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Flashcards in gas exchange Deck (14)
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List the features of the gas exchange surfaces in humans-

Large surface area to allow faster diffusion of gases across the surface
Thin walls to ensure diffusion distances remain short
Good ventilation with air so that diffusion gradients can be maintained
Good blood supply to maintain a high concentration gradient so diffusion occurs faster


Where does the gas exchange takes place?



State the function of cartilage in the trachea.

support the airways and keep them open during breathing
If they were not present then the sides could collapse inwards when the air pressure inside the tubes drops


Describe the function for cilia and mucus ?

- ciliated cells have tiny hairs on the end of them that beat and push mucus up the passages towards the nose and throat where it can be removed
The mucus is made by special mucus-producing cells called goblet cells
The mucus traps particles, pathogens like bacteria or viruses, and dust and prevents them getting into the lungs and damaging the cells there


What controls the ventilation in lungs ?



Describe the ventilation while inhalation ?

- external intercoastal muscles contracts
- rib cage moves up and out
- diaphragm contracts and flattens
- pressure inside thorax decreases
- air is drawn in


Describe the ventilation while exhalation?

- external intercoastal muscles relax
- rib cage moves down and in
- diaphragm relaxes and becomes dome-shaped
- pressure inside thorax increase
- air is forced out


What does exercise increase?

frequency and depth of breathing


Explain the effect of exercise on breathing?

This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid
After exercise has finished, the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalyzing cell reactions
It can only be removed by combining it with oxygen – this is known as ‘repaying the oxygen debt’
This can be tested by seeing how long it takes after exercise for the breathing rate and depth to return to normal – the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid


Carbon Dioxide Concentration & the Brain

As respiration rates increase, more carbon dioxide is produced and enters the blood
Carbon dioxide is an acidic gas in solution and so it can affect the working of enzymes in the cells and needs to be removed as quickly as possible
As blood flows through the brain, the increase in carbon dioxide concentration stimulates receptor cells
These send impulses to the muscles of the lungs, causing them to contract faster and more strongly
This causes the frequency and depth of breathing to increase until the carbon dioxide concentration of the blood has lowered sufficiently



inhale- 21%
exhale- 16%
explanation- oxygen is removed by the respiring cells making the returning blood having lower concentration of oxygen in it.


COMPOSITION OF AIR- carbon-dioxide

exhale- 4%
explanation- CO2 is produced due to respiration happening in the respiring cells which diffuses into the blood



inhale- LOWER
exhale- HIGHER
explanation- water evaporates from the moist lining of the alveoli as a result of the warmth of the body



inhale- 78%
exhale- 78%
explanation- nitrogen gas is very stable , so it cannot be used by the body so the concentration of inhalation and exhalation remains the same.