Chapter 9 - Muscles Flashcards
What is myology?
The scientific study of muscles.
What mass of the body is muscle?
45%.
Functions of muscle?
Maintain posture and body position, movement, heat production, guard orifices, and support visceral organs.
Muscle tissue is?
Excitable, extensible, elastic, and contractile.
What does excitability mean?
The ability to receive and respond to electrical or chemical stimuli.
What does contractility mean?
The ability to shorten forcibly when stimulated.
What does elasticity mean?
The ability to return to original shape after being stretched.
What does extensibility mean?
The ability to be stretched without damaging the tissue.
Are muscles organs?
Yes.
What do muscles consist of?
Connective tissue, arteries/veins nerves, lymphatics, and contractile muscle cells.
Characteristics of skeletal muscle?
Attaches to bone, skin or fascia, striated with light & dark bands, voluntary control, long, thin and multi-nucleated fibers, attach to and cover bony skeleton, contracts rapidly, but tires easily, and may exert great force.
1 muscle cell equals?
Fiber.
What is the belly of the muscle?
Main portion of a muscle.
Where does the belly attach?
Tendons.
Tendons attach to what?
Bone.
What is deep fascia?
Dense irregular CT around muscle, holds it in place and separates it from other muscles.
What is subcutaneous fascia?
Loose CT beneath skin, surrounds several muscles.
What is superficial fascia?
Areolar and adipose tissue layer and sits deep to cutaneous membrane.
What are many muscle fibers bundled together into groups called?
Fascicles.
Characteristics of fascicles?
10-100 muscle cells (fibers), several fasicles make up a muscle.
What are the connective tissues of skeletal muscle?
Epimysium, perimysium, and endomysium.
What is epimysium?
Surrounds the whole muscle.
What is perimysium?
Surrounds fascicles.
What is endomysium?
Separates individual muscle fibers (cells).
All connective tissue extend beyond the muscle belly forming?
Tendon.
What is a tendon that is a thick flattened sheet?
Aponeuroses.
What are myoblasts?
Embryonic cells that fuse to form muscle fibers.
What are myosatellite cells?
Myoblast that do not fuse.
What do myosatellite cells do?
Assist in repair of damaged cells.
What are muscle fibers composed of?
Sarcoplasm, Sarcolemma, and Transverse (T) tubules.
What is sarcoplasm?
Fiber cytoplasm.
What is sarcolemma?
Plasma membrane of a fiber.
What are transverse (T) tubules?
Extensions of the sarcolemma into the sarcoplasm.
What are myofibrils?
Contractile organelles that extend the length of fiber and surrounded by sarcoplasmic reticulum.
What is a functional unit of a myofibril?
Sarcomere.
What are sarcomeres made of?
Thick and thin filaments.
What are thick filaments composed of?
Myosin.
Myosin characteristics?
Twisted protein with globular heads, 1.6um long, and 500/thick filament.
What are thin filaments composed of?
Actin and Regulatory proteins.
Actin characteristics?
Structural protein and coiled “beads”
Regulatory protein characteristics?
Allow/prohibit attachment between actin and myosin.
What are the 2 types of regulatory proteins?
Tropomyosin and troponin.