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Biology: Paper 1: Biological Processes > Module 3 - Exchange Surfaces > Flashcards

Module 3 - Exchange Surfaces Flashcards

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1
Q

Why is diffusion across the outer membranes too slow in multi-cellular organisms?

A
  • Some organisms are deep within the body (a big distance)
  • Large animals have a slower SA:V ratio (as it is difficult to exchange substances)
  • They have a higher metabolic rate than single-celled organisms (they use up oxygen and glucose faster)
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2
Q

How does SA:V and the size of organism correlate?

A
  • The larger the organism, the smaller the SA:V ratio.
  • takes longer for substances to reach the cells.
  • it is impossible to absorb enough oxygen through the surface area to meet the needs of the body
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3
Q

How are gas exchange surfaces adapted to be efficient?

A
  • Increased SA:V: gas exchange takes place quicker.
  • Thin layers: short diffusion distances
  • Good blood supply: steeper the concentration gradient, the faster diffusion takes place.
  • Ventilation - maintains diffusion gradient and makes the process more efficient
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4
Q

how does gas exchange system occur in mammals?

A
  • consists of lungs which air is carried in and out.
  • lungs: inflatable sacs in the chest cavity.
  • air passes through the nose along the trachea, bronchi and bronchioles.
  • It then reaches the alveoli (gas exchange takes place)
  • lungs are protected by the ribcage.
  • Ribcage are held by intercostal muscles.
  • action of these muscles and the diaphragm help with ventilation
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5
Q

What are alveoli?

A

Surfaces where gas exchange takes place

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6
Q

What is the diaphragm?

A

A layer of muscular tissue beneath the lungs

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7
Q

What is ventilation?

A

Breathing movements

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8
Q

What does it mean mammals have a large metabolic rate?

A

If mammals have a large SA:V ratio, it means they have lots of energy and can supply to the cells

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9
Q

what features does the nasal cavity have?

A
  • a large surface area with a good bloody supply: this warms the air to body temperature.
  • Hair lining: this secretes mucus to trap dust and bacteria protecting lung tissue from irritation and infection.
  • Moist surfaces: increases humidity of the incoming air, reduces evaporation from exchange surfaces.
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10
Q

what is the Nasal cavity?

A
  • after air enters the nasal cavity
  • air enters the lung which is similar to temperature and humidity to the air
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11
Q

What do the trachea, bronchi and bronchioles do?

A
  • They are tubes which lead down into the alveoli, delivering oxygen and removing carbon dioxide
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12
Q

What are goblet cells?

A

(lining in the airways) - secretes mucus. This traps microorganism and dust particles which stops air reaching the alveoli.

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13
Q

What is cilia?

A
  • They are hair liked structures on the surface of epithelial cells lining the airways.
  • They beat the mucus secreted by the goblet cells.
  • Upwards away from the alveoli towards the throat
    prevents lung infection
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14
Q

What are elastic fibres?

A
  • In the walls of the trachea, bronchi, bronchioles and alveoli help the process of breathing out
  • they stretch and then recoil to push air out when exhaling.
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15
Q

What are smooth muscles?

A
  • In the walls of trachea, bronchi and bronchioles
  • they contract and relax depending on the level of activity.
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16
Q

How do smooth muscles act during exercise?

A
  • They relax, making the tubes wider.
  • less resistance to air flow and air can move in and out of the lungs more easily
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17
Q

What are cartilages?

A
  • In the walls of the trachea and bronchi
  • Its strong but flexible
    stops the trachea and bronchi collapsing when you breath in
  • so the pressure drops
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18
Q

how is the trachea adapted?

A
  • Large C shaped pieces of cartilage
  • smooth muscles
    elastic fibres
  • goblet cells
    ciliated epithelium
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19
Q

howis the Bronchi adapted?

A
  • smaller piece of cartilage
  • smooth muscles
    elastic fibres
  • goblet cells
    ciliated epithelium
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20
Q

how are Larger bronchioles adapted?

