CSCS

Fibrous connective tissue covering the skeletal muscles; continuous with tendons at the ends of the muscle.

A specialized connective tissue covering all bones; tendon is attached here.

AKA muscle cells; long, cylindrical cells 50-100micrometer diameter; contain several nuclei

Bundles of up to 150 muscle fibers; found under the epimysium

Connective tissue surrounding the fasiculi.

Connective tissue surrounding each muscle fiber; is continuous with the sarcolemma

Muscle fiber's membrane

Nerve cell

The junction between a motor neuron and the muscle fibers it innervates; AKA motor end plate

A motor neuron and the muscle fibers it innervates

The cytoplasm of the muscle fiber; contains contractile components

Contain the apparatus that contracts the muscle cell; hunderds of myofibrils dominate the sarcoplasm

Thick filament about 16 nm in diameter that contain up to 200 myosin molecules

Globular heads protruding away from the myosin filament at regular intervals

Thin filaments about 6nm in diameter; consist of 2 strands arranged in a double helix

Smallest contractile unit of skeletal muscle; average about 2.2 micrometers in length in a relaxed fiber and are repeated the entire length of the muscle fiber.

Dark; corresponds with the alignment of the myosin filaments

Light, corresponds with the areas in two adjacent sarcomeres that contain only actin filaments

The middle line of the I-band and appears as a thin, dark line running longitudinally through the I-band

The area in the center of the sarcomere where only myosin filaments are present

Intricate system of tubules parallel to and surrounding each myofibril that terminates as vesicles in the vicinity of the Z-lines; store calcium ions

Run perpendicular to the sarcoplasmic reticulum and terminate in the vicinity of the Z-line between two vessicles; AKA transverse tubules

Pattern of a T-tubule spaced between and perpendicular to two sarcoplasmic reticulum vessicles

An electrical nerve impulse

Actin filaments at each end of the sarcomere slide inward on myosin filaments, pulling the Z-lines toward the center of the sarcomere and thus shortening the muscle fiber.

A protein that is situated at reular intervals alond the actin filament and has a high affinity for calcium ions; calcium ions released from the sarcoplasmic reticulum bind with troponin

Protein molecule that runs along the length of the actin filament in the groove of the double helix

Little calcium is present in the myofibril, so very few of the myosin cross-bridges are bound to actin; no tension is developed in the muscle

Sarcoplasmic reticulum is stimulated to release calcium ions, which bind with troponin, causing a shift in the tropomyosin. Mysoin cross-bridge head now attaches more reapidly to actin filament

The energy for cross-bridge flexion comes from hydrolysis of ATP to ADP and phosphate, which is catalyzed by ATPase. Another ATP molecule must replace ADP on the myosin cross-bridge head in order for the head to detach from the active actin site and recock.

Measurable muscle shortening transpires only when the binding of calcium to troponin, coupling of the mysoin cross-bridge with actin, cross-bridge fexion, dissociation of actin and myosin, and recocking of the mysosin cross-bridge head is repeated over and over throughout the muscle fiber.

Occurs when the stimulation of the motor neuron stops. Calcium is pumped back into the sarcoplasmic reticulum, which prevents the link between the actin and myosin filaments. Brought on by the return of actin and myosin filaments to their unbound states

Neurotransmitter released by the arrival of the action potential at the nerve terminal, which diffuses across the neuromuscular junction, causing excitation of the sarcolemma

There is no such thing as a motor neuron stimulus that causes onle some of the fibers to contract. Similarly, a stronger action potential cannot produce a stronger contraction.

The brief contraction that results from an action potential traveling down a motor neuron, activating the muscle fibers

When stimuli are delivered at so high a frequency that the twitches begin to merge and eventually completely fuse

One that develops force and also relaxes rapidly and thus has a short twitch time.

One that develops force and relaxes slowly and has a long twitch time

Slow-twitch; generally fatigue resistant and have a high capacity for aerobic energy supply, but limited potential for raped force development

Fast-twitch; characterized as inefficient and fatigable and having low aerobic power, rapid force development, high actomyosin myofibrillar ATPase activity, and high anaerobic power.

Means of vaying skeletal muscle force involving an increase in force through varying the number of motor units activated.