Cardiovascular System & Response to Exercise Flashcards
Cardiac Regulation
SA node - pacemaker, located in R atrium
- intrinsic rate ~72 bpm (60-100 norm)
Can be controlled by AV node under certain circumsances w/ a slower pace than SA node control
-can be influenced by environment (high altitude means less O2 causing an Increased HR)
ECG
electrocardiogram - measure ELECTRICAL activity of the heart (NOT actual contraction)
P wave - atrial depolarization (about to squeeze)
QRS complex - ventricular depolarization
T wave - ventricular repolarization
Major Cardiac Functions (5)
- Deliver O2 & nutrients
- Maintain homeostasis, balance of pH, etc
- Removal of metabolic waste
- Transport hormones
- Prevention (if healthy)
VO2 max
- what is it
- aging?
- response to exercise
maximal oxygen consumption during exercise; how well heart, lungs, vessels work together to support exercise
#1 measure of CV fitness
- decreases as you age
Equation = VO2 max = Q x a-v O2 difference
Response to Exercise:
- submaximal VO2 decreases because the heart is working more efficiently at lower intensities post training
- maximal VO2 increases
A-V O2 difference
- what is it
- normal vs. exercise levels
- response to exercise
the difference in the amount of oxygen in the arterial system and the venous system (A Minus V)
(aka how much O2 our muscles extract)
Normal = 5 mL/O2/100mL/dl
Exercise = 15
WHY - b/c you are extracting more O2 during exercise (ie. arterial (20) minus venous (5) = 15)
Response to exercise:
- increase due to increased capillarization of muscles and mitochondrial density allowing you to extract more O2
Cardiac output
- what is it
- what happens during exercise
- response to training
the amount of blood pumped out of the heart per unit time
(Q = SV x HR)
Resting = 5 L/min, Exercising = 20 L/min (increases LINEARLY w/ exercise)
- up to 50% of maximal capacity, increase in Q is due to increase in SV
- after 50% increase in Q primarily due to increase in HR
Response to training:
- remains unchanged at submaximal intensities b/c of play between HR & SV (SV will increase, but HR will decrease)
- Increased Q at maximal effort or w/ higher intensities b/c increased conditioning and SV
Principles that affect SV
Preload: increase in preload = increase SV = increase Q
-increased via venoconstriction or when in supine
Afterload:
Contractility: contractility influenced by the stretch of the heart; greater volume = greater stretch = increased contractility = increased SV
& HR
Stroke Volume
- what is it
- normal resting vs. maximal
- response to training
end diastolic volume MINUS end systolic volume
(amount of blood in ventricle right before contraction & amount left over)
SV = EF/EDV
**impt factor when determining someone’s VO2 max
Normal = 70 mL/beat, Exercising 100-200mL/beat
increases CURVILINEARLY w/ exercise intensity, tapers off around 50% b/c HR takes over
Response to training:
- SV increases during submax & maximal effort due to greater ability to pump blood
- allows individual to work at a lower HR b/c more efficient
Frank Starling Method
explains why SV increases due to training
More blood in the ventricle causes a greater stretch and contracts w/ increased force
greater stretch = greater contractility = increased SV
Ejection Fraction
- what is it
- avg of healthy adult
- response to exercise
proportion of blood pumped out of the left ventricle per beat
EJ = SV/EDV
average = 60% in healthy adults; meaning 60% of total amount of blood in ventricle is being pumped out
Response to exercise”
- increases
Heart Rate
- normal
- aging
- response to exercise
60-100 bpm
resting HR remains the same or slighly increases as you age due to decreased PNS control
Response to exercise:
- resting HR decreases b/c maximizes SV
(sedentary ppl can decrease by 1bpm/week)
- HR recovery time decreases
- Overtraining indicated by flucuations of 10 bpm
Anaerobic Threshold
- what is it
- above vs. below AT
- response to exercise
rise in Co2 disproportionate to rise in O2 indicating energy can no longer be solely supplied by aerobic metabolism
- -> yields build up of lactic acid
- -> usually around 1.0 RER where you will hit your AT
At or BELOW AT you can sustain exercise intensity comfortable
ABOVE AT you can no longer sustain prolonged workload
Response to Exercise:
- AT can increase via interval training; more efficient at clearing metabolic waste
Respiratory Exchange Ratio
- what is it
- what does it indicate
ratio of VCO2/VO2 in venous blood
Determines what energy source our body is utilizing; a high VCO2 usually indicates high intensity exercise
- 7 = fat (more O2 in venous blood than CO2)
- 85 = carbs & fats 50/50
- 9 - 1.0 = carbs, glycolysis & lactic acid build up
RER > 1.0 indicates anaerobic metabolism
RER > 1.09 indicates MAX effort
- the earlier you reach max (aka hit the AT) the less fit you are
Blood Volume
- response to exercise
blood volume will INCREASE w/ endurance training
- plasma INC, RBC INC, but hematocrit DEC b/c greater increase in plasma
highly coorelated w/ increases in SV & VO2 max
Autonomic Nervous System Control of Heart
Parasympathetic - responsible for housekeeping
- Vagus Nerve
- fibers into atria
- in control during rest & light to mod exercise
Sympathetic - responds to stimuli, maintains homeostasis
- catelcholamines control (epinephrine, norepinephrine)
- increase HR, increase blood flow
- in control during higher intensity (>75% of MHR) & maximal effort (doubles contractility)
