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Biology > Chapter 7- Exchange Surfaces > Flashcards

Chapter 7- Exchange Surfaces Flashcards

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1
Q

Why do you not use the whole length of side to calculate rate of diffusion of cube?

A
  • need to divide by 2

- distance has to be do centre of cube rather than whole length of side

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2
Q

How squamous epithelium improves efficiency of gaseous exchange?

A

-only one cell thick so short diffusion pathway

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3
Q

How large no. of alveoli improves efficiency?

A

Large surface area

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4
Q

How good blood supply improves efficiency?

A

Large conc. gradient

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5
Q

How good ventilation improves efficiency?

A

Supplies O2 to alveoli and removes CO2

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6
Q

Why large multicellular organisms need a transport system?

A
  • small SA:V
  • diffusion too slow to supply enough oxygen + nutrients + prevent CO2 + waste products building up
  • high metabolic rate so high demand for oxygen
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7
Q

What causes the change in the volume of air inside lungs during expiration?

A
  • external intercostal muscles relax
  • diaphragm moves up
  • rib cage moves down + inwards
  • vol. inside lungs decreases
  • pressures inside thorax increase above atmospheric pressure
  • aid leaves down pressure gradient
  • elastic recoil of alveoli
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8
Q

Residual volume is air that cannot be expelled from lungs? Why?

A
  • lungs cannot be completely compressed
  • trachea + bronchi held open by cartilage
  • bronchioles + alveoli held open by elastic fibres
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9
Q

How alveoli enable efficient gas exchange?

A
  • wall is 1 cell thick so short diffusion pathway
  • squamous epithelium provide short diffusion pathway
  • elastic so recoil. Helps ventilation
  • large no. provides large SA
  • small size provides large SA:V
  • moist for efficient diffusion
  • steep conc gradient maintained by constant ventilation + rapid blood flow
  • each alveolus has own blood supply so short diffusion distance
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10
Q

Apparatus used to record air movements created by ventilation?

A

Spirometer

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11
Q

Define tidal volume

A

Vol of air inhaled + exhaled in one breath during regular breathing

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12
Q

Define vital capacity?

A
  • Max vol. of air inhaled in one breath

- tidal volume + inspiratory reserve + exploratory reserve

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13
Q

Explain the significance of the relationship between rate of diffusion + SA:V for large plants?

A
  • have small SA:V
  • so diffusion too slow to supply requirements
  • so need special surface area for gas exchange
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14
Q

How do you calculate rate of diffusion of cube?

A
  • length of side divided by 2

- divide by time taken

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15
Q

How could you use a spirometer trace to measure rate of oxygen uptake?

A
  • measure decrease in volume of chamber
  • can be done by drawing a line along troughs
  • find difference in height from one trough to another
  • measure time taken to use this oxygen
  • divide vol by time taken
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16
Q

risk factors to consider when using a spirometer?

A
  • check health of volunteer
  • sufficient oxygen in chamber
  • sterilised mouthpiece
  • soda lime working
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17
Q

Histamine is a cell signalling molecule that stimulates smooth muscle in alveoli to contract. How?

A
  • Histamine binds to glycoprotein on membrane

- this triggers response inside cells

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18
Q

mechanism of inspiration?

A
  • diaphragm contracts + moves down
  • intercostal muscles contract
  • rib cage moves upwards + outwards
  • vol. inside lungs increases
  • pressure inside thorax decreases to below atmospheric pressure so air enters lungs
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19
Q

What happens to air chamber during inspiration?

A

Goes down

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20
Q

Chemical used inside spirometer to absorb CO2?

A
  • soda lime
  • NAOH
  • KOH
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21
Q

Why person using spirometer should wear nose clip?

A
  • to prevent entry + escape of air through nose

- make results valid

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22
Q

How ciliated epithelium keeps lung surface clear of dust + other particles?

A
  • goblet cells release mucus
  • this traps dust + pathogens
  • cilia wafts mucus to back of mouth
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23
Q

Bronchus wall contains smooth muscle fibres. Why?

A

To constrict the bronchus (reduce diameter)

24
Q

Why blood capillaries + alveoli are very close together?

A

Shirt diffusion pathway so rapid diffusion

25
Q

Why walls of alveoli have elastic fibres?

A
  • recoil
  • expel air
  • prevent bursting
26
Q

Why large organisms need specialised surface area?

A

-small SA:V so diffusion too slow to supply needs

27
Q

How diaphragm + intercostal muscles improve efficiency of gas exchange?

A
  • ventilation

- supply O2 to alveoli + remove CO2

28
Q

How diameter of bronchioles might decrease?

A
  • contractions of smooth muscle
  • inflammation
  • extra mucus production
29
Q

Why is it difficult to expel air from lungs if bronchioles are decreased in diameter?

A
  • increased resistance to air flow

- requires additional force to exhale

30
Q

Drug X acts by binding to protein receptor in lining of bronchioles. In some ppl, not effective. Thought to be because of mutation. Why?

A
  • Mutation causes change in base sequence
  • causes change in amino acid sequence of protein
  • causes change in tertiary structure of protein + this binding site of receptor
  • drug not complementary to shape of receptor + cannot bind
  • no response triggered in cell
31
Q

Diff drug worked. Why?

