CARDIOVASCULAR Flashcards
What are the 5 elements of the oxygen transport system
- Pulmonary ventilation
- Aerobic metabolism
- Peripheral blood flow
- Hemoglobin concentration
- Blood volume and cardiac output
What is flow velocity primarily impacted by
vessel diameter - vasodilation and vasoconstriction
A tubes resistance is … to its radius
inversely proportional to the fourth power of its radius
What forces fluid from capillaries
blood pressure
what forces fluid back into capillaries
osmotic pressure
What are the 3 key components to delivering blood to working muscles
- heart function
- blood flow distribution (including bp)
- Oxygen extraction at muscles
What are 4 anatomical changes to the heart with exercise
- Increase mass and volume - muscles getting bigger and stronger
- Increase size of left ventricle
- Modest increase left ventricle wall thickness (due to increase in muscle)
- Increase left ventricle end diastolic volume (EDV) at rest and with exercise
Why does the left ventricle increase in siize with exercise
More blood coming in and the heart working to pump it out - cavity become bigger and more used to receiving large amounts of blood
Why is there an increase in left ventricle end diastolic volume at rest and with exercise
Because of improvement in cavity size has greater end diastolic volume both at rest and exercise - allows heart to fill with more and eject more
What is the unit for cardiac output
L/min
Blood flow from heart has a ___ Relationship with exercise intensity
linear
What occurs to CO in steady state exercise. why?
plateaus as blood flow matches exercise metabolic requirements
When does stroke volume plateau
~ 50% of VO2max
Does stroke volume increase linear with graded exercise
no
When stroke volume plateaus how do you continue to increase/maintain CO to meet demands
HR can increase until max
Why is HR lower in endurance trained athletes compared to untrained for the same O2
Stroke volume is higher in endurance trained athletes allowing HR to be lower while maintaining CO
what are the 3 mechanisms for an increase in SV with training
- Pre-load
- Enhanced cardiac filling in diastole filling
- Greater systolic emptying
Does an increase in preload take a long time or a short time
quick! 2-3 weeks
How is preload increased with exercise
Increase with plasma volume and greater blood volume
How does plasma volume increase with exercise
Kidney realizes that you are active and helps by secreting anti-diuretic hormone and aldosterone from pituitary glands and improves kidneys capability to hold water which will then be transported into bloodstream to increase blood volume
What is the result of the increase in blood volume with exercise
- Enhances circulating dynamics
- Enhances thermoregulatory dynamics
- Facilitates oxygen delivery to muscle during exercise
- contributes to training-induced enlargement of left ventricle (more strain from having to pump more blood)
What are the mechanisms behind enhanced cardiac filling in diastole filling
- Increased venous return (pre-load)
- Slower heart rate (for given workload)
- Increase compliance of left ventricle
Why do you get greater systolic emptying with exercise
increase end diastolic volume stretches myocardial fibers = more powerful ejection stroke when heart contracts
What is the frank-starling law
realtionship between muscle force and resting fibre length
Blood pressure represents …
the force exerted by blood against the arterial walls during a cardiac cycle
What is the equation for resistance
(length of system x viscosity of blood) / (radius^4)
A small change in the diameter of a vessel results in a ____ change in resistance
large
Do length and blood viscosity change often?
no not substantially
Can radius change a lot?
yes - vasoconstriction + dilation
What is the equation for blood pressure
Cardiac output x total peripheral resistance
What indicates peripheral resistance
diastolic blood pressure
Diastolic blood pressure is…
the ease that blood flows from the arterioles into the capillaries
What is afterload
the resistance the heart has to pump against
What is afterload primarily based upon
blood pressure in the major arteries
what is chrontopic
time - rate of heart rate