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Biology > 3.1 - Exchange surfaces and breathing > Flashcards

3.1 - Exchange surfaces and breathing Flashcards

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1
Q

why are exchange surfaces needed? (Molecules)

A
  • To take in and remove molecules (Take in O2 or glucose and get rid of waste products like CO2)
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2
Q

If the surface area of an object is 12 and the volume is 4 what is the SA:Vol?

A

3:1

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3
Q

How is the SA:Vol affected by the size of the object?

A
  • As the object gets larger (normally) the SA:Vol decreases

- Smaller organisms often have a large SA:Vol but larger objects have a smaller SA:Vol

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4
Q

How does the SA:Vol affect the need for an exchange surface in organisms?

A

Smaller organisms have a large SA:Vol meaning that diffusion is sufficient for gas exchange rather larger organisms have a smaller SA:Vol so they require exchange surfaces

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5
Q

What is an example of an organism that does not require a specialised exchange surface?

A

An amoeba is less than 1mm in size meaning it has a high SA:Vol meaning diffusion is sufficient by itself
or a flatworm is similar however a flatworm is larger but has a much larger SA still

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6
Q

How do levels of activity affect the need for an exchange surface?

A

Organisms that are more active have a higher metabolic rate meaning they are more in need of an exchange surface than organisms that are not as active and have a lower metabolic rate

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7
Q

What are the characteristics of a good exchange system?

A
  • A large surface area = More space across in which diffusion can take place
  • A short diffusion distance = Increases the speed of diffusion from one place to another
  • A good blood supply = Maintains the concentration gradient
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8
Q

What are some examples of exchange surfaces?

A
  • Intestines (Have microvilli)
  • Lungs (Alveoli)
  • Gills (Counter-current flow)
  • The tracheal system in insects (Using tracheal fluid)
  • Leaves (Have the stomata and spongy mesophyll)
  • Root hair cells (Large SA)
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9
Q

How would the lungs be labelled from top down?

A
  • Trachea
  • Ribcage and intercostal muscles lying between the ribs, surround the:
  • x2 Bronchus
  • Many bronchioles
  • Many alveoli
  • Pleural space outside of lungs but within the ribcage
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10
Q

How is the trachea fit for function?

A

-Contains “C shaped” rings of cartilage to support it = keep the trachea open and stops the collapsing (the “C shape allows for flexibility when swallowing large quantities of food)

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11
Q

Where does gas exchange occur in humans?

A

In respiratory bronchioles and the alveoli

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12
Q

How are the bronchi fit for function?

A
  • Contains goblet cells that secrete mucus
  • Contains ciliated epithelial cells that wafts the mucus with particles up the trachea to be swallowed and neutralised by the stomach acid or expelled
  • Contains smooth muscle that constricts the airways
  • Contains connective tissue (with elastic fibres)
  • Contains small blood vessels
  • Contains “C shaped” cartilage
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13
Q

How are the bronchioles fit for function?

A
  • Contains smooth muscle that constricts to narrow the airways to stop harmful air from entering the alveoli
  • Contains connective tissue (With elastic fibres)
  • Contains ciliated epithelial cells that wafts the mucus with particles up the trachea to be swallowed and neutralised by the stomach acid or expelled
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14
Q

How are the alveoli (air-sacs) fit for function?

A
  • Have a dense network of capillaries that provides a good blood supply to maintain the concentration gradient
  • Contains very large surface area due to lots of alveoli
  • Contains squamous epithelial cells that are very thin meaning it provides a short diffusion distance
  • Contains elastic fibres that work to re-inflate the airways in the alveoli
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15
Q

What are the two movements of the diaphragm used to inflate/deflate the lungs?

A
  • The diaphragm moves up when it is relaxed, this increases the pressure in the thorax so that air is forced out
  • The diaphragm moves down when it is contracted, this decreases the pressure in the thorax so that air is forced in
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16
Q

What occurs in the gas exchange in the alveoli?

A
  • The oxygen from the air that is breathed in diffuses into the blood stream in the alveoli
  • The Co2 is diffused out to be expelled during exhalation
17
Q

What is used to measure movement lung volume?

A

A spirometer

18
Q

What does the spirometer produce?

A

A spirometer trace, this shows a graph of volume of air

19
Q

What conditions must be set in place before using the spirometer?

A
  • The user must be healthy (The user shouldn’t be someone with asthma)
  • The mouth piece must be sterile (To prevent transmission of infections)
  • The water must not be over-filled
  • The oxygen must be fresh
  • The soda lime must be fresh to absorb the CO2
20
Q

In what direction is the trace produced?

