ch. 9 Flashcards
Active tension
force applied to an object to be lifted when a muscle contracts
Stretched muscle
not enough cross-bridging
Crumpled muscle
myofilaments crumpled, cross–bridges can’t contract
Total tension
active plus passive
Passive tension
tension applied to load when a muscle is stretched but not stimulated
isometric contractions
(same length) no change in length but tension increases during contraction
isotonic contractions
change in length but tension constant
Concentric
overcomes opposing resistance and muscle shortens
Eccentric
tension maintained but muscle lengthens
Muscle tone
constant tension by muscles for long periods of time
Frequency
number of action potential produced per unit of time
Propagate
Spread from one location to another. Action potential does not move along the membrane: new action potential at each successive location.
Ligand-gated
Ligands are molecules that bind to receptors.
what happens when ACh attaches to __
muscle cell, Na+ gate opens. Na+ moves into cell due to concentration gradient
Repolarization:
return of resting membrane potential. with pump
Synapse
axon terminal resting in an invagination of the sarcolemma
what happens in muscle relaxation
Ca2+ moves back into sarcoplasmic reticulum by active transport; Requires energy
Ca2+ moves away from troponin-tropomyosin complex
Complex re-establishes its position and blocks binding sites.
Creatine phosphate
During resting conditions stores energy to synthesize ATP
Oxygen debt
oxygen taken in by the body, above that required for resting metabolism after exercise. ATP produced from anaerobic sources contributes
msucle fatigue
Decreased capacity to work and reduced efficiency of performance
Physiological contracture:
state of fatigue where due to lack of ATP neither contraction nor relaxation can occur
Rigor mortis
development of rigid muscles several hours after death. Ca2+ leaks into sarcoplasm and attaches to myosin heads and crossbridges form.
No ATP available to release.
Rigor ends as tissues start to deteriorate.
Psychological muscle fatugue
depends on emotional state of individual
Muscular
Caveolae
: indentations in sarcolemma; may act like T tubules
NO Transverse Tubules
Dense bodies
instead of Z disks as in skeletal muscle; have noncontractile intermediate filaments. NO Z disks.
calmodulin
Ca2+ required to initiate contractions; binds to calmodulin which regulates myosin activity
relaxation of a smooth muscle
caused by enzyme myosin phosphatase removes phosphate group while cross-bridges are not attached
relaxation occurs more slowly
latch state
in smooth muscle, the tension it sustains
sustained contractions in sm
types of smooth muscle, which is more common
visceral and multiunit
visceral is more common
visceral smooth muscle
organs such as stomach and urinary tract
sheets reproductive
lack direct contact with NS
Numerous gap junctions; waves of contraction
Often autorhythmic; peristalsis
Most hollow organs (gut), uterus, bladder
multiunit
in sheets, bundels, and single cells cell or groups of cells can operate as independent units; fine innervation or 1 cell Sheets (blood vessels); bundles (arrector pili and iris); Muscles of the iris dilate or constrict Within almost every organ
how long do action potentials last in cardiac muscle
Action potentials of longer duration and longer refractory period
Ca2+ regulates contraction
