Lab 5 Flashcards
Describe the modification to the baroreceptor reflex that occurs during exercise
NO overrides vasoconstriction.
Normally, increased MABP is detected by the baroreceptors and this increases the parasympathetic nerve activity and decreases the sympathetic nerve activity. This decreases SV and HR. This is modified in exercise to decrease parasympathetic and increase sympathetic nerve activity to increase stroke volume and increase heart rate
How was we estimate our max heart rate?
220 - age
How can we estimate our heart rate reserve?
Max HR - resting heart rate = HRR
How can we calculate the ventilation (L/min) in this lab?
Volume in the Douglas/ collection period
How can we calculate VO2?
This is oxygen consumption and it is equal to VE x (FIO2 - FEO2)
At the onset of exercise ATP is synthesised by:
1) Addition of a phosphate to ADP from AMP
2) Addition of a phosphate to ADP from cellular CrP
3) Addition of a phosphate to ADP from lactate
4) By consuming cellular proteins
5) Unsure
2) Addition of a phosphate to ADP from cellular CrP
What is the expiratory exchange ratio?
VCO2/VO2
Describe the heart rate:
- it increases _________
- it plateaus at ________ HR
- determined by _______
- linearly
- maximum
- age
What is the functional threshold power/anaerobic threshold?
This is the point when the anaerobic metabolism becomes dominant. There is accumulation of acid and this causes an increase in CO2 production
What is the aerobic threshold?
This is the maximal level of intensity/power that can be maintained using aerobic metabolism. The aerobic system is still dominant but the anaerobic system increases.
What’s the lactate threshold?
This is when the aerobic system can’s supply sufficient power, anaerobic becomes dominant. H+ accumulation becomes exponential
Above functional threshold power, anaerobic metabolism consumes skeletal muscle stores of:
- ATP
- Cr-P
- glycogen
Once these are depleted, we can no longer use anaerobic metabolism. We must decrease intensity to use aerobic metabolism of fat
What happens during recovery - EPOC?
Skeletal muscles must regenerate their stores of ATP, Cr[P and glycogen after exercise has finished. It required oxygen to replace these stores so ventilation and HR remain higher until the oxygen debt has been repaid
What happens during recovery - EPOC?
Skeletal muscles must regenerate their stores of ATP, Cr[P and glycogen after exercise has finished. It required oxygen to replace these stores so ventilation and HR remain higher until the oxygen debt has been repaid
What happens during recovery - EPOC?
Skeletal muscles must regenerate their stores of ATP, Cr[P and glycogen after exercise has finished. It required oxygen to replace these stores so ventilation and HR remain higher until the oxygen debt has been repaid
How can we calculate the tidal volume?
ventilation/breathing frequency
How can we calculate the CO2 production?
ventilation x (fraction of expired CO2 - fraction of inspired CO2)
How can we calculate the O2 consumption?
ventilation x (fraction of inspired O2 - fraction of expired O2)
How does the ventilation change from low intensity to high intensity exercise?
it increases
How does tidal volume change from low intensity exercise to high intensity exercise?
It increases
How does CO2 production change from low intensity exercise to high intensity exercise?
It increase
How does O2 consumption change from low intensity exercise to high intensity exercise?
it increases
How does the respiratory exchange ratio change from low exercise to high intensity exercise?
it increases
How can we calculate the oxygen extraction from blood in the body?
Vo2 = Q (CaO2 - CvO2)
What are two equations that can be used to calculate the oxygen consumption by the body?
• Oxygen extraction from air in the lungs:
VO2= VE (FIO2 - FEO2)
Oxygen into the blood
• Oxygen extraction from blood in the body:
VO2= Q (CaO2 - CvO2)
How can we estimate VO2 Max?
VO2/weight x 1000
How is the baroreceptor reflex modified in exercise?
Normally, there is an increase in MABP which stimulates the arterial baroreflex. This alerts the brainstem and this increases parasympathetic nerve activity and decreases sympathetic nerve activity. This decreases HR, SR and TPR and there is a decrease in MABP.
During exercise, the central command inhibits the barosensitive cells so there is no response to the baroreceptor input. Instead, there is an exercise pressure reflex stimulated by skeletal muscle contraction and this causes an increase in sympathetic nerve activity and a decrease in parasympathetic nerve activity
Describe the mechanisms, other than by increasing
cardiac output, by which the vascular system can
increase O2 delivery to active muscles.
Though vasodilation (decreased TPR) through functional sympatholysis and B2- adrenergic receptors
Explain the process of functional sympatholysis
- there is mechanical feedforward vasodilation: compression of blood vessels by skeletal muscles starting to contract which feedforward to induce vasodilation
- there is metabolic feedback vasodilation (active hyperaemia): increased metabolic activity in skeletal muscle. There is an increase in metabolites (CO2, H+, NO, adenosine and decreased O2) which feedback to cause vasodilation
- there is flow-mediated vasodilation: increased sheer stress due to increased flow: endothelial cells release NO and other factors which cause relaxation of vascular smooth muscle
