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Chapter 16 Respiratory System Flashcards

1
Q

What are the three main functions included in the respiratory system as described in the text?

A

The respiratory system includes: a) Ventilation — the mechanical process that moves air into and out of the lungs; b) Gas exchange between blood and lungs and between blood and tissues; c) Oxygen utilization by tissues to make ATP (cellular respiration).

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2
Q

What is ventilation?

A

Ventilation is the mechanical process that moves air into and out of the lungs.

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3
Q

What are alveoli and why are they important in the respiratory system?

A

Alveoli are air sacs in the lungs where gas exchange occurs. They are important because there are about 300 million of them providing a large surface area (about 760 square feet) to increase the diffusion rate of gases.

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4
Q

Describe the structure of an alveolus and its significance in gas exchange.

A

Each alveolus is one cell layer thick but has great tensile strength. This thin wall facilitates efficient gas exchange by minimizing the diffusion distance while the tensile strength prevents the alveoli from collapsing.

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5
Q

What are the two types of alveolar cells and their respective functions?

A

Type I alveolar cells constitute 95 to 97% of the total surface area where gas exchange occurs. Type II alveolar cells secrete pulmonary surfactant and reabsorb sodium and water which prevents fluid buildup in the alveoli.

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6
Q

Outline the pathway air takes through the respiratory system starting from the nasal cavity.

A

Air travels from the nasal cavity to the pharynx then the larynx through the glottis and vocal cords followed by the trachea then into the right and left primary bronchi secondary bronchi tertiary bronchi with further branching terminal bronchioles respiratory bronchioles and finally to terminal alveolar sacs.

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7
Q

What are the two anatomical divisions of the respiratory system and what are their functions?

A

The respiratory system is divided into: a) The conduction zone which transports air to the respiratory zone and also warms humidifies filters and cleans the air; and b) The respiratory zone which is the site of gas exchange.

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8
Q

List the functions of the conducting zone as stated in the text.

A

The conducting zone transports air to the respiratory zone produces voice in the larynx as air passes over the vocal folds and warms humidifies filters and cleans the air by trapping small particles in mucus and moving the mucus by coordinated cilia action to the pharynx.

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9
Q

Explain how mucus and cilia function together in the conducting zone.

A

Mucus secreted by cells of the conducting zone traps small particles. Cilia beat in a coordinated fashion to move the mucus up to the pharynx where it can be cleared by swallowing thus helping to clean the air entering the lungs.

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10
Q

According to the introduction to ventilation what causes air to move into and out of the lungs?

A

Air moves from regions of higher pressure to regions of lower pressure. In the respiratory system pressure differences between the two ends of the conducting zone occur due to changing lung volumes which drives ventilation.

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11
Q

What are the important physical properties of the lungs that affect ventilation?

A

The important physical properties of the lungs affecting ventilation are compliance elasticity and surface tension.

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12
Q

Define atmospheric pressure and intrapulmonary (intra-alveolar) pressure as mentioned in the text.

A

Atmospheric pressure is the pressure of air outside the body. Intrapulmonary or intra-alveolar pressure is the pressure within the alveoli of the lungs.

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13
Q

What is intrapleural pressure and what role does the fluid within the intrapleural space serve?

A

Intrapleural pressure is the pressure within the intrapleural space which contains a thin layer of fluid that serves as a lubricant.

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14
Q

During inspiration (inhalation) how does intrapulmonary pressure compare to atmospheric pressure and what term describes pressures below atmospheric?

A

During inspiration intrapulmonary pressure is lower than atmospheric pressure. Pressure below atmospheric is called subatmospheric or negative pressure.

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15
Q

During expiration (exhalation) how does intrapulmonary pressure compare to atmospheric pressure?

A

During expiration intrapulmonary pressure is greater than atmospheric pressure.

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16
Q

According to Table 16.1 what are peak values of intrapulmonary and intrapleural pressures (in cmH₂O) during inspiration and expiration?

A

Inspiration: Intrapulmonary pressure is -1 cmH₂O intrapleural pressure is -8 cmH₂O. Expiration: Intrapulmonary pressure is +1 cmH₂O intrapleural pressure is -5 cmH₂O.

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17
Q

How does intrapleural pressure compare to intrapulmonary and atmospheric pressure during both inspiration and expiration?

