AS OCR Biology - Lungs

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  • Created by: Jess
  • Created on: 11-12-12 17:13
What is the size of an individual alveoli?
100-300micrometres
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What is the size of the alveolus wall?
1 cell thick
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What do the alveoli/capillary walls consits of?
Squamous cells
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What is the size of the capillary wall?
1 cell thick
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What lines the alveoli?
Thin layer of moisture
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Why is a surfactant needed in the lungs?
To reduce the cohesive forces between the water molecules to prevent the alveoli from collapsing
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Outline inspiration
Diaphragm contracts/flattens, intercostal muscles contract to raise ribs, volume of chest cavity increases, pressure here drops below atmospheric pressure so air moves in
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Outline expiration
Diaphagm relaxes, intercostal muscles relax and ribs fall, volume of chest cavity decreases, pressure in lungs increases and rises above atmospheric pressure so air moves out
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What 2 aspects of the lungs maintain a steep diffusion gradient?
Breathing movements and the action of the blood transport system
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Why are the capillaries narrow?
So that the red blood cells are squeezed against the capillary wall so they are closer to the air in the alveoli to reduce the diffusion distance
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What is smaller: the trachea or bronchi?
The bronchi
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Is cartilage more regular in the bronchi or trachea?
Trachea
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What shape is the cartilage?
Incomplete rings/C shaped
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What is loose tissue?
Elastic fibres, smooth muscle, blood vessels, glandular tissue and connective tissue
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What type of epithelium are in the inner lining?
Ciliated
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What part of the lungs has no cartilage?
Bronchioles
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What is the role of the cartilage?
Holds trachea/bronchi open, prevents collapse during inhalation when is low pressure, shape allows flexibility to move neck without constricting airways, allows for expansion of oesophagus to swallow
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What is the role of the smooth muscle?
Contracts to constrict the airway which makes the lumen narrower to control the flow of air to alveoli if there are harmful substances in the air
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Give a specific detail about smooth muscle.
It's not a voluntary action when it contracts
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What is the role of elastic fibres?
They recoil as the smooth muscle relaxes, to their original size and shape to widen the airway
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What happens to the elastic fibres when the smooth muscle contracts?
They are deformed
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What is the role of goblet cells/glandular tissue?
To secrete mucus to trap tiny particles from the air
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What particles are trapped by the mucus?
Pollen and bacteria
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Why is the mucus needed to trap bacteria?
To reduce the risk of infection by removing bacteria
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What is the role of ciliated epithelium?
To waft mucus up the airway to the back of the throat
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Describe the appearance of cilia.
Cilia are numerous tiny, hair-like structures projecting from the membrane of ciliated epithelium
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What happens to the mucus when it reaches the throat?
It is swallowed and killed by the acid in the stomach
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How often do you breathe?
12 times per minute
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What is tidal volume?
The volume of air moved in and out of the lungs with each breath when you are at rest.
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What is vital capacity?
The largest volume of air that can be moved into/out o the lungs in any one breath
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Why do different people's vital capacity vary?
Regular exercise increases it, but it also varies with the person's size and age
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What is residual volume?
The volume of air that always remains in the lungs, even after the biggest possible exhalation
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What is dead space?
The air in the bronchioles/bronchi/trachea where no gas exchange takes place
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What is the inspiratory reserve volume?
How much more air can be breathed in over and above the normal tidal volume when you take in a big breath
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When you you use your inspiratory reserve volume?
When exercising
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What is the expiratory reserve volume?
How much more air can be breathed out over and above the amount that is breathed in a tidal volume breath
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What is the size of your tidal volume?
0.5dm3
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What is the size of your vital capacity?
5dm3
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What is the size of your residual volume?
1.5dm3
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What precautions must be taken before the spirometer is used?
New mouthpiece, nose clip, lips sealed, fresh (medical-grade) O2 used, soda lime in, person is healthy, correct amount of water in tank, hinges work
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What is used in the spirometer to absorb the carbon dioxide?
Soda lime
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Describe a spirometer.
An oxygen-filled chamber that floats on a water tank, a tube which the person breathes in which is connected to the oxygen chamber
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How is a trace made using a spirometer?
A datalogger records the movements of the chamber of oxygen
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What happens to the oxygen chamber during breathing?
Breathe in = chamber sinks down/Breathe out = chamber floats up
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How does the soda lime work?
It absorbs the exhaled carbon dioxide
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Why does the total volume of gas in the spirometer go down?
Because the soda lime is absorbing the carbon dioxide that is exhaled
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What is the volume of carbon dioxide breathed out equal to?
The volume of oxygen breathed in
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What does the total reduction of gas in the spirometer equal?
The volume of oxygen used up by the person breathing in and out
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Smooth muscle and elastic fibres are antagonistic. What does antagonistic mean?
That they are working against each other - smooth muscle contracts to narrow lumen, elastic fibres deformed, muscle relaxes, elastic fibres recoil to their original shape and extend muscle fibres again
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Outline inspiration.
Diaphragm contracts/flattens, intercostal muscles contract to raise ribs, volume of chest cavity increases and pressure here drops below atmosphere-air in
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Other cards in this set

Card 2

Front

What is the size of the alveolus wall?

Back

1 cell thick

Card 3

Front

What do the alveoli/capillary walls consits of?

Back

Preview of the front of card 3

Card 4

Front

What is the size of the capillary wall?

Back

Preview of the front of card 4

Card 5

Front

What lines the alveoli?

Back

Preview of the front of card 5
View more cards

Comments

Roshni

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Thanks Jess, I found this really useful! Didn't really get the lungs much till now :) x

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