Chapter 9 Flashcards
Contractility
ability of muscle to shorten forcefully.
Excitability
the capacity of muscle to respond to a stimulus.
Extensibility
means a muscle can be stretched beyond its normal resting length and still be able to contract.
Elasticity
the ability of muscle to recoil to its original resting length after it has been stretched.
Skeletal muscle
responsible for locomotion, facial expressions, posture, respiratory functions, and many other body movements. The nervous system voluntarily, or consciously, controls the functions of the skeletal muscles.
Smooth muscle
most widely distributed type of muscle in the body. It is found in the walls of hollow organs and tubes, in the interior of the eye, and in the walls of blood vessels, among other areas. Not consciously controlled by the nervous system, controlled involuntarily, or unconsciously, by the endocrine and autonomic nervous systems
Cardiac muscle
ound only in the heart, and its contractions provide the major force for moving blood through the circulatory system; autorhythmic - they contract spontaneously at somewhat regular intervals, and nervous or hormonal
stimulation is not always required for them to contract; involuntary
skeletal muscle fibers
Each skeletal muscle is a complete organ consisting of these cells, associated with smaller amounts of connective tissue, blood vessels, and nerves.
muscle fasciculi
A muscle is composed of numerous visible bundles
perimyseum
Each fasciculus is surrounded by this other, heavier connective tissue layer
epimysium
The entire muscle is surrounded by this layer of connective tissue
Fascia
general term for connective tissue sheets within the body.
Muscular fascia (formerly deep fascia )
located superficial to the epimysium, separates and compartmentalizes individual muscles or groups of muscles. It consists of dense irregular collagenous
connective tissue.
Motor neurons
specialized nerve cells that stimulate muscles to contract.
striated
striped, appearance, as seen in longitudinal section, alternating light and dark bands
myoblasts
Muscle fibers develop from less mature, multinucleated cells
hypertrophy
Enlargement
sarcolemma
plasma membrane of a muscle fiber
two delicate connective tissue layers are located just outside the sarcolemma:
- external lamina: deeper and thinner of the two, consists mostly of reticular (collagen) fibers and is so thin that it
cannot be distinguished from the sarcolemma when viewed under a light microscope.
-endomysium: second layer also consists mostly of reticular fibers, but it is a much thicker layer
transverse tubules or T tubules
the many tubelike invaginations along the surface of the sarcolemma that appear at regular intervals along the muscle fiber and extend inward to it
sarcoplasmic reticulum
The T tubules are associated with this highly organized smooth endoplasmic reticulum
sarcoplasm
Other organelles, such as the numerous mitochondria and glycogen granules, are packed into the cell and constitute the cytoplasm, which in muscles is called the sarcoplasm
myofibrils
bundles of protein filaments found in the sarcoplasm; extends from one end of the muscle fiber to the other
A myofibril contains two kinds of protein filaments, called myofilaments:
- Actin myofilaments: thin myofilaments
- myosin myofilaments: thick myofilaments