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Muscle Vocabulary
Covers Chapters 9 & 10
52
Physiology
Undergraduate 1
11/28/2008

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Term
aerobic endurance
Definition
The length of time a muscle can contract using aerobic pathways.
Term
anaerobic threshold
Definition
The point at which muscle metabolism converts to anaerobic glycolysis.
Term
ATP & Creatine Phosphate stores = what type of activity?
Definition
Sprinting/Lifting and is Anaerobic
Term
Glycolysis = what type of activity?
Definition
Burst-like, Aerobic
Term
Respiration = what type of activity?
Definition
Endurance
Term
internal tension
Definition
The force generated by cross bridges (myofibrils).
Term
external tension
Definition
The force used to move a load.
Term
Slow Oxidative Fibers = what type of activity?
Definition
Aerobic
Term
Fast Oxidative Fibers = what type of activity?
Definition
Aerobic & some Anaerobic Glycolysis
Term
Fast Glycolytic Fibers = what type of activity?
Definition
Anaerobic Glycolysis
Term
diffuse junctions
Definition
Wide synaptic cleft encompassing many smooth muscle cells.
Term
varicosities
Definition
Knoblike swellings of certain autonomic axons containing mitochondria and synaptic vesicles. Releases neurotransmitters into diffuse junctions.
Term
dense bodies
Definition
Attachment sites for intermediate filaments and are anchoring points for thin filaments on smooth muscle cells.
Term
gap junctions
Definition
A passageway between two adjacent cells; formed by transmembrane proteins called connexons. In smooth muscle it allows action potentials to transmit from cell to cell.
Term
calmodulin
Definition
The cytoplasmic, calcium-binding protein that activates myosin in smooth muscle.
Term
stress-relaxation response
Definition
Increased tension in a muscle causes it to adapt to it's new length allowing it to relax but still able to contract on demand.
Term
single-unit smooth (visceral) muscle
Definition
Located in the walls of all hollow organs, contracts rhythmically, has gap junctions between cells, exhibits spontaneous action potentials and is quite common.
Term
myoblasts
Definition
Embryonic mesoderm cells that develop muscle tissue.
Term
synergists = _________
Definition
Fixators.
Term
first-class levers
Definition
LOAD - FULCRUM - EFFORT. Example: bending head backwards & seesaw.
Term
second-class levers
Definition
FULCRUM - LOAD - EFFORT. Example: standing on tip-toes & wheel-barrow.
Term
third-class levers
Definition
LOAD - EFFORT - FULCRUM. Example: biceps curl & tweezers.
Term
excitability
Definition
Ability to receive and respond to a stimulus (change in the environment).
Term
endomysium
Definition
A fine sheath of connective tissue that surround each individual muscle fiber.
Term
perimysium
Definition
Fibrous connective tissue surrounding fascicles.
Term
fascicles
Definition
Groups of muscle fibers.
Term
epimysium
Definition
The layer of dense irregular connective tissue surrounding the whole muscle.
Term
origin
Definition
Immoveable or less movable bone in which the muscle is attached.
Term
insertion
Definition
Moveable bone to which the muscle is attached.
Term
aponeurosis
Definition
Sheet-like anchor attaching muscle to bone.
Term
myoglobin
Definition
Red pigment that stores oxygen and is similar to hemoglobin but found in the sarcoplasm of a muscle fiber.
Term
myofibrils
Definition
Rod-like bundle of contractile filaments inside a muscle fiber.
Term
sarcomere
Definition
Smallest contractile unit of a muscle fiber and is the region of a myofibril between two successive Z discs.
Term
myofilaments
Definition
Smaller structures within sarcomeres. Thin = Actin, Thick = Myosin
Term
actin
Definition
Protein which provides the active sites to which the myosin heads attach during contraction.
Term
tropomyosin
Definition
Rod-shaped protein that spirals about the actin core helping to stiffen it. More importantly it blocks myosin binding sites on actin.
Term
troponin
Definition
Three-polypeptide complex that helps control the myosin-actin interactions involved in contractions. Third helps bind calcium ions.
Term
sarcoplasmic reticulum (SR)
Definition
Interconnecting tubules surrounding each myofibril. Regulates levels of calcium, storing & releasing it when stimulated.
Term
T tubule
Definition
Continuations of the sarcolemma that encircle each sarcomere and ensure that every myofibril in the muscle fiber contracts at the same time.
Term
cross bridges
Definition
Myosin's force generating sites for muscle contraction.
Term
neuromuscular junction
Definition
Area where axon endings meet with individual muscle fibers.
Term
wave summation
Definition
A stimulus occuring after another causing a second contraction before the muscle has relaxed. Primary function is to produce smooth, continuous muscle contractions.
Term
recruitment
Definition
Precise control of muscle contraction caused by increases in voltage resulting in the excitement (recruitment) of more and more motor units.
Term
threshold stimulus
Definition
First observable contraction.
Term
maximal stimulus
Definition
Strongest stimulus representing point in which all of the muscle's motor units are recruited.
Term
isotonic contractions
Definition
Muscle length changes (concentric and eccentric).
Term
concentric
Definition
Muscle SHORTENS and does work.
Term
eccentric
Definition
Muscle generates force as it LENGTHENS.
Term
creatine phosphate
Definition
A unique, high-energy molecule stored in muscles that is tapped to regenerate ATP.
Term
glycolysis
Definition
Breakdown of glucose stored in the muscle into two pyruvic acid molecules which releases enough energy to form small amounts of ATP.
Term
lactic acid
Definition
The end product of cellular metabolism of glucose. Contributes to muscle fatigue and is partially responsible for muscle soreness.
Term
aerobic respiration
Definition
Requires oxygen, occurs in mitochondria and includes glycolysis. Sluggish process.
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