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B3.1 Gas Exchange Flashcards

1
Q
A
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2
Q

What is the vital function of gas exchange in living organisms?

A

Facilitates the interchange of materials required for metabolic reactions

Essential for processes such as aerobic respiration and photosynthesis.

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3
Q

What is required for aerobic respiration?

A

Oxygen

Oxygen is used to produce large amounts of chemical energy (ATP) in cells.

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4
Q

What is a waste product of aerobic respiration that must be removed from the organism?

A

Carbon dioxide

Excess levels of carbon dioxide can be harmful to the organism.

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5
Q

In photosynthesising organisms, carbon dioxide is a required substrate for what process?

A

Synthesis of organic molecules via carbon fixation

This process is essential for producing food in plants.

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6
Q

How are respiratory gases transported in animals?

A

Within the bloodstream

Gas exchange is mediated by specialised ventilation systems such as lungs or gills.

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7
Q

Why do larger organisms require a specialised ventilation system?

A

To ensure adequate gas supply to the tissues

Larger organisms have a greater distance from their center to the exterior and a smaller SA:Vol ratio.

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8
Q

What method do small multicellular organisms, like flatworms, use for gas exchange?

A

Simple diffusion across the external surface

This method is sufficient to meet their respiratory needs.

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9
Q

What type of respiratory system do insects have?

A

Tracheal system

This system is independent of the circulatory system and moves gases throughout the organism.

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10
Q

What structures have aquatic organisms, such as fish, evolved to take up dissolved oxygen?

A

Gills

Gills are heavily folded structures that maximize surface area for gas exchange.

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11
Q

What are the spongy respiratory structures called in mammals?

A

Lungs

Lungs facilitate gas exchange between the bloodstream and the atmosphere.

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12
Q

Why is a ventilation system necessary for gas exchange?

A

To maintain a concentration gradient at exchange surfaces

Gas exchange is a passive process that relies on concentration differences.

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13
Q

What happens to oxygen levels within the respiring tissues?

A

Oxygen levels stay high

This is maintained by the continuous supply from the ventilation systems.

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14
Q

What happens to carbon dioxide levels within the respiring tissues?

A

Carbon dioxide levels remain low

Continuous ventilation helps to remove carbon dioxide effectively.

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15
Q

What is the relationship between ventilation systems and blood vessels?

A

Ventilation systems need to be connected to a dense network of blood vessels

Continuous blood flow is essential for transporting respiratory gases.

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16
Q

Why do ventilation systems need a large surface area?

A

To increase the overall rate of gas exchange

A larger surface area allows for more efficient diffusion of gases.

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17
Q

What is the specialised structure responsible for gas exchange in mammals?

A

Lungs

Lungs are involved in pulmonary ventilation.

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18
Q

How does air enter the respiratory system?

A

Through the nose or mouth

Air passes through the pharynx to the trachea.

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19
Q

What is the function of the ciliated lining in the trachea?

A

To trap and expel foreign particulate matter

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20
Q

What do the bronchi connect to?

A

The lungs

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21
Q

How many lobes does the right lung have?

A

Three lobes

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22
Q

What is unique about the left lung compared to the right lung?

A

It has two lobes and is smaller due to the position of the heart

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23
Q

What are the smaller airways that the bronchi divide into called?

A

Bronchioles

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24
Q

What is the function of smooth muscle in the bronchioles?

