exhange surfaces

why do single celled organisms not need a specilised exchange surface

metabolic action is very low, so oxygen demands and CO2 demands are low . the SA:V is large

why do multi celled organisms need a specilised exchange surface?

metabolic activity is higher, meaning the demand for oxygen is higher so that they can release energy, the distance between the cells are too far for diffusion in and out, have a smaller SA:V, so gases cant be exchanged as easily

what happends to SA as organism increases in size

increases

how is the naval cavity adapted for gas exchange

• large surface area , good blood supply

• mucus secreting cells, traps dust and microbes

• moist surface increases humidity and decreases evaporatiom

how is the trachea adapted for gas exchange

cartalage rings, stops it from collapsing

ciliated epithelial cells and goblet cells, traps dust and microbes and move them towards stomach

how are the bronchus and brnochioles adapted for gas exhcnage

• smooth muscles which allow air to move in and out and maintains high concentration gradient of O2

what happens to body volume as organisms increase in size

increase

what happens to the SA:V as organisms increase

it decreases

how does having a larger surface area help with exchange

overcomes the limitations of the SA:V of larger organisms , by allowing more effecient gas exchange, root hair cells and villi

how does having a thin layer area help with exchange

short diffusion distance, making process fast and efficient , alveoli and villi

how does having a good blood supply help with exchange

the steeper the conc gradient, the faster diffusion, ensures substances are constantly delivered and removed from exchange surfaces, allveoli in lungs, gills in fish and villi in small intestines

describe the structure of the nasal cavity

• large SA with a good blood supply, which warms the air and body temp

• hairy lining secretes mucus

• moist surface

why do tracheas have a c shape cartalige

• its flexible, which stops the cartilage from collapsing

• c shape so that food can move easily down the oesophagus behind the trachea

describe the basic plan of a trachea, bronchi and larger bronchiole walls, in order

lumen

ciliated epithelium with goblet cells

smooth muscle and elastic fibres

cartalige

how are goblet cells and ciliated epitheilum helpful in gaseous exchange?

Goblet cells secrete mucus which traps unwanted bacteria and particles. The cilia then beat and move the mucus away from the lungs. Smokers cilia dont work as well

how are smooth muscles and elastic fibres helpful in gaseous exchange?

when smooth muscle contract the bronchioles close up, when they relax the bronchioles dilate/ open up. Elastic fibres strech and recoil.

what is different about alveolus walls

they dont have cartalige or smooth muscles

instead of smooth muscles they have collagen

instead of cillia epithilium they have squamous epithilium

what adaptations do alveoli have

large surface area- good for diffusion, and theres lots of them

thin- short diffusion distance

good blood supply- capillaries are very close, and they carry O2 and CO2

good ventelation- helping to maintain a steep concentration gradient

what role does the thorax play in ventilating the lungs ?

when the pressure changes in the thorax, air is moved in or out the lungs. The thorax is lined by the pleural membranes, which surround the lungs

what happens during inhilation ?

• diaphragm contracts, flattening and lowering

• the external intercostal muscles contract, moving the ribs upwards

• volume of thorax increases: so pressure decreases to less then the atmos, causing air to rush into lungs

what happens during expiration?

• diaphragm muscles relax, so moves down

• external intercostal muscles relax so ribs move down

• elastic fibres in alveoli return to their normal shape

• volume in thorax decrease so pressure increases, causing air to rush out of lungs

• sternum relaxes

what happens during forced expiration

• internal intercostal muscles contract pulls the ribs down fast and hard ]

• abdominal muscles contract forcing the diaphragm up to increase pressure in lungs

list 3 different ways someone might measure their lung capacity

• a peak flow meter

• vitalograph

• a spirometer

what is meant by tidal volume?

regular breathing. The volume of air that moves in and out of the lungs with each breath

what is meant by vital capacity

the volume of air that can be breathed in with the strongest possible exhalation and the deepest possible intake of breath

what is meant by inspiratory reserve volume ?

maximum volume of air that you can breath over and above the usual inhalation

what is meant by expiratory reserve volume?

the extra amount of air that you can breath out of your lungs over the normal exhalation

what is meant by residual volume ?

the amount of air left in your lungs after you have breathed out as hard as you can

what is meant by total lung capacity ?

the sum of the vital capacity and residual volume

how would you calculate the oxygen uptake

draw a right angle triangle above the spirometer. X being the shortest length and y being the longest. The do X/Y

calculation for ventilation rate

tidal volume x breathing rate (per minute)

how does air enter and leave insects

via spiracles

describe the role of tracheae in insects

• largest tubes in insects

• lined with chitin

• little to no gas exchange happens here

describe the role of tracheoles (insects)

• no chitin lining, so permeable to gases

• very small and found all around the insects body

• where gas exchange happens

what is tracheal fluid

• found at the end of tracheoles

• limits the penetration of air for diffusion

what other ways are insects adapted to gaseous exchange

mechanical ventilation of the tracheal system

collapsible enlarged trachea or air sacs

what adaptations do gills have

• large surface area

• good blood supply

• thin layers needed for sucuessful gaseous exchange

• take o2 from water and get rid of CO2 into the water

what is the operculum

a bony flap that protects the gills, and also active in maintaining a flow of water over the gills

what is the first thing that happens in fish gaseous exchange

• opens mouth and the floor of the buccal cavity in lowered

• increasing the volume of the buccal cavity, causing water to flow in

• at the same time the operculum shuts and the gill cavity expands, lowering pressure in gill cavity

• floor of buccal cavity begins to move up, causing water to move over gills

how do gill filaments help with gaseous exchange

• overlap increasing the resistance of the flow of water, slowing down the water

• more time for gaseous exchange

• large surface area

what does countercurrent mean ?

the movement of water over the gills is opposite from the movement of blood, to maintain a steeper concentration gradient, meaning faster gaseous exchange

describe the adaptations of the gill lamellae

have a rich blood supply

large surface area

main site of gaseous exchange in the fish