Exercise Pathology: Acute and Training CV changes Flashcards
How do you increase cardiac output?
Increase HR, increase SV
How can ventilation be increased?
Increase frequency of breathing, increase tidal volume
Determine dynamic exercise?
by 02 consumption, V02 is the metabollic rate, determined by tissues
Cardiac output?
Q
Circulatory changes?
a-v 02 difference
Increase HR?
decreased parasympathetic tone initially, increased sympathetic tone in heavy exercise
Sv is increased by?
increased end diastolic volume (preload), increased sympathetic activation (contractility)
Increased cardiac output is related to HR and SV?
HR increases linearly with increased work load but SV rises rapidly with increased work load
SV=?
EDV-ESV
decrease SV from increased ESV or decreased EDV
increase SV from decrease ESV or increase EDV
influence ESV?
afterload, contractility
influence EDV?
Stiffness, HR, preload
Increase venous return?
muscle pump (displaces blood form peripheral veins to central veins)
respiratory pump (increase intrathoracic pressure sucks blood into heart, neg pressure in chest becomes more negative draw blood in)
by increasing venous return, increase filling pressure and EDV
Muscle 02 extraction increases in exercise?
increase in arterial-venous 02 difference, increase muscle 02 extraction, systemic redistribution of blood, vasodilation and capillary recruitment increase in active muscle
Blood distribuition and redistribution in excercise, decrease most? increase most?
decrease- splanchnic normally 24%, 1%
increase- skeletal m 21%, 86%
How does blood redistribute in exercise?
via vasoconstriction of blood vessels under alpha 1 receptors
allow less blood in inactive muscle, splanchnic circulation, renal circulation, cutaneous circulation
Rate of diffusion law?
Fick’s law
MAP and TPR during exercise?
because of vasodilation, TPR decreases and BP only increases slightly
BP change in static vs dynamic?
static- increases greatly because less influence of vasodilation in static exercise
dynamic- increase and then decrease
Metaboreceptors?
muscle receptor, sensitive to metabolic environment, group IV sensory afferents, can cause large increase in SNS outflow
Mechanoreceptors?
muscle receptor, sense mechanical environment, group III sensory afferent
Baroreceptors?
they reset during exercise to a higher BP, become less potent, reducing HR when BP increased
V02?
oxygen consumption, increases linearly with work rate up to V02max
increased ventillation, increased cardiac output, increased muscle 02 extraction
Main limitation of V02max?
cardiac output, as maximim cardiac output (Q) increases, V02max incrases
When does the lung limit V02max?
in athletes during severe exercise
exercise induced arterial hypoxemia
can be overcome by breathing higher 02
excessive respiratory muscle work consumes some of the V02
how does training improve V02max?
O2 extraction depends on ability of diffusion from capillary to mitochondria, training increases muscle diffuse capacity, increasing v02max
Muscle fatigue limits exercise performance?
onset of fatigue fiber type accumulation of K, lactate reduction of pH depletion of glycogen, PCr
What does performance rely on in addition to V02max?
mechanical efficiency
edurance at high V02 rates, anaerobic threshold
Women to get same power output do what?
work at a higher % of V02 max, at occurs at decreased power outputs in women
Why can someone run longer?
they have a higher anaerobic threshold, regardless if they have the same V02max
How can you increase V02max?
training will increase it, increase resistance to fatigue due to increased lactate threshold
respiratory system is mostly unchanged by training
CV changes from training?
maximal cardiac output increase, resting HR lower but max is unchanged, max SV increases, modest reduction in BP
