
• Sistem havers tardiri dari kanal havers
• Sebuah kanal havers terdiri dari pembuluh darah, saraf, dan pembuluh limfe, lamela (lempengan tulang yang mengelilingi kanal sentral), kaluna (ruang di antara lamela yang mengandung sel-seltulang atau osteosit dan saluran limfe), dan kanalikuli (saluran kecil yang menghubungkan lakuna dan kanal sentral)
• Saluran ini mengandung pembuluh limfe yang membawa nutrien dan oksigen ke osteosit
• Tulang kanselus juga keras seperti tulang kompakta, tetapi secara mikroskopis terlihat berlubang-lubang (spons)
• Secara miskroskopistulang kanselus terlihat lebih besar dan mengandung sedikit lamela
Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
Slide 5.10b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.3
Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
Slide 5.11a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Lacunae Cavities containing
bone cells (osteocytes)
Arranged in concentric rings
Lamellae Rings around the
central canal Sites of lacunae Figure 5.3
Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
Slide 5.11b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Canaliculi Tiny canals Radiate from the
central canal to lacunae
Form a transport system
Figure 5.3
22
Spongy Bone• Spongy bone is aka cancellous bone
(a)
(c)
Spongy bone Compact bone
(b)
Spongybone
Compactbone
Remnant ofepiphyseal plate
Spongybone
Compactbone
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.
Sel-sel penyusun tulang • Osteoblas : berfungsi menghasilkan jaringan osteosid
danmenyekresi fosfatase alkali yg berperan penting dalam pengendapan kalsium dan fosfat dalam matriks tulang
• Osteosit : adl sel-sel tulang dewasa yang bertindak sebagai lintasan untuk pertukaran kimiawi melalui tulang yang padat
• Osteoklast: sel-sel berinti banyak yang memungkinkan mineral dan matriks tulang dapat diabsorbsi . Sel ini menghasilkan enzim proteolitik yang memecah matriks dan beberapa asam yang melarutkan mineral tulang, sehinggakalsium dan fosfat terlepas ke dalam darah
PERTUMBUHAN &METABOLISME TULANG
Pertumbuhan dan metabolisme tulang dipengaruhi oleh beberapa mineral dan hormon sbb:
1. Kalsium dan fosfor. Jika Ca meningkat, jumlah fosfor berubah. Keseimbangan Ca &fosfor dipertahankan oleh hormon kalsitonin & paratoroid (PTH)
2. Kalsitonin. Diproduksi oleh kelenjar tiroid. Menurunkan konsentrasi Ca Serum.
3. Vitamin D: diperlukan agar kalsium dan fosfor dapatdiabsorbsi dari usus dandigunakan oleh tubuuh. Defisiensi vit D mengakibatkan defisit mineralisasi, deformitas, patah tulang
4. Hormon paratiroid (PTH). bilaCamenurunmaka PTHmeningkat dan menstimulasi tulang untukmeningkatkan aktivitas osteoblastik dan menyumbangka kalsium darah
5. Hormon pertumbuhan/GH: bertanggung jawab meningkatkan panjang tulang dan jumlah matriks tulamg
6. glukokortikoid: mengatur metabolisme protein untuk mengurangi ataupun mengintensifkan matriks organik ditulang danmembantu pengaturan klasiumdi intestinumdan absorbsi fosfor
7. hormon seksuala.Estrogen: menstimulasi aktivitas osteoblasttik
dan cenderung menghambat hormon paratiroid. Estrogen menurun saat menopause sehingga tjd penurunan kadar kalsium pada tulang dalamwaktu lama menyebabkan osteoporosis
b.Androgen seperti testosteron: meningkatkan anabolisme dan massa tulang
28
Factors Affecting Bone Development, Growth and Repair
• Deficiency of Vitamin A – retards bone development• Deficiency of Vitamin C – results in fragile bones • Deficiency of Vitamin D – rickets, osteomalacia• Insufficient Growth Hormone – dwarfism• Excessive Growth Hormone – gigantism, acromegaly • Insufficient Thyroid Hormone – delays bone growth• Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates• Physical Stress – stimulates bone growth
FUNGSI SKELETAL
1. Memberi struktur dan bentuk tubuh2. Mendukung jaringan sekitarnya (otot dan tendon)3. Melindungi organ tubuh (jantung, otak, paru, dan
