1. 골격이나피부등에부착하여몸의형태를이룸 2. 유강장기나혈관, 도관등의벽을구성하고있음 3. 근의기능 1) 골격 ( 뼈대 ) 을움직이는전신적인운동 2) 호흡운동 3) 심장의박동 4) 혈관이나각종선및도관들의수축운동 5) 내장의연동운동등부착하는위치에따라매우다양함 6) 골격근은수축시에많은열을발생시켜정상적인체온을유지하는데관여함 4. 근육의일련의작용은반드시신경의지배를받음 2 HUMAN ANATOMY 2014-09-27
5. 발생학적으로근육의대부분은중배엽성 (mesoderm) 임 동공괄약근과동공산대근, 모양체근, 유선, 모낭및한선등을이루는소수의평활근 ( 민무늬근 ) 들은외배엽성 (ectoderm) 임 6. 골격근 (skeletal muscle) 수의근 (voluntary muscle) : 구조와기능상으로무늬가있음 7. 심장근 (cardiac muscle) 과평활근 (smooth muscle) 불수의근 (involuntary muscle) : 무늬가없으면서, 의지적으로움직일수없음 3 HUMAN ANATOMY 2014-09-27
Size Skeletal ms. Cardiac ms. Smooth ms. 100 μm X 60 cm 10-20 μm X 50-100 μm 5-10 μm X 30-200 μm Nucleus Multi 1 1 Contraction mechanism Ca2+ supply Contraction Energy Neuromuscular junction Sarcoplasmic reticulum Fast, tetanus, fast fatigue Aerobic metabolism, glycolysis, anaerobic metabolism Automaticity, pacemaker cell ECF Slow Aerobic metabolism, lipid & cazrbohydrate Automaticity, nerve or hormone ECF Slow, non-fatigue Aerobic metabolism 4
1 평활근 (smooth muscle) 1. 내장이나혈관들을이루는평활근은전자현미경하에서는골격근과심근에서와같이질서정연한배열상은아니지만방사상배열을한근원섬유무늬가나타남 2. 평활근세포는방추형의단핵세포이며, 세포질에는치밀체 (dens body) 가있어액틴근세사를연결하고있음 3. 평활근수축은골격근의수축기전과같이일어나지만트로포닌 (troponin) 이없기때문에칼슘 (Ca2+) 이칼모둘린 (calmodulin) 과결합하여 myosine light chain kinase(mlck) 를활성화함 5 HUMAN ANATOMY 2014-09-27
Smooth muscle Appendix Lesser energy is required -> 오랫동안그힘을유지함. Slow contraction/relaxation Great force generation Stress relaxation 6
7 Appendix
8 HUMAN ANATOMY 2014-09-27
미오신 head 의연속배열 - 액틴이미오신을따라좀더긴거리로미끄러지게할수있다. - 이런구조는최대장력을유발하고, 최대수축력과이완력을발휘하게한다. 9
Sources of Ca 2+ Ca 2+ 농도의증가는수축의시작신호이며, 10 다양한 ca2+ 농도의증가는수축력의크기를결정함. 1. Through the cell membrane - Voltage dependent Ca 2+ channels - Ligand-gated Ca 2+ channels - store-operated Ca2+ channel - Stretch-activated Ca2+ channel 2. Sarcoplasmic reticulum - Ryanodine receptor - IP3 receptor 평활근의재분극은 Ca 2+ 유입에의해일어나며, Ca 2+ -activated K+ channel 에의해재분극됨.
