Chapter 7- Exchange Surfaces Flashcards
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
2
Q
How squamous epithelium improves efficiency of gaseous exchange?
A
-only one cell thick so short diffusion pathway
3
Q
How large no. of alveoli improves efficiency?
A
Large surface area
4
Q
How good blood supply improves efficiency?
A
Large conc. gradient
5
Q
How good ventilation improves efficiency?
A
Supplies O2 to alveoli and removes CO2
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
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
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
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
10
Q
Apparatus used to record air movements created by ventilation?
A
Spirometer
11
Q
Define tidal volume
A
Vol of air inhaled + exhaled in one breath during regular breathing
12
Q
Define vital capacity?
A
- Max vol. of air inhaled in one breath
- tidal volume + inspiratory reserve + exploratory reserve
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
14
Q
How do you calculate rate of diffusion of cube?
A
- length of side divided by 2
- divide by time taken
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
16
Q
risk factors to consider when using a spirometer?
A
- check health of volunteer
- sufficient oxygen in chamber
- sterilised mouthpiece
- soda lime working
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
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
19
Q
What happens to air chamber during inspiration?
A
Goes down
20
Q
Chemical used inside spirometer to absorb CO2?
A
- soda lime
- NAOH
- KOH
21
Q
Why person using spirometer should wear nose clip?
A
- to prevent entry + escape of air through nose
- make results valid
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
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
Why walls of alveoli have elastic fibres?
- recoil
- expel air
- prevent bursting
26
Why large organisms need specialised surface area?
-small SA:V so diffusion too slow to supply needs
27
How diaphragm + intercostal muscles improve efficiency of gas exchange?
- ventilation
| - supply O2 to alveoli + remove CO2
28
How diameter of bronchioles might decrease?
- contractions of smooth muscle
- inflammation
- extra mucus production
29
Why is it difficult to expel air from lungs if bronchioles are decreased in diameter?
- increased resistance to air flow
| - requires additional force to exhale
30
Drug X acts by binding to protein receptor in lining of bronchioles. In some ppl, not effective. Thought to be because of mutation. Why?
- 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
Diff drug worked. Why?
- mutation resulted in receptor having complementary shape to this drug.
- drug able to bind
- this drug may have diff receptor
32
How smoking causes a smokers’ cough?
- 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
How a smokers’ cough can lead to further lung problems?
- 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
Enzymes can break down elastin. Use this to explain induced fit hypothesis.
- 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
Role of elastic fibres in walls of alveoli during ventilation?
- to prevent bursting
- recoil to return air sac to normal size
- recoil to help expel air
36
How does ventilation help maintain a steep conc gradient?
- 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
Ways in which steep conc. gradient maintained in lungs?
- 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
What is an organ?
A group of diff tissues that work together to compete a function
39
Explain how different cells + tissues enable the effective exchange of gases?
- 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
How spirometer would be used to measure tidal volume?
- 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
Adaptations that increase the rate of diffusion?
- maintaining steep conc. gradient
- large SA
- short diffusion pathway
- efficient ventilation
- large SA:V ratio
42
How do single felled organisms exchange gases?
Directly across body surface
43
How are lungs adapted to maintain step conc gradient?
- rapid blood flow to transport O2 away from lungs+ CO2 towards lungs
- constant ventilation to replace O2 + remove CO2
44
How do tracheae in insects facilitate gas exchange?
- 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
How do plants + insects control gas exchange to limit water loss?
- 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
How are gill filaments adapted for gas exchange?
-covered in lamellae which increases surface area
47
What is the counter current system?
- blood flows through gills in one direction
| - water flows over in opposite direction
48
How does the counter current system mean that gas exchange is more efficient?
- maintains large conc gradient between blood + water
| - so max amount of oxygen moves from water into blood
49
Proposed that simple saliva test could identify.....
| Whoa would be the source of generic material?
Epithelial cells lining the cheek
50
Why single called organisms do not need specialised area for gas exchange?
- large SA:V ratio
- diffusion alone is adequate to meet needs
- small so demand for O2 is low
51
Function of smooth muscle?
Construct the airway
52
Why elastic fibres important in gas exchange system?
- facilitates breathing
- stretch during inhalation
- recoil to expel air during exhalation
- efficient ventilation
53
TB causes fibrosis which damages alveoli. Why do ppl infected with TB suffer from shortness of breath + persistent cough?
- 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
What environmental factors contribute to lung disease?
- smoking
| - exposure to air pollution
55
Emphysema causes inflammation of lung tissue. How does this lead to alveoli having reduced surface area?
- inflammation attracts phagocytes to lung tissue
| - phagocytes release an enzyme that breaks down elastin