jaringan lunak)4. Membantu pergerakan melalui pergerakan otot
danpembentukan sendi5. Membentuk sel-sel darahmerah dalamsumsum tulang
merah6. Sebagai tempaat penyimpanan garam mineral,seperti
garam kalsium dan fosfor
Klasifikasi sendi
• Sendi sinartrosis (sendi tidak bergerak sama sekali) : sutura tulang tengkorak
• Sendi amfiartrosis (sendi bergerak bebas): pelvik, simfisis, tibia
• Sendi diartrosis/sinovial (sendi bergerak bebas). Contoh: siku, lutu, pergelangan tangan
Gerakan sendi sinovial
1. Abduksi: gerakan tungkai menjauhi tubuh2. Adduksi: gerakan tungkai mendekati tubuh3. Ekstensi: meluruskan tungkai pada persendian4. Fleksi: membengkokkan tungkai pada sendi5. Dorso-fleksi: membengkokkan pergelangan
agarkaki keatas6. Plantar-fleksi: meluruskan pergelangan ke
arah bawah
7. pronasi: memutar lengan atas shg telapak tangan berada di bawah
8. Supinasi: memutarlengan atas sehingga telapak tangan berada diatas
9. Inversi: memutar ke dalam10.sirkumduksi: bergerak ke dalam lingkaran11.Internal rotasi: bergerak kedalam pada satu sumbu
pusat12. Eksternal rotasi: bergerak ke luar padasumbu pusat
Klasifikasi sendi berdasarkan strukturnya
1. Fibrosa : tidak memiliki tulang rawan, dan tulang satunya dihubungkan oleh jaringan penyambung fibrossa. Contoh: sutura tulang tengkorak, perlekatan tulang tibia dan fibula bagian distal
2. Kartilago : sendi yang ujung-ujung tulangkanya terbungkus oleh tulang rawan hialin, disokong oleh ligamen dan hanya dapat sedikit bergerak
Fibrous JointsFibrous Joints
Slide 5.46Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Bones united by fibrous tissue – synarthrosis or largely immovable.
Figure 5.27d, e
• Kartilago dibagi menjadi 2:a.Sinkondrosis: sendi-sendi yang seluruh
persendiannya diliputi oleh tulang rawan hialin. Contoh: sendi-sendi kosto-kondral
b.Simfisis: sendi yang tulang-tulangnya memiliki suatu hubungan fibrokartilago dan selapis tipis tulang rawan hialinyang menyelimutii permukaan sendi. Contoh: simfisis pubis dan sendi tulang punggung
Cartilaginous Joints – mostly Cartilaginous Joints – mostly amphiarthrosisamphiarthrosis
Slide 5.47Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Bones connected by cartilage
Examples Pubic
symphysis
Intervertebral joints
Figure 5.27b, c
3. Sendi sinovial : sendi yang dapat digerakkan serta memiliki rongga sendi dan permukaan sendi dilapisi tulang rawan hialin
The Synovial JointThe Synovial Joint
Slide 5.51Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.28
Struktur Anatomi sendi sinovial
Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape
Slide 5.52a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.29a–c
Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape
Slide 5.52b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.29d–f
OTOT
• Otot skeletal secara volunter dikendalikan oleh sistem saraf pusat dan perifer
• Penghubung antara saraf motorik perifer dan sel-sel otot dikenal sebagai motor end-plate
• Otot dibagi dalam 3kelompok dengan funsi utama untuk kontraksi dan menghasilkan gerakan sebagian atau seluruh tubuh
• Kelompokotot: 1. otot lurik, 2. otot viseral, 3. otot jantung
Types of muscle tissue:Skeletal muscle tissue
• Associated with & attached to the skeleton• Under our conscious (voluntary) control• Microscopically the tissue appears striated • Cells are long, cylindrical & multinucleate
Cardiac muscle tissue• Makes up myocardium of heart• Unconsciously (involuntarily) controlled• Microscopically appears striated• Cells are short, branching & have a single nucleus• Cells connect to each other at intercalated discs
Smooth (visceral) muscle tissue• Makes up walls of organs & blood vessels• Tissue is non-striated & involuntary• Cells are short, spindle-shaped & have a single nucleus• Tissue is extremely extensible, while still retaining ability to contract
Anatomy of skeletal muscles
Skeletal muscle
fiber (cell)
Muscle Fascicle
Surrounded by perimysium
