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BIO 102 > Gaseous Exchange > Flashcards

Gaseous Exchange Flashcards

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1
Q

Which part of the human respiratory system is the primary site of gas exchange?

A

D. Alveoli

The alveoli are tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged between air and blood.

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2
Q

Which features adapt the alveoli for efficient gas exchange? (Select all that apply)

A

I. Extremely large collective surface area
II. Walls only one cell thick
IV. Dense capillary network surrounding them

Alveoli have a huge surface area and very thin walls to minimize diffusion distance.

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3
Q

Why is having many tiny alveoli more effective for gas exchange than having fewer large alveoli?

A

A. It provides a greatly increased total surface area for diffusion of gases

Many small alveoli create a vast surface area for gas exchange, allowing more oxygen and CO₂ to diffuse simultaneously.

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4
Q

What is the advantage of the extremely thin walls of alveoli?

A

A. It minimizes the diffusion distance for oxygen and carbon dioxide

Alveolar walls are only one cell thick, facilitating rapid gas exchange.

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5
Q

Why is a moist surface important for gas exchange in the alveoli?

A

A. Oxygen and CO₂ must dissolve in liquid to diffuse across membranes

The moist lining allows gases to dissolve and diffuse through the alveolar wall into blood.

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6
Q

What is the purpose of the dense network of capillaries surrounding each alveolus?

A

A. To maintain steep concentration (partial pressure) gradients for O₂ and CO₂

The capillary network ensures continuous blood flow, enhancing gas exchange efficiency.

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7
Q

What is a consequence of alveoli not containing cilia or mucus-producing cells?

A

A. Particulate matter reaching the alveoli must be cleared by immune cells (macrophages) instead

Alveoli rely on macrophages to keep clean without hindering gas diffusion.

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8
Q

What role does pulmonary surfactant play in the alveoli?

A

A. It reduces surface tension in the alveoli, preventing their collapse during exhalation

Surfactant keeps alveoli stable by reducing surface tension, crucial for maintaining open air sacs.

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9
Q

What is a primary cause of Infant Respiratory Distress Syndrome (IRDS) in premature infants?

A

A. Insufficient surfactant production, leading to alveolar collapse

Premature infants often lack sufficient surfactant, making it hard to reinflate lungs.

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10
Q

Which feature of fish gills makes gas exchange efficient in water?

A

A. Numerous gill filaments with thin, flat lamellae that provide a large surface area and short diffusion path

The structure of gills maximizes surface area for gas exchange in aquatic environments.

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11
Q

What is the benefit of countercurrent flow in fish gills?

A

A. It maintains an oxygen concentration gradient along the entire gill, maximizing O₂ diffusion into blood

Countercurrent exchange allows more efficient oxygen extraction from water.

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12
Q

Which aquatic animal relies on lungs for gas exchange and must surface to breathe?

A

A. Whale

Whales are mammals with lungs and must periodically surface for air.

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13
Q

What drives oxygen and carbon dioxide across the alveolar-capillary membrane in the lungs?

A

A. Simple diffusion down their partial pressure gradients (from high to low partial pressure)

Gas exchange is a passive process driven by concentration differences.

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14
Q

Why does oxygen diffuse from the alveolar air into the blood?

A

A. The partial pressure of O₂ in alveoli (~100 mmHg) is higher than in the deoxygenated blood (~40 mmHg)

The pressure gradient drives oxygen diffusion into the blood.

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15
Q

What causes carbon dioxide to diffuse from the blood into the alveoli?

A

A. The P_CO₂ in blood (≈45 mmHg in venous blood) is higher than in alveolar air (≈40 mmHg)

This gradient facilitates CO₂ diffusion out of the blood.

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16
Q

During external respiration in the lungs, which statement correctly describes the gas movements?

A

A. Oxygen diffuses from alveoli into blood, and carbon dioxide diffuses from blood into alveoli

This process loads blood with oxygen and unloads carbon dioxide.

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17
Q

What is an example of internal respiration?

A

A. Oxygen leaving systemic capillaries and diffusing into the body’s cells

Internal respiration refers to gas exchange between blood and body tissues.

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18
Q

Why does oxygen diffuse from blood into the tissues during internal respiration?

A

A. The partial pressure of O₂ in oxygenated blood (~100 mmHg) is higher than in the interstitial fluid and cells (~40 mmHg or less)

This pressure difference drives oxygen diffusion into tissues.

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19
Q

What is external respiration?

A

Gas exchange in alveoli

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20
Q

What is the difference between ventilation and cellular respiration?

A

Ventilation is breathing; cellular respiration is ATP production

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21
Q

Why does oxygen diffuse from blood into tissues during systemic respiration?

A

The partial pressure of O₂ in oxygenated blood (~100 mmHg) is higher than in interstitial fluid (~40 mmHg or less)

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22
Q

What is cellular respiration?

