BRAINCAKEExchange Surfaces and Breathing
Revision notes for Exchange Surfaces and Breathing in OCR Biology A (H020). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- The Need for Specialised Exchange SurfacesOxygen, glucose and fatty acids are needed for respiration and carbon dioxide needs to be removed.
- Surface Area to Volume RatioExchange of substances with the environment takes place at the surface of an organism, but the materials absorbed are used throughout the whole…
- Specialised Exchange SurfacesExchange Surfaces: should have a large surface area relative to the volume of the organism should be very thin so that the diffusion distance is…
- The Human Gas Exchange SystemHumans like other mammals are aerobic organisms that need a constant supply of oxygen and need carbon dioxide constantly removed from the body as…
- The LungsThe lungs are a pair of structures made up of branched tubules called bronchioles which end in tiny air sacs called alveoli The trachea is a…
- Mechanism of BreathingVentilating the lungs maintains the diffusion gradient across the alveolar epithelium by refreshing the air inside the alveoli.
- InspirationInspiration is an active process that uses energy.
- ExpirationExpiration is a largely passive process that does not require much energy.
- AlveoliAlveoli are the specialised gas exchange surface in the lungs.
- Role of Alveoli in Gas ExchangeThe rate of diffusion is proportional to the surface area and the diffusion gradient and inversely proportional to the diffusion distance.
- AsthmaIn asthma, the airways are sensitive to triggers such as dust mites, cigarette smoke, pollen grains and stress.
- The First BreathWhen a newborn baby takes the first breath it uses a force 15-20 the normal force of inhalation to inflate the lungs.
- Measuring Lung CapacityLung capacity can be measured by: A peak flow meter.
- Lung VolumeTidal volume is the volume of air taken into the lungs with each resting breath and is about 0.5dm3 in adults.
- Breathing Rate and Ventilation RateThe breathing rate and tidal volume depend on the activity of a person.
- Gas Exchange in Unicellular OrganismsSingle-celled organisms have a large surface area to volume ratio because they are small.
- Gas Exchange in InsectsThe need for gas exchange conflicts with the need to conserve water.
- Diffusion GradientFor rapid diffusion to take place, there has to be a steep diffusion gradient maintained in one direction.
- Mass TransportMost tracheoles extend parallel to the muscle fibres.
- Increasing the Rate of DiffusionTracheoles are the small tubes that form the terminal endings of the tracheal system and range from 1 to 0.1 μm in diameter.
- Limitations of the Tracheal SystemReducing Water Loss Gases enter and leave through tiny pores called spiracles.
- Gas Exchange in FishAll gas exchange systems must supply oxygen to respiring tissues and remove carbon dioxide produced by respiration rapidly enough.
- Structure of the GillsFish have a waterproof covering.
- Counter Current ExchangeThe gill lamellae have a rich blood supply.