Surrounded by endomysium
endomysium
perimysium
Skeletal muscle
Surrounded by epimysium
epimysiumtendon
Fungsi otot skelet
• Mengontrol pergerakan, mempertahankanposturtubuh, dan menghasilkan panas
KONTRAKSI OTOT
Struktur laindalam sistemmuskuloskeletal
1. Ligamen : sekumpulan jaringan fibrosa yang tebal yang merupakan akhir suatu otot dan berfungsi mengikat tulang
2. Tendon: perpanjangandari pembungkus fibrosa yang membungkus setiap ototdanberkaitan dengan periosteum jaringan penyambung yang mengelilingi tendon, khususnya pada pergelangan kaki dan tumit
3. Fasia : suatu permukaan jaringan penyambung longgar yang di dapatkan langsung di bawah kulit sebagai fasia superfisial jaringan penyambung fibrosa yang membungkus otot, saraf, dan pembuluh darah
4. Bursae: suatu kantong kecildari jaringan penyambung, yang digunakan di atas bagian yang bergerak, contoh: busae olekranon yang terletak di antara prosesus dan kulit
TUGAS BACA
Microanatomy of a Muscle Fiber (cell)
Microanatomy of a Muscle Fiber (Cell)
sarcolemmatransverse (T) tubules sarcoplasmic
reticulumterminal cisternae
myofibril
thin myofilament
thick myofilament
triad
mitochondria
nuclei
myoglobin
Muscle fiber
myofibril
Thin filaments Thick filaments
Thin myofilamentMyosin molecule ofthick myofilament
sarcomereZ-line
Thin Myofilament
(myosin binding site)
Z-line (Z-disc)
Thick myofilament
(has ATP & actin binding
site)
M-line
Play IP sliding filament theory p.5-14 for overview of thin & thick filaments
Sarcomere
Z line Z lineA band
H zone
I band Zone of overlap M line
Zone of overlap
Thin myofilaments Thick
myofilaments
Sliding Filament Theory• Myosin heads attach to actin molecules (at binding (active) site)
• Myosin “pulls” on actin, causing thin myofilaments to slide across thick myofilaments, towards the center of the sarcomere
• Sarcomere shortens, I bands get smaller, H zone gets smaller, & zone of overlap increases
• As sarcomeres shorten, myofibril shortens. As myofibrils shorten, so does muscle fiber
• Once a muscle fiber begins to contract, it will contract maximally
• This is known as the “all or none” principle
Physiology of skeletal muscle contraction• Skeletal muscles require stimulation from the nervous system in order to contract
• Motor neurons are the cells that cause muscle fibers to contract
cell body
dendrites
axonSynaptic terminals
(synaptic end bulbs)telodendriaaxon hillock
motor neuron
End bulbs contain vesicles filled with Acetylcholine (Ach)
telodendria
Synaptic terminal
(end bulb)
Neuromuscular junction
Synaptic vessicles
containing ACh
Motor end plateof sarcolemma
Synaptic cleftNeuromuscular
junction
Overview of Events at the neuromuscular junction• An action potential (AP), an electrical impulse, travels down the axon of the motor neuron to the end bulbs (synaptic terminals)
• The AP causes the synaptic vesicles to fuse with the end bulb membrane, resulting in the release of Acetylcholine (ACh) into the synaptic cleft
• ACh diffuses across the synaptic cleft & binds to ACh receptors on the motor end plate
• The binding of ACh to its receptors causes a new AP to be generated along the muscle cell membrane
• Immediately after it binds to its receptors, Ach will be broken down by Acetylcholinesterase (AChE) – an enzyme present in the synaptic cleft
Figure 7-4(b-c)2 of 5Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Synapticcleft
Arrival of an action potential at the synaptic terminal
Sarcolemma ofmotor end plate
Arriving action potential
Vesicles
AChAChE moleculesAChreceptorsite
Action potential
Synaptic terminal
Axon
Sarcolemma
Musclefiber
• An action potential (AP), an electrical impulse, travels down the axon of the motor neuron to the end bulbs (synaptic terminals)
Figure 7-4(b-c)3 of 5Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Synapticcleft
Vesicles in the synaptic terminal fuse with the neuronal membrane and dump their contents into the synaptic cleft.
