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muslce tissue
muslce tissue & working together
| Question | Answer | |
|---|---|---|
| muscle make up | skeletal muscle --> bundles of muscle fibres --> myofibrils --> myofilaments ( actin, myosin) | |
| A band | - dark - primarily myosin filament - overlapping actin filaments | |
| I band | - light - actin only In the middle of the thin actin filaments (I bands) are protein discs called the Z line | |
| Z line | - centre of I band - dense fibrous line | |
| H zone | - middle of A band - lighter - thick filaments only | |
| Sarcomere | - area between two Z lines - unit of contraction/ myofibril | |
| What happens during muscle contraction ** | - Z lines closer - actin & myosin dont change length - H zone & I band smaller | |
| Energy requirement | - ATP is required for cross bridges to join at binding site | |
| Step 1 | - muscle stimulated by nervous signal - causes release of calcium ions in sarcoplasm | |
| Step 2 | - causes myosin heads to attach to an actin filament - forms cross bridges | |
| Step 3 | - Power stroke - myosin heads pivot & bend - Result - pulls actin filament towards M line - actin slides over myosin | |
| Step 4 | - thin actin filament slides over thick myosin - Z lines are drawn closer together - Sarcomere shortens | |
| Step 5 | - ATP molecules attach to myosin head - weakens link between A & M - causes myosin head to detach | |
| sarcoplasm | the cytoplasm of striated muscle fibres | |
| sarcolemma | a thin transparent membrane surrounding a muscle cell | |
| tendon | fibrous tissue that attaches muscles to bone | |
| ligament | fibrous tissue that attaches bone to bone | |
| The 3 properties of muscle tissue are | 1. Contractibility: can contract & shorten 2. Extensibility: ability to be stretched 3. Elasticity: ability to return to original length after being stretched | |
| smooth muscle | • Long spindle cells • Non striated • uni-nucelus | • Walls of internal organs |
| cardiac muscle | • Intercalated discs • Cross-striation • uni-nucleus | heart |
| skeletal muscle | • Roughly cylindrical • Parallel • Striated • multi-nucleus | • voluntary/ skeletal muscles |
| posture | : characteristic way that a person holds their body when standing or sitting | § depends on muscle tone – the partial contraction of those muscles that hold the body in position |
| · muscle tone | maintain partial contraction of the skeletal muscles tighten muscle but not enough to move. At any one time, some muscle fibres are contracted while some are relaxed | muscle tone is caused by constant contractions of the same muscle fibres, but different fibres taking turns to contract § this allows contraction over long periods of time · head held up |
| · bicep curl | o during flexion of the forearm the bicep contracts & is the prime mover muscle. The triceps relaxes & is the antagonistic muscle. Bicep is the flexor | o during extension of the forearm, the triceps contracts & is the agonist/PM muscle. The bicep relaxes & is the antagonistic muscle. The tricep is the extensor muscle |
| Anatomy | o Muscles are attached to the bones of the skeleton by tendons: fibrous inelastic connective tissue that attaches muscle to bone | o Origin: the end of a muscle that is fixed to stationary bone o Insertion: the end of a muscle that is fixed to moveable bone o Belly: fleshy portion in the middle of a muscle |
| · Movement about a joint | o Muscles can only contract, they can pull bones together, but they cannot push them apart. If muscles contract, pulling a bone in one direction another set of muscles must contract to pull the bones in the other direction : work in pairs | |
| § Antagonistic pairs | Agonist (prime mover) o Muscle that causes desired action · Antagonist: muscle that has an opposite action to agonist | Synergist o Muscle that helps prime mover § Can produce same movement & steady joint · Fixator o muscle that stabilises origin of the agonist § e.g. rotator cuff during bicep curl |
Created by:
procrast
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