Biology- Unit 1- Lungs & Lung Disease

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  • Created by: FireDwarf
  • Created on: 29-10-13 15:47
Why do mamals require lungs?
They are relativly large and therefore have a large number of cells, they also need to maintain a high body temperture and have high respitory and metabolic rates.
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Why are lungs inside the body?
The air is not dense enough to support the delicate structures, Lose great deal of water and dry out.
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How are they protected?
Rib cage
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What are the parts of the human gas-exchange system?
Lungs, trachea, bronchi, brochioles, alveoli
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Lobed structures, made up of a series of branched structures (bronchioles) and end in scas called alveoli.
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The trachea is a flexable airway supported by rings of cartalige. This prevents the trachea collapsing.
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What lines the trachea? What does it produce? How does this help?
Lined with muscles, cilated epithelium cells and goblet cells. Goblet cells produce mucus that trap dirt and bacteria. Cilia cells move the mucus up the throat, where it passes the osephagous and into the stomach.
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two divisons of the trachea, Leading down to each lung. Simular to the trachea. They are also supported by cartalige.Amount of cartalige decreases as it gets smaller.
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Series of branching subdivisions. Walls lined with muscles lined with epithemal cells. Muscles allow them to constrict so they control air flow in and out of the alveoli.
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Very small air sacs. Contain collagen and elastic fibres, lined with eptihulum. The elastic fibres allow it to epxand as it gets air in and sping back afterwards.
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what is the exchange surface called?
Alveolar membrane
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What are the two procceses of breathing?
Inspiration and Experation
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What two muscules move to allow air to move in and out?
Diaphram & intercostal muscles
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Proccess for inspiration?
external intercostal muscles contract, interal relax. Ribs go upwards and outwards, increases volume of thorax. Diaphram contracts, flattern, increased volume.
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Increased volume of thorax causes a reduction in pressure of the lungs. This causes the atompsheric pressure to be higher then pulmonary.
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How does this help air move in?
gas'es always move from areas of high pressure to areas of low pressure.
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Proccess for experiation?
opposite of insiration
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What is the alveoli?
Small air scas which contain elastic fibres, allwoing for them to expand when air comes in to fill them.
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What part of the alveoli is the membrane for the exchange of gases?
Alveolar membrane- maintains a constant diffusion gradient
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What are the essential features it has that allow efficeny exchange?
Large S:v, thin walls, partially permable, movement of enviromental medium, movement of internal medium
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Large S:V?
More O and C02 come into contact with the exchange surface, allowing for more to be diffused (faster, more efficient)
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Thin? Partially permable?
Shorter diffusion time, only allows for specific materials to move
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Enviromental medium & internal?
Enviro- air (ensure that the diffusion gradient is kept), blood (slows down, increases time to diffuse into it)
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How does a constant diffusion gradient be kept?
By keeping the conc of o high in the aveoli (moving air in- inspiration) and and keeping o used in the body and moved out, c02 kept low in the alveoli via experation
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Describe the proccess of the alveoli in gas exchange?
Red blood cells slow as they pass the membrane, allowing more time to diffuse, distance between is reduced as blood flatterns into the capilliary wall, walls of the cappilary is thin and the alveoli (therefore shorter path), large s:v ratio of the
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capillaries and alveoli, breathing (ventilation) keeps the air moving in and out, therefore keeping a steep conc gradient, and the heart keeps the blood circuling also.
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What is ficks law?
Diffusion is proportional to surface area x diffusion in conc/ lengh of diffusion pathway
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What is a pleural membrane?
They line the thorax and lungs. They have a cavity bellow them which contains pleural fluid. They link the outer wall of the lung and inner wall of the thorax and prevens friction (lube).
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What is a Spirometer?
Used the measure and record volumes of inspired and expired air. Produces a spirogram.
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What are the 5 diffrent types of lung capactities?
Tidal, expiratory, inspiritory, residual, vital
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0,5dm^3, volume of air inhaled or exhaled in a normal breath @ rest
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1.5 dm^3 volume of air breathed out at max effort after the normal expiration
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op of above
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1.5 dm^3, volume of air that cant be removed from the lungs after max expiration. keeps alveolis open to allow gas exchange.
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Max volume of air that can be exchanged. Its IRV + TV+ ERV
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What microbe causes Tubercolosis?
Mycobacterium tubercolosis or Mychobacterium bovis bacteria
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Cough, tirdness, loss of apetite, weight loss.
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Course of infection?
Bacteria gain entry to the lungs and divide there due to the large o2 conc. White blood cells arrive to ingest bacteria and leads to inflamation.This causes enlargement of the lymth.
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What is this caused?
Primary infection
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What happens next?
Infection is usually controlled within a few weeks. However some bactiera usually remains and will come back years later for the post-primary infection.
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What happens in the post-primary tubercolosis?
Infection now easilly controlled and destroys tissue of the lungs. This results in cavities and where the lungs repair itsself, scar tissue. Sufferer coughs up the bactiera & blood. Tb can then spread to rest of body.
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How does it transmit?
Spread through air through droplets released when infected people sneeze, laugh, talk etc. Person needs to be in constant contact with an infected person.
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whos most at risk?
Family, work or close friends of infected. People from counties where TB is common. Reduced immunity (eg: AIDS).
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How to control and prevent TB?
Vaccination, better education about protection, better housing and nutrition, improved health centers and treatment.
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Pulmonary Fibrosis- what is it?
Scars form on the lungs, causing them to become thicker.
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How does this effect ventilation?
It becomes harder for the lungs to expire as the elasticity is reduced. In addition diffusion pathway is increased, causing diffusion to take longer, less o2 absorbed. Less volume for o2 also.
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Shortness of breath- due to less o2 and longer diffusion and slower ventilation. Dry cough- want to remove blockade, nothing there because cant be removed Pain- Increased pressure and scarring Weakness- reduced o2 intake
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Astma- what is it?
localised allergic reaction. Allergens (eg pollen) can trigger it, as well as air pollutants or stress.
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What occurs?
Allergens cause white blood cells on the bronicholes and bronchi cell wall to release histamine. This causes linings to become inflamed and
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causes epithemal lining to secrete large amounts of mucus. Fluid leaves cappliaries and enters airway. Muscle contracts and constricts airway.
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Difficulty breathing- contriction of bronchi and bronchioles, inlflamed lining and mucus. Wheezing- contricted air passage Tight- Cant ventilate lungs Cough- Trying to clear obstruction.
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Caused by?
Genetics seems to play a role and increases in air pullution potentially.
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devleops over 20 years(smokers)Elastic of the lungs becomes permantly streched therefore causing the lungs to not be able to force all air out of alveoli.
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what happens to alveoli?
Surfance area of alveoli reduced. They can also burst. Therefore little, if any, gas exchange occurs across the strched and damaged air scas.
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short breathness- Loss of eclasity, reduced surface area for alveoli so less o2 is diffused. Cough- remove damaged tissue of lungs, bluish skin (low o2 levels)
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Card 2


Why are lungs inside the body?


The air is not dense enough to support the delicate structures, Lose great deal of water and dry out.

Card 3


How are they protected?


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Card 4


What are the parts of the human gas-exchange system?


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