Respiratory Flashcards
1
Q
What is the main function of the respiratory system?
A
To supply cells with oxygen and eliminate carbon dioxide.
2
Q
Why is oxygen important for our cells?
A
So that they can carry out their vital functions.
3
Q
Anatomy: What are the two main parts of the respiratory system?
A
The upper respiratory system and the lower respiratory system.
4
Q
What are the lungs and pleurae?
A
They are part of the respiratory system that help with breathing.
5
Q
What are some developmental aspects of the respiratory system?
A
This is explored in chapter 22, including control of respiration, exercise and high altitude, and what happens when things go wrong.
6
Q
What is the major function of the respiratory system?
A
To supply the body with oxygen and dispose of carbon dioxide.
7
Q
What are the four processes of respiration?
A
Pulmonary ventilation (breathing), external respiration, transport of respiratory gases, and internal respiration.
8
Q
What is cellular respiration?
A
The actual use of oxygen and production of carbon dioxide by tissue cells, which is the cornerstone of all energy-producing chemical reactions in the body.
9
Q
What happens if either the respiratory or circulatory system fails?
A
The body’s cells begin to die from oxygen starvation.
10
Q
What are free radicals?
A
Dangerous by-products generated by tissue cells during cellular respiration.
11
Q
What is the role of the respiratory system in the sense of smell and speech?
A
It is involved in both the sense of smell and speech because it moves air.
12
Q
What is the responsibility of the respiratory system in the four processes of respiration?
A
It is responsible for the first two processes, pulmonary ventilation and external respiration.
13
Q
List the functions of the nose.
A
The nose provides an airway for respiration, moistens and warms entering air, filters and cleans inspired air, serves as a resonating chamber for speech, and houses the olfactory (smell) receptors.
14
Q
What are the structures included in the respiratory system?
A
The respiratory system includes the nose and paranasal sinuses
15
Q
What is the upper respiratory system?
A
The upper respiratory system consists of all the structures from the nose to the larynx.
16
Q
What is the lower respiratory system?
A
The lower respiratory system consists of the larynx and all the structures below it.
17
Q
What are the functions of the nose and paranasal sinuses?
A
The nose and paranasal sinuses warm, humidify, and filter air, and provide an airway for respiration.
18
Q
What are some protective mechanisms of the respiratory system?
A
Cilia and mucus in the respiratory tract trap and remove foreign particles, and coughing and sneezing reflexes expel irritants and pathogens from the respiratory tract.
19
Q
What is the nasal cavity?
A
The internal cavity located in and posterior to the external nose, through which air enters during breathing.
20
Q
What divides the nasal cavity?
A
A midline nasal septum, formed anteriorly by the septal cartilage and posteriorly by the vomer bone and perpendicular plate of the ethmoid bone.
21
Q
What are the surface features of the external nose?
A
The root (area between the eyebrows), bridge, and dorsum nasi (anterior margin), the latter terminating in the apex (tip of the nose).
22
Q
What are the external openings of the nose called?
A
The nostrils or nares.
23
Q
What is the skeletal framework of the external nose made of?
A
The nasal and frontal bones superiorly, the maxillary bones laterally, and flexible plates of hyaline cartilage (the alar and septal cartilages, and the lateral processes of the septal cartilage) inferiorly.
24
Q
What is the purpose of the nasal cavity?
A
To warm, moisten, and filter air during breathing.
25
What is the midline nasal septum made of?
Anteriorly by the septal cartilage and posteriorly by the vomer bone and perpendicular plate of the ethmoid bone.
26
What is the function of the sebaceous glands in the skin covering the nose's anterior and lateral aspects?
To secrete sebum, an oily substance that helps to keep the skin moist and supple.
27
What is the roof of the nasal cavity made of?
The ethmoid and sphenoid bones of the skull.
28
What separates the nasal cavity from the oral cavity below?
The palate.
29
What is the anterior portion of the palate called?
The hard palate.
30
What is the posterior portion of the palate called?
The soft palate.
31
What is the function of the hairs in the nasal vestibule?
To filter coarse particles (dust, pollen) from inspired air.
32
What are the two types of mucous membrane that line the nasal cavity?
Olfactory mucosa and respiratory mucosa.
33
What is the function of seromucous nasal glands?
To secrete mucus containing lysozyme, an antibacterial enzyme, and a watery fluid containing enzymes.
34
What is the function of the ciliated cells of the respiratory mucosa?
To move contaminated mucus posteriorly toward the throat, where it is swallowed and digested.
35
What triggers a sneeze reflex?
Contact with irritating particles (dust, pollen, and the like).
36
What is the function of the nasal conchae?
To greatly increase the mucosal surface area exposed to air and enhance air turbulence in the cavity.
37
What is the function of paranasal sinuses?
To lighten the skull, and they may help warm and moisten the air.
38
What is rhinitis?
Inflammation of the nasal mucosa accompanied by excessive mucus production, nasal congestion, and postnasal drip.
39
What is sinusitis?
Inflammation of the sinuses.
