Muscular System Flashcards
Function of muscular system
Enables body to move by the ability of muscles cells to contract
Skeletal muscle
Composed of skeletal muscle and connective tissue. Extend from one bone across a joint to another bone
Origin
Attached to the bone that remains relatively stationary when movement occurs
Insertion
Point of attachment to the bone that moves when a muscle contracts
Body
Main part of the muscle
Tendons
Strong cords of fibrous connective tissue. Muscles attach to bone by tendons
Bursae
Small synovial lined saves containing small amount of synovial fluid. Between tendons and underlying bone
Thick myofilaments
Contain protein myosin. Myosin heads attach to actin and pull them toward middle of sacromere. Creating contraction
Thin myofilaments
Composed of actin.
Sacromere
Basic functional unit. Separated from each other by dark bands called Z lines. Calcium and ATP molecule required to contract
Movement: prime mover
Muscle whose contraction is mainly responsible for producing movement
Movement: synergist
Muscle whose contractions help prime mover produce movement
Movement: antagonist
Muscle whose actions oppose the action of a prime mover
Posture
Tonic contraction allow us to maintain posture. No movement of body parts
Motor unit: motor neuron
Nerve cell that transmits impulse to a muscle causing contraction
Motor unit: neuromuscular junction
Point of contact between nerve ending and muscle fiber it innervates
Threshold stimulus
Muscle will contract only if an applied stimulus reaches certain min level of intensity
4 types of Muscle contractions
Twitch: quick responses to stimulus
Tetanic: sustained and steady muscular contractions caused by series of stimuli bombarding a muscle in rapid succession
Isotonic
Isometric
Isotonic contractions
Produces movement at a joint. Muscle changes length
Concentric contractions shorten muscle
Eccentric contractions increase muscle length
Isometric contractions
Muscle contractions that do not produce movement or Changes length of muscle.
Tension in muscle increases
Muscles of mastication
Masseter: closes jaw
Temporal
Sternocleidomastoid
Flexes head
