3.1.1 - EXCHANGE AND TRANSPORT Flashcards

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1
Q

Why do organisms need to exchange substances with their environment?

A
  • Cells need to take in things (e.g. oxygen and glucose for aerobic respiration)
  • They need to excrete waste products from such reactions (e.g. carbon dioxide and urea)
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2
Q

What would have a larger SA:V ratio, a mouse or a hippo?

A

The mouse would have a higher SA:V ratio

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3
Q

How to calculate SA:V ratio?

A

SA ÷ V

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4
Q

Why do multicellular organisms need exchange surfaces?

A

An organism needs to supply every one of its cells with substances like glucose + oxygen (for respiration), but also needs to remove waste products to avoid damage

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5
Q

Why is the diffusion rate slower for multicellular organisms than unicellular organisms?

A
  • In unicellular organisms, these substances can diffuse quickly into (or out of) the cell across the cell surface membrane (the distance is small)
  • However in multicellular organisms, some cells are deep within the body (big difference between them and outside world), larger animals have a low SA:V ratio (difficult to exchange substances or supply a large volume of animal through a small outer surface, multicellular organisms have a higher metabolic rate than unicellular organisms (use of oxygen and glucose faster)
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6
Q

How are root hair cells adapted for transport?

A

They grow long ‘hairs’ which stick out into the soil, increasing their surface area

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7
Q

How are alveoli adapted for transport?

A
  • Each alveolus is made from a single layer of thin, flat cells called the alveolar epithelium —> this decreases the distance over which oxygen and carbon dioxide diffusion takes place
  • Alveoli are surrounded by large capillary network (each alveolus has its down blood supply) + lungs are ventilated —> maintains concentration gradients of oxygen and carbon dioxide
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8
Q

How are fish gills adapted for transport?

A
  • They contain a large networks of capillaries for a good blood supply
  • They are also well ventilated (due to fresh water constantly passing over them

These features help maintain a concentration gradient of oxygen

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9
Q

Name four substances an organism needs to exchange with its environment

A
  • Oxygen
  • Glucose
  • Carbon dioxide
  • Urea
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10
Q

Name the components/organs in the human respiratory system

A
  • Trachea
  • Bronchi (singular Bronchus)
  • Bronchioles
  • Alveoli
  • Ribcage
  • Intercostal muscles (internal + external)
  • Diaphragm
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11
Q

What is the function of goblet cells in the mammalian gas exchange system?

A
  • Lines the airways
  • Secret mucus, trapping organisms and dust particles in the inhaled air, stopping them for reaching the alveoli
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12
Q

What is the function of cilia in the mammalian gas exchange system?

A
  • On the surface of cells lining the airways
  • Cilia beat the mucus, moving it upward away from the alveoli towards the throat, where it’s swallowed
    Prevents lung infection
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13
Q

What is the function of elastic fibres in the mammalian gas exchange system?

A
  • Present on the walls of the trachea, bronchi, bronchioles and alveoli to help the process of breathing out
  • On breathing in, ht lungs inflate and the elastic fibres are stretched
  • Then, fibres recoil to help push the air out when relaxing
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14
Q

What is the function of smooth muscle in the mammalian gas exchange system?

A
  • Present in the walls of the trachea, bronchi and bronchioles and allows their diameter to be controlled
  • During exercise, the smooth muscles relaxes, making the tubes wider
    ^— means there’s less resistance to airflow + air can move in and out of the lungs more easily
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15
Q

What is the function of rings of cartilage in the mammalian gas exchange system?

A
  • Lines the walls of the trachea and bronchi to provide support
  • it’s strong but flexible - stops the trachea and bronchi collapsing when you breathe in + the pressure drops
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16
Q

Describe the structure of the trachea in the mammalian gas exchange system

A

Cartilage - large C-shaped pieces
Smooth Muscle
Elastic fibres
Goblet cells
Ciliated epithelium

17
Q

Describe the structure of the bronchi in the mammalian gas exchange system

A

Cartilage - smaller pieces
Smooth muscle
Elastic fibres
Goblet cells
Ciliated epithelium

18
Q

Describe the structure of the larger bronchioles in the mammalian gas exchange system

A

NO cartilage
Smooth muscle
Elastic fibres
Goblet cells
Ciliated epithelium

19
Q

Describe the structure of the smaller bronchioles in the mammalian gas exchange system

A

NO cartilage
Smooth muscle
Elastic fibres
NO goblet cells
Ciliated epithelium

20
Q

Describe the structure of the smallest bronchioles in the mammalian gas exchange system

A

NO cartilage
NO smooth muscle
Elastic fibres
NO goblet cells
NO ciliated epithelium

21
Q

Describe the structure of the alveoli in the mammalian gas exchange system

A

NO cartilage
NO smooth muscle
Elastic fibres
NO goblet cells
NO ciliated epithelium

