Exchange surfaces Flashcards
state 3 factors that affect the need for exchange systems
- SA:VOL ratio
- metabolic rate (oxygen demand)
- endothermic (warm blooded or ectothermic (cold blooded)
what tends to require a circulatory system, a unicellular organism or a multicellular organism
A single celled organism
name 3 feature of an efficient exchange surface
- large surface area to volume ratio
- good blood supply
- permeable (to allow gases to pass through)
in what direction does the blood flow past the alveoli
deoxygenated blood from pulmonary artery and then oxygenated blood, to pulmonary vein
why do alveoli contain capillary’s
in order to have good blood supply, to allow oxygen to diffuse down the concentration gradient into the lungs from the alveoli into the blood, and for carbon dioxide to move down the concentration gradient, from the blood into the alveoli
what do the elastic fibres do, to expel air?
elastic fibres, stretch and recoil in order to expel air
what is the pulmonary surfactant?
a mixture of lipids and proteins, secreted into the alveolar space
what is the role of the pulmonary surfactant?
to lower the surface tension, at the air/ liquid interface, within the alveoli, stopping the walls of sticking together and collapsing, as we exhale
what is the partial pressure of oxygen in the alveoli
104
what is the partial pressure of oxygen in the blood
40
what is the partial pressure of carbon dioxide in the alveoli
40
what is the partial pressure of carbon dioxide in the blood
45
what is the role of cilia
to beat rhythmically, to waft mucus up towards the back of the thoat.
what is the role chemoreceptors
to detect a change in the blood Ph levels, if there is a decrease in blood Ph levels, the sympathetic nervous system will be stimulated by the medulla oblongata, in order to increase heart rate, thus meaning more oxygen is entering the blood and more carbon dioxide is leaving the blood
be able to label the breathing system
describe how inspiration occurs
external intercostals and diaphragm contract -> ribs move up and out and the diaphragm flattens -> increase in volume and a decrease in thorax pressure -> air drawn into lungs, down pressure gradient (opposite for expiration)
what is the function of cartilage
to prevent the collapse of the trachea and bronchus.
what is the function of goblet cells
in order, to secrete mucus (containing glycoproteins) and trap dust, that contains pathogens
what is the function of ciliated cells
to move in a synchronised pattern, to waft mucus up the airways, in order to be digest or coughed out
what is the function of smooth muscle
to narrow the airways, in order to restrict flow if there are harmful substance present in the air. They can dilate to increase air flow
what is the function of elastic fibres
they stretch during inhalation, to prevent alveoli from bursting and recoil, to expel air from the airways
what is the function of squamous epithelium
they are thin cells, to ensure that there is a short diffusion distance, thus resulting in an increased rate of gaseous exchange.
what shape is the cartilage in the trachea
C - shape rings
why does oxygen, always have a steep concentration gradient
due to blood being pumped away from the heart once oxygenated
what does ventilation do
brings in fresh air, increasing the concentration of oxygen in the alveoli and decrease the concentration of carbon dioxide in the alveoli, to ensure a steep concentration gradient
what to the intercostal muscles and the diaphragm do?
work together to change the shape of the thorax, to perform inspiration or expiration.
what are the names of the intercostal muscles
external and internal intercostals
is inhalation an active or passive process
active ( requires energy (ATP))
is exhalation an active or passive process
passive process ( muscles relaxing)
what happens during expiration
The external intercostal muscles relax and so does the diagram, becoming dome shaped, decreasing the volume and increasing the pressure, helping to force air out
when can exhalation become an active process and why?
when we exhale strongly, due, to causing the internal intercostal muscles to contract
how does a spirometer work
- A spirometer works, where the static lower half of the tank, is filled with water and the mobile upper half of the tank is filled with oxygen.
- When the subject breathes out, lid rises, when the subject breaths in lid falls
what is tidal volume
the volume of air breathe in or out the lungs per breath (during quiet breathing) (at rest around 0.5 dm3.
what is the inspiratory reserve volume
is the maximum volume of air that can be inspired in excess of tidal volume.
what is the expiratory reserve volume
the maximum volume of air that can be expired in excess of tidal volume.
what is vital capacity
the maximum volume of air, that can be moved by the lungs in one breath. (2.5 dm3 – 5dm3.
what is residual volume
is the volume of air left in the lungs after forced expiration (1.5 dm3)
What problems, do fish have regarding gaseous exchange
- water is denser and more viscous than air, so the oxygen needs more kinetic energy to cross the gas exchange surface,
- fish have small SA: vol ratio, so diffusion is not enough therefore the fish need a specialised exchange surface
- o2 conc in air is 21% in water it is 1%
how many pairs of lungs do most fish have
4-5 pairs of lungs
what is the role of gill rakers
to stop food particles from reaching gill filaments.
