A&P Test 2 Muscles only Flashcards
What is the plasma membrane of a muscle cell?
Sarcolemma
What are 3 characteristics of skeletal muscle?
It is striated, voluntary and multi-nuclear.
What do T (transverse) tubules do?
They store Calcium and deliver it for muscle contraction.
They transmit action potential in the cell, an electric signal that allows entire muscle to contract simultaneously
What are the thin and thick filaments in muscle?
Thin - actin. Thick - myosin.
What is the contraction unit of a muscle fiber?
Sacomere
What is the cytoplasm of the muscle fiber?
Sarcoplasm
What are myofibrils?
Cylindrical structures that are responsible for muscle fiber contraction.
What do myofibrils consist of?
Thin filaments (actin), thick filaments (myosin) and titin.
What is the network around individual myofilaments?
sarcoplasmic reticulum (SR)
What are sarcomeres?
Myofilaments organized into repeating functional units
What is the smallest contractile unit of a striated muscle cell (fiber)?
Sarcomere
where would the greatest concentration of calcium ions be in resting skeletal muscle?
In the sarcoplasmic reticulum, in the cisternae
Each sarcomere has dark bands and light bands. What are they?
Dark bands are A bands, containing myosin. Light bands are I bands, containing actin.
How many proteins does a typical thin filament have?
4: G-actin, nebulin, tropomyosin and troponin
What are the 4 proteins of a thin filament?
G-actin, nebulin, tropomyosin, troponin
What are the 5 steps of the contraction cycle?
First, a neuron signal releases Ca from SR
- Exposure of active sites (F actin becomes exposed & interacts w/ myosin)
- Formation of cross-bridges
- Pivoting of myosin heads
- Detachment of cross-bridges
- Reactivation of myosin
Calcium ions are released in what process?
Contraction
In contraction, what is released?
Calcium ions
What important function does the SR play in muscle contraction?
It transmits action potential to myofibrils
What is the active site in a muscle contraction?
F-actin is the active site
What blocks the active site in a resting stage?
Tropomin & tropomysin
What binds actin and myosin?
Calcium
What muscle proteins are directly involved in muscle contraction?
Myosin and actin
What are the 2 parts of myosin?
Head and tail
What is the sliding filament theory?
Skeletal Muscle Contraction Sliding filament theory Thin filaments of sarcomere slide toward M line, alongside thick filaments The width of A zone stays the same Z lines move closer together
The thin filaments in a sarcomere…
…extend from the Z lines.
Filament, fiber, fibril: arrange from largest to smallest
Fiber, fibril, filament
What is the order of energy provided to a muscle cell: glucose, creatine phosphate, ATP
ATP, creatine phosphate, glucose
What is the Z line?
Z lines mark the boundary between adjacent sarcomeres.