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Biology A level > 3.1.1 - Exchange and Transport > Flashcards

3.1.1 - Exchange and Transport Flashcards

1
Q

Factors affecting exchange system

A

Size
SA:V ratio
Metabolic activity

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2
Q

How does size affect the need for an exchange system

A

In single-celled organisms, the cytoplasm is very close to its environment. Diffusion will supply enough O2 and nutrients to keep the cells alive and active

In multicellular organisms have several layers of cells, so there’s a longer diffusion pathway. Diffusion is too slow to enable a sufficient supply to the innermost cells

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3
Q

How does SA:V affect the need for an exchange system

A

When organisms have a large SA:V their SA is large enough to supply all the cells with sufficient O2

V increases more quickly than SA so the SA:V is smaller in larger organisms so a specialised exchange surface is needed

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4
Q

How does metabolic activity affect the need for an exchange system

A

Metabolically active organisms need good supplies of O2 and nutrients to supply energy for movement and warmth so the exchange of substances need to be efficient

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5
Q

Features of a good exchange surface

A

Large surface area - achieved by folding walls and membranes
Thin, permeable barrier - shorter diffusion distance
Good blood supply - maintain steep concentration gradient (brings molecules to supply side and removes from demand side)

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6
Q

How are lungs adapted

A

Many alveoli - large SA:V
Thin barrier - short diffusion pathway
Good blood supply (capillaries) to carry dissolved gases to and from alveoli
Ventilation refreshes air in alveoli
Elastic tissue to stretch/ recoil to help expel air

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7
Q

Function of goblet cells

A

Produce mucus

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8
Q

Function of cartilage

A

Prevent collapse of airways

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9
Q

Why do the walls of alveoli contain elastic fibres

A

Expand (inhalation) to increase lung volume
Prevent alveoli bursting
Elastic fibres recoil

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10
Q

Inspiration

A

Diaphragm contracts to move down and become flat. Displaces digestive organs downwards
External intercostal muscles contract moving the ribs outward and upward
Volume of thorax increases
Pressure in thorax < atmospheric pressure
Air is drawn in through the nasal passages, trachea, bronchi and bronchioles into lungs

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11
Q

Thorax

A

Chest cavity
Lined with pleural membranes - space between these membranes is the pleural cavity - usually filled with lubricating fluid

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12
Q

Expiration

A

Diaphragm relaxes and is pushed up by displaced organs underneath
External intercostal muscles relax and ribs fall
Volume of thorax decreases
Pressure in thorax > atmospheric pressure
Air is moved out of the lungs

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13
Q

What does the alveoli consist of

A

Thin, flattened epithelial cells alone with some collagen and elastic fibres

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14
Q

Elastic recoil

A

When the elastic fibres in the alveoli return to their resting size, they help squeeze the air out

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15
Q

What is the inner surface of the alveoli covered in

A

A thin layer of solution of water, salts and lung surfactant

When O2 diffuses out of the alveoli, it first dissolves in the water before diffusing into the blood. Water can also evaporate into the air in the alveoli

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16
Q

Lung surfactant

A

Phospholipid that coats the surfaces of the lungs

Without it, watery lining of alveoli would have surface tension —> collapse

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17
Q

Collagen in alveoli

A

Ensures alveoli aren’t deformed as they stretch (support)

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18
Q

Distribution and function of capillaries

A

Over surface of alveoli

To provide a large surface area for exchange

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19
Q

Distribution and function of cartilage

A

In walls of bronchi and trachea

To hold the airways open and provide structural support

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20
Q

Distribution and function of goblet cells

A

In ciliated epithelium

To produce and release mucus

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21
Q

Distribution and function of smooth muscle

A

In walls of airways

Contracts to constrict or narrow the airways

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22
Q

Loose tissue

A

Contains elastic fibres, glands and blood vessels

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23
Q

Peak flow meter

A

Simple device that measures how much air can move out of (and therefore into) the lungs

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24
Q

Spirometer

A

Device that measures the movement of air in and out of the lungs as the person breathes

Also measures oxygen consumption as the chamber of soda lime absorbs carbon dioxide