11 Na + -Ca2 + antiporter
Control of GI smooth m. contraction 1. Intrinsic Enteric Nervous system 1) Myenteric nerve plexus 2) Submucosal nerve plexus 2. Extrinsic Autonomic NS 1) Parasympathetic (Ach M1) 2) Sympathetic (Norepinephrine-β2) 3. Stretch 4. Local tissue chemicals & hormones 12
13 Mechanisms for Increasing intracellular Ca 2+
1 평활근 (smooth muscle) 4. 일반적으로평활근은위, 장, 자궁, 방광, 혈관등과같이속이빈장기의벽을싸고있으나비장에서는피막과비주에평활근섬유가있으며, 한선및타액선등에서는근상피세포 (myoepithelial cell) 로존재함. 5. 대부분의유강장기벽을이루는평활근은 2 층으로되어있는데, 외층은종축으로길게배열된종주근 (longitudinal muscle) 이고내층은종축에대하여직각으로둥글게배열되어있어윤주근 (circular muscle) 임 6. 평활근 (smooth muscle) 의종류 1) 단단위평활근 (unitary smooth muscle) 2) 다단위평활근 (multiunit smooth muscle) 14 HUMAN ANATOMY 2014-09-27
1 평활근 (smooth muscle) 1. 단단위평활근 (unitary smooth muscle) 1) 내장평활근 (visceral smooth muscle) 이라고도함 2) 소화관이나방광등벽을이루고있음 3) 근세포와근세포사이는교통반 (gap junction) 에의해연결되어있음 4) 교통반 (gap junction) 은전기저항이매우낮기때문에하나의세포흥분이다음세포로전기적으로전도될수있음 2. 다단위평활근 (multiunit smooth muscle) 큰혈관의벽이나눈의홍채를구성하는평활근으로서내장평활근과달리마치골격근처럼운동단위별로수축을나타낼수있음 15 HUMAN ANATOMY 2014-09-27
GI smooth muscle 1. Unitary (single unit) m. 16 -single-unit smooth, unitary smooth muscle 1. Automatism ( 자동능 ) - Cajal cells - Slow wave potential 3 per minute in the stomach 10 per minute in the ileum 3 per minute in the colon
17 Single-unit smooth muscle: Gap-junction 으로연결되어세포들이하나의단위로서수축한다. Multi-unit smooth muscle: Gap-junction 연결이없어세포각각들이독립적으로움직임
2 심장근 (cardiac muscle) 18 HUMAN ANATOMY 2014-09-27
2 심장근 (cardiac muscle) 1. 심장의벽을구성하는근육으로골격근과비슷한구조를하고있으나우리의의지대로움직일수없는횡문불수의근 (striated involuntary muscle) 임 2. 심장근의근섬유는배열이나뭇가지모양으로하나의근섬유끝과다른섬유의양쪽근섬유막이중첩되어서로평행하고있는데, 이부분이골격근의 Z 선에해당하는부위임 3. 인접세포사이를연결시켜주는개재판 ( 사이원반, intercalated disc) 은이온의이동및전기적인흥분전달부위로이용되는교통반 (gap junction) 과반달모양의폐쇄연접으로이루어져있다. 이러한구조적특성으로인하여한곳에서발생한활동전압이쉽게전체로퍼질수있어, 심방이나심실이마치세포하나가수축하듯이동시에수축할수있음 19 HUMAN ANATOMY 2014-09-27
20 HUMAN ANATOMY 2014-09-27
2 심장근 (cardiac muscle) 4. 심장근세포는원주상이고골격근섬유보다작고가늘다. 핵은근세포중앙부에 1 개씩있음세포질에는많은미토콘드리아가함유되어있음근형질세망은골격근과는달리 Z 선근처에수조 (cistern) 를형성하고있음 T 세관 1 개와근형질세망 1 개가합쳐이조체 ( 두동이, diad) 를형성하고있음 5. 심장은흥분을발생시키는동방결절 (sinoatrial node, S-A node) 과방실결절 (atrioventricular node) 이라는특수한근조직이발달해있음 21 HUMAN ANATOMY 2014-09-27
Excitation-contraction coupling in the heart requires Ca ++ influx through L-type Ca ++ channels in the sarcolemma and T tubules 22
Suspension Cardiogram Ventricle Atrium 1) Heart rate 2) Contraction force 23
Basic control mechanisms of heart function 1) Intrinsic regulation: Frank-Starling mechanism SV=Stroke volume (or cardiac output) LVEDP=left-ventricle end-diastolic pressure(or end-diastolic vol.) 2) Autonomic nervous system: Sym. & Parasym 24