A
  • The pen goes down when the participant inhales
  • The pen goes up when the participant exhales
  • The paper is then flipped upside down so that the trace displays the opposite (Down=exhale, Up=inhale)
21
Q

What is the tidal volume?

A

Everyday breathing rate (0.5dm3)

22
Q

What is the residual volume?

A

The volume left over after fully forcing expiration (1.5dm3)

23
Q

What is vital capacity?

A

The total volume in lungs between maximum inhale and maximum exhale (2.5 to 5dm3)

24
Q

What is vital capacity affected by?

A
  • Fitness/exercise
  • Age
  • Size
  • Gender
  • Height
25
Q

How is oxygen uptake measured?

A

Using a spirometer trace to measure the tidal volume of a person over a longer amount of time (1 minute)

  • This is done by first filling the chamber with 100% oxygen
  • The person breathes in the oxygen and exhaling CO2
  • CO2 is absorbed meaning the volume of gas in the chamber is decreasing as the O2 is being inhaled
  • This shows the decreasing rate of oxygen as oxygen uptake from the trace
26
Q

How is oxygen uptake calculated from the spirometer trace?

A

Pick two points at the same point of exhalation/inhalation but at different times:
Point A- 4dm3 at 30 seconds
Point B- 3dm3 at 60 seconds
Work out the change in volume divided by the time
Therefore 1dm3 in 30 seconds
so 1dm3/0.5 =2dm3min-1

27
Q

Why does fish’s gas exchange system have to be more efficient than humans?

A

Because there is a lower percentage of O2 in sea water (few mg of O2 per litre) than in the air (20% O2)

28
Q

How could you describe the gas exchange system in fish?

A
  • Water enters the buccal cavity (mouth)
  • Water flows over the gill arch which contain blood vessels containing:
  • Oxygenated blood (goes back to the fish)
  • Deoxygenated blood (goes to gills to pick up O2)
29
Q

What are primary and secondary lamellae?

A
  • Gill filaments (primary lamellae) are hair like structures attached to the gill arch
  • On the gill filaments are gill plates (secondary lamellae)
30
Q

What is the counter-current system in fish?

Describe it

A
  • As deoxygenated blood enters and goes through the filaments water travels across the other way perpendicular to the deoxygenated blood
  • Blood then flows parallel to the water flow
  • This causes the oxygen to travel down the concentration gradient to the deoxygenated blood which becomes oxygenated
  • As the blood flows in the opposite direction to the water, it maintains the oxygen concentration as higher in the water meaning that the oxygen can still diffuse into the blood
31
Q

What is the graph that shows the counter-current flow

A 
^                        | 
        \ \                    |
          \ \   Water     |       
Blood  \ \                | So blood is up and water is down
              \ \              |
                \ \            |
                    v         |
32
Q

What does the counter-current system in fish accomplish?

A
  • Blood exits the gill filaments having extracted most of the O2 available
  • The counter-current flow maintains a concentration gradient all along the gill plate allowing more oxygen to be extracted
33
Q

How does a fish ventilate?

A
  • Fish can move causing the water to go into the buccal cavity and through the gills
    e. g: Great white sharks are “obligate ram ventilators” meaning they rely on movement to ventilate and have water move through the gills
  • Some other fish’s can open and close their buccal cavities which causes the gills to open and close making the water rush across them allowing oxygen to be extracted
34
Q

What is the insects equivalent of blood called?

A

Haemolymph, this fluid circulates around the body cavity without blood vessels

35
Q

What system supplies oxygen to the haemolymph in the body?

A

The tracheal system

36
Q

What is the tracheal system?

A
  • Spiracle, external opening or pore
  • Trachea, supported by chitin
  • Tracheoles
  • Site of gas exchange, with tracheal fluid
37
Q

How is tracheal fluid used when the insect is inactive?

A
  • When the insect is inactive there is a low demand for oxygen
  • This causes the tracheal fluid to leak into the tracheole meaning there is less surface area available for gas exchange
  • This means less water is lost out of the tracheoles
38
Q

How is tracheal fluid used when the insect is more active?

A
  • When the insect is more active there is a higher demand for oxygen
  • This causes the tracheal fluid to be drawn out of the tracheole and into the tissues meaning there is a larger surface area for gas exchange
  • This means the insects may dry up more quickly
39
Q

How does a insects ventilate?

A
  • Extremely active insects can flex their abdomen to increase ventilation
  • Movement of the flight muscles can increase the ventilation into and out the trachea
  • This is helpful as when flying, the insects are in need of more ventilation as they are more active
  • Locusts are able to actively ventilate to increase the movement of gases in the trachea. This is through the opening and closing of specific combinations of spiracles

Biology (23 decks)

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