40
What can cause a sinus headache?
A change in pressure due to mucus or infectious materials blocking the passages connecting the sinuses to the nasal cavity.
41
Where is the nasopharynx located?
Posterior to the nasal cavity, inferior to the sphenoid bone, and superior to the level of the soft palate.
42
What is the function of the nasopharynx?
To serve as an air passageway.
43
What happens to the nasopharynx during swallowing?
The soft palate and its pendulous uvula move superiorly, closing off the nasopharynx and preventing food from entering the nasal cavity.
44
What is the structure of the epithelium in the nasopharynx?
Pseudostratified ciliated epithelium.
45
What is the function of the pharyngeal tonsil in the nasopharynx?
To trap and destroy pathogens entering the nasopharynx in air.
46
What are the pharyngotympanic tubes and where do they open?
They are tubes that drain the middle ear cavities and allow middle ear pressure to equalize with atmospheric pressure. They open into the lateral walls of the nasopharynx.
47
What is the oropharynx and what is its function?
It is the part of the pharynx that lies posterior to the oral cavity and is continuous with it through an archway called the isthmus of the fauces. It serves as a passageway for both swallowed food and inhaled air.
48
What is the structure of the epithelium in the oropharynx?
Stratified squamous epithelium.
49
What are the palatine tonsils and where are they located?
They are paired tonsils that lie embedded in the lateral walls of the oropharyngeal mucosa just posterior to the oral cavity.
50
What is the lingual tonsil and where is it located?
It is a tonsil that covers the posterior surface of the tongue.
51
What is the laryngopharynx and what is its function?
It is the part of the pharynx that serves as a passageway for both food and air and is lined with a stratified squamous epithelium.
52
What is the homeostatic imbalance associated with infected and swollen adenoids?
They can block air passage in the nasopharynx, making it necessary to breathe through the mouth. This can result in air not being properly moistened, warmed, or filtered before reaching the lungs, and can disturb speech and sleep when chronically enlarged.
53
List the functions of the conducting zone of the respiratory system.
The conducting zone provides a rigid conduit for air to reach the gas exchange sites, cleanses, humidifies, and warms incoming air, and reduces irritants like dust and bacteria.
54
What is the larynx and what are its functions?
The larynx, or voice box, is a structure that extends from the third to the sixth cervical vertebra and has three functions: providing a patent airway, acting as a switching mechanism to route air and food into the proper channels, and voice production.
55
What is the structure of the larynx and what are its cartilages made of?
The larynx has nine cartilages connected by membranes and ligaments, except for the epiglottis, all laryngeal cartilages are hyaline cartilages. The thyroid cartilage is the largest and is formed by the fusion of two cartilage plates at the midline. Three pairs of small cartilages form part of the lateral and posterior walls of the larynx.
56
What is the respiratory zone of the lower respiratory system?
The respiratory zone is the actual site of gas exchange and is composed of microscopic structures such as the respiratory bronchioles, alveolar ducts, and alveoli.
57
What are the organs forming the respiratory passageway in descending order until the alveoli?
The organs forming the respiratory passageway in descending order until the alveoli are the larynx, trachea, bronchi, bronchioles, and alveoli.
58
Which cartilage is known as the guardian of the airways?
The epiglottis.
59
What happens when anything other than air enters the larynx?
The cough reflex is initiated to expel the substance.
60
What are the vocal ligaments composed of?
Elastic fibers.
61
What is the function of the arytenoid cartilages?
To anchor the vocal folds.
62
What is the composition of the epiglottis?
Elastic cartilage and taste bud-containing mucosa.
63
What happens to the larynx during swallowing?
It is pulled superiorly and the epiglottis tips to cover the laryngeal inlet.
64
Why is it not a good idea to administer liquids when attempting to revive an unconscious person?
Because the protective cough reflex does not work when we are unconscious.
65
What is the glottis?
The opening between the vocal folds in the larynx.
66
What is the function of the vocal folds?
To produce sound.
67
What is the function of the cricoid cartilage?
To provide support to the larynx and trachea.
68
What is the function of the thyroid cartilage?
To protect the vocal folds and provide attachment for muscles involved in speech and swallowing.
69
What structures provide the power for the airstream when we yell?
The muscles of the chest, abdomen, and back.
70
What is the glottis?
The medial opening between the vocal folds through which air passes.
71
What is the function of the vestibular folds or false vocal cords?
To help close the glottis when we swallow.
72
What is the epithelium lining the superior portion of the larynx?
Stratified squamous epithelium.
73
What is the epithelium below the vocal folds?
Pseudostratified ciliated columnar epithelium.
74
What is the power stroke of the cilia in the larynx directed towards?
Upward towards the pharynx to move mucus away from the lungs.
75
What causes a boy's voice to become deeper during puberty?
Enlargement of the larynx and thickening of the vocal folds.
76
What is the Valsalva maneuver?
A process where the glottis closes to prevent exhalation and the abdominal muscles contract, causing intra-abdominal pressure to rise.
77
What is laryngitis?
