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OCR Biology > 3.1 EXCHANGE SURFACES > Flashcards

3.1 EXCHANGE SURFACES Flashcards

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1
Q

State the SA:V of single celled organisms

A
  • High surface area to volume ratio
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2
Q

State and explain how single celled organisms obtain nutrients/gases

A
  • Via simple diffusion
  • Because they have large SA:V ratios
  • So short diffusion distance for maxiumum absorbtion
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3
Q

State the SA:V of large organisms

A
  • Low surface area to volume ratio
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4
Q

State the formula for surface area:volume ratio

A

SA:V = Surface area(cm2) ÷ Volume(cm3)

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5
Q

State what more metabolic organisms require

A
  • ENERGY from food and oxygen to release energy in the form of ATP in aerobic respiration
  • Energy to keep them warm
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6
Q

State and explain three features of a good exchange surface

A

1) Large surface area to enhance the space molecules can pas through
2) A thin barrier to reduce the diffusion distance
3) A good blood supply to maintain a concentration gradient and bring in molecules

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7
Q

Define alveoli

A
  • Tiny folds in the lung epithelium to increase surface area
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8
Q

Describe bronchioles

A
  • Smaller, smooth muscle airways leading to the lungs
  • Has no cartilage
  • Made of smooth muscle sp can contrict and dilate to controll airway airflow
  • Narrow with thin walls so some exchange may occur
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9
Q

Describe bronchi/bronchus

A
  • Smaller than trachea but larger than bronchioles
  • Thin walls with a smaller diameter than the trachea
  • Have a full ring of cartilage
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10
Q

Define diaphram

A
  • A layer of muscle between the lungs
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11
Q

Define intercoastal muscles

A
  • Muscles between the ribs
  • Contraction of the intercoastal muscles raise the ribcage
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12
Q

Describe trachea

A
  • The main airway leading from the back of the mouth to the lungs
  • Has C-shaped cartillage rings to prevent friction with the asophagus behind
  • Has cillitaed epithelial cells to waft microbes to filter airways
  • C-shaped cartillage also prevents collapse
  • Has goblet cells that produce mucus to capture dust and microbes
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13
Q

Define ventilation

A
  • The refreshing of air in the lungs so that there is a higher oxygen concentration than in the blood and a lower carbon dioxide concentration than in the blood
  • (Thus, gaseous exchange occurs)
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14
Q

Draw the structure of the lungs

A
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15
Q

Describe inhalation

A

1) External intercoastal muscles contract so that the ribs move up and out
2) The diaphram contracts to move down and flatten
3) Therefore, the volume of the chorax/chest cavity increases
4) The pressure in the thorax drops down below atmospheric pressure
5) So, air is drawn in
6) ACTIVE PROCESS

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16
Q

Describe exhilation

A

1) External intercoastal muscles relax so that the ribs move down and inwards
2) The diaphram relaxes also and becomes dome shaped
3) Therefore, volume in the thorax/chest cavity decreases
4) Pressure inside the thorax/lungs increases above atmospheric pressure
5) So, air is drawn out
6) PASSIVE PROCESS

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17
Q

State five features of the alveoli

A

1) Large surface area
2) Exchange barrier is permeable to oxygen and carbon dioxide
3) Thin barrier to reduce diffusion distance
4) A good blood supply
5) Elastic fibres

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18
Q

Explain the large surface area of the alveoli

A
  • Provides more space for molecules to pass through
  • Also lined with a layer of moisture so gases can dissolve for more efficient diffusion
  • Internal layer of the alveoli is coated in a surficant that reduces cohesion between water molecules
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19
Q

Explain the exchange barrier permeability of the alveoli

A
  • The cells of the alveoli/capillaries and their plasma cell surface membranes are permeable to oxygen and carbon dioxide
  • Because they are small and non polar molecules
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20
Q

Explain the thin barrier of the alveoli

A
  • Reduces the diffusion distance
  • Alveoli and capillaries are one cell thick
  • Both walls are squamous
  • Alveoli and capillaries are in close contact
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21
Q

Explain the good blood supply of the alveoli

A
  • Helps maintain a steep concentration gradient so carbon dioxide diffuses out and oxygen diffuses in
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22
Q

Explain the elastic fibres of the alveoli

A
  • Allows dilation of the alveoli as air is drawn in to maximise space
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23
Q

Define cilliated epithelium

A
  • A layer of cells that have many hair like cilia
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24
Q

Define elastic fibres

A
  • Protein fibres that can deform and recoil to dilate the alveoli
25
Q

Define goblet cells

A
  • Cells that secrete mucus
26
Q

Define smooth muscle

A
  • Involuntary muscle that contracts without the need of conscious thought
27
Q

