Gas Exchange - Animals

Question 1

Operculum function

Answer 1

protects fish gills from damage

Question 2

gas exchange surface in fish

Answer 2

gill plates

Question 3

5 advantages of counter current flow

Answer 3

1. O2 concentration always higher in water than blood
2. equilibrium never reached
3. concentration gradient maintained across entire gill plate
4. gas exchange occurs across entire gill plate
5. max. saturation of blood is higher

Question 4

why do fish have to force water over their gills?

Answer 4

water is more dense than air so have to expend energy to push water over gas exchange surface (gill plates)

Question 5

what type of ventilation do fish have?

Answer 5

unidirectional

Question 6

are fish large or small organisms?

Answer 6

large

Question 7

why are fish less metabolically active?

Answer 7

• they are bouyant in water so less energy required for support
• don’t regulate their own body temperature as take on temperature of environment, which requires less energy

Question 8

how many gill pairs does a fish have on each side?

Answer 8

4

Question 9

3 features of gas exchnage in samall organsims

Answer 9

1. high SA:vol
2. obtain O2 by diffusion across gas exchange surface of membrane or body surface
3. low metabolic rate so low O2 demand

Question 10

3 features for efficient gas exchange in an amoeba

Answer 10

1. cell surface membrane thin and have a large SA:vol
2. cell respires, converting O2 to ATP so O2 levels in cytoplasm lower than external levels
3. membrane moist

Question 11

3 features for efficient gas exchange in a flatworm

Answer 11

1. flattened shape increasesSA:vol and very thin
2. blood flow maintains diffusion gradient by constantly removing O2, taking it to cells while bringing back CO2
3. skin is moist

Question 12

3 features for efficient gas exchange in an earthworm

Answer 12

1. tubular shape increases SA:vol
2. skin thin and moist
3. blood flow maintains diffusion gradient by constantly removing O2 and taking it to cells by bringing CO2 back

Question 13

relationship between and SA:vol

Answer 13

as size or organism increases, SA:vol decreases

Question 14

5 properties of all gas echange surfaces

Answer 14

1. moist
2. thin
3. large SA
4. permeable to gas
5. mechanism for maintatining a diffusion gradient

Question 15

fuction of an insect’s waxy exoskeleton

Answer 15

waterproof to prevent dessication

Question 16

2 functions of valves in spiracles

Answer 16

1. open/close to control movement of air in and out of insect
2. close to reduce water loss

Question 17

what does SA relate to?

Answer 17

rate of of O2 supply to respiring cells

Question 18

what does volume relate to?

Answer 18

demand for oxygen by respiring cells

Question 19

what substance lines the tracheae?

Answer 19

chitin

Question 20

site of gas exchange in insects

Answer 20

tracheoles

Question 21

4 adaptations of the tracheal system in insects that allows efficient gas exchange

Answer 21

1. tracheal system branched, increasing SA available for gas exchange
2. fluid moves into muscle cell during activity so larger SA for gas exchange
3. tracheoles have thin walls so short diffusion distance to cells
4. large number of tracheoles so large SA for gas exchange

Question 22

why do insects have an internal gas exchange system?

Answer 22

reduce water loss and prevent dessication

Question 23

why don’t insects need a respiratory pigment?

Answer 23

every tissue in contact with at least 1 tracheole so very short diffusion distance

Question 24

how does water move into cells in insects?

Answer 24

when active, insect respires, partly anaerobically so produce lactate
this lowers the WP of the muscle cells, so water passes into muscles from tracheoles by osmosis

Question 25

benefit of fluid moving into muscles

Answer 25

* draw air closer to muscle cells * increases SA for O2 to diffuse * diffusion is faster in air than in water

Question 26

when does mechanical ventilation occur in insects?

Answer 26

when active

Question 27

explain the two parts of mechanical ventilation in insects

Answer 27

1. thoracic spiracles open, abdominal spiracles close, abdominal muscles contract, abdomen expands, lowering pressure below atmospheric pressure 2.thoracic spiracles close, abdominal spiracles open. abdominal muscles contract, pulling skeletal plates together and squeezing tracheal system, pumping air into sacs deeper in tracheoles

Question 28

2 ways insect gas exchange occurs

Answer 28

1. diffusion of oxygen down a concentration gradient gcreated by the insect respiring oxygen 2. mechanical ventilation of body muscles

Question 29

type of ventilation of insects

Answer 29

unidiretional

Question 30

why is air warmed and moistened in the nasal cavity?

Answer 30

* warmed - increase kinetic energy of air particles and get it to body temperature * moistened - so O2 can dissolve which is better for diffusion

Question 31

why is the cartilage in the trachea C-shaped?

Answer 31

to accomodate the oesophagus and prevent pain when a bolus of food goes down`

Question 32

function of tracheal cartilage rings

Answer 32

keep trachea open during inhalation

Question 33

what cells secrete mucus in the trachea?

Answer 33

goblet cells

Question 34

function of ciliated epithelium in trachea

Answer 34

beat mucus back towards mouth to prevent bacteria and dust entering lungs

Question 35

function of mucus in trachea

Answer 35

catch bacteria and dust so they dn't enter the lungs

Question 36

gas echange surface of humans?

Answer 36

alveoli

Question 37

which tubules have cartilage connected by muscle and elastic fibres?

Answer 37

larger brochioles

Question 38

what do smaller bronchioles have in their walls? why?

Answer 38

only elastic fivbres and muscle, so they can expand and contract during ventilation

Question 39

what increases the SA in the human gas exchange system?

Answer 39

* large number of alveoli * dense network of capillaires over each alveolus * branching network of bronchioles

Question 40

how ins a concentration gradient maintained in the alveoli?

Answer 40

* oxygenated blood carries O2 away from alveolus * deoxygenated blood flows towards alveolus * inhalation brings in more O2 keepig concentration of O2 in alveolus above that in blood

Question 41

what maintains a short diffusion pathwy in alveoli?

Answer 41

* capillary wall a single layer of squamous endothelium * alveoli wall single layer of squamous epithelium * capillary very close to alveolus

Question 42

function of surfactant

Answer 42

* keeps alveoli open and prevents them sticking together * allows O2 to dissolve so it can diffuse into blood

Question 43

function of elastic fibres in wall of alveoli

Answer 43

allow alveoli to recoil to aid exhalation

Question 44

why is ventilation important?

Answer 44

to move respiratory medium across/over gas exchange surface and help maintain an oxygen concentration gradient

Question 45

9 steps of inhalation

Answer 45

1. diaphragm and ex. intercostals contract 2. diaphragm flattenes and rib cage moves up and out 3. thorax volume increases 4. outer pleural membrane pulled outwards 5. pressure in pleural cavity decreases 6. inner pleural membrane pulls outwards pulling on lung surface 7. alveoli expand 8. pressure in alveoli decrease below atmosheric pressure 9. air pulled into alveoli down pressure gradient

Question 46

9 steps of exhalation

Answer 46

1. diaphragm and ex. intercostals relax 2. diaphragm returns to dome shape and rib cage moves down and in 3. thorax volume decreases 4. no pull applied to outer pleural membrane 5. pressure in pleural cavity increases 6. no pull on inner pleural membrane so no pull on lung surface 7. alveoli compress 8. pressure in alveoli increases above atmosheric pressure 9. air forced out alveoli down pressure gradient