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A Level Biology > Module 3.1.1 Exchange Surfaces > Flashcards

Module 3.1.1 Exchange Surfaces Flashcards

Exchange surfaces - human ventiliation, fish & insects :)

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1
Q

Why does size not matter in exchanging substances?

A

Cells need to take in oxygen & glucose for aerobic respiration & other metabolic reactions. They also need to excrete waste products (CO2 & urea)

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2
Q

What are the 3 main factors that affect the need for an exchange system?

A

Size
Surface area to volume ratio (SA:V)
Level of activity

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3
Q

What is the formula for the volume of a cuboid?

A

Length x width x height

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4
Q

What is the formula for the surface area of a cuboid?

A

(4 x length x height) + (2 x height x width)

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5
Q

Why do unicellular organisms not require a specialised exchange system?

A

1) substances can directly diffuse in/out across the cell surface membrane
2) have a short diffusion rate will be quick because of the short diffusion distance & large SA:V

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6
Q

Why do multicellular organisms require a specialised exchange system?

A

Diffusion is too slow for 3 reasons across the outer membrane

1) some cells are deep within the body - large diffusion distance between them & outside environment
2) have a low SA:V
3) have a higher metabolic rate than single-celled organisms - use up O2 & glucose

Have to have specialised exchange surfaces to ensure movement of substances is efficient

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7
Q

What are the 4 factors of efficient exchange?

A

Large surface area - diffusion works faster as there’s a large area which substances can exchange
Thin layers - short diffusion distance for substances (quicker exchange)
Constant blood supply/ventilation - maintains large diffusion gradient & ensure substances are constantly moving to the area needed
Moist surface - gases can dissolve into the water & diffuse across the cells into the blood

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8
Q

What makes a root hair cell a specialised exchange surface?

A

A) Hairs are projections - increase SA
B) Very thin cell wall - short diffusion distance
C) Substances diffuse into adjacent cells - maintains gradient

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9
Q

What makes an Alveoli a specialised exchange surface?

A

A) Large capillary network & breathing mechanism - maintains gradient
B) Lining is only 1 cell thick - very short diffusion distance
C) Millions of alveoli - large SA

+ moist surface

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10
Q

What makes fish gills a specialised exchange surface?

A

A) Large network of capillaries & fresh water supply - maintains constant steep concentration gradient
B) 1 cell thick - short diffusion distance
C) Lamellae & Filaments provide moisture & large SA

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11
Q

What are the different structures in the human lungs?

A

Larynx
Clavicle (collar bone)
External & internal intercostal muscles
Sternum
Diaphragm
Pleural cavity fluid & membranes
Intercostal muscles
Ribs
Bronchioles
Left & Right lungs
Rings of cartilage
Trachea
Alveoli

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12
Q

What is the structure of cartilage?

A

Composed of cells surrounded by mucopolysaccharides (complex polysaccharides containing amino acids)

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13
Q

What is the function of cartilage?

A

Connective tissue that provides strength & support
Resistant to compression & tension but still flexible

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14
Q

What is epithelium?

A

A layer of cells that form a covering/lining

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15
Q

What is the structure of ciliated epithelial cells?

A

Contains cilia on the surface of the epithelial cells

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16
Q

What is the function of ciliated epithelial cells?

A

The cilia beat constantly to move the mucus & trapped substances towards the top of the trachea

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17
Q

What is the structure of goblet cells?

A

Have a goblet shape with the ‘bowl’ of the goblet containing the mucus reading to secreted

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18
Q

What is the function of the goblet cells?

A

Produce the mucus that lines the trachea, bronchi, & larger bronchioles
Found in between the ciliated cells in the epithelium

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19
Q

What is the function of the smooth muscle?

A

Maintains the tone in the airways & allows expansion when needed
Found in the trachea, bronchi & large bronchioles

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20
Q

What is the function of elastic fibres?

A

Needed for the recoil of lungs during expiration
Found in all lungs tissues

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21
Q

What is the distribution of features in the trachea?

A

C shaped cartilage
Smooth muscle
Elastic fibres
Goblet cells
Ciliated epithelial cells

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22
Q

What is the distribution of features in the bronchi?

A

Small cartilage pieces
Smooth muscle
Elastic fibres
Goblet cells
Ciliated epithelial cells

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23
Q

What is the distribution of features in the larger bronchiole?

A

Smooth muscle
Elastic fibres
Goblet cells
Ciliated epithelial cells

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24
Q

What is the distribution of features in the smaller bronchioles?

A

Smooth muscle
Elastic fibres
Ciliated epithelial cells

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25
Q

What is the distribution of features in the smallest bronchiole?

A

Elastic fibres

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26
Q

What is the distribution of features in the alveoli?

A

Elastic fibres
Alveolar epithelium

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27
Q

What is the structure of the trachea?

