Diaphragm + thorax: These two's actions allows the movement of air in and out of the lungs
Intercostal muscles: Two sets of muscles that join each rib to the next
Bronchal tree: Allows air passage into the lungs
Trachea: Aka. the windpipe => splits into two tubes called the bronchi (one for each lung)
Bronchioles: The smaller tubes of the trachea
Alveoli: The place where gas exchange takes place
Cartilage: Support airways and keep them open when we breathe in
Pleural membranes: Make a continuous envelope around the lungs => airtight seal
2 of 5
How the ventilation of the lungs work
Inhaling: The outer intercostals contract + pull ribs up, the muscles of the diaphragm contract and increase of the volume of the chest occurs. Air then enters the lungs
Exhaling: The outer intercostals relax + internal intercostals constrict => ribs pull down and in. Diaphragm muscles relax + diaphragm goes back to its original shape.
3 of 5
How gas exchange occurs in the alveoli
Alveoli must have a structure that brings air and blood very close together over a very large surface area
Blood is pumped from heart to lungs + passes through capillaries surrounding the alveoli
The blood has come in from the respiring tissues of the body where it has given up some of its oxygen to cells + gained carbon dioxide
Around lungs, blood is separated from air inside each alveolus by two cell layers (cells making up wall of alveolus and capillary wall itself)
Because air in alveolus has higher conc. of oxygen than blood entering the capillary network => oxygen diffuses from air across wall of alveolus and into the blood
At same time there is more carbon dioxide in blood than in lungs => means there is a diffusion gradient for carbon dioxide in the other direction => carbon dioxide diffuses the other way, out of blood and into the alveolus
Blood which has flown through capillaries + heart gains oxygen + loses CO2
4 of 5
The effects of smoking on lungs and tissues
Is linked to emphasemia, lung caner and bronchitis, alongside being a contributer to coronary heart disease
In the tranchea and bronchi of a smoker, cilia are destroyed by chemicals in cigarette smoke => reduced no. of cilia
Reduced no. cilia means mucus is not swept away from lungs but remains to clog air passages
Emphysema => Greatly reduces surface area for gas exchange => becomes inefficient
Blood of a person with emphysema carries less oxygen -> may be unable to carry out exercise
Carbon monoxide => enters the bloodstream and interferes with the ability of carrying oxygen in the blood
Combines with the haemoglobin in the blood to form carboxyhaemoglobin => carries carbon monoxide in preference to oxygen => less gas exchange
Comments
No comments have yet been made