A

To regulate air flow

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25
What are the clusters of air sacs at the end of bronchioles called?
Alveoli
26
Where does gas exchange with the bloodstream occur?
In the alveoli
27
What do certain alveolar cells secrete to reduce surface tension?
Pulmonary surfactant
28
What is the purpose of the dense network of capillary beds connected to the alveoli?
To optimise the exchange of gases with the blood
29
What are the key properties required for ventilation surfaces to allow adequate gas exchange? (List them)
* Surface area * Moisture * Absorptive * Rich blood network * Thin tissue layer
30
What type of cells are Type I pneumocytes?
Squamous (flattened) and extremely thin
31
What is the primary function of Type I pneumocytes?
To function as the gas exchange surface
32
What do Type II pneumocytes secrete?
Pulmonary surfactant
33
What is the role of pulmonary surfactant in the alveoli?
To reduce surface tension and prevent alveoli from collapsing
34
How does surfactant behave as an alveolus expands with gas intake?
It becomes more spread out, increasing surface tension
35
What does the spreading of surfactant ensure during gas intake?
That all alveoli inflate at roughly the same rate and to proportionate dimensions
36
What is breathing?
The active movement of respiratory muscles that enables the passage of air into and out of the lungs ## Footnote Breathing involves both inspiration and expiration processes.
37
What changes in the thoracic cavity facilitate breathing?
The contraction of respiratory muscles changes the volume of the thoracic cavity ## Footnote This change in volume is crucial for creating pressure differentials.
38
How does changing chest volume affect air movement?
It creates a pressure differential between the chest and atmosphere, causing air to move to equalise ## Footnote Air moves from areas of higher pressure to areas of lower pressure.
39
What muscles are primarily responsible for inspiration?
The diaphragm and external intercostals, along with some accessory muscles ## Footnote These muscles work together to increase thoracic volume.
40
What muscles are primarily responsible for expiration?
The abdominal muscles and internal intercostals, along with some accessory muscles ## Footnote These muscles work to decrease thoracic volume.
41
What happens to the diaphragm during inspiration?
The diaphragm contracts, flattens, and increases the volume of the thoracic cavity ## Footnote This contraction is essential for drawing air into the lungs.
42
What occurs during expiration?
The diaphragm relaxes, curves upwards, and reduces the volume of the thoracic cavity ## Footnote This helps expel air from the lungs.
43
What role do accessory muscles play in breathing?
They support the act of breathing, especially during forced inhalation or exhalation ## Footnote Examples include abdominal and pectoral muscles.
44
True or False: The external intercostals contract during expiration.
False ## Footnote They primarily assist with inspiration.
45
Fill in the blank: The muscles that decrease the volume of the chest cause _______.
expiration ## Footnote This is because increased chest pressure leads to air being expelled.
46
What is the function of the intercostal muscles?
To assist in expanding and contracting chest volume ## Footnote They are located between the ribs and play a key role in breathing.
47
What is the result of increased volume in the thoracic cavity?
Pressure within the lungs decreases below atmospheric pressure, allowing air to move into the lungs ## Footnote This is a crucial aspect of the inhalation process.
48
What happens during forced exhalation?
Abdominal muscles contract, pushing the diaphragm upwards ## Footnote This action further reduces thoracic volume and expels air.
49
What is total lung capacity?
Volume of air in the lungs after a maximal inhalation (~ 6 litres in a normal adult male) ## Footnote Total lung capacity includes all volumes of air in the lungs.
50
Define vital capacity.
Volume of air that can be exchanged by the lungs via a maximal inhalation and exhalation ## Footnote Vital capacity is a key measure of lung function.
51
What is residual volume?
Volume of air that is always present in the lungs (~ 20% of total lung capacity) ## Footnote Residual volume cannot be exhaled.
52
Fill in the blank: Tidal volume is the volume of air exchanged via normal breathing, approximately _______ per breath.
500 ml
53
What is inspiratory reserve volume?
Volume of air able to be inspired with maximum effort after a normal inhalation ## Footnote This volume is crucial for understanding lung capacity.
54
Define expiratory reserve volume.
Volume of air able to be expired with maximum effort after a normal exhalation ## Footnote This measurement helps assess lung function.
55
What is inspiratory capacity?
The sum of the inspiratory reserve volume (IRV) and tidal volume (VT) ## Footnote Inspiratory capacity indicates how much air can be inhaled after a normal expiration.
56
Fill in the blank: Functional residual capacity is the sum of _______ and _______.
expiratory reserve volume (ERV), residual volume (RV)
57
What is the typical ventilation rate for a resting adult?
12 – 16 breaths per minute ## Footnote This rate can vary based on several factors.
58
True or False: Ventilation rate can increase substantially with physical activity.
True
59
List factors that contribute to an individual’s total lung capacity and ventilation rate.
* Height * Location * Lifestyle ## Footnote Each factor plays a significant role in respiratory health.
60
What are some methods for measuring ventilation?
* Simple observation (counting breaths) * Chest belts and pressure meters * Spirometers ## Footnote These methods vary in complexity and precision.
61
What does spirometry measure?
The amount (volume) and/or speed (flow) at which air can be inhaled or exhaled ## Footnote Spirometry is essential for assessing lung function.
62
What is a spirometer?
A device that detects changes in ventilation and presents data on a digital display ## Footnote Spirometers are commonly used in clinical settings.
63
Fill in the blank: A more simplistic method of measuring ventilation involves breathing into a _______ and measuring the volume of air.
balloon
64
How can the volume of air in a balloon be determined?
By submerging the balloon in water and measuring the volume displaced (1ml = 1cm3) ## Footnote This method provides a practical way to estimate lung capacity.
65
What is transpiration?