what is the role of lamellae
to increase the surface area for gas exchange
what does each gill consist of
two rows of filaments and gill rakers
why are the walls of the gill filaments thin
to allow for short diffusion distance
why is there a capillary network surrounding the lamellae
to maintain a steep concentration gradient.
why do the tips of gill filaments overlap
to increase resistance to water flow
what is counter current
blood, and water flow in opposite direction, to maintain a high concentration gradient.
explain what happens during inspiration in fish
- the mouths opens and operculum closes,
- thus meaning that buccal cavity floor lowers, thus increasing the volume of the buccal cavity and decreasing the pressure.
- The water that flows into the mouth, is moving down a pressure gradient.
what happens during expiration in fish
- the buccal floor raises as the mouth closes
- thus increasing pressure and decreasing volume in the buccal cavity,
- then water is forced to flow over the gills, and the sides of the operculum, move in and open to allow water to be expelled from fish.
- (Water only flows in one direction).
what do insects have
trachea, tracheoles and spiracles
what is connected to the muscle fibres
the tracheoles
why do insects have a small size
so that diffusion distance are small
what are spiracles
they are what can be opened or closed, to help control the air drawn in and out, but can also control water loss
why is the water potential in the muscles lower
lower meaning that it will move into the muscles via osmosis, increasing diffusion of oxygen.
as the size of the organism increases, what happens to the SA:VOL ratio
it decreases (there will come a point where a specialised exchange system is required)
what cell forms the wall of the alveolus
squamous epithelial cells
what is pulmonary surfactant
a mixture of lipids and proteins, secreted into the alveolar space
what does pulmonary surfactant do
- Lowers the surface tension at the air/liquid interface, within the alveoli
- this, stops the walls sticking together and collapsing as we exhale
what is the trachea lined with
ciliated epithelial cells, which in turn, waft mucus up the airways out fo the trachea
what is the trachea lined with
ciliated epithelial cells, which in turn, waft mucus up the airways and out of the trachea, to be swallowed and digested in the stomach or expelled by a cough
how is cartillage arranged in the trachea
in C-shaped rings
how is cartilage arranged in the trachea
in C-shaped rings
describe a spirometer trace
what is the equation for pulmonary ventilation rate
tidal volume X breathing rate = pulmonary ventilation rate
what are the two adaptations of the trachea
- the trachea has C shaped cartilage rings to allow the oesophagus to change shape, due to there being a region absence of cartilage near the oesophagus
- the walls are lined with ciliated epithelial cells, which have cilia to move the mucus. the Goblet cells produce mucus, which trap and attach to the pathogens
what happens when smooth muscles relaxes in the bronchioles
the walls of the bronchioles widen, allowing for more air, to be passed through
where is the site of gas exchange
the alveoli
how many cells thick are the wall of the alveolus and the wall of the capillary and why
so there is a short diffusion distance
ventilation involves the action of which two sets of muscles
the diaphragm and the intercostal muscles
what are the names for the two intercostal muscles
- internal
- external
what happens during inhalation
the external intercostal muscles contract
the diaphragm contracts, causing them to flatten
why is inhalation an active process
because it involves muscle contraction
why is exhalation a passive process
due to the muscles relaxing
what happens during exhalation
- the external intercostal muscles relax, and return to their original length
- the diaphragm. also relaxes returning to its original domed shape, thus reducing the volume of the thorax and lungs. to force air out
what is the alveoli structure
- walls are 1 cell thick
- outer layer of squamous epithelial cells
- around 100-300um wide airspace
- elastic fibres + collagen are there to stretch and recoil, to help expel air.
why is blood only 95% saturated with oxygen
- some of the inhaled air does not take part in gaseous exchange (dead space)
- some blood in the lungs, doesn’t go through any alveolar capillaries
why does exhalation become an active process
exhalation, becomes an active process as the internal intercostal muscles contract pulling up the ribs down hard and abdominal muscles, contract forcing the diaphragm up to force air out of the lungs more forceful. (this requires energy from respiration)
how might athletic training, affect the condition of the lungs
- stronger intercostal muscles
- stronger diaphragm
- tidal volume will thus increase
- the alveoli, will get bigger
- increase in lung volume
how does the structure of the gills relate to their function?
- gill filaments + lamellae = large SA
- thin walls of the lamellae = short diffusion distances
- gill filaments overlap, to slow down water flow (increasing resistance), this allows for sufficient time for diffusion
- capillary network, to keep a high concertation gradient
- counter current, to maintain a high concentration gradient
