Gas Exchange Flashcards
Describe the structure of the thorax
When we move air in and out of our lungs, different parts in the respiratory system are used. When we breathe in, air enter the nose and mouth, before travelling down the trachea to the lungs. Tiny hairs called cilia cells help remove dirt and microorganisms. The air enters the lungs through the bronchi which branch and divide into bronchioles. At the end of the bronchioles are air sacs called alveoli. They are covered in tiny capillaries, and this is where oxygen and carbon dioxide are exchanged between the blood and air. Surrounding the lungs are the pleural membranes, they contain fluid that helps the lungs and intercostal muscles to Slide Over each other.
Describe the process of inhalation
- The diaphragm contracts and flattens
- The intercostal muscles contract, making the ribs move upwards and outwards
- This causes the volume of the thorax to increase
- This causes the air pressure in the thorax to decrease
- This decrease causes air to enter the lungs
Describe the process of exhalation
- The diaphragm relaxes
- The intercostal muscles relax
- This causes the volume of the thorax to decrease
- This cause the air pressure in the thorax to increase
- This causes air to be forced out of the lungs
How are alveoli adapted for gas exchange?
- Thin, permeable walls, to keep the diffusion difference to a minimum
- A moist lining
- A large surface area, there are millions of alveoli
- High concentration gradients, because blood is continually flowing through the capillaries around the alveoli
How does smoking cause addiction?
Nicotine in tobacco is highly addictive. It also alters peoples moods because it is a stimulant and a relaxant. These mood changes can also be addictive
How does smoking cause bronchitis?
The tar in tobacco smoke can form a black sticky substance in the lungs. The tar can coat the cilia cells and prevent them from clearing dust and microorganisms. As a result mucus can build up in the lungs, resulting in lungs infections and coughing and bronchitis
How does smoking cause emphysema?
Over time, the coughing from trying to clear tar can damage the alveoli, breaking down the divisions between them, reducing their surface area. This causes a disease called emphysema, where the patient can’t get enough oxygen in their blood.
How does smoking cause cancer?
Some chemicals in smoking are carcinogenic, which means they can cause cells to start dividing uncontrollably and cause cancer. Common cancers from smoking are in the mouth, throat and lungs.
How does smoking cause carbon monoxide presence?
Carbon monoxide can increase blood pressure. Carbon monoxide binds to the haemoglobin in RBCs making them unable to transport oxygen, and if too little oxygen reaches cells, they can start to die off. Pregnant women can also pass on the carbon monoxide to their babies, hindering their rate of growth.
How does smoking cause coronary heart disease?
Some chemicals in tobacco cause cholesterol to be released into the blood. When the lining of the blood vessels has been irritated by the smoke, the cholesterol can attach to the lining and cause thickening and blood clots. If a blood clot travels to the brain, it can cause a stroke. If there is a blood clot in a coronary blood vessel, it can cause coronary heart disease.
Investigate the effect of exercise on humans
- Get 4 people and record their breathing rate (breaths/minute) at rest.
- Have those 4 people run on the treadmill at the same speed or do some other form of exercise for two minutes.
- Record their rate of breathing immediately after the 2 minutes
- Then calculate the average difference between resting and after exercising
Investigate the release of carbon dioxide in humans
- Set up two test tubes, both with delivery tubes in bungs and limewater in the bottom
- In one of the tubes exhale into it several times, it will turn cloudy in the presence of carbon dioxide.
- If you leave the other tube of several minutes, then it too will turn cloudy, but much slower, showing that there is a lot higher concentration of CO2 in exhaled air than in inhaled.
