2.46 The breathing system Flashcards
What does the thorax consist of?
-The ribs
-Intercostal muscles
- Diaphragm
- Trachea
- Bronchi
-Bronchioles
-Alveoli
-Pleural membranes
Why are the lungs so well adapted for gas exchange?
-Large surface area
-Thin walls
-Good ventilation with air (to maintain diffusion gradients)
-Good blood supply
What are the ribs?
Bone structure that protects internal organs like the lungs
What are the intercostal muscles?
Muscles between the ribs which control their movement causing inhalation and exhalation
What is the Diaphragm?
Sheet of connective tissue and muscle at the bottom of the thorax which changes the volume of the thorax which allows inhalation and exhalation
What is the Trachea?
Windpipe that connects the mouth and nose to the lungs
What is the Bronchi?
Large tubes branching off the trachea with one bronchus for each lung
What are the bronchioles?
Bronchi split off to form smaller tubes in the lungs connected to the alveoli
What is the Alveoli?
Tiny air sacs in which gas exchange takes place
What happens to the thorax when inhalation takes place?
-Diaphragm contracts and flattens
-The external set of intercostal muscles contract to pull the ribs out and up
-Increased volume in the thorax
-Decreased air pressure
-Air is drawn in
What happens to the thorax when exhalation takes place?
-Diaphragm relaxes and returns to its domed shape
-The external set of intercostal muscles relax to drop the ribs down and in
-Decreased volume in the thorax
-Increased air pressure
-Air is pushed out
How is the alveoli adapted towards increases rates of gas exchange?
-There are many rounded sacs which gives a very big surface area to volume ratio
-They are thin and single-celled which makes diffusion easier
-Ventilation leads to high levels of oxygen and low levels of carbon dioxide, makes a higher concentration gradient
-A good blood supply
