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BIOLOGY OCR A > 3.1 Exchange surfaces > Flashcards

3.1 Exchange surfaces Flashcards

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1
Q

Why is diffusion alone enough to support single celled organisms?

A

Metabolic activity is low
Large surface area to volume ratio

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2
Q

What happens to surface area to volume ratio and diffusion distance as the size of an organism increases

A

Surface area to volume ratio decreases, and diffusion distance increases

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3
Q

What is an exchange surface

A

Where diffusion occurs

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4
Q

What are the four adaptations of an exchange surface

A

Increased surface area, Thin layers, Good blood supply, Ventilation

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5
Q

How does increased surface area increase diffusion rate

A

Overcomes limitations of SA:V ration

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6
Q

How does once cell thick layers increase diffusion rate

A

Decreased diffusion distance, fast and efficient

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7
Q

How does good blood supply increase diffusion rate

A

Substances are constantly delivered and removed from the exchange surface, maintaining a steep concentration gradient

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8
Q

How does ventilation increase diffusion rate

A

Maintain a concentration gradient, as gas is constantly supplied and removed

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9
Q

What happens to gasses in mammals before they are able to diffuse into the blood

A

Oxygen dissolves in water (moist) on gas exchange surface

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10
Q

Why do humans need to have a gaseous exchange system

A

Small surface area to volume ration, high metabolic rate (active, maintain temperature

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11
Q

Where does gaseous exchange occur in humans

A

In the lungs, at alveoli

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12
Q

Recite the path of air going into lungs

A

Mouth, trachea, bronchus, bronchioles, alveoli.

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13
Q

Why is the nasal cavity important?

A

Large surface area with good blood supply - warms air to body temperature
Hairy lining - secrets mucus to trap dust and bacteria, protecting the lungs
Moist surface - Increases humidity of air, reducing evaporation from exchange surface

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14
Q

What is the trachea

A

Main airway

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15
Q

What tissues are found in the trachea

A

Ciliated Epithelium, Cartilage, Elastic fibres, Smooth muscle

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16
Q

What is the role of cartilage

A

Supports the trachea and prevents from collapsing when pressure drops

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17
Q

What shape is the cartilage in the trachea, why?

A

C shaped rings (incomplete) - allow food to move down oesophagus

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18
Q

What is the job of goblet cells

A

Secrete mucus, to trap dust and pathogens

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19
Q

What is the job of ciliated epithelium cells

A

Waft mucus away from the lungs to the throat, where it is swallowed and digested

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20
Q

What is the impact of smoking on the ciliated epithelium

A

Stops cilia being able to waft mucus

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21
Q

What is the role of elastic fibres

A

Stretch and recoil, forcing air out at the end of breath

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22
Q

What is the role of smooth muscle

A

Contracts and relax, changing the diameter of the trachea, altering air flow. Relaxed = wider.

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23
Q

What is the Bronchus (singular)/ bronchi (plural)

