Muscular System 1

cardiac muscle tissue

involuntary muscle tissue found only in the heart

skeletal muscle

a muscle that is attached to the bones of the skeleton and provides the force that moves the bones

smooth muscle

non-striated muscle tissue found inside many internal organs of the body

involuntary, uninucleate cells

smooth muscle and cardiac muscle

voluntary, multinucleate cells

skeletal muscle tissue

striated muscle tissue

cardiac and skeletal muscle tissue

cells are unbranched

skeletal and smooth muscle tissue

sarcomere

contractile unit of muscle

z-disc

sheet of proteins that anchors the thin myofilaments and connects sarcomeres to one another

myosin

thick myofilament

actin

thin myofilament

m-line

supporting proteins that hold the thick myofilaments together in the H zone

A band

dark area of a sarcomere, extends length of the thick filaments and includes myosin and some actin

I band

light area of a sarcomere, contains actin only (and the Z disc)

H zone

the region at the center of an A band of a sarcomere that is made up of myosin only

H zone & I band

Parts of the sarcomere that shorten during contraction

Muscle

Composed of many fascicles, surrounded by epimysium

Fascicle

Composed of many muscle cells, surrounded by perimysium

Muscle fiber

A single muscle cell, composed of many myofibrils & surrounded by endomysium

Fascia

A band or sheet of fibrous connective tissue that covers, supports, and separates muscle

Areolar tissue

Loose connective tissue that binds skin to underlying muscle

Sarcolemma

Muscle cell membrane

T-Tubule

Narrow tubes that are continuous with the sarcolemma and extend into the muscle cell

Sarcoplasm

Cytoplasm of a muscle cell

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

Myoglobin

An oxygen-storing, pigmented protein in muscle cells.

Sarcoplasmic reticulum (SR)

Specialized smooth endoplasmic reticulum, which stores, releases, and retrieves Ca++

Terminal cisternae of sarcoplasmic reticulum

Structures within skeletal muscle cells that serve as reservoirs of calcium ions

Triad

3 structures in a muscle cell: A T-tubule and the 2 terminal cisternae that lie on each side of it

Electrical conductivity

The ability of the sarcolemma to carry an electric current (action potential)

Contractility

Characteristic of muscle cells - ability to shorten

Thermogenesis

Heat production that occurs when muscle cells contract

Sphincters

Muscles arranged in circles that are able to decrease the diameter of tubes. Examples are found within the rectum, bladder, and blood vessels.

Endymysium

Areolar connective tissue covering an individual muscle fiber

Perimysium

Connective tissue surrounding a fascicle

Epimysium

Surrounds entire muscle

Tendon

Connects muscle to bone; a cord of dense regular connective tissue

Aponeuroses

A sheet of dense regular connective tissue that takes the place of a tendon in sheetlike muscles that have a wide area of attachment.