Download Anatomy and Function of the Muscular System: Structure, Contraction, and Diseases and more Exercises Biology in PDF only on Docsity! MUSCULAR SYSTEM Structure of a striated muscle (skeletal muscle - Striped and is attached to bones - It is controlled by the CNS and demonstrates (in)voluntary actions - It contracts when it receives nerve impulses - It has a lot of mitochondria to supply ATP (adenosine triphosphate) for energy used in muscle contractions Muscle structure - Myofibrils are composed of actin (together with myosin) and myosin (together with actin), which are fibrous proteins that forms the contractile filaments of muscle cells and is involved in the motions of other types of cells - Myofibrils join together forming muscle fibres (muscle cells) - Muscle fibres form larger string-like bundles called fascicles - Fascicles combines to form the muscle organ Nerve actions movements - Skeletal muscles can contract by the attachment of myosin to actin filaments in muscles, which ratchets actin filaments towards the centre of cells - Skeletal muscle has striations across its cells caused by arrangements of contractile protein โ myosin and actin Tendons (a fibrous connective tissue - Connects muscle to bone - Inelastic soft tissue made up of strong collagen fibres that merge into bone coverings - Capable of resisting high tensile forces while transmitting contractile forces from muscle to bone - They do not contract or stretch โ they are inflexible - However, when tendons are stressed, it can result in developing micro-tears โ this can heal overtime but worsen if it does not rest Fascia (Fai-shee-uh - Connects muscle to muscle - It is a strong thick sheet of areolar tissue, where smaller muscles can be attached e.g. muscles in the face are responsible for facial expressions - It separates different muscles, protecting them while allowing them to move alongside one another, e.g. facial muscles can move whereas the skull cannot. - It wraps and connects the bones, muscles, nerve and blood vessels Types of muscle contraction Isometric contraction โ joint angle/muscle length does not change during contractions e.g. muscles contract but there is no movement e.g. tug-of-war Eccentric contraction โ when the muscle contracts, it lengthens, which occurs in opposition to the concentric contraction Concentric contraction โ when the muscle contracts, it shortens and tension increase โ antagonistic to eccentric contraction Eccentric and concentric contraction - Isotonic contractions โ when the tension maintains the same but the length changes - Function antagonistically Function of the muscle system โ antagonistic pairs, synergist and fixator Antagonistic pairs โ antagonist and agonist - The muscles opposite to the agonist, the antagonist, relaxes to tallow the agonist (prime mover) to move the bone - E.g. antagonistic pairs would include the cooperation of the triceps and bicep in the arm โ the hamstring and quadriceps in the legs Antagonist (eccentric) examples โ triceps brachii muscles Agonist (concentric) examples โ biceps brachii muscles Synergist e.g. brachialis muscle - Works to assist the agonist and antagonist muscles - Helps to stabilise a joint around which movement is occurring - Synergist muscles also help to create movement Fixator e.g. rhomboideus muscles - Amuscle that holds surrounding bones and joints steady, to form a stable base for the movement - Steading nearby bones so that there is a firm support for the antagonist
