Connective tissue components and morphology of muscle tissue:

Innervation

"put the nerve into something"... when nerves go into muscle fiber, they innervate the muscle fiber (to supply nerves to something or energize)

Thin filaments

(8nm(1nm=one billionth of meter)) in diameter & 1-2 um long and composed of the protein actin (2 thin filaments for every thick filament in regions of filament overlap)

Fascicles (little bundles)

(aka muscle fascicles or fasciculi) large enough to be seen with naked eye. GIve a cut a meat its characteristic grain. If you tear a piece of meat it rips apart along muscle fascicles

Fascia (bandage)

(attaches muscle to muscle) a dense sheet or broad band of irregular connective tissue that lines the body wall/limbs supports & surround muscles & other organs of the body (allows free movement, carries nerves, blood & lymphatic vessels & fills spaces between muscles

Actin

The main component of the thin filament is the protein actin. Individual action molecules join to form an actin filament that is twisted in a helix

Sarcoplasmic reticulum (SR)

a fluid-filled system of membranous sacs encircles each myofibril, releases calcium ions to trigger muscle contraction

Perimysium(peri=around)

a layer of dense irregular connective tissue but surrounds groups of 10 to 100+ muscle fibers, separating them into bundles called muscle fascicles(little bundles)

Triad (=three)

a skeletal muscle substructure responsible for the regulation of excitation-contraction coupling, formed by close apposition of T-tubule and terminal sarcoplasmic reticulum

A-band

darker, middle part of the sarcomere which extends entire length of the thick filaments, toward end of A band is zone of overlap where thick and thin filaments lie side by side

Deep fascia

dense, organized connective tissue located deep to the skin & subcutaneous tissue

Terminal cisterns (=reservoir)

dilated end sacs of the sarcoplasmic reticulum called TC butt against the T tubule from both sides

Superficial fascia

found directly under the skin & superficial adipose layers, separates skin from underlying muscle tissue

Acetylcholine (ACh)

inside each synaptic vesicle are thousands of molecules of Acetylcholine (the neurotransmitter released at the NMJ)

I-band

lighter, less dense area that contains the rest of the thin filaments but NO thick filaments and a z disk passes through the center of each I band

Myosin

main component of thick filaments and functions as a motor protein in all 3 muscle tissue types (ab 300 form of thick filament in skeletal muscle) (shaped like 2 golf clubs twisted together

H-band (zone)

narrow band in center of each A band that contains thick but not thin filaments

Z-band (disc)

narrow, plate shaped regions of dense protein material that separate one sarcomere from the next (sarcomere extends from 1z disc to next)

Epimysium (epi=upon)

outer layer encircling the entire muscle. It consists of dense irregular connective tissue

Tropomyosin

part of a thin filament, when skeletal muscle fiber is relaxed, tropomyosin covers myosin-binding sites on action molecules, preventing myosin from binding to actin

Troponin

part of thin filament, when calcium ion (ca2t) bind to troponin it changes shape, moves tropomyosin away from myosin-binding sites on action molecules & muscle contraction begins as myosin binds to actin

Endomysium (endo=within)

penetrates the interior of each muscle fascicle and separate individual muscle fibers from one another(mostly veticular fibers)

Myoglobin

red-colored protein, this protein is found only in muscle, binds oxygen molecules that diffuse into muscle fibers from interstitial fluid, releases oxygen when needed by the mitochondria for ATP production

M-line

supporting proteins that hold thick filaments together @ center of H band for the M line (bc@ middle of sarcomere)

Sarcomere (=part)

the basic functional units of a myofibril

Sarcolemma(sarc=flesh, lemma=sheath)

the plasma membrane of a muscle fiber

Synaptic cleft

the space between neurons @ a nerve synapse across which a nerve impulse is transmitted by a neurotransmitter

Neuromuscular junction

the synapse between a somatic motor neuron and a skeletal muscle fiber

T- (Transverse tubulues)

thousands of tiny tube-shaped invaginations of the sarcolemma-t tubulues, tunnel in from the surface towards the center of each muscle fiber, open to outside of fiber and filled with interstitial fluid

Myofibrils

thread like structure extending longitudinally through a muscle fiber consisting mainly of thick filaments (myosin) & thin filaments (actin, troponin & tropomyosin)

Aponeurosis (apo=from, neur= a sinew)

when the connective tissue elements extend as a broad flat sheet ex. epicranial aponeurosis on top of skull between frontal & occipital bellies of occipitofrontalis muscle

Tendon

white fibrous cord of dense regular connective tissue that attaches muscles to bones

Filaments

within myofibrils are smaller protein structures called filaments or myofilaments

Sarcoplasm

within the sarcolemma is the sarcoplasm, the cytoplasm of a muscle fiber, includes a substantial amount of glycogen (large molecules composed of many glucose molecules), contains red-colored protein called myoglobin

Thick filaments

16 nm in diameter & 1-2 um long & composed of protein myosin

Titan (=gigantic)

3rd most plentiful protein in skeletal muscle (after actin & myosin) each molecule spans 1/2 a sarcomere, connects z disc to m line of sarcomere (help stabilize position of thick filament)