Exercise Physiology and Sports Science Flashcards
Extensor vs Flexor
Extensor = extending (going outward, triceps, quadriceps)
Flexor = decrease angle between bone (biceps, hamstrings)
Antagonists: pull bone in opposite direction
Z, I, A, H, M lines/bands
Know what filaments make up which band
Z line: contains a-actinin protein. represents repeating contractile unit in skeletal muscle
I band: light band either side of Z line. Contains thin filaments
A band: dark area between 2 Z lines (overlap) that contain thick filaments and thin filaments.
H band: light area located in the middle of A band that contains thick filaments
M line: dark line in middle of sarcomere. Contains proteins (myomesin) critical for alignment of thick filaments.
Thin filaments include:
What do they play a key role in
examples:
Include troponin and tropomyosin
Key role in regulating muscle contraction
TnT = tropomyosin
TnC = calcium
TnI = Myosin - binding site
Muscle contraction mechanism steps
1.) ATP binds to myosin head. Actin myosin complex dissociates
2.) ATP hydrolyzed (phosphate leaves), myosin heads return to resting config
3.) Myosin head binds to new position on actin.
4.) Phosphate released. Myosin head change conformation, power stroke. RELEASE OF P = POWER STROKE
5.) ADP released, back to normal.
Motor neurons stimulate muscle contraction order of events
1.) Signal from CNS -> action potential -> release of neurotransmitter _____, diffuses across _____.
acetylcholine
diffuses across synapse to plasma membrane of muscle fiber.
Ca2+ released from ER. Ca2+ stored outside, or locked in SR & ER.
Stimulation of muscle contraction, order of events after Ca2+ release into cytoplasmic fluid
When Ca2+ binds to troponin, tropomyosin moves away from myosin binding sites, allowing contraction to occur.
Functional element of muscle contraction and facts about it
A single motor neuron and all muscle fibers it activates is called the motor unit
** Motor units are recruited in a progressive order from the smallest (weakest) to the largest (strongest) **
Force exerted by muscle depends on how many motor units recruited / how frequently each of the active motor neurons fire action potentials. More motor units involved, the stronger the force.
Dif between Type I and Type II motor units
Fast twitch: type IIa, IIb. Slow twitch: Type I
Type 1: Type IIa: Type IIb: Speed: Slow. Fast Fastest
Aerobic. Both. Anaerobic Mitochon. High. Higher than IIb. Low content
Rate of. Slow. Med. Rapid
Fatigue
Where does body get energy for muscle contraction
Locally from muscle glycogen and triacylglycerols
Systemically from Liver glycogen and adipose tissue triacylglycerols
Physical performances, energy use and main source of ATP
Power: last few seconds. Uses stored ATP / Phosphocreatine
(PCr)
Speed: Several seconds to a minute. (Non-oxidative breakdown
of carbohydrates stored as muscle glycogen to form ATP)
Endurance: more than 1 minute. Aerobic metabolism
Mixed: Prolonged, low-level activity with intermittent surges.
Aerobic / anaerobic metabolism.
Immediate energy mechanism.
Chemical reaction of ATP and Phosphocreatine provide immediate but limited energy
ADP + Creatine Phosphate ——creatine phosphokinase——> ATP + Creatine
Creatine phosphate thus replenishes the ATP store during muscle contraction.
high intensity exercise mechanism (10-60 sec)
Anaerobic glycolysis provides rapid but self-limited source of ATP
When High-intensity exercise continues for more than 10-60 sec, breakdown of ATP and PCr accelerated by breakdown of intramuscular glycogen to glucose and then lactate.
Lactate drop pH, causes muscle fatigue, can inhibit glycolysis
Endurance energy metabolism (>1 min)
type I or Type IIa:
Glucose from liver glycogen can enter muscle
Breakdown of Intramuscular Glycogen to glucose then to lactate
Lactate can drop pH, causes muscle fatigue
Endurance (> 30-40 min)
Oxidation of FAs, Triacylglycerol -> Fatty acids via Hormone-sensitive lipase
FAs enter skeletal muscle.
Endurance (> 1 hour)
Hepatic gluconeogenesis occurs. Important substrates: Lactate and Alanine
Cori Cycle: Lactose (from muscle) -> Glucose (liver) and vice versa. Cori cycle is important because it takes up the lactate released into the liver to resynthesize glucose.
