Histology and Physiology

myology

study of muscles

functions of muscle tissue

movement, constriction of organs and vessels, maintain body position, respiration, body heat, communication, heart beat

properties of muscle tissue

excitability, contractility, extensibility, elasticity

excitability

ability to receive and respond to stimuli

contractility

ability to shorten forcefully

extensibility

ability to stretch beyond normal resting length

elasticity

ability to return to original shape after stretching

muscle tissue makes up __ to __ % of body weight

40 to 50

types of muscle tissue

skeletal, cardiac, smooth

skeletal muscle

striated/voluntary, most abundant muscle type

muscle fibers

fused set of dozens or hundreds of skeletal muscle

cardiac muscle

striated/involuntary; found in wall of heart

smooth muscle

nonstriated/involuntary; found in walls of hollow organs

skeletal muscle contains __________ _______, _____ _______, ______, and ________ ______ ______

connective tissues, blood vessels, nerves, and skeletal muscle tissue

skeletal muscle enlarges due to increase in size of _____, not increase of ______

fiber, not increase of number

fascia

connective tissue that covers the body by forming a sheet of tissue under the skin and also surrounds individual muscle groups

3 layers of connective tissue

epimysium, perimysium, endomysium

epimysium

dense layer of collagen fibers that wraps the entire muscle; separates muscle from surrounding tissues and organs

perimysium

collagen and elastic fibers that divide the skeletal muscle into a series of compartment

fasciculus

bundle of muscle fibers

endomysium

reticular fibers that surround each individual muscle fiber

connective tissues of _________ and __________ contain blood vessels and nerves that supply the muscle fibers

epimysium and perimysium

muscle action potential

electric current that stimulates muscle contraction

contractions require:

large amounts of nutrients and oxygen

each muscle fiber is also in contact with a:

motor neuron

Myofibers vary from typical cells through:

difference in size, multinucleated

sarcolemna

cell membrane of muscle fiber

sarcoplasm

cytoplasm of muscle fiber

transverse tubules

narrow tubes that are continuous with sarcolemma, form passageways through muscle fibers that allow action potentials to travel

myofibrils

cylindrical structures that run lengthwise through the entire fiber

2 types of myofibrils

thin myofilaments, thick myofilaments

thin myofilaments

composed of the protein actin; contain F and G actin

F actin

tropomyosin and troponin, wraps around G actin

G actin

larger bead-like structures that have active sites of pearls twisted around each other

thick myofilaments

composed of the protein myosin

myosin heads

golf clubbed heads of myosin

sarcomeres

myofilaments organized in repeating functional units