Inflammation of the vocal folds causing hoarseness or limiting the voice to a whisper, often caused by viral infections or overusing the voice.
78
What is the function of the trachealis muscle in the trachea?
To decrease the trachea's diameter, causing expired air to rush upward from the lungs with greater force.
79
What is the carina in the trachea?
A spar of cartilage that projects posteriorly from the inner face of the last tracheal cartilage, marking the point where the trachea branches into the two main bronchi.
80
What is the composition of the tracheal wall?
It consists of several layers, including the mucosa, submucosa, adventitia, and a layer of hyaline cartilage.
81
What is the function of the submucosa in the trachea?
It contains seromucous glands that help produce the mucus sheets within the trachea.
82
What is the effect of smoking on ciliary activity in the trachea?
Smoking inhibits and ultimately destroys ciliary activity, making coughing the only way to prevent mucus from accumulating in the lungs.
83
How long is the trachea in humans?
10-12 cm long and 2 cm in diameter.
84
What is the function of the mucosa in the trachea?
It has the same goblet cell-containing pseudostratified epithelium that occurs throughout most of the respiratory tract. Its cilia continually propel debris-laden mucus toward the pharynx.
85
What is the purpose of the cartilage rings in the trachea?
To prevent the trachea from collapsing and keep the airway patent despite the pressure changes that occur during breathing.
86
Define alveoli in the respiratory system.
Alveoli are small air sacs in the lungs where gas exchange takes place.
87
What is the difference between alveoli and alveolar sacs?
Alveoli are the individual grapes, while alveolar sacs are clusters of alveoli.
88
How many gas-filled alveoli are present in the lungs?
There are approximately 300 million gas-filled alveoli in the lungs.
89
What is the composition of the walls of alveoli?
The walls of alveoli are primarily composed of a single layer of squamous epithelial cells called type I alveolar cells, surrounded by a flimsy basement membrane.
90
What is the respiratory zone in the respiratory system?
The respiratory zone is defined by the presence of thin-walled air sacs called alveoli.
91
What is the structure of respiratory bronchioles?
Respiratory bronchioles are small air passages in the lungs that lead to alveoli and have scattered alveoli protruding from them.
92
What is the function of alveolar ducts in the respiratory system?
Alveolar ducts lead to alveoli and have walls consisting of diffusely arranged rings of smooth muscle cells, connective tissue fibers, and outpocketing alveoli.
93
What is the significance of the thinness of alveolar walls?
The thinness of alveolar walls allows for efficient gas exchange between the lungs and the bloodstream.
94
What is the role of smooth muscle cells in alveolar ducts?
Smooth muscle cells in alveolar ducts provide substantial resistance to air passage under certain conditions.
95
What is the respiratory membrane?
The respiratory membrane is a 0.5-μm-thick blood-air barrier formed by the capillary and alveolar walls and their fused basement membranes.
96
What is the function of the respiratory membrane?
The respiratory membrane allows for gas exchange between the alveoli and the blood through simple diffusion.
97
What covers the external surfaces of the alveoli?
The external surfaces of the alveoli are densely covered with a 'cobweb' of pulmonary capillaries.
98
What is the thickness of the respiratory membrane?
The respiratory membrane is 0.5-μm-thick.
99
What is the role of elastic fibers in the alveoli?
Elastic fibers surround all alveoli and help them to expand and recoil during breathing.
100
What type of cells secrete surfactant in the alveoli?
Type II alveolar cells secrete surfactant in the alveoli.
101
What is the function of surfactant in the alveoli?
Surfactant reduces surface tension in the alveoli, preventing their collapse during exhalation.
102
What is the function of macrophages in the alveoli?
Macrophages in the alveoli engulf and remove debris and pathogens to help keep the lungs clean and healthy.
103
Which type of cells secrete surfactant in the alveoli?
Type II alveolar cells.
104
What is the function of surfactant in the alveoli?
To reduce the surface tension of the alveolar fluid and prevent lung collapse.
105
What is the function of alveolar macrophages?
To crawl freely along the internal alveolar surfaces and consume bacteria, dust, and other debris.
106
What is the function of the fine elastic fibers surrounding the alveoli?
To provide elasticity to the alveoli and allow for passive recoil during expiration.
107
What is the function of the pleurae?
To produce lubricating fluid and compartmentalize the lungs.
108
What is the function of the bronchial tree?
To provide air passageways connecting the trachea with the alveoli and to clean, warm, and moisten incoming air.
109
What is the function of the larynx?
To connect the pharynx to the trachea, serve as an air passageway, and prevent food from entering the lower respiratory tract.
110
What are the two significant features of the alveoli?
They are surrounded by fine elastic fibers and have open alveolar pores connecting adjacent alveoli.
111
What is the trachea?
The trachea is a tube-like structure that connects the larynx to the bronchi of the lungs.
112
What is the thymus?
The thymus is a gland located in the mediastinum that plays a role in the development of the immune system.
113
What is the function of the diaphragm?