A
  • no cartilage
  • smooth muscles
    elastic fibres
  • goblet cells
    ciliated epithelium
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21
Q

how are the Smaller bronchioles adapted?

A
  • no cartilage
  • smooth muscles
    elastic fibres
  • no goblet cells
    ciliated epithelium
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22
Q

how are the Smallest bronchiole adapted?

A
  • no cartilage
  • no smooth muscles
    elastic fibres
  • no goblet cells
  • no cilia
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23
Q

how is the alveoli adapted?

A
  • no cartilage
  • no smooth muscles
    elastic fibres
  • no goblet cells
  • no cilia
24
Q

Why do smoker often develop long term coughs?

A
  • Cigarette smoke stops the cilia beating
  • it cannot waft mucus or trap microorganisms
  • this then causes infection and irritation
25
Q

Why does the amount of cartilage reduces as we move from the trachea to the bronchi to the bronchioles?

A

The airway tubes become smaller in diameter and do not need the same amount of support to hold them open.

26
Q

Why do cilia and goblet cells disappear deeper down in the airways?

A

They produce mucus in the airways to trap microorganisms so it should not be needed further down the airways.
- Cilia would take up too much space in the lumen of very small bronchioles, obstruct air flows.

27
Q

Why is the cartilage c shaped around the trachea?

A
  • They are strong and flexible
  • stops the trachea from collapsing
  • rings are incomplete
  • allows food to move easily down the oesphagus behind the trachea
28
Q

how is the Alveoli adapted?

A
  • gas exchange takes place
  • diameter around 200-300 um
  • consists of thin layers, flattened epithelial cells along with some collagen and elastic fibres
  • elastic recoil of the lungs
29
Q

How the alveoli are adapted for efficient gas exchange?

A
  • Good ventilation - helps maintain steep diffusion gradient.
  • good blood supply - maintains a steep concentration gradient for both carbon dioxide and oxygen.
  • Thin layers - short diffusion distances
  • Large surface area - needed for the amount of oxygen to be diffused into the body
30
Q

Gills

A
  • fish have 4 gills on each side of their head
  • they have a large SA, good blood supply & thin surface area for gas exchange
  • found within the gill cavity covered by a flap called the operculum
  • helps maintain one way flow of water over the gills
  • this brings water in with fresh oxygen, carries water away that has picked up carbon dioxide.
31
Q

Structure of gills

A
  • each gill made up of 2 rows of gill filaments
  • attached to a bony gill arch
  • each filament is thin, surface is folded into lamellae (gill plates)
  • provides a big surface area
32
Q

What is a counter- current system?

A

blood flows through the gill plates in one direction and water flows in the opposite direction.
- means water with a relatively high oxygen concentration gradient always flows next to blood with a lower concentration of oxygen.
- a steep concentration gradient is maintained between water and blood.

33
Q

Water flows over the gills

A
  • fish use their mouth and operculum flap to maintain a flow of water over their gills.
  • tips of the adjacent gill filaments overlap.
    Increases the resistance to the flow of water and slows down water movement
34
Q

Ventilation in bony fish (1)

A
  • fish opens its mouth
  • lowers the floor of the buccal cavity
  • increases volume of buccal cavity
  • pressure inside the buccal cavity to fall
  • water is then drawn into the buccal cavity due to the pressure gradient
35
Q

Ventilation in bony fish (2)

A
  • Fish closes its mouth
  • floor of the buccal cavity raises
  • volume of inside the buccal cavity falls
  • pressure inside the buccal cavity increases
  • water is forced over the gill filaments - where gas exchange occurs
36
Q

How is the structure of a fish gill adapted?

