Chapter 7 - Exchange surfaces and breathing

Question 1

Why is diffusion insufficient for certain organisms ?

Answer 1

• Metabolic activity is too low
• Large SA:V ratio
• High metabolic demand

Question 2

What are the features of effective specialised exchange surfaces ?

Answer 2

• Large SA:V ratio
• Thin layers = distance between destination decreases
• Good blood supply
• Good ventilation = Maintains diffusion gradient

Question 3

What are the key structures of human as exchange systems ?

Answer 3

1 - Nasal cavity
2 - Trachea
3 - Bronchus
4 - Bronchioles
5 - Alveoli

Question 4

What are the adaptations of the nasal cavity ?

Answer 4

• Large SA:V ratio
• Good blood supply
• Covered with hair
• Moist

Question 5

What are the adaptations of the trachea ?

Answer 5

• Made of cartilage = wide, strong, flexible
• Incomplete rings = allows movement of food
• Lined with ciliated epithelial cells and goblet cells

Question 6

What are the adaptations of Bronchioles ?

Answer 6

• No cartilage rings
• Joined with smooth muscles
• Lined with thin layer of flattened epithelium

Question 7

What are the adaptations of Alveoli ?

Answer 7

• Large SA:V
• Thin layers
• Good blood supply
• Good ventilation
• Inner surface of Alveoli is covered in water, salts, and lung surfuctant

Question 8

How does Inspiration work ?

Answer 8

• Takes air in
• Energy using process
• Diaphragm contracts; flattens = external intercostal muscles contract = moves ribs upwards and out
• Pressure in thorax decreases = hence air os drawn in to equalise pressure

Question 9

How does expiration work ?

Answer 9

• Passive process
• External intercostal muscles = relax ribs = ribs move down = pressure increases = Air moves out

Question 10

How can ventilation be measured ?

Answer 10

1 - Peak flow meter
2 - Vitalographs
3 - Spirometer

Question 11

What are the components of a spirometer ?

Answer 11

1 - Tidal volume
2 - Vital capacity
3 - Inspiratory Volume
4 - Expiratory Volume
5 - Residual volume
6 - Total lung capacity

Question 12

How do you calculate Ventilation rate ?

Answer 12

VR = Tidal volume x Breathing rate

Question 13

How are gases exchanged in insects ?

Answer 13

• Oxygen is delivered directly to cells via spiracles
  1 - Air enters through openings known as spiracles between thorax and abdomen

However as gas enters water is lost hence spiracles only open during activity

2 - After spiracles there are tracheoles which are lined by spirals of chitin
3 - Tracheoles transport the gases to their required location

Question 14

What are the two other ways insects can transport gases ?

Answer 14

1 - Mechanical ventilation
2 - Collapsible enlarged trachea

Question 15

How does mechanical ventilation occur ?

Answer 15

• Air is actively pumped into the system by muscular pumping movements of thorax and/or abdomen
• Changes volume of the body = changes in pressure

Question 16

How does collapsible enlarged trachea work ?

Answer 16

• Air sacs and trachea act as air resevoirs
• Increases amount of air moved through the gas exchange system

Question 17

What are the three features of Discontinous Gas Exchange ?

Answer 17

1 - When spiracles are close = no gas exchange
2 - Spiracles flutter = open and close rapidly to move O2 and minimise water loss
3 - When CO2 levels increase spiracles open wide to release CO2

Question 18

Why do fish respire differently than other organisms ?

Answer 18

• Do not need to limit water supply
• Water is more dense and viscous than air hence fish need to cope with this

Question 19

What are some adaptations of gills ?

Answer 19

1 - Large SA:V
2- Good blood supply
3 - Thin layers needed for succesful gaseous exchange

Question 20

What is the structure of the gills ?

Answer 20

Gills are contained within gill cavity adn covered by operculum
- Gill lamella
- Gill filaments

Question 21

What is ram ventilation ?
Why is it necessary ?

Answer 21

• When fish swim they keep a current of water flowing over their gills
• Necessary as operculum must stay open in motion

Question 22

What is the first step to respiration without ram ventilation ?

Answer 22

1 - Mouth opens = Buccul cavity floor drops = increase in buccul cavity volume = decrease in pressure = Water moves into Buccul cavity

2 - Opercular valve is shut = Opercular cavity contiaining gills expands

3- Buccul cavity moves up = increase in pressure = causes water to flow over gills

Question 23

What is the last step to respiration without ram ventilation ?

Answer 23

1 - As the mouth closes, operculum opens = sides of the operculur cavity move inwards = increase in pressure on opercular cavity; forcing water over gills and out of operculum

2 - Floor of the buccal cavity steadily moves upwards = maintaining of flow of water over gills

Question 24

What are the adaptations of the structure of the gills ?

Answer 24

1 - Tips of adjacent gill filaments overlap which increases resistance to water slow over gill surfaces = slowing down of water movement

2 - Counter current between direction of water movement and blood flow causing a steep conc. gradient