Lesson 22 Flashcards
what does ATP supply depend on?
availability of oxygen and organic energy sources
anaerobic fermentation
enables cells to produce ATP in the absence of oxygen; yields little ATP and lactic acid
aerobic respiration
uses the mitochondria to produce far more ATP than fermentation; does not generate lactate; requires a continual supply of oxygen for the mitochondria
what is the primary energy source for short term maximum acitivity?
anaerobic fermentation
what is the primary energy source for long term activity?
aerobic metabolism
oxygen is briefly supplied by _____ inside muscle cells during short, intense exercise
myoglobin
muscle meets most ATP demand by doing what?
borrowing phosphate groups from other molecules and transferring them to ADP
creatine kinase
enzyme that obtains a phosphate from a phosphate storage molecule creatine phosphate and gives it to ADP
phosphagen system
the combination of ATP and CP which provides nearly all energy for short bursts of activity
as the phosphagen system is exhausted, muscles shift to….
anaerobic fermentation
anaerobic threshold
aka lactate threshold
- point at which lactate becomes detectable in the blood
glycogen-lactate system
the pathway from glycogen to lactate
- produces enough ATP from 30 to 40 seconds of maximum activity
after about 40 sec, the respiratory and cardiovascular system do what?
they start delivering oxygen fast enough for aerobic respiration to meet most of the muscle’s ATP demand
after 3-4 min, the rate of oxygen consumption levels off to a _____ _____ where aerobic ATP production keeps pace with deman
steady state
muscle fatigue
progressive weakness from prolonged used of muscles
fatigue in high-intensity (short duration) exercise results from two things
- potassium accumulation
- ADP and Pi accumulation
fatigue in low-intensity (long duration) exercise results from these three things
- fuel depletion
- electrolyte loss
- central fatigue
potassium accumulation
in the T tubules reduces muscle cell excitability by interfering with Ca2+ release from the sarcoplasmic reticulum
ADP and Pi accumulation
slows cross-bridge movements, inhibit Ca2+ release and decrease force production in myofibrils
fuel depletion
glycogen and glucose levels decline
electrolyte loss
lost through sweat, decreased muscle excitability
central fatigue
ammonia released by active muscle inhibits motor neurons and cause less motor signals from the brain to the muscle cells
maximum oxygen uptake (VO2 max)
the point at which the rate of oxygen consumption plateaus and does not increase further with added work
what is the major determinant of one’s ability to maintain high-intensity exercise for more than 4-5min?
maximun oxygen uptake
VO2 max is proportional to what?
body size
when does VO2 max determine?
the max rate of ATP production by aerobic respiration
excess postexercise oxygen consumption (EPOC)
aka oxygen debt
- elevated rate of oxygen consumption following exercise
what is the purpose of EPOC? (4)
- aerobically replenish ATP
- replace oxygen reserves on myoglobin
- provide oxygen to liver that is busy disposing of lactate
- provide oxygen to many cells that have elevated metabolic rates after exercise
what does the liver do with lactate?
converts it back to glucose when O2 is present, then the glucose enters the bloodstream and is delivered to muscles
EPOC can be _____ times basal consumption and last _____
six, one hour
type I fibers
aka red fibers, slow oxidative (SO) fibers, slow twitch fibers
- well adapted for endurance, slow to contract, resist fatigue by oxidative ATP production
what kind of fibers maintain posture?
type I fibers, red fibers
what do type I fiber/type I cells specifically have? (4)
- abundant mitochondria
- lots of capillaries
- many myoglobin
- contains a form of myosin with slow ATPase, and an SR that releases calcium slowly
type II fibers
aka white fibers, fast glycolytic (FG) fibers, fast-twitch fibers
- well adapted for quick responses; utilizes glycolysis and anaerobic fermentation for energy
what do type II fibers/cell specifically have? (3)
- fibers are thick and strong
- low myoglobin
- low blood supply gives pale color
where are type II fibers abundant?
quick powerful muscles like eye and hand muscles
how are type II fibers grouped?
large motor units controlled by larger, less excitable neurons allowing for powerful movement but fatigues quickly
what do type II fibers/cells contain? (2)
- a form of myosin with fast ATPase
- large SR that releases calcium quicky
fast oxidative (FO) fiber
mainly in other mammals but rare in humans except in some endurance-trained athletes
most human muscles are composed of what kind of fiber??
it is a ratio of all three, FO, SO, and FG
muscle size
thicker muscle forms more cross-bridges; a muscles can exert a tension of 3 or 4 kg/cm^2 of cross sectional area
fascicle arrangement
pennate (feather-shaped) are stronger than parallel, and parallel are stronger than circular
size of active motor units
the larger the motor unit, the stronger the contraction
multiple motor unit summation
simultaneous activation of more units increases tension
factors that affect muscular strength (7)
- muscular size
- fascicle arrangement
- size of active motor units
- multiple motor unit summation
- temporal summation
- length-tension relationship
- fatigue
temporal summation
the greater the frequency of stimulation, the stronger muscle contraction
length-tension realtionship
a muscle resting at optimal length is prepared to contract more forcefully than a muscle that is excessively contracted or stretched
fatigue
fatigued muscles contract more weakly than rested muscles
resistance exercise
contraction of a muscle against a load that resists movement (weight lifting)
how does resistance exercise make your muscles grow?
cellular enlargement, not mitosis
- muscle fibers synthesize more myofilaments and myofibrils and grow thicker
endurance exercise
contraction of a muscle against a lot that resists movement (jogging, swimming)
what does endurance exercise improve?
- fatigue resistance of muscles
- increases skeletal strength, red blood cell count, and O2 carrying capacity of blood
- enhances cardiovascular, respiratory and nervous system function
hypertrophy
muscle growth from heavy training
what does hypertrophy increase? (3)
- diameter of muscle fibers
- number of myofibrils
- mitochondria, glycogen reserves
what does atrophy do to your muscles? (3)
- reduces size, tone, and power
what can warming up before exercise do? (3)
promote blood flow , increase muscle temp to help contraction, and increase enzyme function to break down glucose