The diaphragm is a muscle that separates the thoracic cavity from the abdominal cavity and plays a key role in breathing.
114
What is the function of the pleural cavity?
The pleural cavity is the space between the parietal and visceral pleura that contains a small amount of fluid to reduce friction during breathing.
115
What is the function of the parietal pleura?
The parietal pleura is the outer layer of the pleura that lines the thoracic cavity.
116
What is the function of the visceral pleura?
The visceral pleura is the inner layer of the pleura that covers the lungs.
117
What is the function of the bronchi?
The bronchi are the two main branches of the trachea that lead to the lungs and allow air to enter and exit the lungs.
118
What is the function of the pulmonary artery?
The pulmonary artery is a blood vessel that carries deoxygenated blood from the heart to the lungs.
119
What is the function of the pulmonary vein?
The pulmonary vein is a blood vessel that carries oxygenated blood from the lungs to the heart.
120
What is the function of the lobules in the lungs?
The lobules in the lungs are small compartments that contain clusters of alveoli where gas exchange occurs.
121
What is the function of the aorta?
The aorta is the largest artery in the body that carries oxygenated blood from the heart to the rest of the body.
122
What is the function of the esophagus?
The esophagus is a muscular tube that connects the pharynx to the stomach and is responsible for transporting food and liquids to the stomach.
123
Which fissures divide the left and right lungs into lobes?
The left lung is divided into superior and inferior lobes by the oblique fissure, whereas the right lung is partitioned into superior, middle, and inferior lobes by the oblique and horizontal fissures.
124
What are bronchopulmonary segments?
They are pyramid-shaped segments in each lobe of the lung, separated by connective tissue septa, and served by their own artery and vein.
125
Why are bronchopulmonary segments clinically important?
Pulmonary disease is often confined to one or a few segments, and their connective tissue partitions allow diseased segments to be surgically removed without damaging neighboring segments or impairing their blood supply.
126
What are lobules in the lungs?
They are the smallest subdivisions of the lung visible with the naked eye, appearing as hexagons ranging from the size of a pencil eraser to the size of a penny at the lung surface.
127
What is the stroma of the lungs?
It is mostly elastic connective tissue that makes up the balance of lung tissue, or 'mattress' or 'bed'.
128
What is the function of the elasticity of healthy lungs?
It reduces the work of breathing.
129
What is the hilum of the lung?
It is an indentation on the mediastinal surface of each lung through which pulmonary and systemic blood vessels, bronchi, lymphatic vessels, and nerves enter and leave the lungs.
130
How do the left and right lungs differ in shape and size?
The left lung is smaller than the right, and the cardiac notch—a concavity in its medial aspect—is molded to and accommodates the heart.
131
What is the function of the mediastinum?
It houses the heart, great blood vessels, bronchi, esophagus, and other organs.
132
What is the function of pleural fluid in the lungs?
To lubricate the pleurae and allow the lungs to glide easily over the thorax wall during breathing movements.
133
How do the pleurae help in preventing interference of one mobile organ with another?
By dividing the thoracic cavity into three chambers - the central mediastinum and the two lateral pleural compartments, each containing a lung.
134
What are the two circulations that perfuse the lungs and how do they differ?
The two circulations are pulmonary and bronchial. Pulmonary circulation delivers systemic venous blood to be oxygenated in the lungs, while bronchial circulation provides oxygenated systemic blood to lung tissue.
135
What is pleurisy and what are its symptoms?
Pleurisy is inflammation of the pleurae, which results in friction and stabbing pain with each breath. Inflamed pleurae become rough and may produce excessive amounts of fluid, which may exert pressure on the lungs and hinder breathing movements.
136
What physical factors influence pulmonary ventilation?
Physical factors that influence pulmonary ventilation include airway resistance, alveolar surface tension, lung compliance, and the pressure gradient between the atmosphere and the alveoli.
137
What is pleural effusion?
Pleural effusion is the accumulation of fluid in the pleural cavity, which may include blood or blood filtrate, and can hinder breathing movements.
138
What is the role of parasympathetic and sympathetic motor fibers in the lungs?
Parasympathetic fibers cause the air tubes to constrict, while sympathetic fibers dilate them.
139
What is the role of the pulmonary circuit in the body?
The pulmonary circuit is a low-pressure, high-volume circulation that oxygenates the body's blood by passing it through the lungs about once each minute. The lung capillary endothelium is an ideal location for enzymes that act on materials in the blood, such as angiotensin converting enzyme.
140
What is the role of bronchial circulation in the lungs?
Bronchial circulation provides a high-pressure, low-volume supply of oxygenated systemic blood to all lung tissues except the alveoli. The tiny bronchial veins drain some systemic venous blood from the lungs, but most venous blood returns to the heart via the pulmonary veins.
141
What is the function of pleural fluid in the respiratory system?
To secure the pleurae together and maintain a negative intrapleural pressure.
142
What is the transpulmonary pressure and what is its importance?
The transpulmonary pressure is the difference between the intrapulmonary and intrapleural pressures. It keeps the air spaces of the lungs open and determines the size of the lungs.