Titin may contribute to the ability of stretch to increase the force of contraction of the heart 25
Basic control mechanisms of heart function 1) Intrinsic regulation: Frank-Starling mechanism 2) Autonomic nervous system: Sympathetic control Parasympathetic control 26
Heart beat 는자율신경계에의해조절된다. 연수의심혈관조절중추 교감신경 (NE) β1 receptor Na +, Ca 2+ Excitation 부교감신경 (Ach) M receptor K +, Ca 2+ Inhibition * 평상시심장박동은부교감신경에의해억제되어있다. * 카테콜아민은 AV-node 를통한 AP 의전도를증가시킨다. * Ach 는 AV-node 를통한 AP 전도를느리게하여 AV-node 지연을증가시킴. Beat rate Beat rate 27
Heart beat 는자율신경계에의해조절된다. 연수의심혈관조절중추 교감신경 (NE) β1 receptor Na +, Ca 2+ Excitation 부교감신경 (Ach) M receptor K +, Ca 2+ Inhibition * 평상시심장박동은부교감신경에의해억제되어있다. * 카테콜아민은 AV-node 를통한 AP 의전도를증가시킨다. * Ach 는 AV-node 를통한 AP 전도를느리게하여 AV-node 지연을증가시킴. Beat rate Beat rate 28
Conduction System of the Heart In normal heart, SA node functions as pacemaker Depolarizes spontaneously to threshold ( 심박조율기전위 ) (= pacemaker potential) AV node ( 방실결절 ) In septum of ventricles, His divides into right and left bundle branches ( 방실다발갈래 ) Which give rise to Purkinje fibers in walls of ventricles These stimulate contraction of ventricles 29 ( 동방결절 )
Conduction System of the Heart 30
Myocardium ( 심근 ) The heart wall 1. Epicardium ( 심외막 ) 2. Myocardium : cardiac muscle contraction 3. Endocardium ( 심내막 ) Receives blood supply via coronary arteries ( 관상동맥 ) High demand for oxygen and nutrients (5%) Myocardial infarction (MI) Blockage in coronary blood flow results in cell damage Exercise training protects against heart damage during MI. 31
32 The Heart Wall
Comparison of Cardiac and Skeletal Muscle 33
The Cardiac Cycle 1. Systole ( 수축기 ) Contraction phase Ejection of blood ~2/3 blood is ejected from ventricles per beat 2. Diastole ( 이완기 ) Relaxation phase Filling with blood Syncytium structure ( 융합체 ): atriums & ventricles At rest, diastole longer than systole During exercise, both systole and diastole are shorter 34
The Cardiac Cycle at Rest and During Exercise 35
Pressure Changes During the 36 Cardiac Cycle Diastole ( 이완기 ) Pressure in ventricles is low Filling with blood from atria AV valves open when ventricular P < atrial P Systole ( 수축기 ) Pressure in ventricles rises Blood ejected in pulmonary and systemic circulation Semilunar valves open when ventricular P > aortic P Heart sounds ( 심음 ) First: closing of AV valves Second: closing of aortic and pulmonary valves
Relationship Between Electrical Events and the ECG 37
38
3 골격근 (skeletal muscle) 39 HUMAN ANATOMY 2014-09-27
