Chapter 9- Energy + Responses

energy

ATP reserves, creatine phosphate, cellular respiration

ATP reserves

first source, only store small amount

creatine phosphate

initial source to generate ATP from ADP + P, stores in phosphate bond, ATP + this fuels 10 secs of intense contractions

cellular respiration

used to fuel longer periods of muscle contraction, breaks down glucose to produce ATP, glucose stored as glycogen in muscle cells, provides ATP

cellular respiration types

anaerobic (glycolysis), aerobic (citric acid + ETC)

glycolysis

regenerates ATP by transferring its phosphate to ADP, in cytoplasm, fastest way, little ATP, lasts around 8 seconds of contraction

aerobic

in mitochondria, most ATP, myoglobin stores extra oxygen, CO2+ H2O end products, heat is by-product

oxygen debt

muscles use fermentation to supply ATP, most oxygen in strenuous exercise used for ATP production, not lactic acid → glucose, heaving breathing

heaving breathing

getting rid of excess CO2

training

increases mitochondria number, greater reliance on cellular respiration, less oxygen debt

lactic acid threshold

ATP for short term exercise, shift in metabolism during strenuous muscle activity when O2 is depleting

lactic acid steps

glucose → lactate → lactic acid; muscle cramps and fatigue due to ATP lack

muscle fatigue

inability to contract muscle

muscle fatigue causes

decreased blood flow, ion imbalances across sarcolemma, loss desire to exercise, accumulation of lactic acid

cramp

sustained, involuntary muscle contraction, caused by changes in electrolyte concentration in extracellular fluids in the area

muscle responses

degrees of contraction, twitch/summation/tetanic contraction

twitch

one second, latent → contraction → relaxation

summation

many impulses in rapid succession causes increased contraction without relaxing completely (picking up something heavy), leads to tetanic contraction

tetanic contraction

maximal sustained contraction, fused twitches, no relaxation

motor unti

neuron plus all controlled muscle fibers, whole muscle consists of many

coarse movements

many fibers

precise movements

fewer fibers

recruitment

as intensity of stimulation increases, motor units activated, results in stronger muscle contractions + less fatigue

tone

some muscles always contracting, important in posture maintenance

atrophy

decrease in muscle size (unused)

hypertrophy

increase in size (exercise)