chapter 7 Flashcards
exchange surface and breathing
why is diffusion alone able to supply a single celled organism enough oxygen (2 reason)
1) has low oxygen demands and low carbon dioxide
production
2) the SA:V is large
what requires more oxygen a multicellular organism or single cellular
larger multicellular organisms as their metabolic activity is higher
why cant diffusion be the main source of oxygen for multicellular organisms
because the distance between the cells are not close enough for diffusion to take place and its SA:V is low so it would take to long to diffuse the oxygen required
what are the 4 main things most multicellular organisms have adapted to their exchange surfaces (4 things)
1) blood supply- the steeper the concentration gradient the
faster the diffusion
2) thin layers- distance the oxygen has to diffuse is shorter
3) high SA:V- provides the area needed for exchange
4) ventilation- helps maintain the concentration gradient
why are gaseous exchange systems moist (like the alveoli) and what’s its downside
so the oxygen can diffuse faster by dissolving into the water then diffusing into the blood but it means that water can be lost
why do mammals need a specialised exchange system
as they need to regulate their body temperature, the have lots of cells and have a high metabolic rate
the nasal cavity’s features (3 features)
1) large surface area with a good blood supply which warms
the air
2) a hairy lining of mucus to catch dust and bacteria ot
allowing it to go into the lungs
3) moist surface to reduce evaporation from surface exchange
what is the trachea
the main airway carrying clean moist air from mouth and nose into the lungs
what’s the trachea made of
the tube is supported by rings of cartilage to protect it from collapsing
what is the trachea lined with
a ciliated epithelium with goblet cells between and below the cells
what does the goblet cells do in the trachea
it produces mucus onto the lining of the trachea
what does mucus do
trap dust and bacteria which is coughed up or swallowed to be digested
what is the bronchus
the trachea divides into two bronchi. it has the same structure
what are the bronchioles
the bronchus divides into many bronchioles (1mm diameter) no cartilage rings.
what happens in the bronchioles when the smooth muscle contracts
the bronchioles close up this then restricts the air from entering the lungs
what happens in the bronchioles when the smooth muscle relaxes
the bronchioles open up this then allows air to enter the lungs
what are aveoli
they are tiny air sacs covered by blood vessels. they are the main gas exchange surface and are only in mammals.
what are alveoli made from
collagen and and elastic fibres allowing it to stretch. when they go to their resting state its called elastic recoil
what are the 3 adaptions an alveoli withhold as a exchanger of gas
1) thin layers
2) good ventilation (from the trachea)
3) good blood supply (from blood vessels on it)
explain what the diaphragm is
its a dome shaped muscle which forms the floor of the thorax
what’s the external intercostal muscle and the internal intercostal muscle
found between the ribs
what is the thorax lined by
the pleural cavity and has lubricant fluid to help the membranes to move around as you breathe
what happens when you inhale
the diaphragm contracts and lowers, the external intercostal muscle moves ribs up and out, air is drawn into lungs as the thorax volume increases
what happens when you exhale
the diaphragm relaxes and Highers, the external intercostal muscle moves the ribs down and in, the elastic fibres in the alveoli relax, pressure inside thorax is greater than outside so air moves out
how can you measure capacity of the lungs (3 ways)
peak flow meter- this measure the most you can exhale
vitalographs- exhale quick through a mouthpiece which is
put on a graph which shows the volume
breathed out and how fast. this volume of air
is called forced expiration
spirometer- used to measure different aspects of the lung
what’s tidal volume
the volume of air that moves in the lungs
what’s vital capacity
strongest exhalation followed by strongest inhalation
what’s expiratory and inspiratory reserve volume
inspiratory- max volume of air you can breathe in
expiratory- extra amount of air you breathe in over and above the tidal volume
what’s the breathing ate
how many breaths a minute
what’s residual volume
how much is left in your lungs after max exhale
what’s total lung capacity
the vital capacity and the residual volume
what’s the ventilation rate
total volume of air inhaled in a minute
what happens to the tidal volume when oxygen needs are high
it increases to as much as 15-50% of the vital capacity
what gaseous exchange hard for an insect (3 things)
they have a high metabolic rate
they have an exoskeleton which doesnt alow for gaseous exchange to take place
dont have blood pigment so cant carry oxygen in the blood
How do insects go through gas exchange
they have spiricales which alow for oxygen to be directly delivered to the cells
how does the spiricales adapt to lose less water
they have sphincters which close up the spiricles to stop water loss.
what hapens to the spiricles when the insect is inactive and whats its benefit
its spiracles close up to prevent water loss. when oygen demands grow or CO2 levels build upthe spiricles start to open up
how does O2 travel through the insect
through the piricles in the trachea which then splits into the tracheoles
what is the trachea made of and can gas exchange take place
chitin which keeps them open and because chitin is impermeable to gas no gas exchange can take place.
where does most of the gas exchange take place inside of an insect and how does it diffuse into cells
through the tracheoles as they are not made of chitin so gas exchange can take place. the O2 dissolves into the tracheal fluid and then diffuses into cells
for bigger insects with higher O2 demands what are the two adaptations they have
mechanical ventilation- this is where air is pumped into the system by movements from the thorax
bigger air sacs- these act as air resevoirs
do fish need to prevent water loss
no because their in the sea
why dont fish have lungs
because water is 1000 times denser and more viscous than air and has a much lower O2 content so it would use to much energy
why are gills good gas exchangers
thin layers
good blood supply
large surface area
what is the operculum
the flap that covers the gills
whats the gill lamellae
these are within the thin layers whcih are close together with good blood supply and large surface area
what are gill fillaments
a stack of gill plates
how do fish keep a constant water flow over the gills
when they are swimming they just open their mouth and let the water run past the gills but with bony fish they have found a more effcient way
how do bony fish keep take in water
the buccal cavity (mouth) lowers increasing the volume and therefore dropping the pressure which alows for water to enter the mouth. and the opercular valve is shut (the gills valve)
how do bony fish take water out past the gills
the buccal cavity rises and the opercular valve opens which means the pressure in the mouth is more so water runs over the gills
what are the two other things that gills have adapted to for gas exchange
the tips of the gill filaments overlap meaning it slows down the water over the gills
a countercurrent exchange system is set up
what is a countercurrent exchange system
the water moving over the gills runs opposite to the blood flow. this means there is a steeper concentration gradient is achieved throughout the flow. in a result fish take out 80% of oxygen from the water