Skeletal Muscle Human body contains over 400 skeletal muscles 40-50% of total body weight Functions of skeletal muscle 1.Force production for locomotion and breathing 2.Force production for postural support 3.Heat production during cold stress The most obvious function : enable an individual to move freely & breathe 40
Tendon : muscle attached to bones by tough connective tissue Origin : not move Insertion : moved during muscle contraction Muscle actions Flexors Decrease joint angle Extensors Increase joint angles Skeletal muscle composition Muscle cells, nerve tissue, blood, various connective tissues 41
3 골격근 (skeletal muscle) 1. 건 ( 힘줄 ) 과건막또는근막등을거쳐골격이나피부에부착하며운동신경의지배를받아의지대로움직일수있는수의근 (voluntary muscle) 이며, 조직학적으로횡문근 (striated muscle) 임 2. 근세포 (muscle cell) 는원주상이며, 평활근이나심장근보다훨씬큼핵은다핵세포임세포질인근형질 ( 근세포질, sarcoplasm) 에는특수한근원섬유등이있음 이들모두는세포막인근초 ( 근육속막, sarcolemma) 에의하여싸여있음 42 HUMAN ANATOMY 2014-09-27
골격근은모양과위치및크기등에따라명칭이붙여졌음 1. 모양 (shape): 삼각근 ( 어깨세모근, deltoid), 능형근 ( 마름근, rhomboid) 등 2. 크기 (size): 대둔근 ( 큰볼기근 ), 소둔근 ( 작은볼기근 ) 등 3. 위치 (lcation): 대흉근 ( 큰가슴근, pectoralis major), 전경골근등 4. 방향 (drection): 복횡근 ( 배가로근 ), 복직근 ( 배곧은근 ) 등 5. 분기 (diviion): 상완이두근 ( 위팔두갈래근 ), 대퇴사두근 ( 넙다리네갈래근 ) 등 6. 부착 (attachent): 흉쇄유돌근 ( 목빗근 ), 흉골설골근 ( 복장목뿔근 ) 등 7. 작용 (action): 굴근, 신근, 내전근, 외전근, 거상근, 하체근등 8. 복합 (combination): 천지굴근, 소지대립근등 43 HUMAN ANATOMY 2014-09-27
양쪽끝이건 (tendon) 에의하여골막에부착되어있으며, 중간부는근조직이많은근복 (belly) 을이루고있음. 근두는운동성이적고안정되어있으므로기시 (origin) 혹은고정점 (fixed point) 이라고하고, 반대로근미는운동이일어나므로정지 (insertion) 혹은동점 (mobile point) 이라고함 근육의수축방향은근미에서근두쪽으로일어나기때문에근미의뼈가근두의뼈쪽으로굴곡, 신전, 내 외전등이일어남 44 HUMAN ANATOMY 2014-09-27
근의모습은보통근섬유의배열에따라분류함 1. 가장전형적인것은근복 (belly) 이굵고양끝이건 (tendon) 으로되어있는방추상근 (fusiform muscle) 2. 깃털모양을한형태의근은우상근 (pennate) 3. 기시부가톱니모양으로나누어져있는것은거근 (serratus) 4. 근속이둥글게배열되어구멍을좁히는데관여하는괄약근은윤상근 (circular muscle) 이라고함 45 HUMAN ANATOMY 2014-09-27
46 HUMAN ANATOMY 2014-09-27
3. 근육의보조장치 : 근막, 건 ( 힘줄 ) 및건초, 활액낭 ( 윤활주머니 ) 등이있음 1) 건 ( 힘줄, tendon) (1) 근두나근미에위치하여골막에고정되고있음 (2) 폭넓은건막 (aponeurosis) 을이루기도함 (3) 강인한인대나띠모양을이루는경우도있음 2) 건초 ( 힘줄집, tendon sheath) (1) 기다란건을싸서건을보호하는주머니모양의막임 (2) 외층은섬유집 (fibrous sheath) 이지만, 내층은활막 ( 윤활막, synovial membrane) 이며윤활액 (synovia) 을분비함 (3) 뼈의마찰하는건 ( 힘줄 ) 의움직임을원활하게도와줌 47 HUMAN ANATOMY 2014-09-27
3. 근육의보조장치 : 근막, 건 ( 힘줄 ) 및건초, 활액낭 ( 윤활주머니 ) 등이있음 3) 활액낭 ( 윤활주머니, synovial bursa) (1) 건초와마찬가지로근육, 건의작용을원활하게하는주머니모양의막임 (2) 근육의기시부나뼈, 관절주변과피부밑에서볼수있음 48 HUMAN ANATOMY 2014-09-27
각근육의표면을싸거나근육덩어리를싸는결합조직의막 1. 근내막 ( 근육속막, endomysium): 하나의근섬유 ( 근세포 ) 를싸고있는막 2. 근외막 ( 근육다발막, perimysium): 근속 (muscle) bundle 을덮고있는막 3. 근상막 ( 근육바깥막, epimysium): 개별근육전체를싸는막 49 HUMAN ANATOMY 2014-09-27
