Ventiliation of the lungs Flashcards
What is ventilation?
Air is moved in ad out of the lungs as a result of pressure changes in the thorax due to breathing movements
What does the rib cage do?
It provides a semi-rigid case within which pressure can be lowered
What is the diaphragm?
A broad, domed sheet of muscle in which forms the floor of the thorax
What lines the thorax?
Pleural membranes which surround the the lungs
What is the pleural cavity?
The space between and is usually filled with a thin layer of lubricating fluid
What is the function of the pleural cavity?
The membranes slide over eachother easily as you breath
What is inspiration?
Taking air in
What kind of process is inspiration?
It is a active process
What are the stages of inspiration?
- The diaphragm contracts, flattening an lowering.
- The external intercostal muscles contract, moving the ribs upwards and outwards and the sternum moves forwards.
- The volume of the thorax increases so the pressure in the thorax is reduced
What causes air drawn in?
The pressure is the thorax is lower than the pressure in the atmospheric air
How is air drawn in?
It draws in through the nasal passages, trachea, bronchi and bronchioles into the lungs
What is the result of air being drawn in?
The pressure inside and outside the chest is equal
What is expiration?
Breathing out
What type of process is expiration?
It is passive
What are the stages of expiration?
The muscles in the diaphragm relax so it moves up into its resting domed shape, the external intercostal muscles relax so the ribs move down and inwards under gravity and the elastic fibres in the alveoli return to their normal length