143
What is the atmospheric pressure at sea level?
760 mm Hg.
144
How are respiratory pressures described?
Relative to atmospheric pressure.
145
What is intrapulmonary pressure and how does it change during breathing?
The pressure in the alveoli. It rises and falls with the phases of breathing, but eventually equalizes with atmospheric pressure.
146
What is intrapleural pressure and how does it relate to intrapulmonary pressure?
The pressure in the pleural cavity. It fluctuates with breathing phases, but is always about 4 mm Hg less than intrapulmonary pressure.
147
What are the opposing forces that act on the lungs and what is the net result?
The lungs' natural tendency to recoil and the surface tension of the alveolar fluid act to pull the lungs away from the thorax wall and cause them to collapse, while the natural elasticity of the chest wall tends to pull the thorax outward and enlarge the lungs. In a healthy person, neither force wins and the result is a negative intrapleural pressure.
148
Define the term 'inspiration' in the context of the respiratory system.
Inspiration is the process of inhaling air into the lungs, which involves the contraction of inspiratory muscles, such as the diaphragm and external intercostal muscles, leading to an increase in thoracic volume and a decrease in intrapulmonary pressure.
149
What is the usual volume of air that enters the lungs during a normal quiet inspiration?
Almost 500 ml.
150
What is the role of the diaphragm in producing volume changes during normal quiet inspiration?
The diaphragm is far more important in producing volume changes that lead to normal quiet inspiration.
151
What is the action that occurs when a curved bucket handle is raised?
It moves outward as it moves upward.
152
What is the significance of the changes in thoracic volume during inspiration and expiration?
During inspiration, an increase in thoracic volume leads to a decrease in intrapulmonary pressure, allowing air to flow into the lungs. During expiration, a decrease in thoracic volume leads to an increase in intrapulmonary pressure, allowing air to flow out of the lungs.
153
What is the role of external intercostal muscles in changes in thoracic volume during inspiration and expiration?
During inspiration, the external intercostal muscles contract, elevating the ribs and sternum and increasing the anterior-posterior and superior-inferior dimensions of the thoracic cavity. During expiration, the external intercostal muscles relax, allowing the ribs and sternum to be depressed and decreasing the anterior-posterior and superior-inferior dimensions of the thoracic cavity.
154
Name two nonrespiratory air movements.
Coughing and sneezing.
155
What is the major nonelastic source of resistance to gas flow in the respiratory passageways?
Friction or drag.
156
What is the relationship between gas flow, pressure, and resistance in the respiratory passages?
F = ∆P/R.
157
What is the primary muscle responsible for forced expiration?
Abdominal wall muscles, primarily the oblique and transversus muscles.
158
What is the difference between quiet expiration and forced expiration?
Quiet expiration is a passive process that depends more on lung elasticity than on muscle contraction, while forced expiration is an active process produced by contracting abdominal wall muscles.
159
What is the role of accessory muscles in forced expiration?
Accessory muscles further increase thoracic volume during deep or forced inspirations that occur during vigorous exercise and in some chronic obstructive pulmonary diseases.
160
What happens to intrapulmonary pressure during inspiration and expiration?
Intrapulmonary pressure decreases during inspiration and increases during expiration.
161
What is the pressure gradient that causes air to rush into the lungs during inspiration?
The pressure gradient between the intrapulmonary pressure and atmospheric pressure.
162
What is the pressure gradient that causes gases to flow out of the lungs during expiration?
The pressure gradient between the intrapulmonary pressure and atmospheric pressure.
163
According to the text, what is the relationship between gas flow and pressure gradient in the respiratory system?
The amount of gas flowing into and out of the alveoli is directly proportional to the difference in pressure, or pressure gradient, between the external atmosphere and the alveoli.
164
What is the average pressure gradient during normal quiet breathing?
2 mm Hg or less.
165
Why is airway resistance insignificant in the respiratory tree?
Airway diameters in the first part of the conducting zone are huge, relative to the low viscosity of air, and there are progressively more branches as the airways get smaller, resulting in an enormous number of tiny bronchioles in parallel, so the total cross-sectional area is huge.
166
What is surface tension in the respiratory system?
Surface tension is a state of tension at the liquid surface that draws the liquid molecules closer together and reduces their contact with the dissimilar gas molecules, and resists any force that tends to increase the surface area of the liquid.
167
What is surfactant and how does it affect alveolar surface tension?
Surfactant is a detergent-like complex of lipids and proteins produced by the type II alveolar cells. It decreases the cohesiveness of water molecules, reducing the surface tension of alveolar fluid and lessening the energy needed to overcome those forces to expand the lungs and discourage alveolar collapse.
168
What is infant respiratory distress syndrome (IRDS) and how is it treated?
IRDS is a condition common in premature babies where too little surfactant is present, causing surface tension to collapse the alveoli. It is treated by spraying natural or synthetic surfactant into the newborn’s respiratory passageways, and devices that maintain positive airway pressure throughout the respiratory cycle can keep the alveoli open between breaths. Severe cases require mechanical ventilators.