A
  • mutation resulted in receptor having complementary shape to this drug.
  • drug able to bind
  • this drug may have diff receptor
32
Q

How smoking causes a smokers’ cough?

A
  • tar damages cilia
  • smoke damages ciliated epithelium
  • smoke stimulates goblet cells to produce more mucus
  • mucus builds up + cannot be wafted
  • more bacteria accumulates in mucus
  • cough is an attempt to increase air flow + remove microbes by removing the mucus
33
Q

How a smokers’ cough can lead to further lung problems?

A
  • frequent coughing inflames alveoli which causes formation of scar tissue
  • reduced SA
  • bronchi + bronchioles walls thicken
  • lumen of bronchioles + bronchioles narrow
  • flow of air restricted
34
Q

Enzymes can break down elastin. Use this to explain induced fit hypothesis.

A
  • elastin is substrate
  • substrate binds to active site of enzyme
  • substrate changes shape to get closer fit between active site + substrate
  • causes more bonds to form
  • forms ESC
  • straining of bonds in substrate
  • AE reduced
  • EPC formed + products released
35
Q

Role of elastic fibres in walls of alveoli during ventilation?

A
  • to prevent bursting
  • recoil to return air sac to normal size
  • recoil to help expel air
36
Q

How does ventilation help maintain a steep conc gradient?

A
  • increases conc. of O2 in alveoli o so conc of O2 is higher than that in blood
  • decreases conc. of CO2 in alveoli so conc of CO2 is higher than that in blood
37
Q

Ways in which steep conc. gradient maintained in lungs?

A
  • ventilation
  • good blood supply in capillaries. To bring in more CO2 + take away more O2
  • O2 combines with haemoglobin. Keeps conc of O2 low in blood
38
Q

What is an organ?

A

A group of diff tissues that work together to compete a function

39
Q

Explain how different cells + tissues enable the effective exchange of gases?

A
  • squamous epithelium in all alveoli only 1 cell thick. Short diffusion pathway
  • thin endothelium of capillary provides short diffusion pathway
  • erythrocytes transport O2 from alveoli
  • intercostal muscles create diffusion gradient
  • ciliated epithelial cells remove bacteria + dust
  • cartilage holds airways open
  • elastic fibres for recoil + aid ventilation
40
Q

How spirometer would be used to measure tidal volume?

A
  • subject wears nose clip to ensure not breathing through nose
  • subject breathes normally
  • as breathe in, lid goes down
  • as breathe out, lid goes up
  • movement of lid recorded on trace
  • pen attached to lid to record trace
  • measure height of at least 3 waves + calculate mean
41
Q

Adaptations that increase the rate of diffusion?

A
  • maintaining steep conc. gradient
  • large SA
  • short diffusion pathway
  • efficient ventilation
  • large SA:V ratio
42
Q

How do single felled organisms exchange gases?

A

Directly across body surface

43
Q

How are lungs adapted to maintain step conc gradient?

A
  • rapid blood flow to transport O2 away from lungs+ CO2 towards lungs
  • constant ventilation to replace O2 + remove CO2
44
Q

How do tracheae in insects facilitate gas exchange?

A
  • aid moves into tracheae through open spiracles
  • tracheae branch off into tracheoles which have permeable walls
  • O2 moves down conc gradient from air to cells
  • CO2 moves down conc. gradeirm from cells to spiracles + out into atmosphere
45
Q

How do plants + insects control gas exchange to limit water loss?

A
  • spiracles control has exchange in insects
  • stomata + guard cells control in plants
  • if spiracles + stomata left open all the time then water will leave insect/ plant via evaporation
  • will cause organism to dry out + die
46
Q

How are gill filaments adapted for gas exchange?

A

-covered in lamellae which increases surface area

47
Q

What is the counter current system?

A
  • blood flows through gills in one direction

- water flows over in opposite direction

48
Q

How does the counter current system mean that gas exchange is more efficient?

A
  • maintains large conc gradient between blood + water

- so max amount of oxygen moves from water into blood

49
Q

Proposed that simple saliva test could identify…..

Whoa would be the source of generic material?

A

Epithelial cells lining the cheek

50
Q

Why single called organisms do not need specialised area for gas exchange?

A
  • large SA:V ratio
  • diffusion alone is adequate to meet needs
  • small so demand for O2 is low
51
Q

Function of smooth muscle?

A

Construct the airway

52
Q

Why elastic fibres important in gas exchange system?

A
  • facilitates breathing
  • stretch during inhalation
  • recoil to expel air during exhalation
  • efficient ventilation
53
Q

TB causes fibrosis which damages alveoli. Why do ppl infected with TB suffer from shortness of breath + persistent cough?

A
  • fibrosis causes scar tissues which thickens alveoli walls
  • rate of diffusion slowed so gas exchange less efficient
  • alveoli cannot expand properly
  • tidal volume decreases + less oxygen gets to respiring cells
54
Q

What environmental factors contribute to lung disease?

A
  • smoking

- exposure to air pollution

55
Q

Emphysema causes inflammation of lung tissue. How does this lead to alveoli having reduced surface area?

A
  • inflammation attracts phagocytes to lung tissue

- phagocytes release an enzyme that breaks down elastin

Biology (26 decks)

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