Microstructure of Muscle Fibers Myofibril ( 근원섬유 ) 50 Contain contractile proteins Actin (thin filament) Myosin (thick filament) Sarcomere ( 근절 ) Includes Z line, M line, H zone, A band, I band Sarcoplasmic reticulum ( 근형질세망 ) Storage sites for calcium Terminal cisternae Transverse tubules ( 가로관 ) Extend from sarcolemma to sarcoplasmic reticulum
Microstructure of Skeletal Muscle 51
근원섬유 (myofibril) 의근세사 (myofilament) 로굵은마이오신근세사 (myosin filament) 와가는액틴근세사 (actin filament) 로구성되어있음 마이오신근세사 (myosin filament) 1. 2 개의 heavy chain 과 4 개의 light chain 을갖고있음 2. 이중나선구조를하고있음 액틴근세사 (actin filament) 액틴 (actin), 트로포마이오신 (tropomyosin) 트로포닌 (troponin) 이라는 3 종류의단백질로구성되어있음. 52 HUMAN ANATOMY 2014-09-27
1. 액틴 (actin) 구형의 G-actin 과이들이결합하여사슬형태인 F-actin 을만들어나선구조를하고있음 2. 트로포마이오신 (tropomyosin) 액틴의장축에거의평행으로배열된긴단백질임 3. 트로포닌 (troponin) 트로포마이오신과결합하는 Tn-T, 근수축과정에서 Ca2+ 과결합하는 Tn-C, 마이오신과의결합을저해하는 Tn-I 라는 3 개의 subunit 로구성된단백질임 53 HUMAN ANATOMY 2014-09-27
Thick filament ATP ase Thin filament 54
The Relationships Among Troponin, Tropomyosin, Myosin, and Calcium 55 Weak bond VS Strong bond Excitation-contraction coupling
1. 골격근은결합조직층을포함한다양한조직으로구성되어있음 2. 근막은근육의여러표면을덮고있음 56 HUMAN ANATOMY 2014-09-27
57 Sarcomere
골격근의근세사들은배열에의해무늬를형성함 1. I-band(isotropic band) : 명대 ( 밝은부분 ) 액틴필라멘트 (actin filament) 만보이는부위 58 HUMAN ANATOMY 2014-09-27
골격근의근세사들은배열에의해무늬를형성함 2. A -band(anisotropic band) : 암대 ( 어두운부분 ) 액틴필라멘트 (actin filament) 와미오신필라멘트 (myosin filament) 가겹쳐있어어둡게나타나는부위 59 HUMAN ANATOMY 2014-09-27
3. Z선 (line) 액틴 (actin) 사와액틴 (actin) 사를연결하는 I띠의중간에어두운점선부위 4. 근절 (sarcomere) Z선 (line) 과 Z선 (line) 사이를골격근의기능상기본단위 5. H 대 (Hessen s zone) A 띠중가운데에미오신필라멘트 (myosin filament) 만있어서좀더밝게보이는부분 6. M 선 (line) H 대 (Hessen s zone) 중앙에미오신필라멘트 (myosin filament) 가부풀어생긴점 60 HUMAN ANATOMY 2014-09-27
A. 골격근섬유는수많은근원섬유들로구성되어있음 각각은근원섬유마디라고하는반복되는단위구조로이루어져있음 근원섬유마디줄무늬의특징은액틴세사와마이오신세사의배열때문임 61 HUMAN ANATOMY 2014-09-27
근형질막이함입되어형성된가로세관 (transverse tubule, T 세관 ) 이있고, 양측에근형질세망 ( 근육세포질그물, SR) 이부풀어형성된 2 개의종말수조 (terminal cistern) 를합쳐서 T- 계통의삼조체 ( 세동이, triad) 라고하는데, 세포내 Ca2+ 의저장고역할을하는곳으로알려지고있음 62 HUMAN ANATOMY 2014-09-27
가로세관을이루는세포막들은자극에대하여활동전압을쉽게유발하고, 이를전도하는세포막과세포내 Ca2+ 저장고사이의신호전달체계상중요한연결구조임 63 HUMAN ANATOMY 2014-09-27
1. 주동근 (agonist) : 어떤운동에직접관여하는근 2. 협력근 (synergist) : 주동근의운동을보조하는근 3. 길항근 (antagonist) : 주동근과의반대작용을하는근 골격근은다른근육과다르게운동단위 (motor unit) 별로수축하며, 운동신경과감각신경의지배를받고있는데, 이들신경과근육이접하는약 50 100nm 부분을신경근연접 (neuromuscular junction) 이라고함 운동신경축삭돌기의끝부분이약간팽대된부분을신경종말 (nerve ending) 이라고하며, 여기에는핵과미토콘드리아가존재함 64 HUMAN ANATOMY 2014-09-27
