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