Human Respiratory System
- Large organisms require specifically adapted gas exchange surfaces to make sure that oxygen can be delivered to respiring cells at a fast enough rate
- The human respiratory system is adapted to
- take in sufficient oxygen to support aerobic respiration
- remove the carbon dioxide that is produced during respiration
Structures of the human respiratory system diagram
The main structures of the human respiratory system
Structure & function table
| Structure | Function |
| Nasal cavity |
Interior of the nose Humidifies and warms inspired air and removes airborne particles and debris before the air reaches the lungs |
| Lungs | Pair of organs enclosed in the thorax is required for breathing |
| Trachea |
Windpipe that connects the nose and the mouth to the lungs Lined with goblet cells and ciliated epithelial cells |
| Bronchi (singular = bronchus) |
Large tubes branching off the end of the trachea Lined with goblet cells and ciliated epithelial cells |
| Bronchioles |
Smaller tubes that branch from the bronchi connecting to the alveoli |
| Alveoli |
Tiny air sacs surrounded by a network of capillaries The site of gas exchange between oxygen and carbon dioxide |
| Diaphragm | Sheet of connective tissue at the bottom of the lungs that helps change the volume inside the thorax allowing inspiration and expiration |
| Ribs |
Bone structures that surround and protect the lungs. Aid in the action of breathing |
| Intercostal muscles | Muscles between the ribs that control the movement of the ribs, causing inspiration and expiration |
The function of mucus and cilia
- The passages down to the lungs are lined with ciliated epithelial cells
- Cilia cells have tiny hair-like structures 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 (named this because they are shaped like a goblet or cup)
- The mucus traps particles, pathogens like bacteria or viruses, and dust and prevents them from getting into the lungs and damaging the cells there
Cilia and mucus diagram
Mucus traps particles, dust and pathogens and cilia beat and push it up and away from the lungs
Examiner Tip
You need to be able to label the structures covered above in diagrams so do make sure you are confident in doing this on a range of diagrams