A

Intrapleural pressure is lower than both intrapulmonary and atmospheric pressure during both inspiration and expiration.

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18
Q

What is transpulmonary (transmural) pressure and why is it important?

A

Transpulmonary pressure is the difference between intrapulmonary and intrapleural pressure. It is positive during inspiration and expiration and keeps the lungs against the thoracic wall allowing them to expand during inspiration.

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19
Q

State Boyle’s Law as it relates to lung volume and pressure during breathing.

A

Boyle’s Law states that the pressure of a gas is inversely proportional to its volume. When lung volume increases during inspiration intrapulmonary pressure decreases to subatmospheric levels allowing air in. When lung volume decreases during expiration intrapulmonary pressure increases above atmospheric levels forcing air out.

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20
Q

Define lung compliance and explain factors that can reduce it.

A

Lung compliance is the ease with which the lungs expand under pressure and is defined as the change in lung volume per change in transpulmonary pressure (V/P). It is reduced by factors that produce resistance to lung distention such as pulmonary fibrosis.

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21
Q

What is lung elasticity and how does it function during the breathing cycle?

A

Lung elasticity is the ability of lungs to return to their initial size after being stretched due to their elastin fibers. The lungs are under elastic tension because they are stuck to the thoracic wall; this tension increases during inspiration and is reduced by elastic recoil during expiration.

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22
Q

What role does surface tension play in the lungs and where is this force exerted?

A

Surface tension resists distension of the lungs and is exerted by fluid secreted on the alveoli. It raises the pressure of alveolar air as it acts to collapse the alveolus.

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23
Q

Explain the Law of Laplace in relation to alveoli and the significance of surfactant.

A

The Law of Laplace states that pressure is directly proportional to surface tension (T) and inversely proportional to the radius (r) of the alveolus (P = 2T/r). Small alveoli would be at greater risk of collapse without surfactant which reduces surface tension.

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24
Q

What happens during a pneumothorax and how does it affect intrapleural pressure and lung expansion?

A

During a pneumothorax air enters the pleural space raising intrapleural pressure so that the pressure difference keeping the lung against the chest wall is lost which can cause lung collapse.

