1 Watch the
video and put the words into the gaps in the text.
Our circulatory system is designed to provide each
of our 1_____ with the type of diffusion exchange practiced by simple
unicellular 2_____ living in aquatic environments. This exchange occurs at
the level of the tiniest blood vessels, capillaries. Wastes, 3_____, gases
and hormones are 4_____ between the blood and the body cells. With walls only a single cell thick
capillaries are well adapted to their 5_____ in exchange. Most nutrients,
oxygen and carbon 6_____ diffuse rattling through capillary cell membranes.
Salts and small charged molecules including some small proteins move through
fluid-filled spaces within the capillary cell 7_____ or between adjacent capillary
cells. Pressure within capillaries causes a continuous leakage of fluid from
the blood plasma into the spaces surrounding the 8_____ and adjacent tissues.
This fluid 9______ as interstitial fluid consist primarily of water in which
nutrients hormones, gases, wastes and small proteins from the blood are
dissolved.
The exchange of materials between
capillary 10_____ and nearby cells occurs through this 11_____ fluid which
bathes nearly all the cells of the body. Capillaries are so narrow that 12_____
blood cells must pass through them in single file. Consequently, blood is
sure to pass very close to the capillary walls. In addition capillaries are
so numerous that no body cell is more than one hundred micrometers or 4000 of
an inch from a capillary. These factors 13______ the exchange of materials by
diffusion. It is estimated that the total length capillaries in the human is
over eighty thousand six hundred kilometers or 50,000 miles. As blood is
forced through this narrow almost endless 14_____ of capillaries the speed of
blood flow drops very quickly further enhancing 15______ by increasing the
amount of time available for the blood and cells to exchange materials.
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known
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role
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membrane
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cells
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exchanged
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dioxide
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nutrients
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organisms
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capillaries
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facilitate
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interstitial
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diffusion
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blood
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red
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network
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2 Vocabulary focus. Study the words and word combinations, practise
their translation, spelling. Check your knowledge
in the test. Play vocabulary game and set your own vocabulary game record.
3 Mark the following statements as True or False.
1. Total length of capillaries in the human is over five
thousand six hundred kilometers.
2. Most nutrients, oxygen and carbon dioxide diffuse
through capillary cell membranes.
3. Further reduction in diffusion happens through increasing the amount of time available for
the blood and cells to exchange materials.
4. Wastes, nutrients, gases and hormones are exchanged
between the blood and the body cells with walls only a two cells thick.
5. Pressure within veins causes a continuous leakage of
fluid from the blood plasma into the spaces surrounding the capillaries and
adjacent tissues.
4 Answer the Questions.
1. How is our
circulatory system designed?
2. What causes pressure within capillaries?
3. What is interstitial fluid?
4. What is the total length of capillaries?
5. How many red blood cells can pass through capillaries?