A

Rings of cartilage - designed to keep trachea open
Rings of cartilage are c-shaped - dont effect œsophages/cause friction with the oesophageal wall
Lined by ciliated epithelial cells (contains goblet cells that secrete mucus)

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28
Q

What is the function of the trachea?

A

Widest tube in the gas exchange system
Responsible for breathing in air

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29
Q

What is the structure of the bronchi?

A

Similar to trachea
Smaller diameter & thinner walls than trachea
Rings of cartilage are complete

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30
Q

What is the structure of the bronchioles?

A

Vary in size & structure as they get closer to the alveoli
Around 0.3-0.5mm in diameter
Have no rings of cartilage
No mucous glands
Larger bronchioles have goblet cells & walls contain elastic fibres & smooth muscle

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31
Q

What is the structure of the alveoli?

A

Walls consists of a single layer of epithelium but also has an extracellular matrix (contains elastic fibres) - allow alveoli to expand during inspiration & recoil during expiration
Surrounded by capillaries - gas exchange (steep concentration gradient & constant blood supply)
Arranged in groups at the end of the smallest bronchioles

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32
Q

What components of the gaseous exchange system make up the ventilation system?

A

Diaphragm
Internal & External intercostal muscles
Ribcage

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33
Q

What does the ventilation system consist of?

A

Inhalation/Inspiration
Exhalation/Expiration

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34
Q

What is the ventilation system controlled by?

A

Movements of the diaphragm, ribcage & intercostal muscles

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35
Q

What is ventilation?

A

The refreshing of the air in the lungs, so there is a higher concentration of oxygen & a lower concentration of carbon dioxide in the blood

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36
Q

How does inspiration work?

A

The external intercostal muscles contract - causes the diaphragm to flatten & the ribs to move up & outwards
Volume of the thorax increases - decreases the lung pressure below atmospheric pressure
Air flows into the lungs

37
Q

Is inspiration an active or passive process & why?

A

Active - energy is required to make muscles contract

38
Q

How does expiration work?

A

External intercostal & diaphragm muscles relax - causes diaphragm to curve & ribcage moves down & in
Volume of the thorax decreased - increases lung pressure to above the atmospheric pressure
Air is forced out of the lungs

39
Q

Is normal expiration an active or passive process & why?

A

Passive because energy isnt required for muscles to contract

40
Q

What happens in forced expiration?

A

More Air is forced out of the lungs than in normal expiration, the internal intercostal muscles contract pulling the ribcage down & in further

41
Q

What is vital capacity?

A

The maximum volume of air that can be breathed out in a single breath

42
Q

How is vital capacity measured?

A

The individual takes a deep breath & expires all the air possible from the lungs

43
Q

What does vital capacity depend on?

A

Size of the person (especially height)
Age & gender
Level of regular exercise

44
Q

What is residual volume?

A

The volume of air that remains in the lungs even after forced expiration (remains in the airways & alveoli)

45
Q

Why is there residual volume in the lungs?

A

To make sure the lungs dont collapse in on themselves
To make sure the concentration gradient of O2 & CO2 is maintained

46
Q

What is tidal volume?

A

The volume of air that is normally breathed in & out at rest

47
Q

When is tidal volume usually measured?

A

At rest

48
Q

What is the normal value for tidal volume & why?

A

0.5dm3 - usually sufficient to supply all the oxygen required by the body at rest

49
Q

What is oxygen uptake?

A

The amount of oxygen consumed by the subject (dm3 min-1)

50
Q

What does increased oxygen uptake result from?

A

Increased breathing rate
Deeper breaths

51
Q

What is the breathing rate?

A

The number of breaths per minute (breath = taking air in & out)

52
Q

What is breathing rate usually at rest?

A

12-14 breaths per minute

53
Q

What is a spirometer?

A

A machine that produces a trace on a revolving drum/screen when the subject breathes in and out through it

54
Q

What are the main components of a spirometer & what do they do?

A

Oxygen filled chamber tank with removable lid - the subject can breath in & out
Mouthpiece
Pen & revolving drum - spirometer trace is created when subject breaths in & out
Soda lime - absorbs CO2 created by respiration during expiration

55
Q

Why does the total volume in the chamber decrease over time?

A

The air that’s breathed out is a mixture of O2 & CO2 & soda lime filters through CO2 so volume decreases over time

56
Q

Why must the person wear a nose clip when using the spirometer?

A

Makes sure all breathing is done through the mouthpiece of the spirometer - results are valid

57
Q

How is vital capacity measured on a spirometer trace?

A

From the largest peak to the largest trough

58
Q

How is tidal volume measured on the spirometer trace?

A

From each individual peak to trough.

59
Q

How is breathing rate measured on the spirometer trace?

A

The complete number of waves

60
Q

How is oxygen uptake measured on the spirometer trace?

