-The diaphragm contracts/flattens/lowers
-The external intercostal muscle contract
-The ribs move upwards and outwards
-Volume of thorax increases
-The volume in thorax reduces
-Air is drawn in through nasal passages
1 of 7
Expiration
-Diaphragm relaxes so it moves into resting shape
-External intercostal muscles relax
-The ribs move down and inwards
-Elastic fibres in alveoli return to their normal
-Decrease volume of thorax
-Pressure inside the thorax is greater than air out
2 of 7
Ventilating the lungs
-Air is moved in and out of lungs=pressure
-The rib cage provides a semi-rigged case
-Diaphragm is a broad, domed sheet of muscle
-Thorax is lined with by the pleural membranes
-membranes slide over each other because they are fluid
3 of 7
Alveoli
-Tiny air sacs, which are the main gas exchange
Layer of thin, flattened epithelial cells
-Collagen and elastic fibres are also present
-Elastic tissue allows alveoli to stretch
-When they return to their size they squeeze air out.
4 of 7
Adaptions of alveoli
- Large surface area
-Thin layers: short diffusion pathway
-Good blood supply: maintain concentration gradient
-Good ventilation: maintains steep concentration gradient
5 of 7
Bronchus
-Chest cavity the trachea divides to form the left bronchus (left lung)
-Also forms a right bronchus (Right lung)
-Similar in structure to the trachea
-They have rings of cartilage supporting them
6 of 7
Bronchioles
-Bronchus divides to form bronchioles
-They have no cartilage rings
-The walls consist of smooth muscle
-When the smooth muscle contracts ,bronchioles constrict (close up)
-When it relaxes, bronchioles dilate (open up)
7 of 7
Other cards in this set
Card 2
Front
Expiration
Back
-Diaphragm relaxes so it moves into resting shape
-External intercostal muscles relax
-The ribs move down and inwards
-Elastic fibres in alveoli return to their normal
-Decrease volume of thorax
-Pressure inside the thorax is greater than air out
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