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• Muscle A tissue that consist of contractile cells
• Myosin A large protein that capture and convert the chemical energy of ATP into mechanical energy of movements
• Actin Another contractile protein that works together with Myosin
• Striated muscle cells muscle cells with transverse bands (striped appearance), like skeletal muscles and cardiac muscles
• Motor unit A motor neuron and all the muscle fibres it innervates
• Unstriated muscle cells Smooth muscle cells, use actin and myosin but these are not organized into sarcomeres. They are used in organs like blood vessels and intestine
• Dense bodies The place where the actin filaments attach to in the cytoplasm and the inner surface of the cell membrane
• Single-unit smooth muscle Muscle cells are electrically coupled by gap junctions --> depolarised and contract together
• Multi-unit smooth muscle Have few or non gap junction which makes them work as independent units, can be activated by hormones or local chemical stimuli or neurally
• Tonic smooth muscle Maintain contraction force for long periods and have no spontaneous contraction or action potential
• Phasic smooth muscle Contract rapidly and produce spontaneous contractions or action potential from cell to cell through gap junctions
• Muscle fibres long cylindrical cells with many nuclei, part of the skeletal muscle
• Sacrolemma Muscle fibres cell membrane
• Myofibrils Cylindrical part that the muscle fibre is built of
• Sacromere The portion of a myofibril between two Z discs
• Thick filament One of two myofilament contained by the myofibril, that mainly composed of the protein myosin and connects to the A-band of each Sacromere
• Thin filament The second part of the myofilament that mainly is composed of actin like two chins wrapped around each other in a helix shape
• Cross-bridges The heads on the Myosin molecule that generates the force of contraction while binding to actin
• Titin molecule that attaches to both the Z disc and M line and spans the distance between them
• Nebulin an inelastic molecule that specifies the length of the thin filament to optimise the overlap between thin and thick filaments
• Obscurin Protein that binds with proteins in the M line and links to sarcoplasmic reticulum to maintain the structure of the sarcomere
• Troponin, Tropomyosin (TN, TM)Protein molecules that are associated with the actin chains of the thin filaments, regulating the process of contraction by controlling whether or not the myosin cross-bridge can interact with the thin filaments
• Excitation- contraction coupling The relationship between depolarisation and contraction
• Intramuscular connective tissues The component that hold together the various components of the muscle
• Tendons Connect muscles to the bones and other skelatal elements
• Antagonist pair The muscle can only contract to shorten not to lengthen again by its own power, which makes the muscle pairs pulling in different directions very important
• Isometric contraction When the muscle is not shortened but stay the same length, to stay steady in an unmoving posture
• Concentric contraction When the muscle is actively shortened, like when you lift a heavy book your biceps muscle shortens to decrease the angle at your elbow.
• Eccentric contraction When the tissue is being forcefully lengthened by an external force, which makes the muscle both trying to contract and lengthen at the same time
• Isotonic contractions When the muscle is under the same tension by the muscle allowing a contraction at a prescribed and carefully controlled force or speed
• Twitch The mechanical response of muscles to a single action potential --> Fast cross-bridge binding and unbinding
• Tetanic contraction When multiple actions potentials arrive at the same time in the span of a single twitch, the muscle when got no time to relax between the twitches
• Load- velocity relationship The speed of the contraction is increased by the load (how heavy) the thing you lift is
• Twitch fibres Muscle fibres that generate action potentials that give rise to muscle twitch
• Summation When several stimuli come together and add up to a larger contraction

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