Week 3 Gas Transport, Utilisation and Exchange

Question 1

Pulmonary function plays a key role in maintaining blood-gas homeostasis during exercise. What is the other key role?

Answer 1

Acid-base Homeostasis

Question 2

At rest what muscle contracts and relaxes to expire and inspire air? How does it work (using knowledge of the atmospheric pressure)?

Answer 2

The Diaphragm. It contracts and the ribs move up and out so the intrapulmonic pressure is less than 760mmHg. The opposite happens when expiring

Question 3

What happens during exercise that’s different from rest.

Answer 3

During exercise other muscles are involved to work such as muscle within the shoulder, and muscle in the back. This is no longer passiev

Question 4

Is the lung size of a sedentary individual and an athlete different? If so by how much?

Answer 4

No their lung sizes are quite similar.

Question 5

What is the typical value of a Maximum voluntary ventilation?

Answer 5

35-40*FEV1. It is typically only 25% higher than maximal levels of ventilation during max exrcise.

Question 6

What is the typical value of a Maximum voluntary ventilation?

Answer 6

35-40*FEV1. It is typically only 25% higher than maximal levels of ventilation during max exrcise.

Question 7

What’s the equation for Fick’s law of diffusion?

Answer 7

Rate of diffusion = area/thickness * gass diffusion coefficient * (p1-P2)

Question 7

What’s the equation for Fick’s law of diffusion?

Answer 7

Rate of diffusion = area/thickness * gass diffusion coefficient * (p1-P2)

Question 8

What are the partial pressures of the atmosphere?

Answer 8

02: 160mmHg, N2: 600mmHg, CO2: 0.2mmHg

Question 9

Alveolar air?

Answer 9

O2: 100mmHg, N2: 570mmHg, CO2: 40mmHg

Question 10

What are the O2 and CO2 partial pressures in the venous blood, the tissue, and arterial blood at rest?

Answer 10

Venous: PO2 40mmHg, PCO2 46mmHg
Tissue: PO2 40mmHg, PCO2 46mmHg
Arterial: PO2: 95mmHg, PCO2 40mmHg

Question 11

During exercise what happens to the pressure in the blood stream?

Answer 11

In the tissue the Oxygen levels would be even lower than 40 and CO2 will be higher. Therefore more difference in the pressure gradient causes more diffusion to go on. PO2 content in the arterial blood will stay the same.

Question 12

During exercise what happens to the pressure in the blood stream?

Answer 12

In the tissue the Oxygen levels would be even lower than 40 and CO2 will be higher. Therefore more difference in the pressure gradient causes more diffusion to go on. PO2 content in the arterial blood will stay the same.

Question 13

What does Henry’s Law indicate about the pulmonary system (2 main implications)?

Answer 13

1. Since blood temperature varies only a little, and the solubility coefficient doesn’t change, the major determinant of dissolved O2 is the partial pressure.
2. Solubility coefficient for O2 is much lower than CO2. Only a small amount of the O2 dissolves in the blood stream.

Question 14

What are the maximum amount of O2 per volume of blood in male and female?

Answer 14

Male = 200mlO2/L Blood
Female = 174mlO2/L Blood

Question 15

How much O2 can each completely saturated gram of Hb carry?

Answer 15

~1.34ml O2

Question 16

How do you maintain or increase Hb?

Answer 16

• intake iron, Do altitude training to stimulate body to produce more blood cells.

Question 17

Whats the difference in the arterial blood and venous blood HbO2 saturation at rest and during exercise?

Answer 17

only about 25%. For exercise its 90%.

Question 18

How does temperature affect the offloading of oxygen? Why is that useful.

Answer 18

At high temperature and low blood pH offloading is made easier. This is good because when muscles are working hard, oxygen is easily offloaded

Question 19

How does temperature affect the offloading of oxygen? Why is that useful.

Answer 19

At high temperature and low blood pH offloading is made easier. This is good because when muscles are working hard, oxygen is easily offloaded

Question 20

What is significant abou the small amounts of O2 dissolved in plasma?

Answer 20

1. Establishes the fluid pressure gradient

2. Helps regulate breathing in high altitude.

Question 21

Whats the percentage of CO2 transport?

Answer 21

Haemoglobin 20%, Bicarbonate 70%, plasma 10%

Question 22

What is the most contributing factor in a minute ventilation?

Answer 22

Breathing frequency. Small increase in tidal volume but its more about the breathing frequency.

Question 23

Wwhat happens in hyperventilation?

Answer 23

There is an excess demand in O2 therefore one breathes more leading to an excess Carbon Dioxide release, and a decrease in CO2 in the blood steam.

Question 24

What stimulates breathing response?

Answer 24

Decrease in pH

Question 25

In very well trained elite endurance athletes, “exercise-induced hypoxemia” occurs. What is it and why does it occur?

Answer 25

Partial pressure of Oxygen drops. Cardiac output is so high that the blood goes too fast to pick up oxygen.

Question 26

What causes ventilation homeostasis?

Answer 26

No single mechanism controls ventilation during exercise. SImultaneous effects of chemical and neural stimuli initiate and modulate exercise alveolar ventilation.

Question 27

At rest what provides intrinsic control to the respiratory muscles? What are the 2 main extrinsic inputs?

Answer 27

the medulla.

extrinsic inputs are the humoral and the neural (efferent and afferent)

Question 28

Explain the humoral input

Answer 28

Central chemoreceptors: Medulla detects increase in CO2 and H singing afferent signal to resp. control centre.
Peripheral chemoreceptors: Aortic and carotid bodies, detect changes in PCO2, H+, PO2 and K+ of arterial blood and send afferents to respiratory control centre

Question 29

Explain the neural input

Answer 29

Efferent stimulation: stimulus from the central commad when exercise starts. From motor cortex to muscles
Afferent stimulation: From proprioceptors (eg. muslce spindles), and pressure receptors in the joints. possibly also from chemoreceptors in muscle and mechanoreceptors from the atrium

Question 30

Does respiratory system limit aerobic capacity?

Answer 30

Usually considerable breathing reserve. CaO2 levels remain relatively stable at VO2max. Nasal strips doesn’t help to bring up VO2 max
but growing evidence may suggest that elite endurance athletes may feel fatigue in the respiratory muscle.

Question 31

Explain how much aerobic training can enhance pulmonary structure compared to the CV and neuromuscular system

Answer 31

There is less adaptation in the pulmonary structure compared to the CV and neuromuscular systems.

Question 32

How do individuals increase VO2 Max by 50% from training? (explain with the (a-v)O2 difference.

Answer 32

No because of greater arterial O2 rather it’s due to a decrease in Venous O2 content. This can be explained by a better distribution of oxygen by opening more capillaries and increasing the offloading period. It could also be explained by Mitocondrial volume (secondary importance