Chapter 7 Flashcards
1
Q
How is gas exchange in single celled organisms?
A
simple diffusion
- adapted with small diffusion distance
- large SA:V ratio
- high concentration gradient
2
Q
What is the tracheal system of an insect?
A
PASSIVE
- spiracles (holes) on body open/close to allow oxygen in /prevent water loss
- spiracles lead to tracheal tubes which divide into tracheoles which take oxygen to each body cell
3
Q
What is the gas exchange system in fish?
A
- gills
- gill filaments stacked
- gill lamellae project at right angles to increase surface
- one cell thick for short diffusion distance
- covered in capillaries for high concentration gradient
- counter-current flow maintains gradient as oxygenated water always passes over deoxygenated blood
4
Q
How are leaves adapted for gas exchange?
A
- stomata open/close by guard cells to let oxygen in/ keep water in - short diffusion path
- spaces between mesophyll for short diffusion distance
- mesophyll cells have large SA:V
5
Q
How are xerophytes adapted to dry conditions?
A
- few stomata
- small/spine-like leaves
- sunken stomata
- hairs to trap water
- thick waxy cuticlal
- small SA:V ratio
6
Q
What is the human gas exchange system?
A
trachea - bronchi - lungs - bronchioles - alveoli
7
Q
What does the ribcage do during breathing?
A
- inspiration (in) external intercostal muscles contract = ribcage up and out decreasing pressure increasing volume forcing air in
- expiration (out) internal intercostal muscles contract = ribcage down and in increasing pressure dereasing volume forcing air out
8
Q
What is the structure of the trachea?
A
- rings of cartilage prevent it collapsing
- walls lined with ciliated epithelium and goblet cells
- goblet cells produce mucus to trap bacteria and dirt
9
Q
What is the structure of the bronchi and the bronchioles?
A
Bronchi
- 2 divisions of trachea
Bronchioles
- branching sub divisions of bronchi
- walls lined with muscle and epithelial tissue
10
Q
What is the structure of alveoli?
A
- air sacs at end of bronchioles
- constant blood supply maintains concentration gradient
- site of gas exchange
- large SA:V ratio
- one cell thick
11
Q
How does the diaphragm aid gas exchange?
A
- flattened during inspiration to increase volume and decrease pressure - forces air in
