Cardio vascular Flashcards
Explain how an increase in venous return during exercise affects the quality of an athlete’s performance (3)
Causes the walls of the atria to stretch which stimulates the SA node to increase heart rate
Increase blood or oxygen supply to muscles
Increases endurance / delays fatigue
Explain how the re-distribution of blood during physical activity is achieved (4)
More blood goes to the working muscles
Role of the vasomotor centre in passing
on messages about where blood is needed / chemoreceptors / proprioceptors / baroreceptors
Vasodilation of arterioles leading to muscles
Vasoconstriction of arterioles leading to
some organs
Opening of pre-capillary sphincters to muscles
Closing of pre-capillary sphincters to organs
Give an average value for cardiac output for a performer at rest and during maximal exercise
At rest - 4—6 litres/min
During exercise - 20—40 litres/min
Describe how the conduction system of the heart controls the systolic phase of the cardiac cycle (4)
SA node Initiates or sends an impulse
This causes atrial systole
Blood forced from the atria to the ventricles through AV valves
Impulse travels to or is received by the AV node
Describe intrinsic control of the heart during exercise (4)
Temperature increases which increases heart rate
Increased temperature increases the speed of nerve impulses
Increase in venous return / more blood enters the right atrium the right atrium stretches
Which causes the SA node to increase rate of firing
Explain why more oxygen dissociates from the blood into the muscle cell during exercise (5)
Gas or oxygen moves from a high concentration to low concentration
During exercise the muscles use more oxygen
Oxygen dissociation curve shifts to the right / Bohr’s shift
There is a lower partial pressure of oxygen in the muscle
There is an increase in body temperature
Explain the changes to stroke volume during sub maximal exercise (3)
During sub maximal exercise increased VR leads to increased SV
At higher heart rates reduced filling times
Which means heart is only partially filled with blood
Explain the cardiac cycle of the heart using the following key terms: Atrial systole Ventricular systole Diastole
[3]
Atrial systole - atria contract which forces blood into the ventricles
Ventricular systole – ventricles contract which pumps blood out of the heart / into the aorta and pulmonary artery / to the body and the lungs
Diastole – atria /ventricles relax which allows blood to enter heart
During a 5000 metre race, the athlete’s tidal volume increases. Explain how neural control of breathing causes this to happen (2)
Inspiratory centre stimulates nerves/motor neurones to increase depth of breathing
Phrenic nerve stimulates diaphragm to contract more strongly
Identify two neural receptors and explain how each regulates heart rate as the dance routine begins
Baroreceptors detect increase in blood pressure and cause heart rate to decrease
Chemoreceptors detect decrease in blood pH causing heart rate to increase
Explain how venous return mechanisms can aid venous return and prevent blood pooling as part of the netball
player’s recovery (4)
Venous return mechanisms work to maximise blood flow back to heart
Which means netballer will maintain blood pressure/ speed up removal of lactic acid or waste products
Pocket valves in veins prevent backflow of blood (in legs)
Skeletal muscle pump causes muscles of legs to contract squeezing veins forcing blood back to the heart
Define the term ‘stroke volume’ and give a typical resting value for a trained individual
volume of blood pumped out of left ventricle per beat
80 – 120ml
Describe four mechanisms of venous return that maintain blood flow back to the heart
Pocket valves - that prevent backflow of blood
Muscle / skeletal pump - skeletal muscles contract squeezing veins
Smooth muscle - in walls of veins contracts
Gravity helps blood from above heart return to heart
Explain how the conduction system of the heart controls diastole
Atria/ventricles relax whilst they are filling with blood
Due to no electrical impulse
