Unit 2.2 Adaptations for Gaseous Exchange Flashcards
How are single celled organisms able to obtain certain substances such as gases, water and nutrients?
(3 things)
- Diffusion
- Osmosis
- Active transport through cell membrane
As an organism becomes larger…. sa?
Surface area to volume ratio becomes smaller
Disadvantage of smaller surface area to volume ratio?
(4 things)
- Outside surface not large enough
- To let gases and nutrients to enter body
- Fast enough to keep all it’s cells
- Alive
Who does and who doesn’t require specialist exchange surfaces?
Does: Large organisms
Doesn’t: Small organisms
3 examples of specialist exchange surfaces?
- Fish gills
- Alveoli in lungs
- Villi in small intestine
4 common features in all exchange surfaces?
- Large surface area
- Thin barrier
- Has method of maintaining steep con. gradient
- Permeable to respiratory gases
State the SA to V ratio size of:
1. Unicellular organisms
2. Multicellular organisms
- Large
- Even smaller (or just say small bruh)
Why doesn’t a unicellular organism not need a specialist exchange surface?
(2 things)
- Their cell membrane is the gas exchange surface
- it’s a single cell = large sa to v ratio = no need buddy
What happens if unicellular organism increases in size?
(4 things)
- SA to V ratio decreases
- Distance gases have to diffuse = greater
- Until point diffusion across cell surface membrane
- Is tooooooo slow
What it mean for multicellular organisms having a smaller SA?
(4 things)
- Higher rate of metabolism
- = req. more O2 to satisfy needs
- Has evolved specialist gaseous exchange mechanics
- Where adequate grads. for diffusion can be maintained
Why are most gaseous exchange systems located inside the organism?
Most gaseous exchange surface are very delicate and req. protection
Why did flatworms evolve into a flattened shape?
(4 things)
- Overcome problems with increasing size
- Increases SA to V ratio
- Ensures no part of body far from surface
- Maintaining short diffusion pathway
Why did earthworms evolve into tubular and elongated shapes?
(2 things)
- Elongated provides large SA to V ratio
- So no need specialist surface for gaseous exchange
Look in page 4 if concerned with less info on lame earthworms
Okay
Explain an insects gaseous exchange system
(7 things)
- Has one cuz they got small SA to V ratio; can’t use their body surface
- Has unique gaseous exchange system
- Which occurs through a series of small holes
- Called spiracles running along the side of body
- Spiracles lead to system of air-tubes called tracheae
- Spiracles can open & close and can be shut
- To reduce water loss when necessary
What in insects gaseous exchange system is where O2 is delivered to cells?
Tracheoles
Why can the tracheal method of gaseous exchange limit the potential size of insects?
- Insect increase in size = SA to V ratio decrease
- O2 reqs. increase meaning trachea must be
- Much longer and wider to meet O2 demand
- Creates crowding within insect
What 2 things gas exchange surfaces need to be?
(seems kinda weak bruh)
- Thin
- Permeable with a large surface area
Explain gaseous exchange system in amphibians?
(8 things D:,’ )
- Takes place through skin and lungs
- Skin moist + permeable
- with well-developed network of capillaries below surface
- Skin alone efficient for gaseous exchange when
- Animal resting
- Lungs = simple elastic sacs w/ good blood supply
- No rib cage/diaphragm to provide ventilation
- Air forced inside by movements of floor of mouth
Explain gaseous exchange system in reptiles?
(4 things)
- More complex internal breathing system than amphibians
- Better suited to terrestrial life
- Has rib cage similar to that of
- Mammals surrounding lungs and providing ventilation
Explain gaseous exchange system in birds?
(5 things)
- Breathing system similar to reptiles & mammals
- But more efficient to allow **more O2 to reach
- Respiring tissues**
- Lungs supplemented by system of air sacs
- Acts like bellows blowing air into lungs
Describe the gills or summin
(5 things)
- Most fish have 4 gills on each side
- Supported by gill arch
- Along each arch are filaments
- Along each filaments are tiny plates called
- Lamellae (that’s where gaseous exchange take place)
What u see if lamellae outside of water?
Stick together = very difficult to identify
Explain gaseous exchange of gills?
(5 things, wow 5th time not actually)
- Gotta have large SA to provide fish
- Necessary O2 demands
- Err **water = 4-8 parts per mil of
- Dissolved O2** which gills can extract
- No large SA = suffocation
Advantage of cold blooded animals having lower metabolism?
- Aids in ability to handle environments
- Of low available O2
What is the operculum?
Outer skin flap that protects gills
Steps of ventilation of gills ig?
(6 steps)
- Mouth opens
- Vol of buccal cavity inc.
- Water pulled in from outside
- Mouth closes & buccal cavity contracts
- Water forced through gills into gill cavity
- Forces open the operculum
Explain parallel flow mechanism
(5 things)
- Blood flows in same direction as
- Water passing thru gills
- Not efficient
- Doesn’t maintain steep diffusion gradient
- Along whole length of gills
Main reason parallel flow mechanism not efficient?
When equilibrium reached, diffusion stops, no maximum amount of O2 taken
Explain counter current mechanism
(4 things)
- Water flows opposite direction to blood flow
- Helps maintain steep diffusion grad.
- Across whole length of gills
- Way efficient
Main reason why counter current mechanism efficient?
(3 things, why i make complex?)
Equilibrium never reached, diffusion constantly taking place
- Allows maximum amount of O2 to diffuse into blood
- From water available
Look at page 12 for tables of both mechanisms which u know I WISH BRAINSCAPE IMAGES WERE FREE
True
Look at page 16 for labelled diagram of human respiratory system
okay….
Explain how are alveoli adapted for efficient gaseous exchange
(4 steps)
- Walls 1 cell thick - short diffusion path
- Moist walls - gases dissolve in moisture, help pass cross gas exchange surface
- Extensive blood supply - Ensures O2 rich blood taken away from lungs
and CO2 rich blood taken to lungs - Large diffusion gradient - Breathing ensures O2 conc. in alveoli higher than capillaries;
So O2 moves from alveoli to blood and CO2 diffuses in opposite direction
If i started 3 days ago, perhaps i could’ve managed to write the last 2 topics remaining in this booklet
Tragic