Release of acetylcholine
Arrival of an action potential at the synaptic terminal
Sarcolemma ofmotor end plate
Arriving action potential
Vesicles
AChAChE moleculesAChreceptorsite
Action potential
Synaptic terminal
Axon
Sarcolemma
Musclefiber
•The AP causes the synaptic vesicles to fuse with the end bulb membrane, resulting in the release of Acetylcholine (ACh) into the synaptic cleft
Figure 7-4(b-c)4 of 5Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Synapticcleft
Vesicles in the synaptic terminal fuse with the neuronal membrane and dump their contents into the synaptic cleft.
The binding of ACh to the receptors increases the membrane permeability to sodium ions. Sodium ions then rush into the cell.
ACh binding at the motor and plateRelease of acetylcholine
Arrival of an action potential at the synaptic terminal
Sarcolemma ofmotor end plate
Arriving action potential
Vesicles
AChAChE moleculesAChreceptorsite
Action potential
Synaptic terminal
Axon
Sarcolemma
Musclefiber
Na+
Na+
Na+
•ACh diffuses across the synaptic cleft & binds to ACh receptors on the motor end plate
•The binding of ACh to its receptors causes a new AP to be generated along the muscle cell membrane
•Immediately after it binds to its receptors, ACh will be broken down by Acetylcholinesterase (AChE) – an enzyme present in the synaptic cleft
Table 7-1
Physiology of Skeletal Muscle Contraction•Once an action potential (AP) is generated at the motor end plate it will spread like an electrical current along the sarcolemma of the muscle fiber
• The AP will also spread into the T-tubules, exciting the terminal cisternae of the sarcoplasmic reticula
•This will cause Calcium (Ca+2 ) gates in the SR to open, allowing Ca+2 to diffuse into the sarcoplasm
•Calcium will bind to troponin (on the thin myofilament), causing it to change its shape. This then pulls tropomyosin away from the active sites (myosin binding sites) of actin molecules.
•The exposure of the active sites allow myosin to bind to actin, and cause the sliding of the filaments
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin CummingsFigure 7-53 of 7
Resting sarcomere
Myosin head
Active-site exposure
Troponin
ActinTropomyosin
ADP
P+
ADPP +
ADPP+
Active site
Sarcoplasm
Ca2+
Ca2+
ADP
P +
• Calcium (Ca+2 ) gates in the SR open, allowing Ca+2 to diffuse into the sarcoplasm• Calcium will bind to troponin (on the thin myofilament), causing it to change its shape. • This then pulls tropomyosin away from the active sites of actin molecules.
Physiology of skeletal muscle contraction – events at the myofilaments
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin CummingsFigure 7-54 of 7
Resting sarcomere
Myosin head
Active-site exposure Cross-bridge formation
Troponin
ActinTropomyosin
ADP
P+
ADPP +
ADPP+
Active site
Sarcoplasm
Ca2+
Ca2+
ADP
P +
ADP+ P
Ca2+
ADP+P
Ca2+
• Myosin heads are “energized” by the presence of ADP + PO43- at the ATP binding
site (energy is released as phosphate bond of ATP breaks)
• Once the active sites are exposed, the energized myosin heads hook into actin molecules forming cross-bridges
Physiology of skeletal muscle contraction – events at the myofilaments
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin CummingsFigure 7-55 of 7
Resting sarcomere
Myosin head
Active-site exposure Cross-bridge formation
Pivoting of myosin head
Troponin
ActinTropomyosin
ADP
P+
ADPP +
ADPP+
Active site
Sarcoplasm
Ca2+
Ca2+
ADP
P +
ADP+ P
Ca2+
ADP+P
Ca2+
Ca2+
ADP + P
Ca2+
ADP + P
• Using the stored energy, the attached myosin heads pivot toward the center of the sarcomere
• The ADP & phosphate group are released from the myosin head
Physiology of skeletal muscle contraction – events at the myofilaments
Resting sarcomere
Myosin head
Active-site exposure
Cross bridge detachment
Cross-bridge formation
Pivoting of myosin head
Troponin
ActinTropomyosin
ADP
P+
ADPP +
ADPP+
Active site
Sarcoplasm
Ca2+
Ca2+
ADP
P +
ADP+ P
Ca2+
ADP+P
Ca2+
Ca2+
ADP + P
Ca2+
ADP + P
Ca2+
ATP
ATP
Ca2+
