Muscle Tissue Flashcards
Skeletal muscle
Connected to bones, voluntary, striated, and multi-nucleated
Cardiac muscle
Located in the heart, involuntary, striated, and mono-nucleated
Smooth muscle
Located in hollow organs, involuntary, non-striated, and mono-nucleated
Plasticity
Muscle mass can increase based on activity. They have the ability to increase in volume (not number of muscle fibers)
Atrophy
Muscle fiber diameter decreases when they are inactive
Hypertrophy
Muscle fiber diameter increases after continuous activity
Layers of connective muscle tissue
Epimysium, Perimysium, Endomysium
Sarcolemma
plasma membrane of muscle cell
Sarcoplasmic reticulum
Smooth ER of the muscle cell
Titin
Protein that provides the force (“spring”), that contributes to muscle contraction and expansion
Distrophin
Protein that cross links with actin and establishes contact w/ cytoskeleton and ECM.
Cisternae
Located in the sarcoplasmic reticulum. They form around the microfibrils and are divided by T tubules to form sections of the sarcomere
Transverse (T) tubules
protrusions toward the inside of the fiber from the SR that provide support and adds to the cellular structure
Triad
Located in the A-I junction of the myofibril, one T tubule is surrounded by 2 cisternae. They play a role in the release of calcium during the transmission of a nerve impulse.
Actin
Thin filaments
Myosin
Thick filaments
Z line
Form the ends of one sarcomere unit. Actin filaments are attached
I band
only actin filaments (thin)
H zone
only myosin filaments (thick)
M line
middle line myosin is linked with accessory proteins
A band
actin and myosin overlap
Tropomyosin
filament protein, when calcium binds to TnC, tropomyosin moves to reveal the actin binding sites
TnT
Strongly binds to tropomyosin
TnI
Inhibits actin-myosin interaction
TnC
Has the capacity to bind Ca2+ and changes the conformation of the complex
Junctional folds
Forms a wavy membrane around an area of the sarcolemma which contains acetylcholine receptors
Cholinesterase
Breaks down acetylcholine so there is not overstimulation of muscle contraction
Functions of muscle fibers
Proprioception (muscle sensory), muscle tone, and reflexes
Red fibers
Type I, slow twitch
White fibers
Type II, fast twitch
Intermediate fibers
Have properties of both red and white fibers
Intrafusal fibers
Nuclear chain fibers and nuclear bag fibers
Extrafusal fibers
Red, white, and intermediate fibers
Sinoatrial node
Pacemaker of the heart, generates impulses
Purkinje fibers
Muscle cells in the heart, depolarizes the contractile cells of both ventricles
Natriuretic peptides
Maintains blood pressure in the heart
Zonula adherens
Tight junctions in cardiac muscle
Macula adherens
Desmosomes in cardiac muscle
Caveolae
Located on the surface of smooth muscle that isinvolved in sequestering Ca2+
Multi-unit smooth muscle
Loosely packed smooth muscle that is richly innervated for rapid contractions (large arteries)
Visceral smooth muscle
Densely packed smooth muscle that is poorly innervated for slow contractions
Varicosities
regions on nerves that contain neurotransmitters at points where they can be released onto smooth muscle for innervation
