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Title: Echange surfaces
Description: Great notes to understand the lungs, ventilation and much more!
Description: Great notes to understand the lungs, ventilation and much more!
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The need for specialised exchange surfaces
To include surface area to volume ratio (SA:V), metabolic activity, single-celled and multicellular organisms
...
The distance is too large and diffusion takes too long to supply needs
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The features of an efficient exchange surface
To include root hair cells, alveoli and gills/alveolus
The root hair cells increase surface area thus providing the area needed for exchange and overcomes the limitations of the
SA:V ratio of large organisms
...
There are many alveoli
which increases the surface area across which oxygen and carbon dioxide can diffuse
...
Steep gradient can
also be maintained in lungs by the continuous blood flow in the capillaries which brings in more carbon dioxide and takes
away more oxygen
...
They also give ventilation to maintain diffusion gradients which makes the process more efficient
...
The trachea carries clean, warm and moist air from the nose into the chest; it is supported by incomplete rings of strong,
inflexible cartilage which stops the trachea from collapsing and holds the airway open
...
It’s lined with ciliated epithelium and goblet cells
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The cilia waft the
mucus away from the lungs to the back of the mouth
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The bronchi have a similar structure to that trachea but are smaller
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The bronchioles have no cartilage rings
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This changes the amount of air reaching the lungs
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Alveoli consist of a layer of thin, flattened squamous epithelial cells, along with some collagen and elastic fibres
...
The elastic fibres allow the alveoli to stretch as air is drawn in
preventing bursting
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This is elastic recoil
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This refreshes the air in the air sacs by increasing the
partial pressure of oxygen in the air sacs so the concentration of oxygen is higher than the concentration in the blood
...
The mechanism of ventilation in mammals
To include the function of the rib cage, intercostal muscles (internal and external) and diaphragm
...
Inspiration is an energy-using process
...
The
external intercostal muscles contract to move the ribs up and out
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The pressure is lower than the atmospheric air, so air is drawn in through the nasal passages, the
trachea, the bronchi and bronchioles into the lungs
...
Expiration is a passive process
...
The external
intercostal muscles relax so the ribs move down and inwards under gravity
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Air moves out
of the lungs until the pressure inside and out is equal
...
The internal intercostal muscles contract, pulling the ribs down hard and fast
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You can’t completely expel air from the lungs because the lungs cannot be completely compressed
...
The relationship between vital capacity, tidal volume, breathing rate and oxygen uptake
To include analysis and interpretation of primary and secondary data e
...
data logger and spirometer
...
Vitalographs are also used which is a sophisticated version of the peak flow meter
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A spirometer measures breathing patterns and components of lung volume
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The carbon dioxide absorber is a chemical that absorbs carbon dioxide like sodium hydroxide
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A spirometer can be used to measure tidal volume as the person isn’t breathing through their nose so breathes evenly
...
Using a nose clip whilst measuring vital capacity ensures all air breathed comes from the chamber so that results aren’t
invalid
...
Vital capacity is the maximum volume of air inhaled/exhaled in one breath
...
Inspiratory reserve volume is the maximum volume of air you can breathe in during and after normal inhalation
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Residual volume is the volume of air left after exhaling
...
Total lung capacity is the sum of the vital capacity and residual volume
...
When oxygen demands increase (during exercise), the tidal volume increases from 15% to up to 50% of the vital capacity
...
The mechanisms of ventilation and gas exchange in bony fish and insects
The scaly outer covering of fish doesn’t allow gaseous exchange
...
The gills
have a large surface area, good blood supply, and thin layers
needed for successful gaseous exchange
...
There is
countercurrent exchange system occurs where the water moving
over the gills and the blood in the gills flow in different directions
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More gaseous
exchange can take place
...
When fish are swimming, a current of water flows over the gills when the open their mouth and operculum
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The pressure in the
cavity decreases and water moves into the buccal cavity
...
The floor of the buccal cavity moves up, increasing the pressure so water moves from
the buccal cavity over the gills
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The floor of the buccal cavity is steadily
moved up maintaining a flow of water over the gills
...
Along the thorax and abdomen
of most insects are spiracles where air enters and leaves
through and where water is lost
...
When an insect is inactive or has low oxygen demands, the
spiracles will be closed most of the time
...
Leading away from the spiracles are the tracheae (the
longest tubes – 1mm in diameter) carrying air into the body
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Chitin makes up the cuticle
...
The tracheae branch forming tracheoles (narrower tubes –
0
...
8um) which are single, elongated cells with no chitin
lining so are freely permeable to gases allowing gas exchange
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Most of the time, air moves along by diffusion reaching all the tissues
...
Oxygen dissolves in the moisture on the walls of the tracheoles and diffuses into the surrounding cells
...
When oxygen demands build up, a lactic
acid is built up in the tissues resulting in water moving out of the tracheoles by osmosis exposing more surface area for
gaseous exchange
...
Very active insects also have mechanical ventilation where air is actively pumped into the system by muscular pumping
movements of the thorax and/or abdomen changing the body volume and tracheae and tracheoles pressure
...
Collapsible enlarged trachea or air sacs which act as air reserves are also used by active insects
...
They are usually inflated and deflated by the
ventilating movements of the thorax and abdomen
...
Gill filaments – site of gas exchange
2
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Gill arches – Supports the gills
The examination of microscope slides to show the histology of exchange surfaces
Title: Echange surfaces
Description: Great notes to understand the lungs, ventilation and much more!
Description: Great notes to understand the lungs, ventilation and much more!