A

The intracellular process of using O₂ to oxidize nutrients and produce ATP, with CO₂ as a byproduct

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23
Q

How does inhalation (inspiration) occur?

A

Contraction of the diaphragm and external intercostal muscles expands the chest cavity

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24
Q

During normal quiet breathing, how does exhalation (expiration) occur?

A

Occurs passively when the diaphragm and intercostal muscles relax

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25
Which statement is FALSE about the bronchi and bronchioles?
They participate directly in gas exchange with the blood
26
How is the vast majority of oxygen transported in the blood?
Bound to hemoglobin inside red blood cells (as oxyhemoglobin)
27
How many oxygen molecules can one hemoglobin protein bind when fully saturated?
4
28
What is the primary form in which CO₂ is carried in blood?
As bicarbonate ions (HCO₃⁻) in plasma
29
Which enzyme catalyzes the conversion of CO₂ and water into carbonic acid?
Carbonic anhydrase
30
What is the chloride shift in CO₂ transport?
The exchange of bicarbonate (HCO₃⁻) and chloride (Cl⁻) ions across the red blood cell membrane
31
Carbaminohemoglobin is formed when:
Carbon dioxide binds to hemoglobin in the blood
32
What is the Haldane effect in the context of gas transport?
Oxygenation of hemoglobin decreases its affinity for CO₂
33
Why is carbon monoxide (CO) inhalation dangerous?
CO binds to hemoglobin with ~200–250× greater affinity than O₂
34
How do earthworms accomplish gas exchange?
Through their moist skin by direct diffusion
35
In insects, how is gas exchange carried out?
By a system of internal air tubes called tracheae
36
What is the role of spiracles in the insect respiratory system?
Valve-like openings that admit air into the tracheae
37
What is true about countercurrent flow in fish gills?
Water flowing over the gills moves in the opposite direction to blood flow
38
Which pairing of respiratory structures is correct?
Spider or scorpion – book lungs for air breathing
39
Which pairing is correct for respiratory organs?
A. Spider or scorpion – book lungs for air breathing ## Footnote Spiders and scorpions (arachnids) have book lungs, which are internal stacked, leaf-like respiratory surfaces for gas exchange with air.
40
What respiratory structure do frog tadpoles use when aquatic?
Gills ## Footnote Frog tadpoles have gills for underwater breathing, not lungs.
41
How do frogs exchange gases?
Across their moist skin, using lungs when on land, across the lining of the mouth ## Footnote Frogs can breathe through their skin, simple lungs, and the moist lining of the buccal cavity.
42
What change occurs as a tadpole transforms into an adult frog?
It loses the gills and develops lungs, enabling it to breathe air ## Footnote As tadpoles metamorphose into adult frogs, they resorb gills and develop lungs.
43
How do plants primarily obtain the gases needed for respiration and photosynthesis?
Through pores called stomata on leaves ## Footnote Stomata allow CO₂ in and O₂ out, functioning as the primary route for gas exchange.
44
When are stomata generally open in most plants?
In daylight, when light is available for photosynthesis ## Footnote Stomata open during the day for CO₂ intake and close at night to conserve water.
45
How do woody plants exchange gases through their bark?
Through small pores in the bark called lenticels ## Footnote Lenticels allow O₂ to diffuse in and CO₂ out of internal tissues.
46
Do plants require oxygen for their metabolism?
Yes. Plants conduct cellular respiration continuously ## Footnote Plants use O₂ for aerobic respiration day and night, consuming O₂ and releasing CO₂.
47
Why can over-watering a potted plant kill it?
Waterlogged soil lacks air, so roots cannot get oxygen for respiration ## Footnote Roots require oxygen for aerobic respiration; excess water limits O₂ availability.
48
How many oxygen molecules can one hemoglobin molecule carry at maximum?
Four O₂ molecules ## Footnote Hemoglobin can bind up to four O₂ molecules when fully saturated.
49
What property of hemoglobin causes its S-shaped oxygen dissociation curve?
Cooperative binding ## Footnote When one O₂ binds, hemoglobin's affinity for additional O₂ increases, creating the S-shape.
50
What is the Bohr effect regarding hemoglobin’s oxygen-binding?
Higher CO₂ levels and lower pH reduce hemoglobin’s affinity for O₂ ## Footnote This promotes O₂ release in metabolizing tissues.
51
Which factor does NOT cause hemoglobin to release oxygen more readily?
A higher pH (more alkaline blood) ## Footnote Alkaline conditions increase hemoglobin's O₂ affinity, hindering O₂ unloading.
52
What is true about fetal hemoglobin compared to adult hemoglobin?
Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin ## Footnote This helps the fetus extract O₂ from maternal blood effectively.
53
How does myoglobin differ from hemoglobin?
Myoglobin is a single-chain protein that binds one O₂ at a time and has a higher O₂ affinity at low Po₂ ## Footnote Myoglobin serves as an O₂ reserve in muscle cells.
