A&P Quiz 3 Part One Content Definitions

Epimysium

Deep to the fascia another layer of connective tissue, surrounds the whole muscle.

Perimysium

Deeper layer of connective tissue, binds with epimysium to form tendons which bind the muscle to its attaching structure, surrounds individual fascicles or groups of muscle fibers.

Fascicle

Bundle of muscle fibers, surrounded by a layer of connective tissue called the perimysium.

Striations

The arrangement of myofilaments within the myofibril.

Endomysium

Surrounds myofibrils, extracellular matrix that blends with neighboring connective tissue.

Myofibril

Cylindrical organelles located in the sarcoplasm, bundles of specialized proteins.

Sacrolemma

Plasma membrane of muscle cell, composed of phospholipid bilayer with multiple specialized integral and peripheral proteins.

Thin filament

Made up of contractile, regulatory, and structural proteins, many subunits of actin.

Thick filament

Largest diameter, composed of many units of the contractile protein myosin.

Fascia

Encloses skeletal muscles, thick layer of connective tissue that anchors them to surrounding tissues and holds groups of muscles together.

Elastic filament

Thinnest type, composed of a single massive structural protein called titin.

Axon terminal

A knoblike structure at the end of an axon that contains synaptic vesicles with neurotransmitters.

T-tubules

Transverse tubules, extensions that form inward that dive into the muscle fiber and surround each myofibril, forming a tunnel-like network within the muscle fiber, filled with ECF.

Troponin

Second regulatory protein, consists of several subunits that hold the tropomyosin in place, both tropomyosin and troponin help to switch on and off the process of muscle contraction.

Tropomyosin

Long, ropelike regulatory protein, spirals around the two actin strands so that, at rest, it covers the active sites on actin.

Terminal Cisterna (of the SR)

Flanking each side of a T-tubule and are enlarged portions of the SR.

Synaptic Cleft

Narrow space between the axon terminal and the muscle fiber into which ACh is released.

Motor end plate

At neuromuscular junction, ACh flows, where receptors are, part of muscle cells plasma membrane, axon terminal releases ACh at motor end plate, specialized region of the sarcolemma.

Sarcoplasmic reticulum

Modified smooth ER that forms a weblike network surrounding each myofibril, bowl/stores the calcium.

Actin

Thin, bead-shaped protein that has an active site that can bind to the myosin head.

Myosin

Thick, has two globular 'heads' and two intertwining polypeptide chains making up the 'tail', the heads protrude from the myosin tail on a 'neck'.

Sarcomere

Functional unit of contraction, where muscle tension is produced, section of a myofibril that extends from one Z-disc to the next Z-disk.

Sarcoplasm

Cytoplasm of muscle cells, contains cytosol and all organelles.

Motor End Plate

specialized region of the sarcolemma w/ a folded surface containing many receptors for ACh