muscular system

tendon

tendon

attaches muscle to bone

fascicles

bundles of muscle fibers

muscle fiber

a single muscle cell

endomysium

connective tissue surrounding a muscle fiber

perimysium

connective tissue surrounding a fascicle

epimysium

membrane that covers the entire skeletal muscle

sacrolemma

cell membrane of a muscle fiber

sarcoplasm

cytoplasm of a muscle fiber

myofibrils

protein structures that make up muscle fibers

myosin

thick filament in the A band that produces dark striations

actin

thin filaments in I bands that produces light striations; contains the active or binding site for myosin crossbridge

sarcomere

contractile unit of a muscle fiber between the z lines

sarcoplasmic reticulum

specialized endoplasmic reticulum of muscle cells

transverse tubules (T-tubules)

transmit action potential through cell, allow entire muscle fiber to contract simultaneously, have same properties as sarcolemma

motor neurons

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

synapse

functional junction or point of close contact between two neurons or between a neuron and an effector cell

neurotransmitters

chemicals that transmit information from one neuron to another

neuromuscular junction

point of contact between a motor neuron and a skeletal muscle cell

motor end plate

specialized part of a muscle fiber membrane at a neuromuscular junction

synaptic cleft

the narrow gap that separates the presynaptic neuron from the muscle fiber

crossbridge

this forms when the myosin heads attach to actin during muscle contraction

sliding filament model

states that the thick and thin filaments slide past each other so that their degree of overlap increases.

acetylcholine

neurotransmitter that enables muscle action

creatine phosphate

an energy storage molecule used by muscle tissue. The phosphate from creatine phosphate can be removed and attached to an ADP to generate ATP quickly.

oxygen debt

the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose

muscle tone

the state of balanced muscle tension that makes normal posture, coordination, and movement possible

prime mover

muscle with the major responsibility for a certain movement

antagonist muscle

the muscle opposite the agonist, which must relax and lengthen during contraction of the agonist.

muscle atrophy

lack of muscle activity; reduces muscle size, tone, and power

isotonic muscle

contracts and shortens; produce movement

isometric contraction

muscle contracts but there is no movement, muscle stays the same length

thin filaments are composed of

actin, troponin, tropomyosin

muscle origin

point of muscle attachment to bone that remains stationary

muscle insertion

attachment to movable bone

muscle functions

producing movement, maintaining posture, stabilizing joints, generating heat

connective tissue superficial to deep

epimysium, perimysium, endomysium

striations in muscle

"stripes" visible under the microscope due to the organized overlapping of myosin and actin (the sarcomere organization)

muscle cramps

temporary atp deficiency

named for the shape of the muscle

trapezius, deltoid

flexion

decreases the angle of a joint; hamstring flexes the knee; bicep flexes the arm, flexor carpi flexes the wrist

synergist

muscle that assists a prime mover

name for the number or origins

triceps, biceps