• A new molecule of ATP binds to the myosin head, causing the cross bridge to detach from the actin strand• The myosin head will get re-energized as the ATP ADP+P
• As long as the active sites are still exposed, the myosin head can bind again to the next active site
Physiology of skeletal muscle contraction – events at the myofilaments
Resting sarcomere
Myosin head
Myosin reactivation
Active-site exposure
Cross bridge detachment
Cross-bridge formation
Pivoting of myosin head
Troponin
ActinTropomyosin
ADP
P+
ADPP +
ADPP+
Active site
Sarcoplasm
Ca2+
Ca2+
ADP
P +
ADP+ P
Ca2+
ADP+P
Ca2+
Ca2+
ADP + P
Ca2+
ADP + P
Ca2+
ATP
ATP
Ca2+
Ca2+
Ca2+
ADPP +
+ P
ADP
http://www.youtube.com/watch?v=CepeYFvqmk4 -animation
http://www.youtube.com/watch?v=kvMFdNw35L0 –
animation with Taylor Swift song
Physiology of skeletal muscle contraction – events at the myofilaments
Physiology of Skeletal Muscle Contraction• If there are no longer APs generated on the motor neuron, no more ACh will be released
• AChE will remove ACh from the motor end plate, and AP transmission on the muscle fiber will end
• Ca+2 gates in the SR will close & Ca+2 will be actively transported back into the SR
• With Ca+2 removed from the sarcoplasm (& from troponin), tropomyosin will re-cover the active sites of actin
• No more cross-bridge interactions can form
• Thin myofilaments slide back to their resting state
Table 7-1
Skeletal muscle fibers shorten as thick filaments interact with thin filaments (“cross bridge”) and sliding occurs (“power stroke”). The trigger for contraction is the calcium ions released by the SR when the muscle fiber is stimulated by its motor neuron. Contraction is an active process; relaxation and the return to resting length is entirely passive.
These physiological processes describe what happen at the cellular level – how skeletal muscle fibers contract
But what about at the organ level? How do skeletal muscles (like your biceps brachii) contract to create useful movement?
• Skeletal muscles are made up of thousands of muscle fibers
• A single motor neuron may directly control a few fibers within a muscle, or hundreds to thousands of muscle fibers
• All of the muscle fibers controlled by a single motor neuron constitute a motor unit
The size of the motor unit determines how fine the control of movement can be –
small motor units precise control (e.g. eye muscles large motor units gross control (e.g. leg muscles)
Play IP Contraction of motor units p. 3-7
Recruitment is the ability to activate more motor units as more force (tension) needs to be generated
There are always some motor units active, even when at rest. This creates a resting tension known as muscle tone, which helps stabilize bones & joints, & prevents atrophy
Play IP Contraction of motor units p. 3-7
Hypertrophy – “stressing” a muscle (i.e. exercise) causes more myofilaments/myofibrils to be produced within muscle fibers; allows for more “cross bridges” resulting in more force (strength) as well as larger size
Anatomy of the Muscular System
•OriginMuscle attachment that remains
fixed•Insertion
Muscle attachment that moves•Action
What joint movement a muscle produces
i.e. flexion, extension, abduction, etc.
• For muscles to create a movement, they can only pull, not push
• Muscles in the body rarely work alone, & are usually arranged in functional groups surrounding a joint
• A muscle that contracts to create the desired action is known as an agonist or prime mover
• A muscle that helps the agonist is a synergist
• A muscle that opposes the action of the agonist, therefore undoing the desired action is an antagonist
Skeletal muscle movements at joints
Flexion/extension
Abduction/adduction
Rotation – left/right; internal(medial)/external(lateral)
pronation/supination
Elevation/depression
Protraction/retraction
Dorsiflexion/plantarflexion
Inversion/eversion
Naming of skeletal muscles
• An Overview of the Major Skeletal Muscles
Figure 7-11(a)
• An Overview of the Major Skeletal Muscles
Figure 7-11(b)
TERIMAKASIHSEMOGA MENJADI ILMU YANG
BERMANFAAT
Recommended