Gas Exchange in Humans Flashcards
How the alveoli are adapted for efficient gas exchange?
- Good ventilation - helps maintain steep diffusion gradient.
- good blood supply - maintains a steep concentration gradient for both carbon dioxide and oxygen.
- Thin layers - short diffusion distances
- Large surface area - needed for the amount of oxygen to be diffused into the body
how is the Alveoli adapted?
- gas exchange takes place
- diameter around 200-300 um
- consists of thin layers, flattened epithelial cells along with some collagen and elastic fibres
- elastic recoil of the lungs
What are alveoli?
Surfaces where gas exchange takes place
What is the diaphragm?
A layer of muscular tissue beneath the lungs
What is ventilation?
Breathing movements
What does it mean mammals have a large metabolic rate?
If mammals have a large SA:V ratio, it means they have lots of energy and can supply to the cells
what features does the nasal cavity have?
- a large surface area with a good bloody supply: this warms the air to body temperature.
- Hair lining: this secretes mucus to trap dust and bacteria protecting lung tissue from irritation and infection.
- Moist surfaces: increases humidity of the incoming air, reduces evaporation from exchange surfaces.
what is the Nasal cavity?
- after air enters the nasal cavity
- air enters the lung which is similar to temperature and humidity to the air
What do the trachea, bronchi and bronchioles do?
They are tubes which lead down into the alveoli, delivering oxygen and removing carbon dioxide
What are goblet cells?
(lining in the airways) - secretes mucus. This traps microorganism and dust particles which stops air reaching the alveoli.
What is cilia?
- They are hair liked structures on the surface of epithelial cells lining the airways.
- They beat the mucus secreted by the goblet cells.
- Upwards away from the alveoli towards the throat
prevents lung infection
What are elastic fibres?
- In the walls of the trachea, bronchi, bronchioles and alveoli help the process of breathing out
- they stretch and then recoil to push air out when exhaling.
What are smooth muscles?
- In the walls of trachea, bronchi and bronchioles
- they contract and relax depending on the level of activity.
How do smooth muscles act during exercise?
- They relax, making the tubes wider.
- less resistance to air flow and air can move in and out of the lungs more easily
What are cartilages?
- In the walls of the trachea and bronchi
- Its strong but flexible
stops the trachea and bronchi collapsing when you breath in - so the pressure drops
