exchange surfaces

Question 1

do small organisms have a big/ small SA: volume ratio?

Answer 1

big SA: volume ratio

Question 2

how to calculate SA of sphere?

Answer 2

4 x pi x r2

Question 3

how to calculate volume of sphere?

Answer 3

4/3 x pi x r3

Question 4

why do multicellular organisms need an exchange surface?

Answer 4

• large diffusion distance between cell and outside environment
  -small SA: volume ratio
  -higher metabolic rate

Question 5

how are specialised exchange surfaces adapted?

Answer 5

• large surface area (root hair cells)
• thin (decrease diffusion distance)
  -good blood supply
  -well ventilated (both of these maintain concentration gradient of O2 and CO2)

Question 6

pathway of air to lungs?

Answer 6

-trachea
-two bronchi
-bronchioles
-alveoli

Question 7

5 key features of gaseous exchange system?

Answer 7

• goblet cells
• elastic fibres
• cartilage
• cilia
• smooth muscle

Question 8

what role and location do goblet cells have?

Answer 8

line the airways, secrete mucus, which trap dust particles and microorganisms, preventing them from reaching alveoli

Question 9

what role and location does cilia have?

Answer 9

hair like structures on surface of epithelial cells lining the airways
waft mucus to back of throat, away from alveoli, to be swallowed

Question 10

what role and location do elastic fibres have?

Answer 10

in trachea, bronchi, bronchioles and alveoli
stretch during inhalation, recoil to expel air during exhalation

Question 11

what is the role and location of smooth muscle?

Answer 11

in walls of trachea, bronchi and bronchioles
control diameter, relax during exercise, making tube wider, so less resistance to airflow

Question 12

what role and location does cartilage have?

Answer 12

in walls of trachea and bronchi
prevent trachea and bronchi from collapsing under low pressure during inhalation

Question 13

structure of trachea?

Answer 13

-C shaped cartilage
-smooth muscle
-elastic fibres
-goblet cells

Question 14

structure of bronchus?

Answer 14

-alternating smooth muscle and cartilage pieces
-elastic fibres
-goblet cells

Question 15

structure of bronchiole?

Answer 15

-smooth muscle
-elastic fibres
-goblet cells

Question 16

steps of inspiration?

Answer 16

• external intercostal muscles and diaphragm contract
  -ribcage moves up and out, diaphragm flattens
  -thorax volume increases, lung pressure decreases
  -air flows in to lungs

Question 17

steps of expiration?

Answer 17

-external intercostal muscles and diaphragm relax
-ribcage moves down and in, diaphragm curves
-thorax volume decreases, air pressure increases (to above atmospheric)
-air forced out of lungs

Question 18

how is active expiration different to passive?

Answer 18

internal intercostal muscles contract, to pull ribcage down and in

Question 19

what machine measures breathing?

Answer 19

spirometer

Question 20

what is tidal volume?

Answer 20

volume of air in each breath

Question 21

what is viral capacity?

Answer 21

maximum volume of air that can be breathed in or out

Question 22

what is oxygen uptake?

Answer 22

rate at which a person takes up oxygen

Question 23

what is expiratory and inspiratory reserve volume?

Answer 23

additional volume of air that can be breathed in/ out after tidal volume

Question 24

what is residual volume?

Answer 24

volume of air that remains in lungs even after forced expiration (stops lungs collapsing)

Question 25

how to use a spirometer?

Answer 25

- person breathes into tube connected to oxygen chamber - lid of chamber moves up and down during breathing - these movements are recorded by spirometer trace - soda lime in tubes absorbs CO2

Question 26

why does volume of gas in chamber decrease over time?

Answer 26

O2 used in body, and CO2 absorbed by soda lime

Question 27

precautionary steps in spirometer?

Answer 27

- wear nose clip to ensure all air they breathe goes through spirometer) - use medical grade oxygen - sterilise mouthpiece

Question 28

how is oxygen uptake measured on spirometer trace?

Answer 28

decrease in volume of gas in spirometer slope decrease/time

Question 29

what adaptation do fish have and why?

Answer 29

gills because O2 concentration is lower in water than air

Question 30

gill structure?

Answer 30

- made up of thin plates called gill filaments -gill filaments covered in gill plates -each gill is supported by gill arch - lots of blood capillaries and thin surface layer of cells

Question 31

what is the counter current system?

Answer 31

-blood flows through gill plates in one direction, water over gills in another -this means that water with high O2 concentration, flows next to blood with lower O2 concentration (steep concentration gradient, as much O2 diffuses into blood as possible)

Question 32

ventilation in fish steps?

Answer 32

-fish opens mouth, buccal cavity lowers, pressure decreases, volume increases -water flows in, mouth closes, pressure increase leads to water pushed out of cavity over gill filaments -operculum covers gill, forced open by pressure, letting water leave

Question 33

gas exchange in insects?

Answer 33

-air moves into trachea via spiracles -O2 travels down concentration gradient to cells -O2 travels down tracheoles, diffuse from fluid in tracheoles to cells CO2 does this in opposite direction

Question 34

ventilation in insects?

Answer 34

- rhythmic abdominal movement to change volume of bodies and move air in and out of spiracles -wing movement used too

Question 35

fish dissection?

Answer 35

- push back operculum, remove gills -cut gill arch to view gill filaments

Question 36

insect dissection?

Answer 36

-remove piece of exoskeleton -fill abdomen with saline solution -thin silvery grey tubes are trachea (colour due to being filled with air) -view under microscope