Neuromuscular Junction ( 신경근연접 ) Junction between motor neuron and muscle fiber Motor unit ( 운동단위 ) Motor neuron and all fibers it innervates Motor end plate ( 운동종말판 ) Pocket formed around motor neuron by sarcolemma ( 근육속막 ) Neuromuscular cleft ( 신경근틈새 ) Short gap between neuron and muscle fiber Acetylcholine is released from the motor neuron Causes an end-plate potential (EPP; 종판전위 ) Depolarization of muscle fiber 65
66 The Neuromuscular Junction
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한개의운동신경이수많은신경섬유들로근섬유를지배하는집단을말하며, 이렇게한개의운동신경섬유가지배하는근섬유의수를지배비율 (innervation ratio) 라함. 지배비율은근육에따라달라, 손처럼섬세하고빠른근육들은낮고, 몸통과자세근육들은높음 68 HUMAN ANATOMY 2014-09-27
Motoneuron Muscle membrane Ca + + Ca + + Ach vesicle Acetylcholine Ach receptor T-tubule Na + Na + Na + K + K + K + Na + channel Ca ++ channel K + channel Voltage sensor SR Ca + + Ca ++ Thin filament Thick filament 69
Steps in contraction 1. Action potential of motor neuron 2. Release of Ach at motor end-plate 3. Binding of Ach to acetylcholine receptors 4. Increased permeability of membrane to Na + & K + 5. Generation of end-plate potential 6. Generation of action potential in muscle fibers 7. Inward spread of depolarization along T tubules 8. Release of Ca ++ from sarcoplasmic reticulum(sr) 9. Binding of Ca ++ to troponin C 10. Formation of cross-linkages 70
71 Acetylcholine receptor 전압의존성 Na 통로 T- tublule 의전압의존성 Ca 통로근소포체의 Ca 유리통로
Neuromuscular junction 10-7 M 10-3 M 72 (Ryanodine receptor)
Plasma membrane invagination 73
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Mechanics of Muscle Contraction Nerve impulse Increased calcium ions into sarcoplasm surrounding myofilaments Myosin binding sites exposed ATPase splits ATP at myosin cross bridge Cross bridges activate cross bridge cycling 76
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Effect of muscle length on number of potentially active cross bridges A. Optimal length, maximum strength B. Too much stretch, fewer effective cross bridges, reduced strength C. Too much shortening, antagonistic cross bridges, reduced strength 78
Characteristics of Individual Fiber Types Type IIx fibers (fast) Fast-twitch fibers Fast-glycolytic fibers ATPase : V max / efficient Type IIa fibers (fast) Intermediate fibers Fast-oxidative glycolytic fibers Type I fibers (slow) Slow-twitch fibers Slow-oxidative fibers Chemical : mitochondria, capillaries & myoglobin : high resistance to fatigue Mechanical : slower V max, specific tension, more efficient 79
Characteristics of Individual Fiber Types 80
Distribution of Fiber Type in Athletes 81
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