Muscles Flashcards
muscle fatigue
progressive weakness and loss of contractility from prolonged use of muscles
Factors in muscle fatigue: high-intensity/short time
- Potassium accumulation makes fiber less exciteable
- ADP accumulation - slows the cross bridge cycling of contraction
- P accumulation - inhibits Calcium release from SR and sensitivity of contractile mechinism
Factors in muscle fatigue: low-intensity, long-duration exercise
- fuel depletion - declining muscle glycogen and blood glucose leave less fuel for ATP synthesis (why runners eat high-carb before race to load muscles with extra glycogen)
- electrolyte loss - losing through sweat can decrease the muscle exciteability
- central fatigue - exercising generates ammonia which is absorbed by the brain and inhibits motor neurons
maximum oxygen uptake (Vo2max)
determines ability to maintain high-intensity for more than 4-5 minutes
is proportional to body size, larger in men, peaks at 20, and is greater in trained endurance atheletes
sedentary adult (35 milliliters/O2/min/kg of body weight) vs 70 ml/min in elite endurance atheletes
denervation atrophy
if a muscle nerve connection is severed or poisoned, muscle is paralyzed and atrophies
muscle endurance exercises
increased fatigue resistance - enhanced delivery and use of oxygen
jogging and swimming are good endurance exercise
slow-twitch fibers - grow more capillaries, mitochondria, glycogen as a result of conditioning
increased skeletal strength which increases RBC and oxygen transport capacity of the blood improves cardiovascular, respiratory, and nervous systems
deconditioning
if muscles not sufficiently active become weak and easily fatigued
Oxygen Debt / how to end it
post-exercise, heavy breathing
now called excess postexercise oxygen consumption
body needs Oxygen to regenerate ATP aerobically, regenerate creatine phospate, dispose of lactate, increased temp. uses more oxygen
remains elevated as long as 1 hr EPOC can be 6x typical consumption
Functions of Muscles
Movement (skeletal-locomotion, pumps heart, controls body openings/passageways, moves fluids)
Stability/posture
Stabilize joints - maintain tension on tendons
generate heat
control blood glucose
Purpose of all muscle
To convert ATP into the energy of motion (book)
muscle organ (components smallest to largest)
(see card)
tendons
attach muscles to bone at the origin and insertion
aponeuroses
tendon as a sheet - such as scalp, palmar aponeurosis
retinaculum
band of connective tissue “bracelet”
wrists/ankles
holds tendons in place
prime mover (agonist)
muscle producing most of the force of movement
synergist
muscle that is helping the prime mover
belly of muscle
largest/center of a fusiform muscle like the calf or biceps
intrinsic muscle
same region as use
Ex. hand muscle located in hand
extrinsic muscle
different region of origin
Ex. hand muscle origin in forearm
action
effect of muscle to produce or prevent a movement
fascicle
bundle of muscle fibers within a muscle
enclosed by perimysium
antagonist
muscle opposite the prime mover
antagonist pair
muscles around a joint - act together at times depending on movement (see class note)
fixator
holds a bone in place so another muscle can perform
Ex. rhomboids hold the scapula close to vertebral column while biceps contract, postural muscles hold bones steady
ensures bicep force moves radius rather than scapula