Exchange surfaces Flashcards
List the orders of magnitude
pm, nm, um, mm, cm, m,
4 features that effective exchange surfaces have
Increased SA- provides area needed for exchange and overcomes the limitations of SA:V ratio of larger organisms
Thin layers- distance substances have to diffuse are short making the process and efficient
Good blood supply- the steeper the conc gradient the faster diffusion takes place. Having good blood supply ensures substances are constantly delivered and removed (maintains a steep conc gradient for diffusion).
Ventilation to maintain diffusion gradient- for gases ventilation systems help maintain conc gradient (i.e the flow of water carries dissolved substances)
Bronchioles adaptation
The walls contain smooth muscle (contracts, bronchioles constrict, close up). When relaxes they dilate, open up
They’re lined with a thin layer of flattened epithelium, making some gaseous exchange possible.
Bronchus adaptation
In chest cavity the trachea divides to form 2 bronchi.
Similar in structure to the trachea, same supporting rings of cartilage but smaller.
Nasal cavity adaptation
Hair lining- secrets mucus traps dust and bacteria, protecting delicate lung tissue from irritation and infection
A large SA with good blood supply, warms the air to body temp, so the air that entering the lungs is similar to to the temp and humidity of the air there.
Moist surfaces increases humidity of incoming air, reducing evaporation form exchange surfaces
Trachea adaptations
Wide tubes supported by incomplete rings of strong flexible cartilage to stop collapsing. Rings incomplete (food move easily behind the oesophagus, no friction).
The trachea and its branches are lined with ciliated epithelium, where the goblet cells between below the epithelial cells, which secrete mucus onto lining trachea, trap microorganisms, dust that escaped nose lining.
Cilia beat a move/whaft the mucus with trapped dirt and microorganisms from the lungs. Must go to the throat and is swallow and digested
Why is keeping the exchanges surfaces moist and humid important?
The Inner layer surface of alveoli covered in layers of solution of water salts and lungs surfactants. Surfactants Makes it possible for alveoli to remain inflated. But oxygen dissolved into water before diffusing into blood and water can evaporate into the air in the alveoli (needs to be reduced as much as possible).
Alveoli adaptation (SA)
Light surface area, 300 to 500 million per adult. Not enough oxygen would be delivered if they were balloon like structures (importance of SA:V)
Alveoli adaptation (size)
Thin layers, alveoli, capillaries have walls that are one single epithelium cell thick. Therefore the diffusion distance is as short as possible
Alveoli adaptation (good ventilation)
Reading news are in an out of the alveoli helping maintain a steep diffusion gradient for oxygen and carbon dioxide in the air and blood
Alveoli adaptation (Good blood supply)
Constant flow of blood through capillaries allows them to bring carbon dioxide and carry off oxygen, maintaining a steep concentration gradient for both carbon dioxide and oxygen between the air in the alveoli and blood in the capillaries
Alveoli
- Tiny air sacs, main gas exchange surfaces of the body
- Consists of a layer of thin flattened epithelial cells with some collagen and elastic fibres (composed of elastin).
- These elastic tissues allow the alveoli to stretch as egg is drawn in and when returning to their normal/ resting size they help squeeze air out (elastic recoil).
Diffusion
Diffusion is the net movement of particles
From an area of higher concentration to an area of lower concentration
Down a concentration gradient
Until equilibrium is reached
Lung function- Spirometry
Spirometers is a pulmonary function test (PFT)
It is used to measure 2 things relating to inhalation and exhalation of air:
-Volume
-Speed (flow)