Define buccal cavity

A
  • A fish mouth
28
Q

Define fillament

A
  • Branches of tissue that make up the gill (aka primary lamellea)
29
Q

Define lamellea

A
  • (Aka secondary lamellea or gill plates)
  • Are folds in the fillament to increase surface area and is the site of gas exchange
30
Q

Define operculum

A
  • A bony flap that covers and protects the gills
31
Q

Define counter current flow

A
  • Where blood and water flow in opposite directions
32
Q

Describe the counter current exchange of bony fish

A
  • Blood flows along the gill arch and out along the fillament to the lamellea
  • The blood then flows through capillaries in opposite direction to the flow of water over the lamellea
  • The countercurrent flow absorbs the maximum amount of water
33
Q

Describe ventillation in bony fish

A
  • The buccal cavity can change volume
  • The floor of the mouth moves downwards which decreases the pressure and draws in more water
  • The mouth closes and the floor is raised again, pushing water through the gills
  • As water is pushed from the buccal cavity, the operculum moves outwards
  • This movement decreases pressure in the opercular cavity, helping water flow to the gills
34
Q

State the three ways large insects can ventilate

A

1) Movement of the wings - (alters thorax volume)
2) Expansion of tracheal system - (expand air sacs)
3) Locusts specialised breathing movements (air control via valves)

35
Q

Draw the structure of an insect

A
36
Q

Draw the structure of insect tracheoles

A
37
Q

State the circulatory system of insects

A
  • Open circulatory system
  • Slow circulation and can be affected by body movements
38
Q

Describe the exchange of insects

A
  • Air enters via spirical pores through to the tracheae tubes
  • Then through to smaller tracheoles which are open ended and filled with tracheal fluid
  • Gaseous exchange occurs between the air in the tracheoles and the tracheal fluid
39
Q

Describe exchange in insects with high metabolic activity

A
  • Tracheal fluid gets withdrawn into the body fluid in order to increase the surface area of the tracheole wall that is exposed to air
  • This means that more oxygen can be absorbed when the insect is active
40
Q

Describe the movement of insect wings on ventillation

A
  • Alters the thorax volume
  • As the thorax volume decreases, air in the tracheal system is put under pressure
  • Therefore, its pushed out of the tracheal system
  • When the thorax volume increases, the pressure inside the thorax decreases
  • Therefore, air is pushed into the tracheal system from outside
41
Q

Describe the expansion of insect tracheal system on ventilation

A
  • Tracheal expansion occurs to increase flexibility of the walls
  • These act as air sacs which can be squeezed by the action of flight muscles
  • Repetative expansion and contraction of these sacs ventilate the tracheal system
42
Q

Describe the abdomine volume alteration of insects on ventillation

A
  • Abdomine volume alteration is co-ordinated by opening and closing valves in the spiricals
  • As the abdomine expands, spiricals at the front end of the body open and air enters the tracheal system
  • As the abdomine reduces in volume, the spiricals near the end of the body open and air leaves the tracheal system
43
Q

Define breathing rate

A
  • The number of breaths per minute
44
Q

Define oxygen uptake

A
  • The volume of oxygen absorbed by the lungs in one minute
45
Q

Define spirometer

A
  • A device that can measure the movement of air into and out the lungs
46
Q

Define vital capacity

A
  • The maximum volume of air that can be expelled from the lungs after taking deepest possible breath
47
Q

Define tidal volume

A
  • The volume of air inhaled or exhaled in one breath, usually measured at rest
48
Q

Define residual volume

A
  • The volume of air that remains in the lungs after forced exhilation
  • (Remains in the airways and alveoli)
  • (Aprox. 1.5dm3)
49
Q

Draw a labled spirometer

A
50
Q

State precautions to take with spirometers

A
  • The subject should be healthy/asmtha free
  • The soda lime should be fresh/functioning
  • There should be no air leaks in the apparatus (invalid/inaccurate result)
  • The mouthpeice steralised
  • The water chamber must not be overfilled (or water may enter air tubes)
51
Q

State three factors that vital capacity depends on

A

1) The size of the person (particularly height)
2) Their age/gender
3) Their level of exercise

52
Q

State the average vital capacity

A
  • 2.5dm3 to 5.0dm3
53
Q

State the average tidal volume

A
  • 0.5dm3
54
Q

Draw a labled spirometer trace

A
55
Q

State an assumption about oxygen uptake/CO2 removal

A
  • That the volume of carbon dioxide absorbed by the soda lime is equal to the oxygen uptake into the blood
56
Q

Describe how to calculate oxygen uptake from a spirometer trace

A
57
Q

State how to measure breathing rate from a spirometer trace

A
  • Count the number of peaks in each minute
58
Q

State two factors explain increased oxygen uptake

A
  • Increased breathing rate (excercise)
  • Deeper breaths (excercise)

OCR Biology (27 decks)

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