Exchange surfaces & breathing. - Spec
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- Created by: rachel
- Created on: 10-03-13 17:19
Why do multicellular organisms need specialised exchange systems in terms of SA:V?
They have a higher demand for oxygen & a greater need to remove carbon dioxide. They have a smaller SA:V & their surface area is too small & the distance to cells is too large to supply their needs - Diffusion takes too long.
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Why do single celled organisms not need specialised exchange systems in terms of SA:V?
They have a large SA:V & they are small so the demand for O2/CO2 removal is low. Diffusion alone is adequate to meet their needs.
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Describe the features of an efficient exchange surface with reference to the diffusion of O2 & CO2 across as alveolus.
Alveoli - large surface area for diffusion of O2 & CO2 into/out of blood. The squamous epithelium of alveoli is very thin providing a short diffusion distance. Alveoli have capillaries running over their surface delivering CO2 - removed & O2 - away
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Explain how a short diffusion distance is maintained in the alveoli which makes the mammalian lung an efficient gaseous exchange system.
Alveoli have a thin, squamous epithelium & the surrounding capillaries have a thin endothelium which provides a short diffusion distance.
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Explain what prevents the alveoli collapsing when the pressure changes inside the lungs, which makes the mammalian lung an efficient gaseous exchange system.
The epithelial cells of the alveoli produce a surfactant which reduces the surface tension & prevents the alveoli collapsing when the pressure changes.
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Explain the transportation of gases in the lungs making the mammalian lung an efficient gaseous exchange system.
The erythrocytes transport oxygen & carbon dioxide to & from the alveoli.
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Describe what creates the steep concentration gradient in the lungs which makes the mammalian lung an efficient gaseous exchange system.
The diaphragm & intercostal muscles maintain a concentration gradient.
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Descibe how bacteria etc are removed from the lungs, which makes the mammalian lung an efficient gaseous exchange system.
The ciliated epithelial cells & goblet cells remove dust/bacteria/pollen/spores.
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Describe what holds the air-ways open, which makes the mammalian lung an efficient gaseous exchange system.
Cartilage holds the airways open.
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Describe what can constrict & control the diameter of the airway which makes the mammalian lung an efficient gaseous exchange system.
The smooth muscle can constrict & control the diameter of the airway.
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What aids ventilation by helping to expel air? This shows one of the ways in which the mammalian lung is adapted to have an efficient gaseous exchange system.
Elastic fibres recoil aiding ventilation by helping to expel air.
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What two things destroy pathogens? This shows one of the ways in which the mammalian lung is adapted to have an efficient gaseous exchange system.
Macrophages & neutrophils engulf & destroy pathogens.
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How can ventilation maintain a steep concentration gradient? (Talk about O2 & CO2)
Ventilation increases the concentration of O2 in alveoli so the concentration of oxygen is higher than that in blood. Ventilation decreases the concentration of CO2 so the concentration of CO2 is lower than that in blood.
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Describe the differences between the trachea & bronchi.
They have a similar structure but bronchi are narrower than trachea.
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What is on the inside surface of the cartilage in the walls of the trachea & bronchi?
On the inside surface of the cartilage is a layer of glandular tissue, connective tissue, elastic fibres, smooth muscle & blood vessels. The inner layer is an epithelium layer that has two types of cells - most are ciliated epithelium & goblet cells.
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Describe the distribution of cartilage, ciliated epithelium, goblet cells, smooth muscle & elastic fibres in the trachea & bronchi.
Trachea & bronchi have similar structure - bronchi narrower. They have thick walls made of several layers of tissue. Much of wall consisted of cartilage. Trachea - regular C-rings. Bronchi - less regular. There are also many others on inside of cart.
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Describe the distribution of cartilage, ciliated epithelium, goblet cells, smooth muscle & elastic fibres in the Bronchioles.
They are much narrower than the bronchi. Larger bronchioles have some cartilage, but the smaller ones don't. The wall is made mostly of smooth muscle & elastic fibres.
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Describe the distribution of cartilage, ciliated epithelium, goblet cells, smooth muscle & elastic fibres in the Alveoli.
Wall is one cell thick. 100-300 um diameter. Good blood supply.
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Describe the functions of cartilage.
It holds the trachea & bronchi open. It prevents collapse when air pressure is low during inhalation.
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Describe the functions of cilia.
Cilia move in a synchronised pattern to waft mucus up the airway to the back of the throat. Once there, the mucus is swallowed & the stomach acid will kill any bacteria.
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Describe the functions of goblet cells.
They secrete mucus & trap tiny particles from the air (dust, pollen, bacteria, viruses etc.) It reduces the risk of infection.
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Describe the functions of smooth muscle.
Smooth muscle can contract to constrict the airway & prevents harmful substances from reaching the alveoli (e.g. smoke & pollen).
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Describe the functions of the elastic fibres.
They recoil to their original size & shape, expelling air & preventing alveoli from bursting.
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Outline the mechanism of inspiration which reference of the function of the ribcage, intercostal muscles & diaphragm.
1. Dia. contracts becoming flatter, pushing digestive muscles down. 2. external IC muscles contract to raise ribs. 3. Volume of thorax >. 4. pressure in thorax drops below atmospheric pressure. 5. Air moves in to lungs.
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Outline the mechanism of expiration which reference of the function of the ribcage, intercostal muscles & diaphragm.
1. Dia relaxes & is pushed up by displaced organs underneath. 2. External IC muscles relax & ribs fall. 3. Volume of thorax decreases. 4. Pressure in thorax increases & rises above atmospheric pressure. 5. Air moves out of the lungs.
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Explain the meaning of the term tidal volume.
The volume of air moved in & out of the lungs during breathing when at rest.
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Explain the meaning of the term vital capacity.
The largest volume of air that can be moved in & out of the lungs in any one breath.
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Describe a spirometer.
Chamber filled with O2 floating on tank of water. Healthy person breaths from disinfected mouth piece attached to tube connected to O2 tank. Breathing in - chamber down. Breathing out - chamber up. NaOH absorbs & removes CO2. Datalogger records move.
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Describe how a spirometer can be used to measure vital capacity.
Breath in as deeply as you can, then breath as much as you can.
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Describe how a spirometer can be used to measure tidal volume.
You breath in & out normally whilst sitting at rest.
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Describe how a spirometer can be used to measure breathing rate.
Breathe normally & then divide the number of breaths by the time in minutes to calculate the no. breaths per minute.
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Describe how a spirometer can be used to measure oxygen uptake.
Divide the amount of oxygen (dm3) by the time taken in seconds or minutes.
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look at the poster on the wall and point to the place where:
tidal volume, inspiratory reserve volume, expiritory reserve volume, residual volume, vital capacity & total lung capacity are shown.
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Other cards in this set
Card 2
Front
Why do single celled organisms not need specialised exchange systems in terms of SA:V?
Back
They have a large SA:V & they are small so the demand for O2/CO2 removal is low. Diffusion alone is adequate to meet their needs.
Card 3
Front
Describe the features of an efficient exchange surface with reference to the diffusion of O2 & CO2 across as alveolus.
Back
Card 4
Front
Explain how a short diffusion distance is maintained in the alveoli which makes the mammalian lung an efficient gaseous exchange system.
Back
Card 5
Front
Explain what prevents the alveoli collapsing when the pressure changes inside the lungs, which makes the mammalian lung an efficient gaseous exchange system.
Back
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