Cardiovascular and Respiratory Systems

• What is heart rate?

  The number of times your heart beats per minute
• How do you calculate heart rate?

  Heart rate = 220 - age
• What is a resting untrained value of heart rate?

  70-72bpm
• What is a resting trained value of heart rate?

  50bpm
• What is stroke volume?

  The volume of blood pumped out of the left ventricle per beat
• What is a resting untrained value of stroke volume?

  70 ml
• What is resting trained value of stroke volume?


  100 ml
• What is cardiac output?

  The volume of blood pumped out of the left ventricle per minute
• What is a resting value of cardiac output?

  5 L/min
• How do you calculate cardiac output?

  Cardiac output = stroke volume x heart rate
• What is the cardiac cycle?

  Atrial systole , ventricular systole , Atrial diastole , ventricular diastole
• What is the cardiac conduction system?

  the SA node initiates an electrical impulse casing atrial systole The Av node then conducts an electrical impulse down the bundle of HIS to the Purkinje fibres causing ventricular systole causing atrial diastole causing ventricular diastole
• What is diastole?

  Relaxation of the atria and ventricle
• What is systole?

  Contraction of the atria and ventricle
• What is a conduction system?

  A set of structures in the cardiac muscle which create and transmit an electrical impulse forcing the atria and ventricle to contract
• What are the two types of energy intensities?

  Maximal and sub-maximal
• What is sub-maximal exercise?

  A low-to-moderate intensity of exercise within a performers aerobic capacity
• What is maximal exercise?

  A high intensity of exercise above a performers aerobic capacity that will induce fatigue
• How does exercise affect heart rate?

  Heart rate increases in proportion to the intensity of exercise until we reach our maximum During maximal exercise there will be no plateau
• What is the effect of exercise on stroke volume?

  Stroke volume increases as exercise intensity increases but only up to 40-60% of maximal effort. Once a performer reaches this point SV plateaus so the ventricles do not have as much to fill up with blood due to increased heart rate.

  Increased Venus return leads to increased stoke volume due to an increased stretch on ventricular walls and therefore force of contraction
• What is the effect of exercise on cardiac output?

  Cardiac output increases in line with exercise intensity and plateaus during maximal exercise In recovery there is a rapid decrease followed by a slower decrease to resting values
• What is venous return?

  The volume of blood returning to the right atria via the veins
• What is starlings law?

  Increased venous return leads to increased SV - greater diastolic filling the cardiac muscle is stretched more This leads to a more powerful force of contraction which increases ejection fraction
• What are the 5 venous return mechanisms?

  Pocket valves

  Muscle pump

  Respiratory pump

  Smooth muscle of the veins

  Gravity
• How do pocket valves increase venous return?

  They are one way valves that prevent the back flow of blood
• How does muscle pump increase muscle pump?

  Veins are between skeletal muscle which when contracting push the blood back to the heart
• How does respiratory pump increase venous return?

  During exercise breathing is deeper increasing the pressure in the thoracic cavity squeezing the large veins in that area forcing blood back to the heart
• How does smooth muscle of veins increase venous return?

  Venoconstriction and Venodilation of the smooth muscle in the middle layer of the vein pushes blood back towards the heart
• How does gravity increase venous return?

  Blood from the upper body is aided by gravity so flows back to the heart quicker superior vena cava will have a faster VR than the inferior
• What is the vascular shunt mechanism?

  The redistribution of cardiac output around the body from rest to exercise which increases the percentage of blood flow to skeletal muscles
• What are arterioles?

  Blood vessels carrying oxygenated blood from the arteries to the capillary beds which can vasodilator and vasoconstrict to regulate blood flow
• What are pre-capillary sphincters?

  Rings of smooth muscle at the junction between arterioles and capillaries which can dilate or constrict to control blood flow through the capillary bed
• How does the vascular shunt mechanism redistribute blood during exercise?

  Chemoreceptors detect an increase in CO2 and Lactic acid

  Info is sent to the Vasomotor Control Centre

  Vasodilation of arterioles leading to working muscles

  Opening of pre-capillary sphincters to working muscles

  Vasoconstriction of arterioles to non-essential organs
• Why does The vascular shunt mechanism redistribute blood like that during exercise?

  Increased blood flow to the muscles as more oxygen is required for aerobic respiration

  Decreased blood flow to non-essential organs as less oxygen is needed astray can cope with reduction in blood
• How does the vascular shunt mechanism redistribute blood during recovery?

  Chemoreceptors detect an increase in O2 and decreased lactic acid

  Info sent to the vasomotor control centre

  Vasodilation of arterioles leading to non-essential organs

  opening of pre-capillary sphincters to non-essential organs

  Vasoconstriction of arterioles to muscles

  Closing of pre-capillary sphincters to muscles
• Why does the vascular shunt mechanism redistribute blood like this during recovery?

  Increased blood flow to non-essential organs for digestion

  Decreased blood flow to the muscles as less aerobic respiration is taking place
• How is the heart rate regulated?

  The Automatic Nervous System (ANS) involuntarily regulates the firing of the SA node this is controlled by Cardiac Control Centre (Medulla)
• How does the system help regulate heart rate during exercise?

  Increases the sympathetic nervous system impulses and firing of the SAN via the Accelerator nerve to increase heart rate during exercise
• How does neural control regulate heart rate during exercise?

  Chemoreceptors detect an increase in blood CO2

  proprioceptors detect an increase in movement

  Baroreceptors detect and increase in blood pressure
• How does intrinsic control regulate heart rate during exercise?

  Increased temperature and speed of nerve impulse transmission

  Increased venous return and force of ventricular contraction and stroke volume