Gas exchange in humans Flashcards
Where is the gas exchange system located?
The thorax
Describe what happens when we breath in?
- Air passes down trachea
- Trachea splits to form the two bronchi
- These tubes lead to the lungs
- Bronchi branch into smaller and smaller tubes called bronchioles
- At the end of each bronchiole there are alveoli
- These are the sight of gas exchange
What are the lungs surrounded by? (Clue: Pleural)
Pleural Membrane
What does the Pleural Membrane do? (Clue: Combined with pleural fluid)
The pleural membrane combined with pleural fluid forms a air tight seal and prevents the lungs sticking to thorax wall
What do the ribs do?
Help to protect the organs in the thorax
What do intercostal muscles do and where are they located?
- They are located between the ribs
- They are important in moving air in and out of the lungs
What does the diaphragm do?
Important in moving air in and out of the lungs
What is ventilation?
Process of moving air into and out of the lungs
What are the two types of ventilation (Clue: Breathing in and breathing out)
Inhalation and Exhalation
Describe the process of inhalation?
- Diaphragm contracts
- Intercostal muscles contract
- This causes the volume of thorax to increase and air pressure in thorax to fall
- Air pressure in the thorax is less than atmospheric pressure
- Air moves into lungs
Describe the process of exhalation?
- Diaphragm relaxes
- Intercostal muscles relax
- This causes the volume of thorax to decrease and air pressure in thorax to rise
- Air pressure in the thorax is more than atmospheric pressure
- Air moves out of lungs
Where does Gas Exchange in humans occur (Clue: Air Sacs)
Alveoli
How does oxygen diffuse in the alveoli? (Clue: Red blood cells)
Oxygen diffuses from the air into red blood cells, where it binds with haemoglobin for transport.
How does carbon dioxide diffuse in the alveoli? (Clue: Plasma)
Carbon dioxide, dissolved in the plasma, diffuses from blood into the alveolus
Why do alveoli have a large surface area? (Clue: Speed up diffusion)
Increases the rate of diffusion
What is each alveolus surrounded by and what do they do? (Clue: Speed up diffusion)
- Capillaries constantly carry deoxygenated blood to the alveolus and oxygenated blood away.
- This maintains a high concentration gradient and so speeds up diffusion
How thick are alveoli and what do they do? (Clue: Speed up diffusion)
- One cell thick
- Gases need to move a very small distance speeding up diffusion
What happens during exercise? (Clue: Breathing)
Our breathing rate increases
What happens when our breathing rate increases?
We excrete CO2 more rapidly
Why does are heart pump faster when doing exercise?
To supply more oxygen for aerobic respiration
How do we measure breathing rate?
- Count the number of breaths per minute at rest and for a minute after exercise. Then work out the difference.
How do we measure breathing depth?
- Use a spirometer
What does CORMS stand for?
Change (Dependant and Independant) Organism Repeats Measure (Equipment) Same (Fair test)
What makes tobacco addictive?
Nicotine
What is in tobacco that can alter the DNA and increase the risk of cancer?
Carcinogens
Carbon monoxide is in tobacco. What does this do when inhaled?
Carbon monoxide irreversibly binds to the haemoglobin forming carboxyhemoglobin
What does tobacco destroy which results in mucus production?
It destroys cilia which leads to an increase in mucus production. The mucus can’t be moved out of airways and so builds up causing smokers cough.
How is bronchitis caused by tobacco?
Caused by the build up of infected mucus in the bronchi and bronchioles
How is emphysema caused?
- Alveoli walls break down and fuse together
- This forms large irregular air spaces
- This decreases the surface area for gas exchange
- Less oxygen diffuses into the blood