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25
Vital capacity
Maximum volume of air that can be moved by the lungs in one breath Measured by taking a deep breath and expiring all the air possible from the lungs Usually in the region or 2.5-5.0 dm^3
26
What does vital capacity depend on
The size of the person (particularly their height) Their age and gender Their level of regular exercise
27
Tidal volume
Volume of air moved in and out with each breath Usually measured at rest (0.5 dm^3) - sufficient to supply all the oxygen Increases when exercising
28
Residual volume
Volume of air that remains in the lungs even after forced expiration Air remains in airways and alveoli Approx. 1.5 dm^3
29
Total lung capacity
Sum of vital capacity and residual volume
30
Precautions to take when using a spirometer
Subject should be healthy and free from asthma Wear a nose clip Sterilise mouthpiece No air leaks in apparatus - invalid/ inaccurate results Don’t overfill water chamber - water may enter air tubes
31
How do we know the volume of oxygen absorbed by the blood
We can assume that the volume of carbon dioxide released and absorbed by the soda lime is equal to the volume of O2
32
How is breathing rate calculated
Counting the number of peaks in one minute
33
Calculating oxygen uptake
Divide the difference between the first peak and last peak by the time (s)
34
What will increases oxygen uptake result from
Exercise (more O2 and less CO2) | Deeper breaths
35
Why do insects require a gas exchange system
Very active in life cycle | Tough exoskeleton through which little/ no gas exchange takes place
36
Spiracles
Air opening in each segment of the insect | Allows air to enter inside the insect
37
Why do insects frequently close their spiracles
To minimise water loss
38
Insect tracheae
Leads away from the spiracles Run both along and into the body of the insect Carry air into the body
39
What are insect tracheae lined with
Spirals of chitin which keeps them open if they are bent or pressed
40
Why does little gas exchange take place in insect tracheae
Chitin is mostly impermeable to gases
41
Tracheoles
Further branches of the tracheae Vast number gives a large surface area Some oxygen dissolves in moisture in the walls of the tube and diffuses into the surrounding cells
42
Where is tracheole fluid found
In the ends of tracheoles
43
Why do insects frequently close spiracles
To reduce water loss
44
How do larger insects ventilate their tracheal system
Sections of the tracheal system can be expanded and contacted by flight muscles Movement of wings can alter volume of the thorax Abdomen volume can also be expanded then reduced
45
Oxygen conc. in water is
Typically lower than that in air
46
Operculum
Covers and protects the gills and is active in maintaining a flow of water over the gills
47
Gill arch
Bony structure with two rows of gill filaments (primary lamellae) coming off it
48
Gill filaments
Very thin and their surface is folded into many secondary lamellae
49
Where does gas exchange take place in bony fish
Secondary lamellae - blood capillaries carry deoxygenated blood close to the surface
50
Advantages of counter current flow
Absorbs maximum amount of oxygen from the water Ensures steeper conc. gradients are maintained vs a parallel system Bony fish can remove approx. 80% of O2 from the water
51
Ram-ventilation
Only occurs when fish are moving | Fish open their mouths and operculums to keep a current of water flowing over their gills
52
Buccal - opercular pump
Used when fish aren’t moving
53
How does the buccal-opercular pump work
Base of mouth moves downward, lowering pressure in buccal cavity - water is drawn in Mouth then closes, pressure of buccal cavity increases - pushing water through gills At the same time, operculum opens, reducing pressure in opercular cavity helping water flow over gills
54
Inspiratory capacity
The maximum volume of air that can be breathed in
55
Function of ciliated epithelial
Move mucus
56
Function of squamous epthelial
Provide a short dffusion distance
57
Features of nasal cavity
Large SA w/ good blood supply - warms air to body temp Hairy lining - secretes mucus to protect lung tissue from infection Moist surfaces - Increase humidity of incoming air, reducing evaporation
58
Bronchus
Division of trachea Also has supporting rings of cartilage but much smaller Ciliated cells but v. little goblet cells
59
Bronchiole
No cartilage Walls contain smooth muscle, contracts to constrict bronchioles, changes amount of air reaching lungs Lined w/ thin layer of flattened epithelium
60
Adaptations of gills
Large SA for diffusion Rich blood supply to maintain conc gradient Thin layers - short diffusion distance Tips of adjacent gill filaments overlap - increases resistance to flow of water over gill surfaces and slows down movement of water - more time for gas exchange
61
How is the steep conc gradient maintained in the lungs
Blood is constantly flowing through and out of lungs, bringing a fresh supply of RBC Blood arrives in the lungs w/ a lower [O2] and a higher [CO2] than air in alveoli

Biology A level (32 decks)

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