Chapter 9 Muscle Tissue

What are the Characteristics of Muscles

Excitability - able to respond to stimuli

contractility - shorten forcibly

extensability - can be stretched

elasticity - able to recoil

Primary Functions

movement, maintianing postion/posture, support soft tissues, control orfices (openings in body), heat generation

Skeletal Muscle

attatched to bones, voluntary, multinucleated, striated

Cardiac Muscle

in wall of heart, involuntary, uninucleate, striated

Smooth Muscle

in walls hollow organs, involuntary, uninucleate, spindle-shaped, nonstriated

Origin of Muscle

stationary during contraction

Insertion of Muscle

mobile during contraction

Direct Attachments

attachment of muscle by fusion of muscle sheath to periosteum of bone

Indirect Attachments

connection through tendon of Aponeurosis (flat sheet)

Epimyseum

outermost layer of muscle

What makes up muscle tissue?

muscle facicles

Perimysium

peremeter around muscle fascicles

what makes up muscle facicles?

muscle fiber (long muscle cells)

endomyseum

surrounds muscle fibers

plasma membrane of muscle fibers

sarcolemma

cytoplasm of muscle fibers

sarcoplasma

what makes up muscle fibers

myofibrils

sarcomere

smallest contractile unit

thick filaments

each filament contains bundle of myosin with tail + 2 heads. During contraction heads bond to thin filaments (cross bridges)

Thin Filaments

twisted strands of actin subunits that bind to myosin head

tropomysin

strands around actin that block binding sites

troponin

complexes that bind to actin, tropomysin, and Ca2+ (can hold tropomysin in place or move when stimulated to cause flexion)

elastic filaments

composed of titin which is a spring like protein that cause muscles to recoil

myofilaments

thin, thick, elastic filaments

neuromuscular junction

where the nerve meets and sends e- signal

motor neuron

stimulates a group of muscle fibers (motor units)

First class lever

fulcrum in the middle [nodding movement with skull]

Second-Class Lever

load is in the middle [standing on tip toes]

Third-Class Lever

applied force in the middle (most common)

Examples of Muscles Named by Location

temporalis, intercostal

Examples of Muscles Named by shape

deltoid, rhomboideus

Examples of Muscles Named by size

gluteus maximus, (longus)

Examples of Muscles Named by direction of fibers

rectus ___, external, internal, transverse

Examples of Muscles Named by number of heads

biceps, triceps

Examples of Muscles Named by location of attachments

[sternocleidomastoid] (uses compound names)

Examples of Muscles Named by relative position

lateralis/medialis

Examples of Muscles Named by action

adductor, exgtensor