LECTURE 4: Cardiovascular responses to exercise, glycolysis, middle-distance athlete Flashcards
list three purposes of the circulatory system
deliver O2 & nutrition, remove CO2 and waste, regulate body temperature
list the two major adjustment of blood flow during exercise
increased CO, redistribution of blood flow
when the heart remodels as an exercise response, do the chambers increase or decrease in volume?
increase
when the heart remodels as an exercise response, to the cardiac wall increase or decrease in thickness?
increase
what is the Morganroth hypothesis?
endurance athletes experience eccentric cardiac remodelling that create large ventricle volumes and relatively low wall thickness, power athletes experience concentric remodelling that create thick ventricle walls and relatively small ventricle volume
what is the leading cause of mortality in athletes during sport?
sudden cardiac death
at rest, which is longer: diastole or systole
diastole
in exercise, which is longer: diastole or systole
neither - same length
the length of which of the following is decreased in exercise: diastole or systole?
diastole
what causes the first heart sound?
closure of the AV valves
what causes the second heart sound?
closure of the semilunar valves
what is pulse pressure?
the difference between systolic and diastolic pressure
what is mean arterial pressure?
mean pressure in the arteries
what is the calculation for mean arterial pressure?
MAP = DBP + 0.33 (SBP - DBP)
what blood pressure value is considered hypertensive?
> 140/90mmHg
list five factors influencing blood pressure
blood volume, heart rate, stroke volume, blood viscosity, peripheral resistance
what is the short term regulator of blood pressure?
SNS
what is the long term regulator of blood pressure?
kidneys
what is the calculation for cardiac output?
CO = HR x SV
what regulatory properties does the PNS have on HR?
slowing HR by inhibiting SA & AV nodes via the vagus nerve
what regulatory properties does the SNS have on HR?
speeding up HR by stimulating SA & AV nodes via cardiac accelerator nerves
is the SNS stimulation or PNS withdrawal responsible for the initial rise in HR? (~100beats/min)
parasympathetic withdrawal
is it more healthy to have a wide heart rate variability (HRV) or low HRV?
wide HRV
what do beta-blockers do to heart rate in submax and maximal exerciser?
lowers HR
list three factors affecting stroke volume?
Preload/EDV, afterload (average aortic BP or MAP), strength of ventricular contraction
describe the frank-starling mechanism
greater EDV results in more forceful ventricular contraction due to greater stretch of ventricle walls
list three mechanisms that increase venous return?
venoconstriction (by SNS), skeletal muscle pump, respiratory pump
what is the calculation for ejection fraction?
EF% = SV / EDV
describe ejection fraction
proportion of blood pumped out of ventricles with each pump
what is the average EF% at rest and is it greater or lesser during exercise?
60% at rest, greater in exercise
list the three functions of blood
transport gas, nutrients & waste, regulate temperature, buffer & balance acid/base
what is the mandated haematocrit cap according to anti-doping authorities?
48%
how much does muscle O2 demand increase in exercise from rest?
x15-20
at what %VO2max does the increase in SV plateau?
~40%
do elite athletes experience an SV plateau at a higher or lower %VO2max?
neither - elite athletes do not experience plateau
does HR increase at a linear or non-linear rate as exercise intensity increases?
linear
state whether the following increase or not during exercise: systolic BP, diastolic BP, MAP
increase, no increase, increase
where is most glycogen stores: the liver or skeletal muscle/
skeletal muscle
what is the ATP input requirement for using glucose in glycolysis
2ATP
what is the ATP input requirement for using glycogen in glycolysis
3ATP
when does glycogenolysis begin in relation to glycolysis?
soon after glycolysis begins and blood glucose has begun to drop
what triggers up-regulation of glycolysis?
dropping ATP levels in the cell
what triggers down-regulation of glycolysis?
rising levels of ATP in the cell (IE when fat metabolism meets energy demands)
what is the main regulatory enzyme of glycolysis?
phosphofruktokinase (PFK-1)
what cellular actions inhibit PFK-1 action?
raised ATP, citrate and H+ levels
why does citrate presence inhibit PFK-1?
citrate indicates high use of the krebs cycle and FFA to meet ATP demands, reducing the need for glycolysis
why do high H+ levels inhibit PFK-1?
H+ is a result of glycolysis, if levels rise too high cellular damage may occur. Thus, PFK-1 is inhibited to lower glycolysis rates
what triggers activation of PFK-1?
low ATP, high ADP & AMP
what energy system do middle distance athletes use most?
glycolysis
do middle distance athletes produce the least or the most lactate?
the most
what two systems produce energy in the initial stages of a middle distance event?
ATP-PC system, GLycolysis
define oxygen deficit
lag in oxygen uptake at the beginning of exercise
will people with higher fitness levels engage aerobic systems earlier or later than people with lower fitness in middle distance events? Why?
faster, means they can reserve their PC and glycogen stores for later
describe the rapid portion of the O2 debt
resynthesis of stored PC, replenishing muscle and blood O2, takes up first part of recovery
describe the slow portion of the O2 debt
elevated HR & breathing leads to higher energy needs, higher body temperature and catecholamine levels lead to higher metabolic rate, involves conversion of lactic acid to glucose (gluconeogenesis) occurs later in recovery after rapid portion
how long does a middle distance event last for?
1-8mins
what is the primary cause of exhaustion in 3-7mins of max effort?
accumulation of H+ in the cell
do high H+ levels create an acidic environment in the blood or in the cell?
cell
what is the resting pH of blood
7.40
do high lactate levels cause acidity of the blood or cells?
blood
what happens to ‘recycled’ lactate?
some taken by liver and undergoes gluconeogenesis, some taken by heart & muscles and converted to pyruvate for other biomechanical processes
how is H+ cleared from the body after exercise?
reacts with bicarbonate in blood to be neutralised
