1.1 Flashcards
(43 cards)
what is the all or none law
when stimulated all the fibres within a motor unit contract completely or not at all
how a warm up would affect speed and strength of skeletal muscle contractions (10)
increase *C muscle; greater force/speed contraction; increase elasticity/flexibility/RoM; reduce viscosity of muscles; more efficient contraction; increase speed nerve transmission; increase speed muscle relaxation; increase motor unit recruitment/coordination; increased antagonistic muscle pair coordination; increase enzyme activity
what causes extension at the hip
gluteus maximus
how the function of type 2b fibres suit the performance of a discus throw (2)
large force contraction SO higher power/discus travels greater discus; high speed of contraction SO discus released at high speed/stay in air for longer
describe nervous stimulation of a motor unit (6)
action potential travels down axon; release of Na+ causes depolarisation; ACh released, travels across synaptic cleft; if electrical charge is above threshold; impulse stimulates muscle fibres to contract; all or none law means all fibres in motor unit contract
main agonist of hip abduction
gluteus medius/minimus
explain how neural control of breathing causes tidal volume to increase in exercise (5)
sternocleidomastoid/pecs minor; receptors to RCC; ICC stimulates nerves to increase depth of breathing; phrenic nerve stimulates diaphragm to contract more storngly; intercostal nerves stimulate external IC muscles to contract w more force
why a trained athlete will have lower minute ventilation than untrained, despite identical tidal vols (3)
more efficient gas exchange; higher RBC/mitochondria/capillary; lower breathing frequency
identify 3 neural receptors, explain how each regulate HR
chemo: detect increase acidity/CO2 cause HR to increase; proprio: detect movement changes cause HR to increase; baro: detect increase blood Pa cause HR to decrease
explain how venous return mechanisms can aid venous return and prevent blood pooling (6)
they increase blood back to heart; increase removal waste products; pocket valves prevent black flow of blood; skeletal muscle pump cause leg muscles contract squeezing veins; smooth muscle in walls of veins contract; respiratory pump cause Pa differences in thoracic cavity (all aid movement of blood)
how changes in distribution of blood to muscles and organs is achieved in exercise (5)
increase CO mean greater vol blood to muscle; to muscle: vasodilation arterioles, dilation pre capillary sphcinters; organs: vasoconstriction arterioles, constriction pre capillary sphcinters
how changes in mechanics of breathing in exercise would enhance performance of an endurance swimmer (7)
external ICs/diaphragm contract more force which increase vol thoracic more; greater decrease Pa which means more air in; sterno../pecs minor mean more air in; internals ICs/rectus ab reduce vol thoracic; increase Pa in lungs means air forced out; expiration is active to increase breath rate; greater vol air in/out means more O2 to muscles
compare gas exchange at muscles during exercise to rest (6)
in exercise pO2 is lower in muscles than rest; pCO2 higher in muscles than rest; steeper diffusion gradient during exercise; O2/CO2 diffuses at a faster rate in exercise; bohr shift; O2 dissociates from Hb more readily in exercise
cardiac output for performer at rest
4-6l/min
cardiac output for performer in maximal exercise
20-40l/min
how conduction system of heart controls systolic phase of cardiac cycle (6)
SA node sends impulse; causes atrial systole; blood forced atria to ventricles; impulse travels to AV node; impulse continues down bundle of his and to purkinjie fibres; causes ventricular systole; blood ejected from ventricles
process of O2 diffusion at alveoli during exercise (6)
O2 diffuses high to low pPa; higher pO2 in alveoli; muscles use more O2 in exercise; so lower pO2 in blood; steeper pO2 gradient; faster rate of diffusion of O2 from alveoli to blood
how increase venous return in exercise affects quality of performance (7)
cause walls of atria to stretch; stimulate SA node to increase rate of impulses; cause walls of ventricles to stretch/increase end diastolic vol; cause stronger force of contraction; increase SV/CO; increase O2 blood supply to muscles; delay fatigue/OBLA
short term effects of exercise on gas exchange at alveoli (7)
in exercise blood at lungs has lower pO2; air in alveoli has higher pO2; gas diffuse high to low; more O2 diffuses alveoli to blood; blood at lungs has higher pCO2; air in alveoli has lower pCO2; more CO2 diffuses blood to alveoli
intrinsic control of heart during exercise (7)
increase venous return/more blood into R atria; R atrium stretches; causes SA to increase rate; increases end diastolic vol; more blood enter L ventricle cause to stretch/recoil more force; increases SV; increase *C increases HR; increase *C increases speed of nerve impulse
why more O2 dissociates from blood into muscle cell in exercise (9)
O2 moves high to low pO2; muscles use more O2 in exercise; more O2 dissociates from Hb/bohr shift; lower pO2 in muscle; high pO2 in blood; greater Pa/diffusion gradient; increase muscle/blood *C; increase CO2 in muscle; increase acidity
explain changes to SV in exercise (5)
SV dependent on venous return; increase VR=increase SV; at high HR reduced filling time of the heart; smaller end diastolic volume; heart only partially filled (SV plateau)
discuss that there are many factors that influence positioning (of netball) on energy continuum (6)
position on court; standard of game; tactics; motivation to win/effort/importance of game
compare energy expenditure and intake of elite to untrained (5)
elite will have greater expend due to demands of training; so intake will need to be greater; to maintain energy balance; higher carb than average eg marathon; increased protein for muscle repair than average eg rugby; reduced fat than average eg gymnast to prevent weight gain
