Ch 10

Characteristic of all Muscles

Excitability, Contractility, Extendibility, and Elasticity

Excitability

Ability to receive and response to stimuli

Contractility

Ability to shorten forcibly when stimulated

Extensibility

Ability to be stretched

Elasticity

Ability to recoil to resting length

Medical Terminology Prefixes

Myo, Mys, Sacro

Types of Muscle Tissue

Skeletal, Cardiac, Smooth

Skeletal Tissue

Attached to bone (or some facial muscles) to skin

• Single, very long cylindrical, multinucleate cells with obvious striations

Cardiac Tissue

Walls of the heart

• Branching chains of cells, uni or binucleate; striations

Smooth Tissue

Unitary muscle in walls of hollow visceral organs (other than the heart); multiunit muscle and intrinsic eye muscles, airways, and large arteries

• Single, spindle shaped, uninucleate; no striations

Fascicles

Muscle fibers of skeletal muscles are organized in these bundles that determine what type of movement a muscle can make

Connective Tissue Sheaths

Supports cells and reinforces

Epimysium, Perimysium, Endomysium

Perimysium

Surrounds muscle fascicles

Myoblast

Fusion of these help form skeletal muscle fibers, consists of:

• Myosatellite cells

• Skeletal muscle stem cells

Repair/regenerates muscle after injury or exercise

Epimysium

Surrounds entire muscles

• Dense irregular connective tissue

Endomysium

Surrounds each muscle fiber

• Areolar connective tissue

Mitochondria, Glycosomes, and Myoglobin

Skeletal muscle fibers are abundant in ?

Myoglobin

protein that stores O2, gives meat red pigment

Sarcolemma

Muscle fiber plasma membrane

Sacroplasm

Muscle fiber cytoplasm

Myofibrils

Densely packed rod like elements that account for 80% of muscle cell volume

• Single muscle fiber can contain thousands

• Responsible for striations which are formed from repeating series of dark & light bands along length

• Sarcomeres, myofilaments, actin, myosin, elastic filaments, and dystrophin

M line

part of A bands (dark regions in myofibril) that bisects A band vertically

Z disc

sheet of proteins on midline of I band: lighter regions

• Thin actin anchor

Sarcomere

Functional unit of muscle fiber, smallest contractile unit

• Consists of area between Z discs

• Individual ________ align end to end along myofibril like boxcars of train

• Made up of thick (myosin) and thin (actin) myofilaments

Myofilaments

Thin filaments composed of fibrous protein: actin

• these subunits bear active binding sites for myosin head attachment

Troponin & Tropomyosin

Two long fibrous actin strands, Ca2+ binding regulatory proteins

Myosin

Thick filaments connected at M line

• Contain heavy & light polypeptide chains

• Heavy chains: form tail

• Light chains: form globular head & bind actin subunits

Elastic filament

Composed of protein: titin

• Holds thick filaments in place, helps recoil after stretch

Dystrophin

Links thin filaments to proteins of sarcolemma