169
What are some important sources of airway resistance in those with respiratory disease?
Local accumulations of mucus, infectious material, or solid tumors in the passageways are important sources of airway resistance in those with respiratory disease.
170
What happens during an acute asthma attack?
Histamine and other inflammatory chemicals can cause strong bronchoconstriction that almost completely stops pulmonary ventilation, regardless of the pressure gradient. Conversely, epinephrine dilates bronchioles and reduces airway resistance.
171
13. On the graph of intrapulmonary pressure below, label the periods of inspiration and expiration, and all of the points where air flow is zero. Explain.
The question is asking to label the periods of inspiration and expiration on the graph of intrapulmonary pressure and also label all the points where air flow is zero. During inspiration, intrapulmonary pressure decreases, and during expiration, it increases. The points where air flow is zero are at the end of inspiration and expiration. These points are called the end-inspiratory and end-expiratory pauses, respectively.
172
14. On the diagram at right, indicate where the following pressures would be measured and what their values would be at the middle of inspiration: atmospheric pressure, intrapulmonary pressure, intrapleural pressure, and transpulmonary pressure.
The question is asking to indicate where the following pressures would be measured and what their values would be at the middle of inspiration: atmospheric pressure, intrapulmonary pressure, intrapleural pressure, and transpulmonary pressure. Atmospheric pressure is measured outside the body and is equal to 760 mmHg. Intrapulmonary pressure is measured inside the lungs and is about 760 mmHg at the middle of inspiration. Intrapleural pressure is measured in the pleural cavity and is about -4 mmHg at the middle of inspiration. Transpulmonary pressure is the difference between intrapulmonary pressure and intrapleural pressure and is about 764 mmHg at the middle of inspiration.
173
10. What is the driving force for pulmonary ventilation?
The driving force for pulmonary ventilation is the pressure gradient between the atmosphere and the alveoli.
174
11. What causes the partial vacuum (negative pressure) inside the pleural cavity? What happens to a lung if air enters the pleural cavity? What is the clinical name for this condition?
The partial vacuum (negative pressure) inside the pleural cavity is caused by the opposing forces of the elastic recoil of the lungs and the surface tension of the pleural fluid. If air enters the pleural cavity, it disrupts the balance between these forces and causes the lung to collapse. This condition is called pneumothorax.
175
12. Premature infants often lack adequate surfactant. How does this affect their ability to breathe?
Premature infants often lack adequate surfactant, which makes it difficult for them to keep their alveoli open during expiration. This leads to collapsed alveoli and decreased lung compliance, which makes it harder for them to breathe and can lead to respiratory distress syndrome (RDS).
176
What is vital capacity?
The total amount of exchangeable air, which is the sum of TV, IRV, and ERV.
177
What is total lung capacity?
The sum of all lung volumes.
178
Why are lung volumes and capacities smaller in women than in men?
Because of women's smaller size.
179
What is anatomical dead space?
The volume of conducting respiratory passageways that never contributes to gas exchange in the alveoli.
180
What is the typical volume of anatomical dead space in the lungs?
About 150 ml.
181
What is residual volume (RV)?
The amount of air remaining in the lungs after a forced expiration.
182
What are the respiratory capacities?
Inspiratory, functional residual, vital, and total lung capacities.
183
What is inspiratory capacity (IC)?
The total amount of air that can be inspired after a normal tidal volume expiration, which is the sum of TV and IRV.
184
What is functional residual capacity (FRC)?
The amount of air remaining in the lungs after a normal tidal volume expiration, which is the combined RV and ERV.
185
What is the maximum amount of air contained in the lungs after a maximum inspiratory effort?
Total lung capacity (TLC), which is the sum of TV, IRV, ERV, and RV.
186
What is the maximum amount of air that can be expired after a maximum inspiratory effort?
Vital capacity (VC), which is the sum of TV, IRV, and ERV.
187
What is the maximum amount of air that can be inspired after a normal tidal volume expiration?
Inspiratory capacity (IC), which is the sum of TV and IRV.
188
What is tidal volume (TV)?
The amount of air inhaled or exhaled with each breath under resting conditions.
189
What is inspiratory reserve volume (IRV)?
The maximum amount of air that can be forcefully inhaled after a normal tidal volume inspiration.
190
What is expiratory reserve volume (ERV)?
The maximum amount of air that can be forcefully exhaled after a normal tidal volume expiration.
191
What is the alveolar ventilation rate (AVR)?
The flow of fresh gases in and out of the alveoli during a particular time interval, taking into account the volume of air wasted in the dead space.
192
What is the equation to compute AVR?
AVR = frequency x (TV - dead space) / (ml/min) (breaths/min) (ml/breath)
193
What is the usual AVR in healthy people?
About 12 breaths per minute times the difference of 500 - 150 ml per breath, or 4200 ml/min.
194
What happens to AVR during rapid shallow breathing?
AVR drops dramatically because most of the inspired air never reaches the exchange sites.
195
What is anatomical dead space?