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25
What causes the lung to collapse in a pneumothorax?
The lung collapses due to its elastic recoil when air enters the pleural space and eliminates the pressure difference that keeps the lung against the chest wall.
26
How can a spontaneous pneumothorax occur?
A spontaneous pneumothorax may occur without disease or trauma by air leaking from the lung due to a puncture from a broken rib or lung disorders such as COPD cystic fibrosis or rupture of a lung blister.
27
Why does a pneumothorax usually affect only one lung?
Each lung is in a separate pleural compartment so a pneumothorax usually occurs in only one lung.
28
What role does surfactant play in the lungs?
Surfactant secreted by type II alveolar cells reduces surface tension between water molecules by reducing hydrogen bonds prevents alveolar collapse and allows a residual volume of air to remain in the lungs.
29
What is respiratory distress syndrome (RDS) and why does it occur in premature babies?
RDS is a condition of alveolar collapse caused by insufficient surfactant production which begins late in fetal life; premature babies may be born without enough surfactant and are at high risk for RDS.
30
What are possible causes of acute respiratory distress syndrome (ARDS) in adults?
ARDS can be caused by septic shock or pneumonia leading to reduced lung compliance reduced surfactant and resulting hypoxemia.
31
What is spirometry and what does it measure?
Spirometry is a test where a subject breathes into and out of a device that records volume and frequency of air movement on a spirogram. It measures lung volumes and capacities and can diagnose restrictive and obstructive lung disorders.
32
Define tidal volume in lung volume measurements.
Tidal volume is the amount of air expired or inspired in each breath of quiet breathing.
33
What is expiratory reserve volume and how is it measured?
Expiratory reserve volume is the amount of air that can be forced out after a tidal volume.
34
Explain inspiratory reserve volume in the context of lung volumes.
Inspiratory reserve volume is the amount of air that can be forced in after a tidal volume.
35
What is residual volume in lung measurements?
Residual volume is the amount of air left in the lungs after maximum expiration.
36
Describe vital capacity as a lung capacity measurement.
Vital capacity is the maximum amount of air that can be forcefully exhaled after a maximum inhalation.
37
What does total lung capacity represent?
Total lung capacity is the amount of gas in the lungs after a maximum inspiration.
38
Define inspiratory capacity.
Inspiratory capacity is the amount of gas that can be inspired after a normal expiration.
39
What is functional residual capacity?
Functional residual capacity is the amount of air in the lungs after a quiet expiration.
40
How are vital capacity inspiratory reserve volume expiratory reserve volume and tidal volume related?
Vital capacity equals the sum of inspiratory reserve volume expiratory reserve volume and tidal volume.
41
What is anatomical dead space and its significance?
Anatomical dead space is the volume of air in the conducting airways to the respiratory zone where fresh air is mixed with exhaled air. The oxygen content is lower and carbon dioxide content is higher than external air so the amount of fresh air reaching the alveoli with each breath is less than the tidal volume.
42
Differentiate between restrictive and obstructive lung disorders based on vital capacity and forced expiration.
Restrictive lung disorders damage lung tissue causing reduced vital capacity but normal forced expiration (e.g. pulmonary fibrosis and emphysema). Obstructive lung disorders have normal lung tissue and vital capacity but reduced forced expiration (e.g. asthma).
43
What is the Forced Expiratory Volume (FEV1) test and its diagnostic use?
FEV1 test measures the percentage of vital capacity exhaled in the first second. A value significantly less than 80% suggests obstructive pulmonary disease and is used to diagnose obstructive lung disorders.
44
How is atmospheric pressure measured and what is its value at sea level?
Atmospheric pressure is measured using a barometer. At sea level it is 760 mmHg or one atmosphere.
45
State Dalton’s Law as it applies to gas mixtures.
Dalton’s Law states that the total pressure of a gas mixture equals the sum of the pressures of each individual gas in it.
46
How is partial pressure of an individual gas determined?
Partial pressure is calculated by multiplying the fraction of that gas in the mixture by the total pressure.
47
How is the partial pressure of oxygen (P O2) calculated from atmospheric pressure at sea level?
Partial pressure of O2 is calculated by multiplying atmospheric pressure by the percentage of oxygen in the atmosphere: 760 mmHg x 21% = 159.6 mmHg.
48
Why does addition of water vapor affect the calculation of partial pressure of oxygen in the lungs?
Because air is humidified in the lungs water vapor takes up part of the pressure (47 mmHg at 37°C) reducing the partial pressure available for other gases including oxygen.
49
What is the partial pressure of oxygen (P O2) in the lungs after accounting for water vapor?
P O2 in the lungs is calculated as 0.21 x (760 mmHg - 47 mmHg) = approximately 150 mmHg.
50
What role do alveoli and blood capillaries play in gas exchange regarding partial pressures?
