ch10pt3 Flashcards
length of sarcomere is related to how much zone of overlap there is. how much over lap is related to how many ___ ___ can grab on to ___
myosin heads, actin
The number of pivoting cross-bridges, the fiber’s resting length at the time of stimulation, and the frequency of stimulation all affect ____ ____
tension production
_____ __ _____ between thick and thin fibers and number of pivoting cross bridges affects Length-Tension Relationships
amount of overlap
______ ______ produces greatest amount of tension
optimum overlap
Too much or too little overlap reduces efficiency because
no room for sarcomere to contract, myosin heads can’t reach active sites on actin (too far away)
optimal rest length of sarcomere
2-2.5 micrometers
no tension will be produced if sarcomere is <___ or >____ of optimal length
60%, 175%
skeletal system limits __________ of muscles
overstretching
CNS monitors resting sarcomeres and maintains muscle ____
tone
must be reached for action potential to be generated in muscle fiber
threshold voltage
at threshold voltage, a single neural stimulus causes a
twitch
sustained muscle contractions require
repeated stimuli
phases of a twitch (3)
latent period, contraction phase, relaxation phase
Muscle has been stimulated, Not yet contracting
latent period
The action potential moves through t-tubules, Ca2+ released from SR
latent period
Elastic components tensed (_______ Tension)
latent period, Internal
Phase which sarcomere shortens, Tension builds to peak (_____ Tension)
contraction phase, External
Ca2+ levels fall, Active sites are covered and tension falls to resting levels
relaxation phase
The normal range of sarcomere lengths in the body is ___ to ___ percent of the optimal length.
75, 130
successive stimulations before the end of relaxation phase. Increases tension in a wave patterns
wave summation / temporal summation
Rapid stimulation continues, twitches reach maximum tension, muscle is in sustained fluttering contraction
incomplete tetanus
If stimulation frequency is high enough, muscle never begins to relax, and is in continuous contraction (Not a normal physiologic state)
complete tetanus
Bacteria Clostridium tetani releases a toxin. CNS cannot inhibit unwanted contractions.
tetanus
Results in Spastic Paralysis
“LockJaw”
tetanus
Bacteria Clostridium botulinum releases a toxin. _______ toxin blocks Ach release. Results in flaccid paralysis.
botulism
types of contraction (2)
isotonic and isometric
Skeletal muscle changes length resulting in motion
isotonic contraction
if muscle tension is greater than load (resistance), muscle will ______, causing _______ contraction (flexion)
shorten, concentric
if muscle tension is less than load (resistance), muscle will ______, causing _______ contraction (extension)
lengthen, eccentric
Skeletal muscle develops tension equaling the load / resistance. Muscle does not change length.
isometric contraction
Used to maintain position / posture
isometric contraction
The pull of elastic elements (tendons, elastic components of sarcomere), expands the sarcomeres to resting/relaxed length.
elastic forces
to move body to original position, ______ ______ contract
opposing muscles
skeletal muscles exist in _______ pairs. one contracts, other lengthens, visa versa
opposing
Can take the place of opposing muscle contraction to return a muscle to its resting state
gravity
Provides Energy For Muscle Contraction. Sustained muscle contraction uses a lot of this energy. Myosin heads need this to be loaded into their cocked position.
ATP
myosin heads hydrolyze ATP to
ADP + Phosphate
Muscles store enough energy to start contraction. Muscle fibers must manufacture more ATP for
future contractions
active energy molecule used by muscles
adenosine triphosphate (ATP)
storage molecule for excess energy in resting muscle
creatine phosphate (CP)
using this enzyme ADP is recycled back into ATP by taking a phosphate from creatine phosphate (CP)
creatine kinase (CK)
this enzyme makes an ATP by taking a phosphate from ADP
myokinase
new ATP can be generated by
Aerobic metabolism or anaerobic glycolysis
Is the primary energy source of resting muscles and moderately active muscles. Breaks down fatty acids or pyruvic acid.
aerobic metabolism
Is the primary energy source for peak muscular activity. Produces two ATP molecules per molecule of glucose. Breaks down glucose stored in skeletal muscles (glycogen). Produces Lactic Acid.
anaerobic glycolysis
When muscles can no longer perform a required activity, they are
fatigued
Depletion of metabolic reserves, low pH (lactic acid buildup), muscle exhaustion and pain.
results of Muscle Fatigue
in the ____ _____, the removal and recycling of lactic acid is done by the _____
Cori Cycle, liver
Liver converts lactate to ______, then pyruvate to _____ (gluconeogenesis)
pyruvate, glucose
______ is released to recharge muscle glycogen reserves.
glucose
