CVS and Respiration Physiology Flashcards
What 4 physiological changes happen when you exercise?
Increased HR
Increased respiratory rate
Sweating
Feeling warm
Why do these physiological changes come about when you exercise?
Increased muscle metabolism leads to
Increased oxygen consumption and CO2 production
Increased substrate consumption & by-prouct generation
Increased thermogenesis = sweating and skin vasodilation
What factors change the source of ATP production?
Duration and intensity of exercise
What is the phosphagen system, and when is it used?
ATP generation from creatine phosphate
Used in anaerobic, short-high intensity exercises
What is anaerobic glycolysis, and when is it used?
Lactate generation to make ATP
Used in moderate-high intensity exercise
What is aerobic respiration, and when is it used?
Glucose and fats are converted to ATP
Used in low-moderate intensity exercise
What is the timing of ATP sources switching during exercise?
Immediately after starting exercise = creatine phosphate
Under 2 mins = anaerobic glycolysis peaks and does NOT reach 0 again
After 2 mins = aerobic metabolism slowly increases
What exercise is the most suitable for fat burning?
Exercising for over 30 minutes, not too high intensity
Glycogen acts as source of glucose for around 20-30mins
Once glycogen stores are depleted = fatty acids become the substrate for aerobic metabolism
When we exercise, what happens to cardiac output?
Sympathetic activity and epinephrine increases:
Acts on SA to increase HR
Increases cardiac contractility = increase SV
Increases peripheral vasoconstriction = increased VR
( positive feedback leading to increased SV )
What is our resting cardiac output vs eexercise?
5 L/min resting
20-40 L/min exercise (sedentary vs trained)
What happens to SV in response to exercise?
SV increases with exercise intensity
SV plateaus at 40-60% of cardiac output MAX
Why does SV plateau?
Because the heart is at its MAX contractility
So any increase in cardiac output is due to increased HR
Why does ESV decrease during exercise?
ESV decreases because of increased contractility = less blood left in the heart
Why does EDV increase during exercise?
Muscles pump
Respiratory pumps
Redistribution of blood
All increasing venous return, causing an increase in blood present at rest
What is the difference in SV at rest vs during UPRIGHT exercise, and why?
SV max during upright exercise = 2X SV at rest
This is due to an increase in EDV and decrease in ESV
SV = EDV - ESV
In supine exercise, will the SV be greater or lower than upright exercise?
When lying down = CO increases because NO gravity pulling blood down
So increased venous return, causing increased EDV = increased SV
SV in supine exercise is LARGER than upright
Are the SV max the same in supine and upright exercise?
Yes, they are the same because during max exercise SV reaches a plateau
This is because the heart has reached max contractile capacity
What is the HR response to exercise?
HR rises linearly = increases with exercise intensity then plateaus
What are the two equations for %HRmax calcualtions?
220 - age bpm
208 - (0.7 x age) bpm
Will HR stay the same when you exercise at FIXED intensity for a long period?
NO, because of cardiovascular drift
What is cardiovascular drift?
HR gradually increasing despite exercising at FIXED intensity
Why does cardiovascular drift occur?
Because of increased heat generation = body initiates mechanisms to maintain constant temp
Sweating (sudomotor response) = reduces body fluid volume (blood volume) = reduce EDV = reduced SV
Skin vasodilatation to dissipate heat (vasomotor response) = reduced EDV = reduced SV
Reduced SV means HR must increase to maintain cardiac output
If you eat a full meal before running, what will happen?
Feel discomfort due to blood flow redistribution to muscles
What happens to blood vessels supplying muscle during exercise?
During exercise = skeletal muscle cell rapidly use oxygen
Reduced muscle O2 conc = vasoactive compounds locally released by endothelium
Act on smooth muscle of blood vessels = relax and dilate
Increase blood supply
How does the cardiovascular system respond to FIXED intensity exercise for a prolonged period?
CO increases then plateaus through the exercise
SV increases then drops due to sweating and vasodilation leading to reduced EDV and thus reduced SV
Reduced plasma volume because of sweating
HR increases to compensate for drop in SV and maintain CO at constant value (cardiovascular drift)
How does the cardiovascular system respond to INCREASING exercise intensity until exhaustion?
SV increases until about 40-60% of CO then plateaus (may drop a bit in untrained)
SV and PV will vary depending on training
CO increases until certain level then plateaus
HR increases proportionally to maintain CO
HR doesn’t plateau until reaching max CO (SV will plateau before that)
So when HR hits max, CO also hits max
What is the equation for ventilation?
Tidal volume x frequency
What factors stimulate central and peripheral chemoreceptors?
Elevated CO2 due to increased tissue respiration
Increased H+ during exercise (particularly heavy exercise)
Why does H+ increase during exercise?
Because of elevated CO2 ad lactic acid accumulation
What parts of respiration increase ventilation during exercise?
Increases in tidal volume and increased frequency of breathing (respiratory rate = RR)
How does ventilation change just before exercise?
Increase can begin before exercise starts because of psychological factors & signals from muscles and joints
Ventilation increases in proportion to metabolic needs
Rapid increase in ventilation and tidal volume
How does ventilation change during exercise?
Metabolic needs vs respiratory functions are in balance
Oxygen supply and CO2 removal stabilized
How does ventilation change when we stop exercising?
There is a lag before ventilation returns to resting rate
This is due to excess post exercise O2 consumption (EPOC)
What is Excess Post-Exercise O2 Consumption (EPOC) needed for?***
Phosphocreatine restoration
Lactate removal
Support ventilatory muscles
What does VO2 measure?
Volume of oxygen that the body uses per minute
Indicator of aerobic capacity
What is the units of VO2?
mL/kg/min
What does the Fick equation tell us and what is the equation?
VO2 = cardiac output x (arterioles - venous) oxygen conc difference
What is VO2 max?
The maximum rate at which an individual can take in and use oxygen during maximal exercise
What does having a higher VO2 max indicate?
Increased oxygen utilization = greater endurance potential
What factors affect VO2 max?
Genetics
Age
Training
Altitude
What factors influence the Fick Equation (VO2 max)?
Cardiac Output = oxygen delivery by CVS
HR, SV (EDV-ESV)
Heart size & contractility
Blood volume & composition
Arterial - venous oxygen = oxygen utilization
Muscle vascularization
Mitochondria density
OXPHOS enzymes
Muscle type
Metabolic enzymes
What does training improve?
Exercise performance and capacity to resist fatigue
Efficiency of energy utilization
How does training affect SV?
Increased cardiac efficiency
Increased plasma volume, LV compliance, ejection fraction, peak diastolic filling
Decrease cardiac afterload
How does training affect arterial oxygen conc?
Increased pulmonary function
Increased ventilatory efficiency, lung diffusion capacity & ventilation/perfusion matching
Decreased respiratory fatigue and decreased dead space (due to increased V-P matching
How does training affect venous oxygen conc?
Muscle adaptation, lowering oxygen conc in venous blood (increases VO2 max)
Increased mitochondrial content, oxygen utilization T1 fibres & time for lactate production
Decreased time for oxygen extraction
How can dead space be decreased?
By increasing ventilation-perfusion matching
How does the blood adapt to training?
INCREASED BLOOD VOLUME
Increase in both plasma and RBC volume = but more increase in plasma
Leads to decreased hematocrit and blood viscosity
What causes the increase in plasma volume post-training?
Increased albumin synthesis = increased oncotic pressure
Thus, increased plasma volume = increased blood volume
What happens to the heart in endurance athletes?
Left ventricular hypertrophy