Alveoli and blood capillaries quickly reach equilibrium for O2 and CO2 maximizing the amount of gas dissolved in the fluid as predicted by Henry's Law.
51
According to Henry's Law what factors affect the amount of gas that can dissolve in a liquid?
The factors include: 1) Solubility of the gas in the liquid (constant for each gas) 2) Temperature of the fluid (more gas dissolves in colder liquids) and 3) Partial pressure of the gases (the primary determining factor).
52
How does a pulse oximeter work to measure oxyhemoglobin saturation?
A pulse oximeter clips on a fingertip and noninvasively measures absorbing light at different wavelengths absorbed by oxyhemoglobin and deoxyhemoglobin determining the percent saturation of oxyhemoglobin.
53
What brain areas control voluntary and involuntary breathing?
Voluntary breathing is controlled by the cerebral cortex while involuntary breathing is controlled by respiratory centers in the medulla oblongata and pons.
54
What are the roles of the apneustic and pneumotaxic centers in the pons?
The apneustic center promotes inspiration by stimulating medulla inspiratory centers whereas the pneumotaxic center inhibits inspiration.
55
How do central and peripheral chemoreceptors regulate breathing?
Central chemoreceptors in the medulla monitor pH of brain fluids; peripheral chemoreceptors in the carotid and aortic arteries monitor pH P CO2 and P O2 of the blood. This feedback influences automatic control of breathing.
56
What happens to blood pH and CO2 levels during hypoventilation and hyperventilation?
During hypoventilation CO2 levels rise causing pH to fall (acidic); in hyperventilation CO2 levels fall causing pH to rise (alkaline).
57
Why are oxygen levels not a good index for control of breathing?
Because oxygen levels in blood do not change as rapidly due to oxygen reserves in hemoglobin so CO2 levels are a more reliable factor for breathing control.
58
What is the significance of maintaining constant levels of P CO2 in the blood?
Ventilation is controlled to maintain blood P CO2 at about 40 mmHg to keep acid-base balance and efficient gas exchange.
59
What is the Hering-Breuer reflex and how does it influence ventilation?
This reflex is stimulated by pulmonary stretch receptors during inhalation; it inhibits the respiratory centers to prevent inhaling too deeply.
60
What is obstructive sleep apnea?
Obstructive sleep apnea is a condition in which there are periods of hypopnea and apnea during sleep caused by a partial or complete collapse of the upper airway.
61
What happens to arterial oxygen and carbon dioxide levels during obstructive sleep apnea?
When the pharyngeal air passages narrow during sleep causing apnea arterial P O2 and oxyhemoglobin saturation fall and arterial P CO2 rises.
62
How do changes in arterial P O2 and P CO2 during apnea affect the body?
The fall in arterial P O2 and rise in arterial P CO2 stimulate chemoreceptor reflexes which can cause the apnea to end with a gasp and jerk.
63
What is a serious cardiovascular consequence of obstructive sleep apnea?
Pulmonary hypertension that results in right ventricle hypertrophy is a danger associated with obstructive sleep apnea.
64
How is obstructive sleep apnea commonly treated during sleep?
People with obstructive sleep apnea often wear continuous positive airway pressure (CPAP) devices when they sleep to keep the oropharynx air passage open.
65
What is hemoglobin and what is its role in the blood?
Hemoglobin is a protein in red blood cells that binds most of the oxygen in blood; it has 4 polypeptide globins (2 alpha and 2 beta chains) and 4 iron-containing hemes.
66
How many oxygen molecules can one hemoglobin molecule carry?
Each hemoglobin molecule can carry 4 molecules of oxygen.
67
What are the forms of hemoglobin and how do they differ?
Oxyhemoglobin has iron in the reduced form Fe2+ and is bound to oxygen. Deoxyhemoglobin has released oxygen but iron remains Fe2+. Each form has a unique color and absorption spectrum.
68
What does percent oxyhemoglobin saturation represent and what is its normal value?
Percent oxyhemoglobin saturation is the ratio of oxyhemoglobin to total hemoglobin measured to assess how well lungs oxygenate blood. Normal value is 97%.
69
How is percent oxyhemoglobin saturation commonly measured?
It is measured with a pulse oximeter or a blood gas machine.
70
What conditions affect oxygen-carrying capacity of blood as measured by hemoglobin concentration?
Anemia is below-normal hemoglobin levels reducing oxygen capacity; polycythemia is above-normal hemoglobin levels which may occur at high altitudes.
71
What hormone stimulates hemoglobin and red blood cell production and under what condition?
Erythropoietin made in the kidneys stimulates hemoglobin/red blood cell production in red bone marrow when oxygen levels are low.
72
What do 'loading' and 'unloading' mean in terms of hemoglobin and oxygen?
Loading refers to hemoglobin binding to oxygen in the lungs; unloading is hemoglobin releasing oxygen to tissues.
73
What determines the direction of the reaction between oxyhemoglobin and deoxyhemoglobin?
The direction depends on the partial pressure of oxygen (P O2) in the environment and hemoglobin's affinity for oxygen. High P O2 favors loading oxygen while low P O2 favors unloading oxygen.
74
What is the typical oxygen saturation of hemoglobin in systemic arteries and systemic veins?