A
  • Gills have a large SA - diffusion
  • Rich blood supply - maintain steep concentration gradient
  • Tips of adjacent gills overlap- shows water flow
  • thin layers - short diffusion pathway
37
Q

Dissecting fish gills

A
  • Place your chosen fish in a dissection tray or on a cutting tray.
  • Push back the operculum and use scissors to carefully remove the gills. Cut each gill arch through the bone at the top and bottom.
  • You should be able to see the gill filaments
  • then draw the gills
38
Q

Gas exchange and ventilation in insects

A
  • they have high demands for oxygen
  • have a hard exoskeleton - prevents gas exchange occuring across the body
  • they have a open circulatory system
  • no blood or blood vessels
  • oxygen is delivered directly to the cells
  • CO2 removed directly from the cells
39
Q

How does this occur in insects?

A
  • Insects have spiracles: small openings where air enters and leaves the insects.
  • tubes lead to TRACHAE: carrying air into the body
  • tubes have CHITIN around them - which provide flexible support (keeping the tubes open)
  • smaller tubes (TRACHEOLES) - it is a single elongated with no chitin
  • walls are permeable and very thin
40
Q

How are insects adapted for gas exchange?

A
  • Tracheoles: site for gas exchange. (large SA)
  • Single layer of cells - short diffusion pathway
  • steep concentration gradient
  • good ventilation
41
Q

Limits to the diffusion of oxygen

A
  • end if the tracheole is the tracheal fluid - limits air getting to the end of the tracheoles
  • can be overcome when the insects is very active
  • insect activity increases, cell respiration increases, some anareobic respiration occurs producing lactic acid in cells
42
Q

Active ventilation in insects

A
  • tracheal system are expanded and have flexible walls.
  • Repetitive expansion and contraction of these sacs ventilate the tracheal system
  • movement of wings alter the volume if the thorax.
  • when the thorax increases in volume, the pressure inside drops and air is pushed into the tracheal system from outside
  • locusts can alter volume of their abdomen by specialized breathing movements.
  • They coordinate and closing valves in the spiracles
  • as the abdomen reduces in volume, the spiracles at the rear end of the body open and air can leave the tracheal system.
43
Q

How can this reduces the volume of fluid in the tracheoles?

A
  • contains the tracheal fluids: flooding the tracheoles and limits air penetration.
  • Increase in lactic acid
  • water potential decreases.
  • tracheal fluid enters muscle cells
  • moves out by osmosis
    CO^2 produced in muscle cells -> tracheoles and out of spiracles
44
Q

why are there sphincter around the spiracles of an insect?

A
  • This so air can enter and leave the cells when it needs to depending on their activity. They need to conserve water
45
Q

How does inspiration work?

A
  • external intercostal and diaphragm muslces contract
  • ribcage moves upwards and outwards, diaphragm flatterns
  • increases volume of thorax,
    lung pressure decreases
  • causes air to flow into the lungs
46
Q

Inspiration

A

It is an active process - requires energy

46
Q

How does expiration work?

A
  • external intercostal and diaphragm muscles relax
  • ribcage moves downwards and inwards, diaphragm becomes curved
  • thorax volume decreases
  • air pressure increases
  • air is forced out of the lung
47
Q

Expiration

A

passive process - does not require energy

48
Q

Spirometer

A

Is a piece of equipment that can be used to investigate breathing.

48
Q

How does a spirometer work? (1)

A
  • The person breathes in and out of their mouth via the mouthpiece
  • air is trapped between the enclosed chambers between the float and water
  • when breathing in, the volume of air in the chamber decreases and float drops
49
Q

How does the spirometer work (2)

A
  • when breathing out, the volume of air inside the chamber increases and the float rises.
  • the float is attached to a pen which writes on the paper on the revolving drum, recording the breathing movements.
  • when soda lime is used, the carbon dioxide breathed out into the mouthpiece is absorbed and it does not reach the chamber.
50
Q

Tidal volume

A

the volume of air in each breath (about 0.4dm^3)

51
Q

Vital capacity

A

the maximum volume of air that can breathed in and out in one breath

52
Q

Breathing rate

A

How many breaths are taken per unit time

53
Q

Oxygen uptake

A

the rate at which the person uses up oxygen

Biology: Paper 1: Biological Processes (12 decks)

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