The loss of water vapour from plants, predominantly from the leaves as a consequence of gas exchange.
66
How is water converted into vapour in the leaves?
Light energy converts the water within the leaves into vapour, which then evaporates and diffuses from the leaf via the stomata.
67
What creates the pressure difference between leaves and roots during transpiration?
New water is absorbed from the soil by the roots, creating a difference in pressure between the leaves (low) and roots (high).
68
What is the transpiration stream?
The flow of water via the xylem along the pressure gradient to replace the water lost from the leaves.
69
Name an abiotic factor affecting the rate of transpiration.
Sunlight, temperature, wind, humidity.
70
How does sunlight affect transpiration?
Light stimulates the opening of stomata, as gas exchange is required for photosynthesis to occur.
71
What effect does high temperature have on transpiration?
High temperatures increase the vaporisation of water, leading to greater diffusion from the leaf.
72
What role does wind play in transpiration?
The flow of air removes the water vapour surrounding the leaf, increasing diffusion rates.
73
How does humidity affect the rate of transpiration?
A higher concentration of water vapour in the air will decrease the rate of diffusion from the leaf.
74
Where does transpiration begin in the leaf?
In the spongy mesophyll of the leaf.
75
What happens to some of the light energy absorbed by leaves?
It is converted into heat, which evaporates the water within the leaf tissue.
76
What creates a negative pressure gradient within the leaf?
The diffusion of vapour out of the leaf via stomata.
77
What is the role of capillary action in transpiration?
It causes water to be drawn out of xylem vessels and through cell walls, generating tension.
78
How does water move up the xylem vessels?
In opposition to gravity, moving in a continuous stream via mass flow.
79
What are the two key properties of water that facilitate its movement through xylem vessels?
Cohesion and adhesion.
80
What is cohesion in the context of water movement?
Water molecules are polar and can form hydrogen bonds that drag water molecules up the xylem.
81
What is adhesion in the context of water movement?
The xylem wall is polar and forms intermolecular associations with water molecules, generating tension.
82
How is the water vapour lost from the leaf replaced?
By water taken up from the soil by the roots, maintaining a pressure gradient.
83
What process allows plants to take up mineral ions from the soil?
Plants may actively pump protons into the soil to displace mineral ions that then diffuse into the roots.
84
How does water enter the roots?
Water is absorbed into the roots via osmosis, moving towards the region with the higher solute concentration.
85
What regulates the rate of water uptake in roots?
Specialised water channels called aquaporins on the root cell membrane.
86
What are root hairs?
Cellular extensions on the epidermis of roots that increase the surface area for absorption.
87
What regulates the amount of water lost from leaves?
Transpiration rate is regulated by the opening and closing of stomata ## Footnote Stomata are small openings on the leaf surface that facilitate gas exchange and transpiration.
88
What are guard cells and their role?
Guard cells flank the stomata and can occlude the opening by becoming increasingly flaccid in response to cellular signals ## Footnote Guard cells control the size of the stomatal opening, thus regulating gas exchange and transpiration.
89
What triggers the release of abscisic acid (ABA) in plants?
Dehydrated mesophyll cells release the plant hormone abscisic acid (ABA) when a plant begins to wilt from water stress ## Footnote ABA plays a critical role in plant responses to stress conditions.
90
What is the effect of abscisic acid on guard cells?
Abscisic acid triggers the efflux of potassium from guard cells, decreasing water pressure within the cells ## Footnote This loss of potassium leads to a loss of turgor in guard cells.
91
What happens to guard cells when they lose turgor?
When guard cells lose turgor, they become flaccid and block the stomatal opening ## Footnote This closure of stomatal pores reduces transpiration rates.
92
How does the state of stomatal pores affect transpiration rates?
Transpiration rates will be higher when stomatal pores are open than when they are closed ## Footnote Gas exchange impacts transpiration, as open stomata allow for more water vapor to escape.
93
What factors may cause variations in the density of stomata?
Variations in the density of stomata may arise due to genetic factors or growth under different environmental conditions ## Footnote Environmental factors include light, humidity, and soil moisture.
94
What is the primary function of the xylem?
To facilitate the movement of water throughout the plant ## Footnote The xylem is essential for water transport from roots to shoots.
95
What type of cells compose the xylem?
Dead cells that are hollow ## Footnote The lack of protoplasm allows for unimpeded water movement.
96
How does water movement occur in the xylem?
It is an entirely passive process and occurs in one direction only (from roots to shoots) ## Footnote The passive nature is due to the cells being dead.
97
What are the pores in the xylem walls called?
Pits ## Footnote Pits enable water to be transferred between xylem cells.
98
What materials reinforce the xylem walls?
Thickened cellulose and lignin ## Footnote These materials provide strength as water is transported under tension.
99
What are the two types of structures that can compose xylem?
Tracheids and vessel elements ## Footnote Tracheids are found in all vascular plants, while vessel elements are found in certain vascular plants.
100
What is the shape and function of tracheids?
Tapered cells that exchange water solely via pits ## Footnote This leads to a slower rate of water transfer compared to vessel elements.
101
What distinguishes vessel elements from tracheids?
The end walls of vessel elements have become fused to form a continuous tube ## Footnote This fusion results in a faster rate of water transfer.
102
Fill in the blank: The xylem is a tube composed of _______.
dead cells that are hollow
103
True or False: The movement of water in the xylem can occur in multiple directions.
False ## Footnote Water movement in the xylem is unidirectional, from roots to shoots.

IB Bio (14 decks)

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