MSK 11 - Muscles-I Flashcards
What do the terms “sarcoplasm” and “sarcolema” refer to?
The cytoplasm and plasma membrane of a myocyte, respectively.
What is a syncytium?
A single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei. Skeletal muscle fibers are a syncytium.
How many myocytes make up a single muscle fiber? How is the muscle fiber formed?
A muscle fiber consists of just one myocyte that is a syncytium of numerous myoblasts.
What is the length of a muscle fiber?
Varies from milimeters to almost a meter
How do muscle fiber repair, heal, and renew?
How do myocytes appear on a light micrograph?
What is an endomysium? Discuss its composition and function.
What is a perimysium? Discuss composition and function.
A layer of connective tissue that surrounds each muscle fascicle and contains blood vessels and nerves that are larger than those found in endomysium
What is an epimysium? Discuss composition and function
What are the four ways skeletal muscle is classified?
Facts to know about Type 1 Skeletal Muscle
Facts to know about Type IIa skeletal muscle
Facts to know about Type IIb skeletal muscle
What is a myofibril? Discuss composition and function
On a light micrograph of skeletal muscle tissue there will be striations and dark and light bands present. What are these?
Striations are caused by the regular arrangement of the myofilaments and the fact that one of the filaments is thick (myosin-II, dark band) and the other is thin (actin, light band)
The light band is the I band and the dark band is the A band.
Discuss the polarity of the thin filament in a sarcomere.
What is the tromponin complex made up of? What do each of these components do?
What is the thick filament composed of and how are these components arranged?
What is titin and what does it do in skeletal muscle?
Titin is an accessory muscle protein that anchors the thick filament to the Z line
What is myomesin and what does it do in skeletal muscle?
Myomesin is an accessory muscle protein that binds myosin and helps to align the thick filaments at the M-line
What is alpha-actinin and what does is do in skeletal muscle?
Alpha-actinin is an accessory muscle protein that binds actin that helps to bundle and anchor the thin filaments at the Z-line
What is nebulin and what does it do in skeletal muscle?
Nebulin is an accessory muscle protein that helps anchor thin filaments at the Z-line and regulates their length during development
What is C-protein and what does it do in skeletal muscle?
C-protein is an accessory muscle protein that binds myosin and helps to align thick filaments at the M-line
What is tropomodulin and what does it do in skeletal muscle?
Tropomodulin is an accessory muscle protein that maintains and regulates the length of the actin filament by acting as an actin cap
What is desmin and what does it do in skeletal muscle?
Desmin is an intermediate filament that surrounds the sarcomere at Z-lines and attaches them to one another and to the plasma membrane.
What is dystrophin and what does it do in skeletal muscle?
Facts to know about Duchenne Muscular Dystrophy.
What does this image depict?
Muscle fibers without dystrophin. A result of DMD
SR - Sarcoplamic Reticulum
Td - Triad
Tc - Terminal cisternae
M - mitochondria
What is a motor unit? How many types of muscle fibers can be in a motor unit?
What occurs if a muscle loses innervation?
It atrophies
The bottom one is synaptic cleft
What is Myasthenia Gravis? Discuss causes and symptoms