A

Measure the height of the slope

61
Q

What are teleosts?

A

bony fish - fish that have skeletons made of bone

62
Q

What are elasmobranchs

A

fish with a skeleton made of cartilage

63
Q

What are the difficulties fish have to overcome to obtain oxygen?

A

a) water is 1000x denser than air
b) water is 100x viscous than air
c) water has a lower oxygen content

64
Q

Why wouldn’t the mammalian ventilation system work in fish?

A

uses to much energy to move water in & out the lung

65
Q

Why does water move in only 1 direction over the gills?

A

much simpler and economical in terms of energy

66
Q

What is the organ used for unitary movement of H20

A

Gills

67
Q

What is the operculum?

A

a flap of tissue that covers the gills in bony fish

68
Q

What is the buccal cavity?

A

The mouth of the fish

69
Q

What is the structure of the gills?

A

Each gill consists of 2 rows of gill filaments (primary lamellae) attached to a bony arch
Filaments are very thin & surface is folded into secondary lamellae (gill plates)
Blood capillaries carry deoxygenated blood close to the surface of the secondary lamellae

70
Q

Why are the gill filaments very thin & folded into secondary lamellae

A

provides a large surface area for diffusion

71
Q

Why are the capillaries so close to the surface of the secondary lamellae?

A

gas exchange takes place

72
Q

How many gills do most fish have?

A

5 pairs (each side of the head)

73
Q

What is the function of the gill rakers?

A

stop objects getting trapped/damaging the gills

74
Q

What is counter-current flow?

A

Where 2 fluids flow in opposite directions

75
Q

Why does water & blood flow in opposite directions over & In the gills?

A

Means that water with a relatively high oxygen concentration always flows next to blood with a lower concentration of oxygen
Maintains a steep concentration gradient between blood & water to ensure maximum diffusion of o2 into blood

76
Q

What would happen if fish had a parallel flow instead of a counter current flow?

A

diffusion from water into the blood would reach equilibrium at a certain point meaning diffusion would stop & the fish would only remove 50% of the o2 from the water making it non efficient.

77
Q

What happens during the inspiration of a fish?

A

The mouth opens & the floor of the mouth lowers so the volume of the buccal cavity increases & the pressure decreases. This forces water into the mouth. The muscles of the operculum bulge outwards which reduces pressure in the gill chamber. As there is now a higher pressure outside than inside the buccal cavity the operculum closes and water is forced into the gills.

78
Q

What happens during the expiration of a fish?

A

The mouth of the fish closes, which then the floor of the buccal cavity is raised and any remaining water is pushed from the mouth to the gills decreasing the volume & increasing the pressure. The muscles in the operculum walls squeeze inwards so the pressure in the gill chamber is further increased. This higher pressure opens the flexible edge of the operculum so water flows between the gills & out of the gill chamber & gas exchange happens, water then flows out the operculum

79
Q

Why cant gas exchange take place across the membrane of an insects body?

A

Many insects have a tough exoskeleton

80
Q

What is the blood equivalent for an insect?

A

haemolymph

81
Q

What is a spiracle?

A

An external opening/pore that allows air in/out the tracheae

82
Q

What is tracheal fluid?

A

The fluid at the ends of the tracheoles in the tracheal system

83
Q

What is the function of tracheal fluid?

A

To allow gas exchange to be faster - diffusion is faster in a fluid

84
Q

What is the tracheal system?

A

A system of air-filled tubes in insects?

85
Q

How does inhalation happen in insects?

A

Muscle contraction of the underbelly causes it to lower which increases the volume inside the thoracic space. This decreases the pressure to below atmospheric pressure and air is drawn in through the spiracles & tracheal system.

86
Q

How does exhalation happen in insects?

A

Muscle relaxation of the underbelly causes it to rise which decreases the volume inside the thoracic space. This increases the pressure to below atmospheric pressure and air is forced out through the spiracles & tracheal system.

87
Q

How does oxygen and carbon dioxide make its way down the tracheal system to the tissues?

A

1) Air moves into the tracheae through the spiracles
2) O2 travels down a concentration gradient towards to the cells
3) CO2 from the cells moves down its own concentration gradient towards the spiracles
4) The tracheae branch off into smaller tracheoles which have thin permeable walls to to individual cells
5) Tracheoles contain tracheal fluid which O2 diffuses in
6) O2 then diffuses from this fluid into the body cells & CO2 then diffuses in the opposite way

88
Q

How does flight affect respiration and how does an insect combat it?

A

During flight the respiratory rate of the flight muscles increases so more O2 is required. Movement of the wings brings about thoracic movement which pumps air in & out of the thoracic tracheae so O2 ends up reaching muscles directly. This pumping alone is adequate enough to ventilate the thorax & rest of the body.

A Level Biology (18 decks)

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