gas system and ventilation in humans. Flashcards
state what is meant by ventilation.
it is also known as breathing. It involves moving air in and out of the lungs.
state all th structures of th human gas exhange system.
air passes from the nasal cavity, into the trachea. then into the bronchi, then bronchioles, and then the alveoli.
what are the majour muscles we use during exercise.
the internal intercostal muscles, external intercostal muscles, and diaphragm.
describe inhalation.
The diaphragm contracts.
The external intercostal muscles contract.
the volume in the thorax increases, and the pressure decreases.
Thus, air is forced into the lungs down a pressure gradient
describe exhalation/ expiration.
The diaphragm relaxes.
The internal intercostal muscles, contract.
the volume of the thorax decreases, and the pressure increases.
Thus, air is forced out of the lungs.
what are Alveoli?
Tiny air sacs which are found in our lungs.
describe the structure of an alveoli.
contains a one-cell thick layer of epithelial cells, which work together in order to form the alveolar epithelium.
describe the structure of the tissue sorrounding the alveoli.
wrapped around every alveolus, are mainly capillaries, which each consist of a one cell thick layer of endothelial cells.
what is the main site for gas exchange?
the alveolar epithelium.
describe how oxygen and carbon dioxide, diffuse through the alveoli.
When red blood cells (RBC), ass through a capillary next to the alveoli.
The high oncentration of oxygen in the alveolus, causes oxygen to diffuse into the blood.
The high concentration of CO2 inside the RBC, causes it to diffuse into the alveolus.
What are the 3 main features of an alveoli, which ensure efficient gas exhange.
- Alveolar epithelium only one-cell thick.( This means short diffusion pathway).
- The alveoli are numerous ( meaning they provide a large surface are, for rapid gas exchange)
- constant ventillation, and good blood supply. ( ensures a steep concentration gradient of O2 and CO2).
