respiration and gas exchange Flashcards
2.37 what is the word equation for respiration?
glucose + oxygen –> carbon dioxide + water
2.37 whats the chemical equation for respiration?
C6H12O6 + 6O2 –> 6CO2 + 6H20
2.38 word equation for anaerobic respiration in plants & fungi?
glucose –> ethanol + carbon dioxide
2.38 word equation for anaerobic respiration in animals?
glucose –> lactic acid
2.36 what’s the difference between aerobic and anaerobic respiration?
aerobic: uses oxygen, more ATP released as glucose completely oxidised
anaerobic: no oxygen, less ATP/energy as glucose not completely broken down, also produces toxic waste products which must be excreted or broken down
2.39 practical: investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms (germinating peas)
germinating peas:
- put some pea seeds soaked in Milton solution (preservative & kills bacteria) into two thermos flasks (1 for alive peas, other for dead peas)
- put a cotton wool plug over the lid in the thermos, with a thermometer sticking into it & into the pea mixture
- as peas start 2 grow they respire, releasing heat. thermos flask insulated, so heat not transferred 2 surroundings & we can measure change in temp
- only see temp rise in thermos w alive peas, as peas in other are dead (boiled)
- in both thermoses peas are soaked in milton solution (bleach), which kills any bacteria (would also respire & affect results)
- could also use gas delivery tubes 2 collect any gas produced, then bubble through limewater - gas from flask w alive peas would turn it cloudy
2.39 practical: investigate the evolution of carbon dioxide & heat from respiring seeds or other suitable living organisms (hydrogen carbonate indicator & insects)
- put an insect in a test tube with a support under it, and some hydrogen carbonate indicator at the bottom of test tube
- put a tightly fitting bung on the top of the tube
- make a control test tube too
- as insect respires, carbon dioxide will be produced, which will turn the indicator from red to yellow as co2 conc. inc.
2.46 describe the structure of the thorax
gas exchange system located in thorax (upper part of body)
- when breathe in, air passes down trachea (windpipe). tube surrounded by C-shaped rings of cartilage, keep trachea open but make swallowing easier
- trachea splits 2 form 2 bronchi - these tubes lead to lungs, they’re also surrounded by cartilage rings
- bronchi divide/branch into smaller & smaller tubes called bronchioles, which carry air deep into thorax
- at end of each bronchiole are microscopic air sacs (alveoli). these are site of gas exchange
- lungs surrounded by pleural membrane - this forms double layer between lungs & thorax walls. in between membranes is thin layer of pleural fluid. together form air tight seal & prevent lungs from sticking to thorax wall as inflate & deflate
- ribs help protect organs in thorax
- intercostal muscles between ribs help connect bones & are important in moving air into/out of lungs
- below lungs, separating organs of thorax & abdomen, is diaphragm. domed sheet of muscle & fibrous tissue also important in moving air into/out of lungs
2.46 what does the pleural membrane do?
- lungs surrounded by pleural membrane - this forms double layer between lungs & thorax walls
- in between membranes is thin layer of pleural fluid
- together form air tight seal & prevent lungs from sticking to thorax wall as inflate & deflate
what is ventilation?
the process of moving air into and out of the lungs (inhalation & exhalation)
2.47: what do the diaphragm & intercostal muscles do during inhalation?
- diaphragm contracts, moving down and flattening. intercostal muscles contract, moving rib cage up & out
- this causes volume of thorax to increase and air pressure in thorax to fall
- air pressure in thorax now less than atmospheric pressure, causing air to move into lungs
2.47: what do the diaphragm & intercostal muscles do during exhalation?
- diaphragm relaxes, moving up & doming. intercostal muscles relax, moving rib cage down & in
- this causes volume of thorax to decrease and air pressure in thorax to rise
- air pressure in thorax now more than atmospheric pressure, causing air to move out of lungs
2.48 how are the alveoli adapted for gas exchange by diffusion between air in the lungs & blood in capillaries?
- large surface area inc. rate of diffusion
- each alveolus surrounded by network of capillaries, which constantly carry deoxygenated blood to alveolus & move oxygenated blood away - maintains high conc. gradient and so speed diffusion up
- walls of alveoli only one cell thick (and this cell is flattened). capillary walls immediately next to alveoli and are again only one, flattened, cell thick. this means gases only need to move very small distance, speeding up diffusion
2.49 what are the biological consequences of smoking in relation to the lungs?
- at least 17 carcinogens in tobacco smoke, including tar
- tobacco smoke contains CO. it irreversibly binds to the haemoglobin, forming carboxyhaemoglobin, and so reducing amount of O transported by blood
- chemicals in tobacco smoke destroy cilia & at same time mucus production will inc. (in response to smoke). mucus can’t be moved out of airways quickly and so builds up - causes smokers cough & inc. risk of infections. bronchitis is disease resulting from build up of infected mucus in bronchi(oles)
- emphysema: smoke can also reach alveoli, damaging them. alveoli walls break down in places & fuse together, forming larger irregular air spaces. this dec. SA for gas exchange, so less O diffuses into blood
2.49 what are the biological consequences of smoking in relation to the circulatory system (incl. coronary heart disease)?
also hm = heart muscle, hmc = heart muscle cells
- coronary arteries supply HM w blood, this blood provides glucose & O needed 4 aerobic respiration and removes CO2 produced by it
- if have lots of saturated fats in diet, fatty deposits build up in artery walls - they narrow the lumen of artery. in narrow coronary arteries, it restricts blood flow to HMC
- fatty deposits cause HMC to receive less blood, which means that HMC receive less O (and glucose) for aerobic respiration. as result, aerobic respiration reduces & anaerobic respiration inc. in HMC. lactic acid builds up due to inc. in anaerobic respiration, poisoning HMC & causing heart attacks
- smoking inc. blood pressure & inc. risk of fatty deposits forming
