4. The Lungs and Lung Disease Flashcards
Why does carbon dioxide need to be removed from the body?
Because a build-up can be poisonous
Why are lungs located inside the body?
Because air is not dense enough to protect the delicate structures and they would otherwise lose lots of water and dry out
What is the function of the rib cage?
To support and protect the lungs
What are the lungs?
A pair of lobed structures made up of a series of bronchioles which end in tiny air sacs called alveoli
What is the trachea?
A flexible airway supported by rigs of cartilage to prevent collapse due to changes in air pressure
The walls are made of muscles lined with ciliated epithelial cells and goblet cells which produce mucus which traps dirt when it is breathed in
The cilia move the mucus up the throat towards the oesophagus, where it is passed down into the stomach
What are the bronchi?
Two divisions of the trachea each leading to one lung
Similar to the structure of the trachea
The amount of cartilage reduces as the bronchi get smaller
What are the bronchioles?
Branching sub-divisions of the bronchi
Walls made of muscle lined with epithelial cells
Muscle allows them to constrict to control the flow of air in and out of the alveoli
What are the alveoli?
Minute air sacs at the end of the bronchioles
Contain some collagen and elastic fibres which are lined with epithelium
Elastic fibres allow the alveoli to stretch
The alveolar membrane is the gas exchange surface
Read over the mechanism for breathing.
Done!
What is pulmonary ventilation?
PV = breathing rate x tidal volume
What is an average human tidal volume when at rest?
0/5dm^3
How many times does an average healthy adult breathe in and out?
12-20 times
What are the essential features of gas exchange surfaces?
Large SA:V ratio
Very thin
Partially permeable, to allow selected materials to diffuse easily
Movement of an envionmental medium e.g. air to maintain the concentration gradient
Movement of an internal medium e.g. blood
Why are specialised surfaces often easily damaged?
Because they are very thin - this is why they are often found inside of an organism. The organism must therefore have a way of moving the environmental medium over the exchange surface e.g. by vetilation
How do alveoli help maintain fast exchange of gases?
Red blood cells are slowed as they are passed through the pulmonary capillaries, so there is more time for diffusion
Red blood cells are flattened against capillary walls to shorten the diffusion pathway
Walls of alveoli and capillaries are very thin
Both have a very large total SA
Ventilation and a good blood supply maintain a steady concentration gradient