A

Trachea divides to form left and right bronchus, smaller then the trachea

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24
Q

What tissues are found in the bronchi

A

Ciliated epithelium, cartilage, elastic fibres, smooth muscle

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25
What shape is cartilage in the bronchi
Irregular blocks
26
What is the bronchioles
Bronchi divide to form many bronchioles
27
What tissues are found in the bronchioles
Ciliated epithelium, Elastic fibres, smooth muscle,
28
What is the alveolus (singular)/alveoli (plural)
tiny air sacs where gas exchange occurs
29
What tissues are found in the alveoli
Squamous epithelium, Elastic fibres
30
What is the role of squamous epithelium
One cell thick, creating a short diffusion distance, allowing for efficient gas exchange
31
Why are elastic fibres important, especially in the alveoli
Allows for stretch and recoil, when gas enters, alveoli expand, when gas leaves it returns to the original shape
32
How are goblet cells distinguishable under a microscope?
Have circles with outer casing, surrounded by ciliated epithelium
33
How are ciliated epithelium distinguishable under a microscope?
Many hair like projections
34
How are squamous epithelium distinguishable under a microscope
One cell think
35
How are cartilage distinguishable under a microscope?
Looks like eyes
36
How are Elastic fibres distinguishable under a microscope?
stringy
37
How are smooth muscle distinguishable under a microscope?
uniform, spindle shapes
38
What are the four adaptations of alveoli?
large surface area - many hundreds of millions of alveoli in an adult lungs One cell thick (squamous epithelium) - short diffusion distance Good blood supply - maintains a steep concentration gradient Good ventilation - maintains a steep concentration
39
What is the movement of air through the lungs called
Ventilation
40
What is the use of the ribs
Protect organs inside
41
Where are intercoastal muscles found
Between the ribs
42
What is the diaphragm
A broad, domed sheet of muscle, forming the floor of the thorax
43
Where are pleural membranes found
surrounding the lungs
44
What is the space between the lungs called
pleural cavity, filled with lubricating fluid, so membranes can slide as you breathe
45
What is inspiration, is it energy requiring?
Taking in air, energy using process
46
What happens during inspiration
Diagram contracts and flattens, intercostal muscles contract, moving the ribs up and out, increasing the volume of the thorax, so pressure is reduced, to below atmospheric pressure, so air is forced into the lungs
47
What is expiration, is it energy requiring?
Breathing out, passive process
48
What happens during expiration
Diagram relaxes, becoming dome shaped, intercostal muscles relax, ribs move down and inwards, elastic fibres in alveoli return to normal length, volume of thorax decreases, increasing pressure to above atmospheric pressure, so air move out of lungs until equilibrium is reached
49
What is asthma?
A condition that has airways that are sensitive to triggers
50
What happens during an asthma attack
cell lining in the bronchioles release histamines, inflaming epithelial cells, overstimulating goblet cells, and contracting smooth muscles. Airways are narrow and filled with mucus
51
What are the two was to treat asthma
Relievers, attach to active sites on membranes, relaxing muscles Preventors - steroids that reduce sensitivity of the lining
52
What is a peak flow meter
measures rate at which air an be expelled from the lungs
53
What is a vitalographs
Patient breathes out as quicky as possible, instrument produces a graph, measuring the forced expiratory volume in one second
54
What does a spirometer measure
Aspects of lung volume, investigate breathing patterns
55
What is the tidal volume
Volume of air moving in and out of lungs which each resting breath (average)
56
What is vital capacity
Voulme of air that can be breathed in and out, strongest exhalation and deepest intake
57
What is inspiratory reserve volume
maximum volume of air that can be breathed in - normal inhalation
58
What is expiratory reserve volume
Extra volume of air in the lungs that could be forced out after a breath
59
What is the residual volume
Volume of air left in the lungs when you have exhaled as hard as possible
60
What is the total lung capacity?
sum of the vital capacity and residual volume
61
What is the breathing rate
Number of breaths per minute
62
What is the ventilation rate
total volume of air inhaled in a minute VR = tidal volume x breathing rate
63
What happens to tidal volume and breathing rate as exercise is increased
increases
64
Why do plants have a different gaseous exchange system to humans
Have a tough exoskeleton, where no gas exchange can occur, oxygen is delivered directly into cells.
65
How does gas exchange occur in insects?
Air enters through spiracles (small openings). air then enters the tracheae, which then divides into tracheoles, oxygen then dissolves in moisture on the walls, and diffuses into the cell
66
How is gas exchange in insects made more efficient
Spiracles can open and close to prevent water loss. When oxygen demands are low, spiracles are closed, when carbon dioxide levels raise, or demand increases, they open
67
Where is tracheal fluid found?
towards the end of tracheoles
68
What job does tracheal fluid serve
Limits oxygen diffusion. When oxygen demands increase, fluid moves out of the tracheoles, increasing diffusion
69
How many some larger insects get extra oxygen?
mechanical ventilation Collapsible enlarged tracheae or air sacs
70
What is mechanical ventilation
Air is actively pumped into the system via muscles in the thorax and/or abdomen, changing the volume and pressure in the trachea and tracheoles
71
What is collapsible enlarged trachea or air sacs
increasing the amount of air moved
72
Why do fish need specialised respiratory systems
Viscosity of water and lower oxygen content, leading too slower rate of diffusion
73
What is the gaseous exchange system in fish
Gills
74
What are the adaptations of gills
Large surface area, good blood supple, thin layers
75
What is the gill filaments
Occur in large stacks - gill plates. large surface area for gaseous exchange. Fan out when in water to increase surface area
76
What are the gill lamellae
Bumps on the gill filament which increases surface area
77
What is the operculum
The flap that covers the gill
78
What do most fish rely on for gills to work, what is this called
Constant flow of water Ram ventilation
79
How do bony fish do diffusion while not having a constant flow of water
Mouth is opened and the floor of buccal cavity is lowered. increasing the volume and decreasing the pressure. This forces water into the mouth. Floor of buccal cavity moves up, increasing pressure, and decreasing volume, forcing water over the gills, the mouth closes, operculum opens, maintaining a constant flow of water over the gills
80
What happens to the gill filaments when water runs over them
They fan out, increasing surface area
81
What are some things that make gaseous exchange in bony fish effective
Tips of adjacent gill filaments overlap, increasing resistance to water, decreasing speed of water, increasing time for diffusion Counter current exchange system, water flows over gills in one direction, blood flows the other way. Creating steep concentration gradient, as when oxygen diffuses into gills, it is immediately transported by the blood Large surface areas, Hundreds of gill filaments, Lamella, Gills fan out in water

BIOLOGY OCR A (25 decks)

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