17 Exercise and the CVS Flashcards
What balance needs to be met in acute exercise?
increased VO2
maintained ABP
What are the responses produced in acute exercise?
metabolic vasodilation
increased CO to muscles
What causes metabolic dilation of blood vessels in acute exercise?
K+ H+ adenosine ATP Pi
What is the change in cardiac output to muscles in acute exercise?
1 L/min
to 22 L/min
What 3 factors determine rate of O2 transport and hence performane?
VO2 max
muscle perfusion
diffusion
What can be done to increase muscle perfusion?
vasodilation
What is VO2 max?
the rate of maximum O2 uptake from the air and/or the rate of maximum O2 use by mitochondria
these should be balanced
What is VO2 max dependent on?
max CO
haematocrit
what might the CO max of an athlete be?
25 L/min
What might the VO2 max of an untrained and trained person be?
3 L/min untrained
5 L/min trained
What might increase eccentric hypertrophy?
endurance training - growth factor release
What is eccentric hypertrophy?
new sarcomeres added in series, increasing muscle length and not width
What is the effect of eccentric hypertrophy on the heart?
increased chamber size
LV mass increase by 20%
increased contractility and inoropy of each myocyte
In a given pre-load we can produce a higher SV
What happens to the sarcomere in hypotension?
sarcomeres added in parallel
What is the significance of laplace’s law in eccentric hypertrophy?
the change in pressure generated would theoretically be less in the trained heart due to increased radius
however, this effect is outweighed by the increase in inotropy (and pre-load)
how does EDV increase in training?
increased chamber size
increased circulating blood volume
increased central venous pressure
What is the effect of O2 demands being the same at rest for trained and untrained people?
trained people have a bigger SV
they hence have a decreased HR
What 3 things causes a resting bradycardia?
increased tonic vagal activity
increased local ACh release
decreased intrinsic pacemaker activity
What is enhanced respiratory sinus arrhythmia?
during inspiration, central inspiratory drive inhibits vagal activity, increasing HR
What is the biggest factor for variability in HR?
age
How might you increase cardiac perfusion?
increase in capillary number increase capillary : fibre ratio decreased diffusion distance increased number of arterioles increased coronary artery diameter decreased vascular resistance increased blood flow
What does increased sheer result in?
upregulation of eNOS and antioxidant enzymes
increased bioavailability of NO, and vascular health
What do antioxidant enzymes do?
maintain vascular health
they also quench NO, and reduce bioavailability of NOS
this is why we have to increase the release of NOS
What intrinsic factors about the myocardium change with training?
increased mitochondria and myoglobin