54
What statement about hemocyanin is correct?
Hemocyanin uses copper to bind oxygen and is found in the hemolymph of many mollusks and arthropods ## Footnote Hemocyanin gives their blood a bluish color and is different from hemoglobin.
55
Why is carboxyhemoglobin dangerous?
It prevents O₂ from binding to hemoglobin, effectively reducing the blood’s oxygen-carrying capacity ## Footnote CO binds to hemoglobin with much higher affinity than O₂, leading to severe tissue hypoxia.
56
What is the effect of carbon monoxide on hemoglobin?
Hemoglobin’s affinity for CO is ~240 times greater than for O₂, causing severe tissue hypoxia.
57
What factor increases the rate of gas exchange across the respiratory membrane according to Fick's law?
A greater difference in partial pressure of the gas between the two sides of the membrane.
58
Which condition does NOT enhance gas diffusion?
Thickening of the alveolar-capillary membrane (e.g. due to pulmonary fibrosis).
59
How does emphysema affect gas exchange?
It reduces the total surface area available for diffusion, thereby decreasing gas exchange efficiency.
60
What effect does fluid accumulation in the alveoli have on gas exchange?
It increases the diffusion distance for gases between air and blood, making diffusion slower.
61
How does ascending to a high altitude affect gas exchange in the lungs?
The lower atmospheric O₂ partial pressure decreases the gradient driving O₂ into blood, so less oxygen diffuses into the bloodstream.
62
Why does carbon dioxide diffuse as readily as oxygen despite a smaller partial pressure gradient?
CO₂ is about 20 times more soluble in blood and alveolar fluid than O₂.
63
Why do large, multi-cellular animals need specialized respiratory organs?
Diffusion alone is efficient only over very short distances; in a large organism, interior cells would not get oxygen quickly enough without a transport system.
64
Where is the basic respiratory rhythm generated in the body?
In the respiratory centers of the brainstem – specifically the medulla oblongata.
65
What is the most powerful stimulus driving an increase in breathing rate under normal conditions?
An increase in arterial CO₂ levels (hypercapnia), which causes a drop in pH in the brain’s extracellular fluid.
66
How do central chemoreceptors regulate breathing?
They respond primarily to changes in pH of the cerebrospinal fluid (which reflects CO₂ levels in blood).
67
Where are the peripheral chemoreceptors for respiration located?
In the carotid and aortic bodies, sensing mainly a fall in arterial O₂.
68
What triggers the Hering–Breuer inflation reflex?
Stretch receptors in the walls of bronchi/bronchioles fire when the lungs are inflated, sending signals via the vagus nerve to the medulla to terminate inspiration.
69
Why can’t a person hold their breath indefinitely?
Rising CO₂ and H⁺ levels in the blood and brain will force the inspiratory drive to resume, overriding voluntary control.
70
What happens to blood pH if a person hypoventilates?
CO₂ accumulates, leading to an increase in H⁺ (carbonic acid) and a drop in pH (respiratory acidosis).
71
How does hyperventilation affect blood gases and pH?
It 'blows off' CO₂, causing blood CO₂ to drop and pH to rise (respiratory alkalosis).
72
During exercise, how does the body adjust breathing to meet increased oxygen demand?
Breathing rate and depth increase (hyperpnea) due to both neural signals and chemical changes.
73
What is the effect of excessive hyperventilation on CO₂ and pH balance?
It dangerously alters CO₂/pH balance.
74
During exercise, how does the body adjust breathing to meet increased oxygen demand?
Breathing rate and depth increase (hyperpnea) due to neural signals and chemical changes.
75
What triggers an increase in ventilation during exercise?
CO₂ and H⁺ rise in active muscles stimulate chemoreceptors.
76
What is the immediate respiratory adjustment when a person ascends to high altitude?
An increase in ventilation (hyperventilation) due to peripheral chemoreceptors sensing low arterial O₂.
77
Which part of the brain allows voluntary control over breathing?
The cerebral cortex.
78
What role do the nasal passages play in conditioning incoming air?
They warm, humidify, and filter the air before it reaches the lungs.
79
What is vital capacity defined as?
The maximum volume of air that can be exhaled after a maximal inhalation.
80
What is residual volume in the lungs?
The volume of air remaining in the lungs after a forceful, complete exhalation.
81
How does emphysema primarily damage gas exchange?
By destroying alveolar walls and reducing surface area for exchange.
82
What happens during an asthma attack?
The bronchioles constrict spasmodically and may fill with mucus.
83
How does pneumonia impair gas exchange?
Fluid in the alveoli increases the diffusion distance for gases and can collapse some alveoli.
84
What blood vessels carry oxygen-rich blood from the lungs back to the heart?
The pulmonary veins.
85
