Chapter 14

Question 1

how is ventilatory control coordinated?

Answer 1

intricate neural circuits relay information from higher brain centres, the lungs, and other bodily sensors

Question 2

how is alveolar ventilation coordinated? *

Answer 2

gaseous and chemical states of the blood that bathes the medulla, aortic and carotid artery chemoreceptors pick up information

Question 3

where does the blood’s chemical state exert the greater control? *

Answer 3

pulmonary ventilation at rest

Question 4

what are 4 variations that adjust ventilation and maintain arterial blood chemistry?

Answer 4

1. arterial PO2
2. arterial PCO2
3. pH
4. temperature

Question 5

what is the relationship between arterial PO2 and alveolar ventilation?

Answer 5

when arterial PO2 decreases, alveolar ventilation through the aortic and carotid chemoreceptors increase

Question 6

what is the function of the aortic and carotid chemoreceptors?

Answer 6

protects against reduced oxygen pressure in inspired air

Question 7

what is the function of peripheral chemoreceptors?

Answer 7

stimulates ventilation during exercise

defends against arterial hypoxia

helps regulate exercise hyperpnea

Question 8

what is the limiting factor for oxygen consumption during exercise?

Answer 8

delivery of oxygen to the muscles is lacking

Question 9

how does cortical influence affect ventilatory control?

Answer 9

neural outflow from regions of the motor cortex and cortical activation in anticipation exercise stimulate respiratory neurons in medulla to initiate abrupt increase in ventilation

Question 10

how does peripheral influence affect ventilatory control?

Answer 10

sensory input from joints, tendons, and muscles influence ventilatory adjustments throughout exercise

Question 11

what are the 3 ventilation phases during exercise and recovery? *

Answer 11

phase 1
neurogenic stimuli from cerebral cortex and feedback from active limbs stimulate medulla to abruptly increase ventilation

phase 2
after plateau, ventilation rises exponentially to achieve steady state related to metabolic gas exchange demands

phase 3
fine tuning of steady-rate ventilation through peripheral sensory feedback mechanisms

Question 12

what are 2 factors that impact the decline in ventilation when exercise stops?

Answer 12

1. removal of central command drive (desire)

2. decreased sensory input from previously active muscles (mechanoreceptors)

Question 13

what are 2 factors that slows recovery phase?

Answer 13

1. gradual cut of short-term nerve impulse increases of respiratory centre
2. reestablishment of body’s normal metabolic, thermal, and chemical environment

Question 14

what is the aerobic threshold (VT1) and anaerobic threshold (VT2) test?

Answer 14

3 minute stages to achieve steady state

not ideal for maximal testing due to peripheral fatigue

best for graded maximal exercise test to identify anaerobic threshold

Question 15

what is the VO2 max test?

Answer 15

1 minute stages allow for peak speed/wattage

inappropriate for threshold identification

Question 16

what are 4 characteristics of aerobic threshold (VT1)? *

Answer 16

RER = 0.92-0.94
increase in FEO2
non-linear increase VE
non-linear increase VCO2

Question 17

what are 3 characteristics of anaerobic threshold (VT2)? *

Answer 17

RER = 0.98-1.02
decrease in FECO2
non-linear increase in VE

Question 18

what is steady state?

Answer 18

when the rate of entry into blood is equivalent to the rate of disappearance from blood

Question 19

what is the lactate threshold 2 (LT)?

Answer 19

highest VO2 or exercise intensity before 1.0 mM increase in blood lactate concentration above pre-exercise level

Question 20

what does onset of blood lactate accumulation (OBLA) signify?

Answer 20

when blood lactate concentration systematically increases to 4.0 mM

Question 21

what is the relative intensity (%VO2 max), blood lactate (mmol/L), and heart rate (% max) for aerobic threshold?

Answer 21

70% VO2 max
2.0 (1.0-3.0) mmol/L
75% (70-80%)

Question 22

what is the relative intensity (%VO2 max), blood lactate (mmol/L), and heart rate (% max) for anaerobic threshold?

Answer 22

85% VO2 max
4.0 (2.5-5.5) mmol/L
85% (80-95%)

Question 23

what is the relative intensity (%VO2 max), blood lactate (mmol/L), and heart rate (% max) for VO2 max

Answer 23

100% VO2 max
> 10.0 mmol/L
95% (90-100%)

Question 24

what is maximum lactate steady state (MLSS)?

Answer 24

the highest work rate at which a balance of lactate production and removal exists

blood lactate concentration of no more than 1 mM during final 20 minutes of constant intensity exercise lasting at least 30 minutes

Question 25

what are 4 factors that impact lactate threshold? *

Answer 25

1. capacity of muscle to oxidize pyruvate
2. removal at renal and splanchnic removal sites
3. capillary density (how vascular)
4. reduced O2 content (how hypoxic)

Question 26

why do we measure lactate threshold? (3) *

Answer 26

1. sensitive indicator or aerobic training status
2. predicts endurance performance, greater accuracy than VO2 max
3. establishes effective training intensity geared to active muscles’ aerobic metabolic dynamics