The volume of air inhaled that does not take part in the gas exchange.
196
What is the difference between obstructive and restrictive pulmonary diseases in terms of pulmonary function tests?
In obstructive diseases, TLC, FRC, and RV may increase because the lungs hyperinflate, whereas in restrictive diseases, VC, TLC, FRC, and RV decline because lung expansion is limited.
197
What is forced vital capacity (FVC)?
The amount of gas expelled when a subject takes a deep breath and then forcefully exhales maximally and as rapidly as possible.
198
What is forced expiratory volume (FEV)?
The amount of air expelled during specific time intervals of the FVC test.
199
What is the minute ventilation during normal quiet breathing in healthy people?
About 6 L/min (500 ml per breath multiplied by 12 breaths per minute).
200
Why do slow, deep breaths ventilate the alveoli more effectively than rapid, shallow breaths?
Because increasing the volume of each inspiration (breathing depth) enhances AVR and gas exchange more than raising the respiratory rate.
201
What is the process of gas exchange during external respiration?
Oxygen enters and carbon dioxide leaves the blood in the lungs by diffusion.
202
Name two gas laws that provide most of the information about gases.
Boyle's law and Dalton's law of partial pressures.
203
What is Dalton's law of partial pressures?
The total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture.
204
What is the partial pressure of nitrogen in air?
PN2 is 78.6% x 760 mm Hg, or 597 mm Hg.
205
What is the partial pressure of oxygen in air?
PO2 is 20.9% x 760 mm Hg, or 159 mm Hg.
206
What is Henry's law?
When a gas is in contact with a liquid, the gas will dissolve in the liquid in proportion to its partial pressure.
207
What is the clinical application of Henry's law?
Hyperbaric oxygen chambers are used to force greater-than-normal amounts of O2 into the blood of patients suffering from carbon monoxide poisoning.
208
What happens to gas solubility in a liquid when the temperature rises?
Gas solubility decreases.
209
Why does nitrogen form bubbles in the blood of divers rising rapidly from the depths?
Dissolved nitrogen forms bubbles in their blood, causing 'the bends'.
210
What is the most soluble gas in water?
Carbon dioxide.
211
What is the solubility of oxygen in water compared to carbon dioxide?
Oxygen is only 1/20 as soluble as CO2.
212
What is the solubility of nitrogen in water compared to oxygen?
N2 is only half as soluble as O2.
213
What determines the amount of gas that will dissolve in a liquid?
The partial pressure of the gas in contact with the liquid, the solubility of the gas in the liquid, and the temperature of the liquid.
214
What is equilibrium in the respiratory membrane?
A PO2 of 104 mm Hg on both sides of the respiratory membrane.
215
How long does it take for equilibrium to occur in the respiratory membrane?
0.25 seconds.
216
What is the composition of alveolar gas?
It contains more CO2 and water vapor and much less O2.
217
What are the factors that cause the differences in the composition of alveolar gas and atmospheric gas?
Gas exchanges occurring in the lungs, humidification of air by conducting passages, and mixing of alveolar gas that occurs with each breath.
218
How can the alveolar partial pressures of O2 and CO2 be changed?
By increasing breathing depth and rate.
219
What is external respiration?
It is the pulmonary gas exchange where dark red blood flowing through the pulmonary circuit is transformed into the scarlet river that is returned to the heart for distribution by systemic arteries to all body tissues.
220
What causes the color change of blood during external respiration?
O2 uptake and binding to hemoglobin in red blood cells (RBCs), but CO2 exchange (unloading) is occurring equally fast.
221
What are the three factors that influence external respiration?
Partial pressure gradients and gas solubilities, thickness and surface area of the respiratory membrane, and ventilation-perfusion coupling (matching alveolar ventilation with pulmonary blood perfusion).
222
What drives the diffusion of O2 and CO2 across the respiratory membrane?
Partial pressure gradients of O2 and CO2.
223
What is the steep gradient for the partial pressure of oxygen across the respiratory membrane?
The PO2 of deoxygenated blood in the pulmonary arteries is only 40 mm Hg, as opposed to a PO2 of approximately 104 mm Hg in the alveoli.
224
Explain why equal amounts of CO2 and O2 are exchanged in the respiratory system.
CO2 is 20 times more soluble in plasma and alveolar fluid than O2.
225
What is the thickness of the respiratory membrane in healthy lungs?
0.5 to 1 μm.
226
What is the surface area of the alveoli in an adult male's lungs?
Approximately 90 m2, which is 40 times greater than the surface area of his skin.
227
What is ventilation-perfusion coupling?
It is the close match between ventilation and perfusion for optimal gas exchange, controlled by local autoregulatory mechanisms.
228
How does PO2 control perfusion in the respiratory system?
By changing arteriolar diameter.
229
How does PCO2 control ventilation in the respiratory system?
By changing bronchiolar diameter.
230
What happens to the respiratory membrane when the lungs become waterlogged and edematous?
The effective thickness of the respiratory membrane increases dramatically, leading to inadequate gas exchange and oxygen deprivation in body tissues.
