Ch6 Gas exchange

Question 1

Mammalian gas exchange efficiency

Answer 1

1. cartilage rings keep airway open
2. wide trachea with branching bronchi for efficient flow of air
3. intercostal muscles and diaphragm ventilate lungs to maintain diffusion concentration gradient
4. many alveoli walls and blood capillaries provide large SA
5. walls of alveoli and capillaries thin for short diffusion pathway
6. walls of alveoli and capillaries have flattened cells(squamous epithelium)
   7.cell membrane permeable to gases

Question 2

Human inspiration

Answer 2

1. internal intercostal muscles relax
2. diaphragm relaxes
3. external intercostal muscles contract
4. ribcage pulled up and out
5. pressure decrease in thoracic cavity
6. volume increase
7. air enters lungs down pressure gradient

Question 3

Human expiration

Answer 3

1. internal intercostal muscles contract
2. diaphragm contracts
3. external intercostal muscles relax
4. ribcage moves downwards and inwards
5. pressure increase in thoracic cavity
6. volume decrease
7. air exits lungs down pressure gradient

Question 4

Pulmonary ventilation rate

Answer 4

tidal volume x breathing rate

Volume of air taken in in 1 minute

Question 5

Diffusion formula

Answer 5

SA x concentration difference / length of diffusion path

Question 6

Insect gas exchange efficiency

Answer 6

1. spiracles open to allow diffusion of oxygen
2. tracheoles are highly branched so large SA
3. tracheole walls are thin so short diffusion pathway
4. tracheole walls are permeable to oxygen and close to cells
5. exoskeletons are impermeable so reduce water loss
6. maintained diffusion gradient in trachea
7. ventilation replacing air in tracheae

Question 7

Fish gas exchange efficiency

Answer 7

1. many filaments and lamellae for large SA
2. large number capillaries maintains diffusion gradient
3. thin epithelium in lamellae wall so short diffusion pathway
4. counter-current flow
5. circulation replaces blood saturated with O2
6. ventilation replaces water as O2 is removed

Question 8

Fish counter-current principle

Answer 8

1. water always meets blood with higher oxygen concentration
2. concentration gradient maintains along the entire gill
3. more oxygen diffuses into blood

Question 9

How fish maintains flow of water

Answer 9

1. mouth opens, operculum shuts
2. floor of mouth lowered
3. water enters due to decreased pressure
4. mouth closes, operculum opens
5. floor raised causes increased pressure
6. increased pressure forces water over gills

Question 10

Water loss in insects

Answer 10

1. exoskeletons are impermeable so reduce water loss
2. spiracles can close valves so no water loss
3. hairs around spiracles reduce water loss

Question 11

Insect diffusion gradient

Answer 11

1. cells respire
2. oxygen concentration at end of tracheoles decreases
3. gaseous oxygen diffuses from atmosphere along trachea and tracheoles to cells
4. down concentration gradient

Question 12

Insect mass transport

Answer 12

1. muscles contract
2. trachea is squeezed
3. mass movement of air in and out

Question 13

Insects tracheole water

Answer 13

1. anaerobic respiration produces lactate
2. lowers water potential in muscle cells
3. via osmosis, water moves into cells from tracheoles
4. water volume in tracheoles decreases
5. air is drawn into tracheoles down pressure gradient
6. greater water evaporation

Question 14

Tidal volume

Answer 14

Volume of air taken in by one breath in resting conditions

Question 15

Water loss plants

Answer 15

1. Waxy cuticle impermeable to water
2. sunken stomata in pits traps layer of air, maintaining humidity
3. stomata can close, reducing area for evaporation
4. hairs traps layer of air, maintaining humidity

Question 16

How oxygen in the air reaches capillaries

Answer 16

1. trachea and bronchi and bronchioles
2. down pressure gradient
3. down diffusion gradient across alveolar epithelium
4. across capillary endothelium