Differentiate between internal and external respiration.
- External respiration is the exchange of gases with the external environment, and occurs in the alveoli of the lungs.
- Internal respiration is the exchange of gases with the internal environment, and occurs in the tissue respiratory membrane The actual exchange of gases occurs due to simple diffusion.
Can you list the four steps involved with oxygen transport
- Pulmonary ventilation
- Pulmonary diffusion
- Gaseous transport
- Capillary diffusion
Define diffusion
- Diffusion is the process by which atoms or molecules move from an area of high concentration to low concentration
What examples could you use to explain diffusion in human physiology?
- A tea bag immersed in a cup of hot water will diffuse into the water and change its colour.
- A spray of perfume or room freshener will get diffused into the air by which we can sense the odour.
Detail the mechanics of ventilation
- Divided into conducting zones, trachea.
- Transitional and respiratory zones, bronchioles, aleovli
- Ventilation, or breathing, is the movement of air through the conducting passages between the atmosphere and the lungs. The air moves through the passages because of pressure gradients that are produced by contraction of the diaphragm and thoracic muscles
• What is a common position assumed after strenuous exercise and how might this aid breathing?
- The tripod position
- muscles of the neck and upper chest work to get more air into the lungs. With the position of the arms secure, contraction of the pectoralis results in elevation of the anterior wall of the chest.
Define tidal volume, residual lung volume and forced vital capacity
- Tidal volume is the volume of air inhaled in a single, normal breath.
- while residual volume is the amount of air left in the lungs after forceful respiration
- Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inhalatio
Explain the function of residual lung volume in pulmonary function.
- it keeps the small airways open
- prevents the complete emptying of the lungs during each respiratory cycle.
- If there is no FRC, the alveolar PO2 and PCO2 will vary widely during breathing and will interfere with the diffusion of the respiratory gase
• Example common obstructive and restrictive pulmonary conditions and describe how these alter common spirometric tracings
- chronic obstructive pulmonary disease (COPD), asthma, and bronchiectasis.
- Your FEV1 will fall between 50 percent and 79 percent of the predicted normal values with an FEV1/FVC of less than 70 percent
What is FEV
Force expiratory volume
Identify the physical activity implications of gender differences in lung function measures.
- reduced airway diameter, and a smaller diffusion surface than age- and height-matched men.
- The volume of adult female lungs is typically 10–12% smaller
- Smaller vital capacity and maximal expiratory flow rates
Describe the relationship between pulmonary ventilation and exercise intensity.
- As exercise commences pulmonary ventilation (breathing) increases in direct proportion to the intensity and metabolic needs of the exercise
- resting values of around 5–6 litre min−1 to >100 litre min−
Define physiologic dead space.
- total dead space is equal to anatomic plus alveolar dead space which is the volume of air in the respiratory zone that does not take part in gas exchange
Detail how athletes maintain alveolar ventilation during intense aerobic exercise
Increases in the rate and depth of breathing
- . In moderate exercise, increasing tidal volume and only minimally increasing breathing rate
• Explain how, when and why the Valsalva maneuver alters blood pressure.
increase in intrathoracic pressure, leading to a reduction in preload to the heart. Cardiovascular changes occur during and after this maneuver due to baroreflex and other compensatory reflex mechanisms that are initiated by decreased preload.
- venous return to the heart is decreased and peripheral venous pressures become increased.
What is the pathway in which oxygen diffuses across the alveolar wall
partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. As a result, oxygen diffuses across the respiratory membrane from the alveoli into the blood
Pathway of oxygen from the air to the lungs
- Nostrils →→ Nasal Cavity →→ Pharynx →→ Trachea →→ Bronchi →→ Bronchiole →→ Alveoli.
List the 5 factors that govern the rate of gas diffusion into a liquid
- he partial pressure difference across the diffusion barrier.
- The solubility of the gas.
- The cross-sectional area of the fluid.
- The distance molecules need to diffuse.
- The molecular weight of the gas
Ambient air is made up of oxygen, carbon dioxide and nitrogen. Describe how their physical properties and solubility in different bodily fluids differ
- Carbon dioxide is more soluble in blood then oxygen
- Nitrogen as a low solubility in blood
- O2 is twice as soluble as N
How may alveolar gas transfer be impaired
- diffusion coefficient of the gas, which is influenced by: molecular size, temperature , fluid viscosity/chemical properties of the membrane
What is anaemia
- and how can it affect exercise performance
- a condition in which there is a deficiency of red cells or of hemoglobin in the blood, resulting in pallor and weariness.
- a reduction in oxygen-transport capacity of blood cells and a decrease in maximal consumption of oxygen peripheral
Define oxygen cascade
- The oxygen cascade describes the transfer of oxygen from air to mitochondria.
• Outline the relationship between the partial pressure of oxygen and the oxygen transport cascade.
- In each step of the cascade the PaO2 falls. It demonstrates that oxygen delivery to tissues relies on the passive transfer of gas
• What role does myoglobin pay in gas exchange
- it stores oxygen for use during heavy exercise, and it enhances diffusion through the cytosol by carrying the oxygen. By binding O2, myoglobin (Mb) provides a second diffusive pathway for O2 through the cell cytosol
