3.2 Human Gas Exchange Flashcards
What is the order of the human gas exchange structures?
Trachea
Bronchi
Bronchioles
Alveoli
How do humans achieve a high surface area in the lungs?
Millions of alveoli
How are alveoli adapted to increase the rate of gas exchange?
Walls are one cell thick to provide short diffusion pathway
What process increases the concentration gradient in the lungs?
Breathing
How does breathing increase the concentration gradient in the lungs?
Pulls fresh oxygenated air into the lungs
Why is having a good blood flow advantageous for human gas exchange?
Blood at the lungs is always low in oxygen
How do humans inhale?
External intercostals contract and internal intercostals relax
Diaphragm contracts and pulls downwards
The space in the thoracic cavity increases
What happens to the pressure inside the thoracic cavity during inhalation?
Decreases so air rushes in from the atmosphere
What does decreased pressure in the thoracic cavity create?
A pressure gradient between the atmosphere
How do humans exhale?
Internal intercostals contract and external intercostals relax
Diaphragm relaxes and moves upwards
The space inside the thoracic cavity increases
What is the forced expiratory volume?
The greatest volume of air a person can breathe out in one second
What is vital capacity?
The greatest volume of air a person can breathe in/out in a single breath
What is residual volume?
The air that never leaves the lungs no matter how an individual exhales
What is the piece of equipment that can be breathed into to measure breathing?
Spirometer
What is tidal volume?
The normal volume of air pulled in/out of the lungs when breathing
How can pulmonary ventilation rate be calculated?
tidal volume x breathing rate
How does an asthma attack affect the lungs?
Muscles walls of bronchioles contract
Walls of bronchioles secrete more mucus
Diameter of airways reduced
Flow of air reduced
Emphysema causes the forced expiratory volume to be reduced due to alveoli merging in the lungs - how does this cause problems?
Less CO₂ removed
Less oxygen absorbed into the blood
Less respiration to provide ATP for muscle contraction
Why would merging alveoli cause forced expiratory volume to go down?
Reduced surface area
Why would a thickened alveoli wall cause reduced gas exchange?
Longer diffusion pathway
The elasticity of lungs can be reduced by lung disease - why is this a problem?
Lungs will not fully inflate during inhalation
Breathing out is no longer passive - have to force breath out
When using a sample to study lung diseases, what must be ensured about the sample size?
It is large enough to be representative
When using a sample to study lung diseases, what must be ensured about how long the study is done for?
Needs to be done for long period of time to see long term effects
When using a sample to study lung diseases, what must be ensured about human trials?
Double blind to avoid bias
