32-37 Cardiovascular system Flashcards
What is increased Cardiac output?
Cardiac output (Q) is the amount of blood ejected by the left ventricle of the heart per minute. Measured in L/min (litres per minute)
As exercise intensity goes up, does cardiac output also go up?
Yes
Cardiac ouput formula：
Q = HR x SV.
Cardiac ouput at rest:
the av hr is70beats per minuteand stroke volume is roughly 70millilitres per beat. Gives cardiac output (Q˙=HR×SV) of roughly5litres per min.
Cardiac Output (Q) at submaximal Exercise
During submaximal exercise, such as paced jogging, heart rate will increase until it meets the demands of the body, plateauing when it reachessteady state.
What percentage of your max heart rate should a submaximal activity be at?
= 70 – 85 % of MHR
What is steady state:
Steady state occurs during submaximal activity where the oxygen demands of the body are being met.
Cardiac output at submaximal exercise.
Heart rate may increase to approximately140bpm, with stroke volume peaking at about120mL/beat, giving a cardiac output of approximately16–17litres per minute.
Cardiac Output (Q) at maximal intensities
High intense intensity. Maximal Intensities = 85 - 95 % of MHR
At maximal activity, increased cardiac output is due to?
At high to maximal intensities, any increase in cardiac output is due to this increase in heart rate, NOT stroke volume. Stroke volume tends to plateau when exercise intensity reaches around40–60%of the individual’s maximal exercise capacity.
Important info for cardiac output:
Average blood pressure at rest
Average BP at rest is120/80mm hg (120 is systolic) (80 is diastolic)
Blood pressure maximum systolic
Under maximal intensity, systolic BP can reach around200mm
Diastolic bloood pressure:
Remains unchanged
Increased blood flow
Speed of blood flow increases due to the increases in heart rate, stroke volume and cardiac output.
blood vessel diameter
Blood vessels will increase their diameter to accommodate the increase in blood flow (vasodilation).
Blood flow redistribution
During exercise, blood flow is redistributed to the working muscles and away from areas of the body that are less needed for the activity, such as the gut and kidneys.
How Blood flow redistribution is achieved:
capillaries supplying the working muscles expanding in diameter (vasodilation) and blood flow to the organs is reduced by the narrowing (vasoconstriction) of the capillaries that supply them with blood.
Blood flow to muscles resting and during exercise:
Rest 1.5l/min (16%)
During exercise 10l/min (84%)
Decreased Blood Volume
During exercise, blood volumes decrease due to the decrease in blood plasma levels. caused by the loss of fluid through the processes of sweat and evaporation, as well as the removal of by-products associated with energy production.
how to determine decreased blood volume:
The size of the decrease depends on the intensity and duration of the exercise, the hydration level of the individual and environment conditions, such as temperature and humidity.
Increased Arteriovenous Oxygen difference (a-VO2 diff)
The difference between the concentration of oxygen in the arterial blood and the concentration of oxygen in the blood from the veins. Measured in mL/100ml of blood.
During exercise in (a-VO2 diff)
the working muscles demand more oxygen for energy production, so the arterial blood will have more oxygen extracted by the working muscles than when they are at rest.
