Muscle Lab Human Phys
True
Slow oxidative fibers generate ATP mainly by aerobic respiration
Filaments
Smaller structures within myofibrils
True
A fiber is categorized as slow or fast depending on how rapidly the ATPase in its myosin heads hydrolyze ATP
Step 2 of muscle contraction
ACh (excitatory neurotransmitter for skeletal muscle) that is stored in the synaptic vesicle of the synaptic end bulb is released and diffused across the synaptic cleft
Step 3 of muscle contraction
ACh binds to nicotinic ACh receptors on the motor end plate
Contractility
Ability of muscle to contract forcefully when adequately stimulated
Elasticity
Ability of muscle to return to its original length and shape after contraction or extension
Electrical excitability
Ability to respond to certain stimuli by producing action potentials
Step 11 of muscle contraction
Another molecule of ATP binds to the ATP binding site on myosin allowing for myosin to detach from actin
Step 6 of muscle contraction
At the onset of muscle fiber contraction, the sarcoplasmic reticulum releases calcium ions into the sarcoplasm
H zone
Center of the A band; contains only thick filaments
I band
Contains only thin filaments
Step 4 of muscle contraction
Depolarizing graded potential called end plate potential (EPP) is generated
False
Fast glycolytic fibers are intermediate in diameter and have a high resistance to fatigue True: have MODERATE resistance to fatigue
True
Fast glycolytic fibers have low myoglobin content, few blood capillaries, few mitochondria, and appear white in color
M line
Formed by supporting proteins holding thick filaments together in the center of the H zone
T tubules
Invaginations of the sarcolemma; filled with extracellular fluid
Step 8 of muscle contraction
Now that the binding sites are free, ATP is hydrolyzed into ADP and a phosphate. This energizes the myosin head which then assumes the "cocked" position
Sarcolema
Plasma membrane of a muscle fiber
Myoglobin
Red, oxygen-binding protein that is only found in the muscle; stores oxygen until it is needed by mitochondria for ATP
Titin
connects a Z disc to the M line of a sarcomere, helping stabilize the position of the thick filament
Myomesin
forms the M line of the sarcomere. It also binds to titin molecules and connects adjacent thick filaments to one another
Alpha-actinin
present in the Z discs, it will attach to actin and titin molecules
slow oxidative muscle fibers
running a marathon
Tropnonin
this protein is a component of the thin filament and is where calcium ions will bind to during skeletal muscle contraction
Tropomyosin
this protein is a component of the thin filament that will cover the myosin-binding sites on the actin molecules
fast oxidative muscle fibers
walking to the bus stop
fast glycotic fibers
weight lifting for bodybuilding
Nebulin
wraps around the entire length of each thin filament. It also helps to anchor thin filaments to Z discs in addition to regulating the length of thin filaments during development
Myofibril
Contractile element of the skeletal muscle fiber; containing thick and thin filaments
A bands
Entire length of the thick filament; contains area of overlap with thin filament
False
Fast oxidative-glycolytic fibers are fast-twitch fibers adapted for intense movements of short duration like weight lifting or throwing a ball True: best for walking or sprinting
False
Fast oxidative-glycolytic fibers have a high intracellular glycogen level, which allows them to generate ATP by aerobic respiration True: ATP is generated via ANAEROBIC glycolysis
Triad
Formed by transverse tubules and two terminal cisternae
Extensibility
Ability of muscle to stretch without being damaged
Z discs
Narrow, plate shaped regions of dense protein
Myosin and actin
Proteins that are considered contractile proteins
Tropomyosin and troponin
Proteins that are considered regulatory proteins
Titin, alpha-actinin, myosin, nebulin, dystrophin
Proteins that are considered structural proteins
Sarcomere
Repeating units of a myofibril
Step 7 of muscle contraction
The calcium ions then bind to troponin, which moves tropomyosin away from myosin binding sites on actin
Step 9 of muscle contraction
The energized myosin head then attaches to the myosin binding site on actin and a phosphate is released. This is referred to as the "crossbridge"
Step 10 of muscle contraction
The myosin head pivots changing its position from 90 degrees to 45, pulling the thin filament past the thick filament towards the center of the sarcomere. This is referred to as the power stroke
Dystrophin
links thin filaments of the sarcomere to integral membrane proteins in the sarcolemma. This might help transmit the tension generated by sarcomeres to tendons
Actin
main component of the thin filament that has an active myosin-binding site
Myosin
makes up the thick filaments. It consists of two heads and a tail
True
Skeletal muscle fibers that have a high myoglobin content are termed red muscle fibers
True
Slow oxidative fibers are smallest in diameter and are the least powerful type of muscle fibers
Glycogen
Serves as storage form of glucose; can be broken down and used to synthesize ATP
Step 1 of muscle contraction
Action potential occurs in the somatic motor neuron
Step 5 of muscle contraction
Adjacent regions of the sarcolemma are then depolarized, resulting in the generation of a muscle action potential. This action potential propagates through the muscle fiber membrane in both directions away from the NMJ towards the end of the fiber
Sarcoplasmic reticulum
Storage center for calcium in relaxed muscle
Sarcoplasm
Surrounded by the sarcolemma; the cytoplasm of the muscle fiber