Gaseous Exchange Flashcards
(29 cards)
Describe one feature of the trachea that makes it suitable for gaseous exchange?
It has incomplete rings of cartilage to keep airways open when food is transported down the oesophagus
What prevents the rib cage causing damage?
Lubricative substance is secreted to stop friction between the rib cage and lungs during inflation and deflation
What is the bronchi wall composed from?
Majority cartilage and epithelial layer
What is cartilage composed of?
‘loose tissue’: including glandular tissue, connective tissue, elastic fibre and smooth muscle)
What is the epithelial layer of the bronchi composed of?
Ciliated epithelium and goblet cells
What is the bronchioles made up of? (The wall)
Smooth muscle and elastic fibres
What do larger, and smaller, bronchioles contain?
Larger - contain cartilage
Smaller - have alveoli at the end
What are features of the alveoli that reduce diffusion distance?
- one cell thick wall
- surrounded by capillaries
What feature of alveoli maintain a steep concentration gradient?
A constant blood supply through capillaries
What feature of alveoli means they have a very large surface area?
Over 300 million of them
What is the function of cartilage?
To prevent the lungs from collapsing during exhalation by supporting the trachea
What is the function of ciliated epithelium?
Moving mucus from the lungs up the throat to prevent infection
What is the function of goblet cells?
To secrete mucus to trap dust and bacteria to prevent infection (also contains lysosomes to digest bacteria)
What is the function of smooth muscle?
Constricts the airways to control the flow of air to and from the alveoli
What is the function of elastic fibres?
To stretch during exhalation and recoil during inhalation to control the flow of air
What is ventilation?
The flow of air in and out of the alveoli
What happens during inhalation with the intercostal muscles?
External intercostal muscles contact
Internal intercostal muscles relax
What does the rib cage do during inhalation?
Raises upwards
What does the diaphragm do during inhalation?
It contracts (flattens)
What occurs during inspiration (pressure wise) and what does this mean?
- volume in the thorax increases so pressure lowers
- difference between pressure inside the lungs + atmospheric pressure creates a gradient + forces air into the lungs
What do the intercostal muscles do during expiration?
- external intercostal muscles relax
- internal intercostal muscles contract
What does the rib cage do during expiration?
The rib cage lowers
What does the diaphragm do during expiration?
The diaphragm relaxes and lifts
What does the pressure do during expiration + what does this mean for airflow?
- decreases the volume inside the thorax + increases pressure
- difference between the pressure inside the lungs + atmospheric pressure creates a gradient + forces air out of the lungs
