**4.3 Gas exchange** Flashcards
1
Q
Alveoli
A
- Air sacs found at the end of bronchioles which provide larger SA.
2
Q
Bronchi
A
- 2 airways branching out from trachea, leading to smaller bronchioles.
3
Q
Bronchioles
A
- Branch from bronchi and end at alveoli.
4
Q
Buccal cavity
A
- Space in mouth of bony fish.
5
Q
Counter current flow
A
- Adaptation for gaseous exchange in bony fish.
- Blood in gill and water go in opp directions.
- Maintains steep O2 conc. gradient.
6
Q
Diaphragm
A
- Large sheet of muscle under lungs to create pressure changes for ventilation.
7
Q
What happens during expiration (diaphragm, ribs, thorax, air)?
A
- Diaphragm relaxes and resorts to dome.
- External intercostal muscles relax, ribs move in + down.
- Volume of thorax decreases + thoracic pressure exceeds air pressure.
- Air moves out of trachea.
8
Q
External intercostal muscles + what type of air movement are they involved in?
A
- Muscles found between the ribs on the outside.
- Forced + quiet inhilation.
9
Q
Gill filaments
A
- Small divisions in the gills in fish that extend off the gill arch.
10
Q
Gill lamellea
A
- Small protrusions on gill filaments to increase SA for gas exchange.
11
Q
Gill plates
A
- Large stacks of gill filaments.
12
Q
Goblet cells
A
- Specialised cells that secrete mucus onto trachea lining.
- Mucus traps harmful substances (e.g. microorganisms) preventing them from entering the lungs.
13
Q
Guard cells
A
- Usually found in pairs, specialised to control opening + closing of stomata.
14
Q
What happens during inspiration (diaphragm, ribs, thorax, air)?
A
- Diaphragm contracts + flattens.
- External intercostal muscles contract, moving ribs up + out.
- Volume of thorax increases + thoracic pressure falls below air pressure.
- Air moves into trachea.
15
Q
Internal intercostal muscles + what type of air movement are they involved in?
A
- Set of muscles between ribs on inside.
- Forced exhalation.
16
Q
Lenticels
A
- Porous + loosely packed sections of tissue found on surfaces of plants that allows for gas exchange.
17
Q
Opercular cavity
A
- Space exterior to gills which is below buccal cavity of bony fish.
18
Q
Operculum
A
- Bony flap which covers gills of fish.
19
Q
Sphincters
A
- Rings of muscles that surround the openings to spiracles.
- Control size of opening to maintain balance between gas exchange + water loss.
20
Q
Spiracles
A
- Small openings on the surface of insects that allow for exchange of gases with their environment.
21
Q
Stomata
A
- Small openings in leaves or stem of a plant that can be opened or closed by guard cells in response to varying conditions.
22
Q
Tracheae (insects)
A
- Tubes leading from spiracles to tracheoles.
23
Q
Ventilation
A
- Process of exchanging air between lungs + atmosphere.
24
Q
Where does gas exchange take place in mammals?
A
- Lungs.
25
What is Boyle's Law?
- Volume is inversely proportional to pressure.
26
Where does oxygen move from the alveoli via diffusion?
- Into capillaries.
27
How are alveoli and capillaries specialised?
- Large SA.
- 1 layer of flattened epithelial cells.
- Large conc gradient.
28
Insects have an exoskeleton, what does this prevent them from doing?
- Taking oxygen through their skin via diffusion.
29
How does oxygen enter insects?
- Through openings called spiracles that are opened + closed by sphincters.
30
Why does gas exchange not happen in the trachea of insects?
- Lined w/ rings of chitin ∴ impermeable.
31
Why do the trachea of insects have chitin rings?
- To stop trachea from collapsing.
32
What is the journey of gas in an insect?
- Spiracles.
- Trachea.
- Tracheoles.
33
Where does gas exchange occur in insects?
- Tracheoles.
34
What can happen in tracheoles that can slow down diffusion?
- Water can build up in the bottom.
35
How is water removed from the tracheoles in **active insects**?
- Lactic acid builds up in cells reducing their water potential.
- Osmosis —> water into cells.
- ∴ gas exchange can occur.
36
How do some **active** insects ventilate their respiratory systems?
- **Mechanical ventilation** - by pumping abdomen.
- **Air reserves**.
37
Why is gas exchange harder for fish?
- Water is more dense + contains less O2 than air does.
38
What are gills made of?
- Filaments covered in folds called lamellae.
39
How do gills not stick together?
- Continuous movement of water - increased SA.
40
What is the flap that covers the gills called?
- Operculum.
41
How does the process of gas exchange in fish occur?
- Floor of mouth opened + operculum closes.
- Floor of mouth raised to increase pressure (valves stops water escaping).
- Increased pressure forces operculum to open + water forced over gills.
42
How is a conc. gradient maintained between the water and capillaries in the lamellae?
- **Countercurrent exchange system**.
43
What is a **countercurrent exchange system** in fish?
- Water on gills and blood in gills flow in opposite directions.
- Maintains steep conc. gradient over entire gill filament.
44
What are the layers of a leaf?
- Waxy cuticle.
- Upper epidermis.
- Palisade mesophyll.
- Spongy mesophyll.
- Lower epidermis (guard cells + stomata).
45
What is the function of the waxy cuticle?
- Prevents water loss.
46
What is the purpose of the upper epidermis?
- Transparent it allow max. amount of sunlight through to cells w/ chloroplasts.
47
What is the purpose of the palisade mesophyll?
- Cells stacked vertically to fit as many as possible.
- These cells contain the most chloroplasts.
48
What is the purpose of the spongy mesophyll?
- Air spaces provide large SA for gas exchange.
49
What is the purpose of the lower epidermis (guard cells + stomata)?
- Guard cells control stomata to prevent excessive water loss.
- Guard cells thicker on side adjacent to stomata to enable opening + closing.
50
What are the 2 processes that plants undergo?
- Photosynthesis + respiration.
51
Do the stomata open or close during the day?
- Open - conditions favorable for photosynthesis.
- CO2 in, O2 out.
52
How do the stomata open?
- Ions (mainly K+) move into guard cells by active transport.
- Causes water to move in by osmosis due to water potential decrease.
- Causes cells to go turgid + swell ∴ stomata open.
53
What are **lenticles**
- Areas of loosely arranged cells which act as a pore to allow gas exchange in lignified (woody) plants.
