4.3 Gas exchange in mammals Flashcards
(24 cards)
What are three features an organism must have to maximise gas exchange ?
- A large SA:V ratio compared to the small SA:V ratio of an organism as a whole
- Thin, permeable membranes for short diffusion distance and allow free passage of substances
- Maintaining a steep concentration gradient
Where are the two lungs found in the human body?
Thorax/chest cavity
What do hairs in the nasal cavity do and what else does it do?
Trap dust particles and other pathogens, warms and moistens the air before it enters the lungs
What are three adaptations of the Trachea
- Walls of trachea contain cartilage which prevents the walls of the cartilage to collapse when we inhale
- Absence of a full ring of cartilage around the trachea allows food to pass down easily in the oesophogus
- Trachea walls are covered with ciliated epethelial cells and goblet cells.
What do goblet cells do?
They secrete mucus which traps dust and pathogens
What do ciliated epithelial cells do?
The cillia on the cell membrane beat to move the mucus up the throat, mucus then swallowed and dust particles and pathogens are digested by digestive enzymes in the stomach
What do the bronchi split into to?
Bronchioles
What do bronchioles do when their smooth muscle relaxes?
They widen allowing more air into the lungs
What do the bronchioles lead to ?
Alveoli
How are the alveoli adapted to maximise gas exchange ?
- Hundreds of millions of alveoli therefore providing a large SA:V ratio
- The wall of the alveoli and the surrounding capillaries are only one cell thick which allows for short diffusion distance
- Once blood is oxygenated, the blood is rapidly carried away from the alveoli via the capillaries ensuring a steep conc gradient, co2 is continuously brought to the alveoli in the bloodstream
Why dont the alveoli collapse ?
The alveoli is coated with a special phospholipid called lung surfactant which makes breathing easier
What are insects covered with which makes it difficult for gas exchange to occur
Exoskeleton made up of chitin
What are the small openings called on the surface of the exoskeleton ? (abdomen area)
- Spiracles
What are the spiracles controlled by ?
Sphincters
When are the sphincters open and when are they closed ?
OPEN - When the insect needs oxygen
CLOSED - When it doesn’t need oxygen
Why is it important the sphincters stay closed when it doesnt need oxygen
To prevent water loss
What to the spiracles lead to?
The trachea, which extend down and along the insects body and they are 1mm thick.
What are the trachae supported by to keep them open ?
Chitin spirals which hold the trachea open
What since next to no gas exchange can occur in the trachea, what do they branch off into?
Tracheoles
What is the difference between trachea and tracheoles
Tracheoles contain no chitin rings and are permeable to gases because of this.
How is there a short diffusion distance in gas exchange of insects ?
Very short distance between the tracheoles and the cells of the insect
How is there a large surface area for gas exchange in insects ?
- There a large amount of tracheoles which provide a large SA:V ratio
What is the link between high levels of activity in a insect and tracheol fluid
- When insects do high levels of activity, the cells respire anaerobically and produce lactic acid
- This lowers the water potential of the cells which causes the tracheol fluid to move into the cells.
- This means that more air can move into the tracheoles and there more of the tracheoles are available for gas exchange
Where are the gills kept on a fish
In the gill cavity covered by a bony flap called the operculum
