Lab 5

Question 1

Describe the modification to the baroreceptor reflex that occurs during exercise

Answer 1

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

Question 2

How was we estimate our max heart rate?

Answer 2

220 - age

Question 3

How can we estimate our heart rate reserve?

Answer 3

Max HR - resting heart rate = HRR

Question 4

How can we calculate the ventilation (L/min) in this lab?

Answer 4

Volume in the Douglas/ collection period

Question 5

How can we calculate VO2?

Answer 5

This is oxygen consumption and it is equal to VE x (FIO2 - FEO2)

Question 6

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

Answer 6

2) Addition of a phosphate to ADP from cellular CrP

Question 7

What is the expiratory exchange ratio?

Answer 7

VCO2/VO2

Question 8

Describe the heart rate:

• it increases _________
• it plateaus at ________ HR
• determined by _______

Answer 8

• linearly
• maximum
• age

Question 9

What is the functional threshold power/anaerobic threshold?

Answer 9

This is the point when the anaerobic metabolism becomes dominant. There is accumulation of acid and this causes an increase in CO2 production

Question 10

What is the aerobic threshold?

Answer 10

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.

Question 11

What’s the lactate threshold?

Answer 11

This is when the aerobic system can’s supply sufficient power, anaerobic becomes dominant. H+ accumulation becomes exponential

Question 12

Above functional threshold power, anaerobic metabolism consumes skeletal muscle stores of:

Answer 12

• 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

Question 13

What happens during recovery - EPOC?

Answer 13

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

Question 13

What happens during recovery - EPOC?

Answer 13

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

Question 13

What happens during recovery - EPOC?

Answer 13

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

Question 14

How can we calculate the tidal volume?

Answer 14

ventilation/breathing frequency

Question 15

How can we calculate the CO2 production?

Answer 15

ventilation x (fraction of expired CO2 - fraction of inspired CO2)

Question 16

How can we calculate the O2 consumption?

Answer 16

ventilation x (fraction of inspired O2 - fraction of expired O2)

Question 17

How does the ventilation change from low intensity to high intensity exercise?

Answer 17

it increases

Question 18

How does tidal volume change from low intensity exercise to high intensity exercise?

Answer 18

It increases

Question 19

How does CO2 production change from low intensity exercise to high intensity exercise?

Answer 19

It increase

Question 20

How does O2 consumption change from low intensity exercise to high intensity exercise?

Answer 20

it increases

Question 21

How does the respiratory exchange ratio change from low exercise to high intensity exercise?

Answer 21

it increases

Question 22

How can we calculate the oxygen extraction from blood in the body?

Answer 22

Vo2 = Q (CaO2 - CvO2)

Question 23

What are two equations that can be used to calculate the oxygen consumption by the body?

Answer 23

• 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)

Question 24

How can we estimate VO2 Max?

Answer 24

VO2/weight x 1000

Question 25

How is the baroreceptor reflex modified in exercise?

Answer 25

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

Question 26

Describe the mechanisms, other than by increasing
cardiac output, by which the vascular system can
increase O2 delivery to active muscles.

Answer 26

Though vasodilation (decreased TPR) through functional sympatholysis and B2- adrenergic receptors

Question 27

Explain the process of functional sympatholysis

Answer 27

• 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