Systemic arteries typically have a P O2 of 100 mmHg with about 97% oxyhemoglobin saturation while systemic veins have a P O2 of 40 mmHg with about 75% oxyhemoglobin saturation.
75
Describe the shape and significance of the Oxyhemoglobin Dissociation Curve.
The curve is sigmoidal (S-shaped). At high P O2 changes in P O2 have little effect on oxygen loading (plateau section). At the steep part of the curve (lower P O2) small changes in P O2 cause large changes in hemoglobin saturation enabling efficient oxygen unloading to tissues.
76
How do pH and temperature affect hemoglobin's affinity for oxygen and why is this important during exercise?
Hemoglobin affinity for oxygen decreases at lower pH (Bohr effect) and at higher temperatures. This causes more oxygen to unload to muscles during exercise when metabolism increases CO2 (lowering pH) and body temperature rises shifting the curve to the right and increasing oxygen delivery.
77
What is the Bohr effect and how does it influence oxygen transport?
The Bohr effect refers to the decrease in hemoglobin's affinity for oxygen at lower pH levels. This leads to more oxygen unloading in conditions of increased metabolism and CO2 production as the oxyhemoglobin curve shifts to the right enhancing oxygen delivery to tissues.
78
What role does 23-diphosphoglyceric acid (23-DPG) play in oxygen transport?
23-DPG is produced in red blood cells during anaerobic glucose metabolism. Its levels increase in anemia or at high altitude and cause a decrease in hemoglobin's affinity for oxygen shifting the oxyhemoglobin dissociation curve to the right and enhancing oxygen unloading.
79
List the factors that decrease hemoglobin's affinity for oxygen and shift the oxyhemoglobin dissociation curve to the right.
Decreased pH (Bohr effect) increased temperature and increased levels of 23-DPG all decrease hemoglobin's oxygen affinity and shift the curve to the right promoting oxygen unloading to tissues.
80
In what three forms is carbon dioxide transported in the blood?
Carbon dioxide is carried dissolved in plasma as carbaminohemoglobin bound to hemoglobin's amino acids and mainly as bicarbonate ions.
81
What is the role of carbonic anhydrase in carbon dioxide transport?
Carbonic anhydrase catalyzes the reaction of carbon dioxide with water inside red blood cells facilitating the formation of bicarbonate ions which is the primary method for carbon dioxide transport in blood.
82
What enzyme catalyzes the formation of carbonic acid from CO₂ and water at high P CO₂?
Carbonic anhydrase catalyzes the reaction to form carbonic acid at high P CO₂.
83
Describe the dissociation of carbonic acid in red blood cells.
Carbonic acid dissociates into bicarbonate (HCO₃⁻) and hydrogen ions (H⁺).
84
What is the chloride shift in red blood cells?
The chloride shift is the exchange of bicarbonate ion diffusing out of the RBC into plasma and chloride ion (Cl⁻) entering the RBC which helps maintain electrical neutrality.
85
What happens to the hydrogen ions left in red blood cells after bicarbonate ion forms?
Hydrogen ions attach to hemoglobin and attract chloride ions into the RBC.
86
What occurs during the reverse chloride shift in pulmonary capillaries?
In pulmonary capillaries increased P O₂ promotes oxyhemoglobin formation causing hydrogen ions to dissociate from hemoglobin and recombine with bicarbonate to form carbonic acid. Carbonic anhydrase then converts carbonic acid back into CO₂ and water. Chloride ions diffuse out as bicarbonate enters the RBC. CO₂ is subsequently exhaled.
87
How does the body maintain acid-base balance in the blood?
The lungs and kidneys maintain blood pH within a constant range of 7.35 to 7.45 through regulation of CO₂ and bicarbonate levels.
88
What causes respiratory acidosis and how does it affect blood pH?
Respiratory acidosis is caused by hypoventilation leading to a rise in CO₂ which increases hydrogen ion concentration lowering blood pH below 7.35.
89
What causes metabolic acidosis?
Excessive production of acids (like lactic acid or ketone bodies) or loss of bicarbonate (such as from diarrhea) causes metabolic acidosis.
90
What defines alkalosis and what are its respiratory and metabolic causes?
Alkalosis is when blood pH rises above 7.45. Respiratory alkalosis results from hyperventilation blowing off CO₂ (which decreases H⁺) and metabolic alkalosis results from inadequate acid production or excessive bicarbonate such as loss of digestive acids from vomiting.
91
How does ventilation affect the respiratory component of acid-base balance?
Ventilation controls CO₂ levels: hypoventilation causes CO₂ retention increasing carbonic acid and leading to respiratory acidosis; hyperventilation leads to excessive CO₂ removal reducing carbonic acid and causing respiratory alkalosis.
92
What respiratory change occurs in a person with metabolic acidosis and how does it affect CO2 H and pH?
A person with metabolic acidosis will hyperventilate to blow off CO2 which decreases H and causes the pH to rise.
93
What respiratory change occurs in a person with metabolic alkalosis and how does it affect CO2 H and pH?
A person with metabolic alkalosis will hypoventilate (slow respiration) leading to a buildup of CO2 which increases H and causes the pH to lower.

Physiology (15 decks)

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