Exchange surfaces and Breathing

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What features affect whether an organism needs a specialised exchange surface?
Size, Surface Area:Volume Ratio, Metabolic Activity
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what are the features of an efficient gas exchange system?
A large surface area, a short diffusion distance, a good blood supply/ventilation, a steep concentration gradient
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what are the function of the elastic fibres of the alveoli?
1) they stretch allowing the alveoli to expand during inspiration (preventing bursting). 2) They recoil during expiration to help force air out.
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Why would smooth muscle need to contract to constrict the airway?
If there were harmful substances in the air.
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why do we feel light headed when we hyperventilate?
because we breathe out more CO2 than we are producing- concentration in the blood drops- blood pH rises- causes vasoconstriction- reduces blood supply to organs including the brain
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On a spirometer trace the peaks of the graph are .... and the troughs of the graph are...?
Peaks- exhalations Troughs- inhalations
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What is the breathing rate?
the number of breaths per minute
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What is the residual volume?
The volume of air that remains in the lungs even after forced expiration.
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What is the total lung capacity?
The vital capacity+ the residual volume
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What is the purpose of soda lime in a spirometer chamber?
to absorb the carbon dioxide as it is exhaled to ensure the person doesn't then breathe it in.
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How does air travel through the circulatory system in insects?
In gaseous form
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Why can't fish survive out of water?
When a fish is taken out of water- its gills collapse/stick together. This greatly decreases their surface area meaning diffusion of gases happens too slowly to be efficient
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What happens when an insect respires anaerobically?
The build up of lactic acid in the muscles causes water to move out of the trachael fluid via osmosis. This increases the surface area of the tracheal wall exposed to air, meaning more oxygen can be absorbed.
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what type of ventilation do cartilaginous fish such as sharks use?
Ram ventilation- where they constantly swim so there is a constant flow of water over the lungs
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what support the trachae in insects?
rings of chitin
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Why is the cartialage in the trachea arranged in C-shaped rings?
To allow food to pass smoothly down the oesophagus- which sits adjacent to it.
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Why does the trachea have cartilage?
For support to stop it from collapsing when the pressure drops.
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Counter current flow allows for what percentage of oxygen saturation in the blood? What about a concurrent flow?
countercurrent about 80% concurrent about 50%
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What precautions must you take when using a spirometer?
Use medical grade oxygen, disinfect the mouthpiece, ensure soda lime is functioning, make sure the patient is generally in good health, ensure that the level of water is correct to produce accurate readings
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Why do adjacent gill filaments overlap?
To increase the resistance to the flow of water over the gill surfaces. This slows down the water and allows more time for gas exchange.
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Describe the process of inspiration in mammals.
The external intercostal muscles contract and the diaphragm flattens. The ribcage moves up and out increasing the volume of the thorax. The pressure in the thorax decreases to below atmospheric pressure drawing air into the lungs.
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How many alveoli does the average adult have?
about 300 million
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What is the average surface area of a pair of adult lungs?
75 square metres
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What opens and closes the spiracles?
Sphincters
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How do you calculate the ventilation rate?
tidal volume multiplied by breathing rate.
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What is the inspiratory reserve volume?
the maximum volume of air that you can breathe in over and above a normal inhalation
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On a lung volume graph the peaks are... and the troughs are...?
peaks-inhalations troughs- exhalations
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What is asthma?
An allergic reaction to certain irritants such as pollen or dust. The reaction triggers the cells lining the bronchioles to release histamines which make the epithelial cells inflamed and swollen and stimulate the goblet cells to secrete excess mucus
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What are alveoli made up of?
A single layer of squamous epithelial cells, some collagen and elastic fibres made of elastin.
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When do the internal intercostal muscles contract?
During forced exhalation- pull the ribs down forcing air out.
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What is lung surfactant and what is its function?
A substance made of phospholipids which coats the surface of the alveoli. Without it the watery lining of the alveoli would create a surface tension which would cause them to collapse.
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Where is lung surfactant secreted from?
the pleural membranes' epithelial cells
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Why is the nasal cavity important in gas exchange?
the large surface area and good blood supply helps warm the air to body temp, the moist surfaces humidify the air reducing the evaporation from gas exchange surfaces, the hairy lining secretes mucus to trap pathogens/ dust
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What is the function of the nostrils in fish?
to detect chemicals- help the fish to sense pollution, predators and direction. NOT INVOLVED IN GAS EXCHANGE!
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Why does a fish's gas exchange system have to be particularly efficient?
because water has a lower oxygen concentration compared to air and is more viscous (harder to move)
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Describe two ways an insect can increase its levels of gas exchange.
1) collapsible enlarged trachae- act as air reservoirs 2)Mechanical ventilation- this involves muscular pumping of the wing muscles which changes the volume and pressure of the abdomen forcing air in and out.
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What is DGC?
Discontinuous gas exchange- this involves opening and closing the spiracles very rapidly so they flutter.
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Why does DGC occur?
originally scientists thought it was an adaptation to reduce water loss. However, it is now believed to be a way of helping gas exchange in insects which live in burrows and to reduce the entry of fungal spores.
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Why do you have to wear a nose clip when using a spirometer?
To ensure that the lung volume measurements are accurate. Ensures you are only breathing in air from the chamber and that no air is lost to the surroundings as you breathe out.
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what is emphysema
Chronic obstructive pulmonary disease- the alveoli rupture creating one large space greatly decreasing surface area
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Other cards in this set

Card 2

Front

what are the features of an efficient gas exchange system?

Back

A large surface area, a short diffusion distance, a good blood supply/ventilation, a steep concentration gradient

Card 3

Front

what are the function of the elastic fibres of the alveoli?

Back

Preview of the front of card 3

Card 4

Front

Why would smooth muscle need to contract to constrict the airway?

Back

Preview of the front of card 4

Card 5

Front

why do we feel light headed when we hyperventilate?

Back

Preview of the front of card 5
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