Cardiovascular System Flashcards
Outline cardiac output
Amount of blood pumped by the left ventricle in 1 minute, measured in l/min
Product of stroke volume and heart rate = stroke volume (SE) × beats per minute (HR)
State the expected stroke volume for an elite athlete at rest
Averages at 90–110 ml/beat
Explain the response of an elite athlete’s stroke volume when exercise levels increase from rest to maximal effort
Increase in stroke volume prior to start of exercise period, due to release of hormones (adrenaline & noradrenaline)
More blood is pumped out of ventricles
Increased venous return, increased myocardial contraction during ventricular systole
Increases to maximal values during submaximal work. Doesn’t increase further as work increases towards maximal effort - heart already expanding & contracting to fullest size
Outline the two phases of the cardiac cycle during physical activity
2 phases in cycle: relaxation – diastolic 0.5 and contraction – systolic 0.3 secs
Diastolic:
Right & left atria fill with blood & atrioventricular valves closed (mitral & tricuspid)
Rising atrial pressure forces open atrioventricular valves & ventricles begin to fill
Semi-lunar valves to aorta & pulmonary arteries closed
Systolic
SA node initiates impulse causing wave of contraction across atrial myocardium, forcing remaining blood out of atria into ventricles
Semi-lunar valves remain closed, atrioventricular valves close after passage of blood
Impulse reaches AV node - spreads 2nd contraction through ventricle walls
Rising ventricular pressure forces open semi-lunar valves to lungs & systemic arteries (pulmonary artery & aorta)
Once blood has left heart &contraction ceases, semi-lunar valves shut
Examine the structural and physiological/functional adaptations to the cardiovascular system experienced by an endurance athlete following a prolonged period of aerobic training
Structural:
With exercise heart becomes stronger and bigger, cardiac hypertrophy
Increase in RBCs – RBC volume & haemoglobin content is higher in trained athlete, which facilitates the transport of O2 around body
Body parts where O2 required may experience growth of new capillaries. Increased vascularisation
Functional:
Increase in rates of diffusion, moving from area of high pressure to low.
Vascular shunting occurs where blood is diverted to skeletal muscle tissue where it’s needed
Increase in RBC & haemoglobin levels - higher in trained athletes, which facilitates transport of O2 around body
Increased lactate threshold
BC LIVID
Throughout a training session an athlete’s body will respond in numerous ways.
Comment on the physiological/functional responses of the muscular and respiratory system when an athlete is conducting an aerobic training session.
Muscle cell respiration increases – increased use of glycogen & O2 & increased production of CO2
Fatigue – muscle fatigue = short-term decline in ability of muscle to generate force - result of training or overexertion during exercise
HR - increases, to transport oxygenated blood to muscles quicker & return deoxygenated blood to heart & lungs
Muscles involved in breathing can themselves utilise up to 10% of total O2 uptake
Gaseous exchange rate increases to deliver increased O2 to working muscles & remove CO2 & lactic acid
MFHUG
Define the term cardiac hypertrophy and describe two adaptations which can occur as a result of endurance training
Cardiac hypertrophy = heart muscle becomes larger & stronger - heart pumps a larger volume of blood out per beat, hence stroke volume is greater
Enlargement caused by increase in thickness of cardiac muscle in ventricular wall & increase in size of ventricular chamber
Can lead to a greater stroke volume, reduced resting heart rate & increased maximum cardiac output
Increases RBCs
Outline responses of the cardiovascular system to physical activity
Increase in stroke volume
Increased heart rate
Increased cardiac output
Redistribution of blood flow to the working muscles
Define the term vascular shunting
Automatic opening up of blood vessels (arterioles) to active muscle tissue & constriction of blood vessels to non-active tissue as response to increase in exercise
Vascular shunting refers to distribution of blood around body
During exercise blood is redistributed to muscles – away from organs (stomach, kidneys, liver) where majority of blood is at rest
Explain how vascular shunting assists the performance of an athlete
Vasomotor control diverts blood to skeletal muscle tissue where it’s needed
Vasodilation = increase//Vasoconstriction = reduces
Vascular shunting aids performance by increasing blood flow to working muscles. O2 facilitates energy production & performer can work for longer
Examine factors that influence blood pressure during exercise
Diastolic blood pressure decreases in trained performers
Diastolic blood pressure increases during maximal intensity exercise/in activities involving isometric muscular contractions
Age, anxiety/stress, caffeine consumption, medical conditions (obesity, CHD) & environmental factors (heat, humidity) may affect systolic blood pressure