What percentage of the air we breathe is oxygen, approximately?
~21%.
86
What does a spirometer measure?
Lung volumes and capacities.
87
On average, how many breaths per minute does a healthy adult at rest take?
Roughly 12–16 breaths per minute.
88
What adaptation occurs to improve oxygen delivery to tissues during prolonged exposure to high altitude?
The kidneys secrete more erythropoietin (EPO), stimulating increased red blood cell production.
89
Why is residual volume important?
It prevents the alveoli from collapsing and allows continuous gas exchange between breaths.
90
What percent of O₂ and CO₂ are present in exhaled air?
About 16% O₂ and 4% CO₂.
91
What does it imply if blood leaving the tissues is still about 75% saturated with oxygen at rest?
Only about 1/4 of the oxygen delivered to tissues is unloaded at rest.
92
What is the saturation of arterial blood at rest?
~97–100% saturated with O₂
93
What is the saturation of venous blood returning from tissues at rest?
~75% saturated with O₂
94
What does a venous O₂ saturation drop indicate during exercise?
More O₂ is extracted by tissues to support metabolism
95
Which statement best describes ventilation-perfusion coupling?
Blood flow to each lung area is matched to airflow for efficient gas exchange
96
What happens to pulmonary arterioles in poorly ventilated lung regions?
They constrict to redirect blood to better-ventilated areas
97
Why is nitrogen gas (N₂) largely ignored by the body in respiratory function?
It is inert and has low solubility in blood
98
In which group is surfactant often insufficient, leading to respiratory problems?
Premature infants with Infant Respiratory Distress Syndrome
99
How do the kidneys compensate for prolonged hyperventilation at altitude?
They excrete more bicarbonate to counteract respiratory alkalosis
100
What is the Respiratory Quotient (RQ) for a person consuming O₂?
Approximately 0.8
101
How does the ventilation-perfusion ratio (V/Q) vary from apex to base of the lungs?
Higher at the apex and lower at the base due to gravity
102
What causes the bends (decompression sickness) in divers?
Nitrogen bubbles forming in blood during rapid ascent
103
What could happen if someone breathes 100% oxygen at sea level for an extended period?
Oxygen toxicity could develop
104
Why is carbonic acid (H₂CO₃) considered a volatile acid in the body?
It is in equilibrium with CO₂, which can be exhaled
105
Why does breathing pure helium make a person's voice sound high-pitched?
Sound travels faster through helium due to its lower density
106
How does breathing into a paper bag help someone who is hyperventilating?
It forces rebreathing of exhaled CO₂, correcting alkalosis
107
What does a mixed venous blood oxygen saturation of 20–30% indicate?
Active muscles extracted a large portion of the delivered oxygen
108
What is an example of a ventilation-perfusion (V/Q) mismatch?
A pulmonary embolism blocking blood flow to part of the lung
109
What does the term 'shunt' refer to in the respiratory system?
Blood passing through the lungs without being oxygenated
110
What is a pulmonary shunt?
Blood that enters systemic arterial circulation without going through ventilated lung tissue ## Footnote This can occur due to anatomical defects or physiological conditions that prevent gas exchange.
111
What causes a pulmonary shunt to lower arterial O₂ content?
Blood bypasses gas exchange in ventilated lung tissue ## Footnote Shunted blood remains deoxygenated.
112
What happens to the oxygen-hemoglobin dissociation curve during a fever?
It shifts to the right, meaning hemoglobin releases oxygen more readily ## Footnote Increased temperature reduces O₂ affinity, benefiting metabolically active tissues.
113
What is the end product of anaerobic respiration (fermentation) in human muscle cells?
Lactic acid (lactate) ## Footnote This process occurs during intense exercise when oxygen is insufficient.
114
What is aerobic respiration?
A metabolic process that requires molecular oxygen to produce energy (ATP) from nutrients ## Footnote It generates CO₂ and H₂O as waste products.
115
What constitutes total lung capacity (TLC)?
The total volume of air the lungs can hold: the sum of vital capacity and residual volume ## Footnote TLC varies with age, sex, body size, and lung diseases.
116
How is total lung capacity (TLC) calculated?
TLC = vital capacity (VC) + residual volume (RV) ## Footnote For an average adult male, TLC is around 5–6 liters.
117
What is the significance of vital capacity (VC) in relation to TLC?
Vital capacity is the part of TLC that can be exchanged ## Footnote Residual volume is the air that remains after maximal exhalation.
118
True or False: Aerobic respiration produces oxygen as an end product.
False ## Footnote Oxygen is consumed, not produced; photosynthesis generates O₂.
119
What happens to the oxygen-hemoglobin dissociation curve at lower temperatures?
It shifts to the left, increasing hemoglobin's affinity for oxygen ## Footnote This means hemoglobin holds onto O₂ more tightly.

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