22
Q

Describe the process of inspiration in the mammalian gas exchange system

A
  • Breathing in
  • External intercostal and diaphragm muscles contract
  • Ribcage moves upwards and outwards + diaphragm flattens (increasing volume of the thorax)
  • As thorax volume increase, lung pressure decreases
  • Causes air to flow into lungs

INSPIRATION IS AN ACTIVE PROCESS - REQUIRES ENERGY

23
Q

Describe the process of expiration in the mammalian gas exchange system

A
  • Breathing out
  • External intercostal and diaphragm muscles relax
  • Ribcage moves downward and inwards + diaphragm becomes curved again (relaxes)
  • Thorax volume decreases, causing the air pressure to increase
  • Air is forced out of the lungs

NORMAL EXPIRATION IS A PASSIVE PROCESS - DOESN’T REQUIRE ENERGY

EXPIRATION CAN BE FORCED THOUGH (e.g. blowing out candles on birthday cake)
^— when forced, internal intercostal muscles contract, to pull the Ribcage down and in

24
Q

What is meant by tidal volume?

A

The volume of air in each breath (usually about 0.4 dm³)

25
Q

What is meant by vital capacity?

A

The maximum volume of air that can be breathed in or out

26
Q

What is meant by breathing rate?

A

How many breath are taken - usually in a minute

27
Q

What is meant by oxygen consumption/uptake?

A

The rate at which an organism uses up oxygen (e.g. the number of dm³ used up per minute)

28
Q

What is a spirometer?

A

A machine that can give readings of tidal volume, vital capacity, breathing rate and oxygen uptake

29
Q

Describe how a spirometer can be used

A
  • A spirometer is an oxygen-filled chamber with a movable lid
  • The person breathes through a tube connected to the oxygen chamber
  • As the person breathes in and out, the lid of the chamber moves up and down
  • These movements can be recorded by a pen attached to the lid of the chamber - this writes on a rotating drum, creating a spirometer trace
  • Or the spirometer can be hooked up to a motion sensor - this will use the movements to produce electronic signals, which are picked up by a data logger
  • The soda lime in the tube the subject breathes into absorbs carbon dioxide
30
Q

How are fish specially adapted to get enough oxygen from the water?

A
  • Water, containing oxygen, enters the fish through its mouth + passes out through the gills
  • Each gill is made of a lot of thin branches called gill filaments (primary lamellae), which give a big surface area for exchange of gases | The gill filaments are covered in lots of tiny structures called gill plates (secondary lamellae), which increase surface area. Each gill supported by a gill arch
  • Gill plates have lots of blood capillaries and a thin surface layer of cells to speed up diffusion
  • Blood flows through the gill plates in one direction + water flows over in the opposite direction (counter current system) | Maintains a large conc. gradient between the water and the blood - the conc. of oxygen in water is always higher than blood (so as much oxygen as possible diffuses from the after into the blood)
31
Q

Describe how fish gills are ventilated

A
  • The fish opens its mouth, which lowers the floor of the buccal cavity space inside the mouth) | Volume of buccal cavity increases, decreasing pressure in the cavity - water then sucked into cavity
  • When fish closes its mouth, the floor of the buccal cavity is raised again | The volume inside the cavity decreases, the pressure increases, and water is forced out of the cavity across the gill filaments
  • Each gill is covered by the operculum | The increase in pressure forces the operculum on each side of the head to opens, allowing water to leave the gills
32
Q

What is the operculum?

A

The bony flap on each side of the fish’s head, covering and protecting the gills

33
Q

Describe how insects exchange gases

A
  • Insects have microscopic air-filled pipes called tracheae which they use for gas exchange
  • Air moves into the tracheae through pores on the insect’s surface called spiracles
  • Oxygen travels down the conc. gradient towards the cells | Carbon dioxide from the cells moves down its own concentration gradient towards the spiracles to be released into the atmosphere
  • The tracheae branch off into smaller tracheoles which have thin, permeable walls and go to individual cells | The tracheoles also contain fluid, which oxygen dissolves in
  • The oxygen then diffuses from this fluid into body cells | Carbon dioxide diffuses into the opposite direction
  • Insects use rhythmic abdominal movements to change the volume of their bodies and move air in and out of the spiracles | When larger insects are flying, they use their wing movements to pump their thoraxes too
34
Q

Name the structures on an insect’s surface that allow air to enter the tracheae

A

Spiracles

35
Q

Describe the structure on an insect’s tracheoles

A

Tracheoles come of tracheae branches and are single elongated cells which run between tissues
No chitin - so are permeable and allow for easier gaseous exchange

36
Q

What is the function of the rings of chitin surrounding the tracheae?

A

They are impermeable (so there is no gas exchange in the tracheae) and provide structure for the tracheae