BRAINCAKEMuscles
Revision notes for Muscles in OCR Biology A (H420). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Types of MuscleThere are three types of muscle: skeletal, cardiac and smooth muscle Skeletal muscles are responsible for movement e.g. biceps.
- Difference in Structure of Different Types of MuscleSkeletal muscle is striped or striated.
- Cardiac MuscleCardiac muscle is involuntary and contraction is intermediate between skeletal and smooth muscle in speed and duration.
- Smooth MuscleSmooth muscle is involuntary.
- Muscle FibresSkeletal muscles are specialised cells made up of bundles of long, tubular, multinucleate cells called muscle fibres.
- MyofibrilsMyofibrils are long, cylindrical rod-like organelles found in muscle fibres.
- ActinMyofibrils are made from two types of protein filaments (myofilaments), the thinner actin filament and the thicker myosin filaments.
- MyosinA myosin molecule has a long tail and a hinged globular head which allows the head to move back and forwards and bend.
- A SarcomereA sarcomere is the contractile element and functional unit of a myofibril and is delineated by two Z lines.
- Neuromuscular JunctionWhen an action potential arrives at a neuromuscular junction it stimulates calcium ion channels to open.
- Sliding Filament ModelThe muscle contracts when the actin and myosin filaments slide past each other.
- Release of Calcium Ions into the SarcoplasmThe depolarisation of the sarcolemma is spread throughout the muscle fibre by the T-tubles which are in contact with the sarcoplasmic reticulum (SR).
- The Power StrokeIn the resting state the myosin head has ADP and Pi bound.
- The Role of Ca2+ and ATP in Muscle ContractionCalcium ions have a dual role in muscle contraction.
- Energy Supply during Muscle ContractionLarge quantities of ATP are required for the movement of the myosin heads, the active transport of calcium ions into the SR and the sodium-potassium…