Topic 4.2- Gas Exchange Flashcards
How does gas exchange work in small organisms? How can it work like this?
They exchange gases mainly by simple diffusion.
They have a large SA to V ratio.
The diffusion distance between the outside and inside is short.
They metabolic demands of these organisms is less.
Small organisms don’t need gas exchange systems
What factors affect the rate of diffusion?
- The surface area, the bigger SA the more particles that can be exchanged at once.
- the concentration gradient, particles diffuse from high to low, the bigger the difference the faster this action occurs.
- the distance over which diffusion takes place, a shorter distance means diffusion can occur faster.
What makes for an effective gas exchange system in organisms?
- a large surface area allows for as many particles to move at once
- thin layers, walls, or membranes minimises diffusion distances
- a rich blood supply helps to maintain a steep concentration gradient as deoxygenated blood is always replacing oxygenated
- moist surfaces as diffusion takes place with gases in solution
- permeable surfaces that will allow for the free movement of particles
What are the adaptations of the alveoli?
Squamous epithelial cells are only 1 cell thick and make up the partially permeable membrane for alveoli.
Large surface area due to folding of the squamous epithelial cells.
They have a consistent good blood supply providing a consistent steep concentration gradient.
They have lung surfactant on the alveoli which helps diffusion to take place.
What are the cells which the line the alveoli called?
Squamous epithelial cells.
What is lung surfactant?
A phospholipid which stops the alveoli from collapsing and makes breathing easier
What are the endothelial cells?
They line the capillaries and are as well only 1 cell thick. The overall distance that gases travel to exchange is between 0.5 and 1.5 um
What is the elastic recoil of the cells?
There is elastic connective tissue between the capillaries and the alveoli. It stretches when you breath in and helps to force the air easier out of the lungs
Mass transport system
Is an arrangement of structures by which substances are transported in the flow of a fluid with a mechanism for moving it around the body
Inhalation
Breathing in
Exhalation
Breathing out
Describe the movement of the respiratory system during inhalation
Inhalation is an active nerdy using process.
The diaphragm contracts and as a result is flattened and lowered. The external intercostal muscles contact pulling the rib cage up and out,
These movement cause the volume of the chest cavity to increase which reduces the pressure.
The pressure within the chest cavity is now lower than the atmospheric air outside so air moves in through the trachea to equalise the pressure inside and out
What happens during exhalation?
Normal exhalation is a passive process.
External and internal intercostal muscles relax.
The diaphragm relaxes so it moves up into a dome shape. The elastic fibres around the alveoli relax and return to their normal length.
As a result the volume of the chest cavity decreases causing an increase in pressure. The pressure in the chest a pity is now higher than outside this draw air into the lungs.
What happens during forced expiration?
The internal intercostal muscles contract pulling the ribs down and in, the abdominal muscles contract forcing the diaphragm upwards. This increases the pressure in the chest cavity causing exhalation
How do the lungs protect themselves?
The trachea bronchus and bronchioles are lined with mucus that traps particles and pathogens.
Cilia sweep this mucus back up the throat and down your throat where stomach acid dissolves everything.