231
What happens to the alveolar surface area in emphysema?
The walls of adjacent alveoli break down and the alveolar chambers enlarge, reducing the alveolar surface area.
232
What can reduce the alveolar surface area in the respiratory system?
Tumors, mucus, or inflammatory material can block gas flow into the alveoli, reducing the alveolar surface area.
233
What is internal respiration?
Capillary gas exchange in body tissues.
234
What are the factors that prevent complete balance of ventilation and perfusion in every alveolus?
Regional variations in blood and air flow due to gravity, and occasional alveolar duct plugged with mucus.
235
What is the reason for the slight drop in PO2 from alveolar air to pulmonary venous blood?
Blood shunted from the bronchial veins.
236
What is the PO2 in systemic arterial blood and in tissues?
100 mm Hg and 40 mm Hg, respectively.
237
What happens to O2 and CO2 during internal respiration?
O2 moves from blood into tissues, while CO2 moves from tissues into blood.
238
What is the PO2 and PCO2 of venous blood draining the tissue capillary beds and returning to the heart?
40 mm Hg and 45 mm Hg, respectively.
239
What happens to terminal arterioles when local PO2 is low?
They constrict, redirecting blood to respiratory areas where PO2 is high and oxygen pickup is more efficient.
240
What happens to pulmonary arterioles in alveoli where ventilation is maximal?
They dilate, and blood flow into the associated pulmonary capillaries increases.
241
What happens to bronchioles servicing areas where alveolar CO2 levels are high?
They dilate, allowing CO2 to be eliminated from the body more rapidly.
242
How does the changing diameter of local bronchioles and arterioles synchronize alveolar ventilation and pulmonary perfusion?
Poor alveolar ventilation results in low oxygen and high carbon dioxide levels in the alveoli, causing pulmonary arterioles to constrict and airways to dilate, bringing blood flow and air flow into closer physiological match. High PO2 and low PCO2 in the alveoli cause bronchioles serving the alveoli to constrict, and promote flushing of blood into the pulmonary capillaries.
243
What is ventilation-perfusion coupling?
Autoregulatory events resulting in local matching of blood flow (perfusion) through the pulmonary capillaries with the amount of alveolar ventilation.
244
Explain how hemoglobin carries oxygen in blood.
Hemoglobin carries oxygen in blood in two ways: bound to hemoglobin within red blood cells and dissolved in plasma. Only about 1.5% of the oxygen transported is carried in the dissolved form. Hemoglobin carries 98.5% of the oxygen in a loose chemical combination.
245
What is oxyhemoglobin?
The hemoglobin-oxygen combination is called oxyhemoglobin.
246
What is reduced hemoglobin?
Hemoglobin that has released oxygen is called reduced hemoglobin, or deoxyhemoglobin.
247
What is the oxygen-hemoglobin dissociation curve?
The oxygen-hemoglobin dissociation curve shows how local PO2 controls oxygen loading and unloading from hemoglobin.
248
What is the normal oxygen content of arterial blood?
Under normal resting conditions (PO2 = 100 mm Hg), arterial blood hemoglobin is 98% saturated, and 100 ml of systemic arterial blood contains about 20 ml of O2. This oxygen content of arterial blood is written as 20 vol % (volume percent).
249
What is the oxygen content of venous blood?
As arterial blood flows through systemic capillaries, it releases about 5 ml of O2 per 100 ml of blood, yielding an Hb saturation of 75% and an O2 content of 15 vol % in venous blood.
250
What is the venous reserve?
Substantial amounts of O2 are normally still available in venous blood (the venous reserve), which can be used if needed.
251
What is the Oxygen-Hemoglobin Dissociation Curve?
It is a graph that shows the relationship between the partial pressure of oxygen (PO2) and the percent saturation of hemoglobin with oxygen.
252
What does the x-axis of the Oxygen-Hemoglobin Dissociation Curve represent?
The partial pressure of oxygen (PO2) in the fluid surrounding the hemoglobin.
253
What does the y-axis of the Oxygen-Hemoglobin Dissociation Curve represent?
The percent saturation of hemoglobin with oxygen.
254
What is the percent saturation of hemoglobin with oxygen in the tissues of other organs where PO2 is low (40 mm Hg)?
75%.
255
What is the percent saturation of hemoglobin with oxygen in the lungs where PO2 is high (100 mm Hg)?
98%.
256
What does the Oxygen-Hemoglobin Dissociation Curve help us understand?
How the properties of hemoglobin affect oxygen binding in the lungs and oxygen release in the tissues.
257
What is the shape of the Oxygen-Hemoglobin Dissociation Curve?
S-shaped.
258
What does the amount of oxygen bound to hemoglobin depend on?
The amount of oxygen available locally (partial pressure of oxygen).
259
How many oxygen molecules can each hemoglobin molecule bind to at 100% saturation?
4
260
What is the PO2 in the lungs at sea level?
100 mm Hg.
261
What is the percent O2 saturation of hemoglobin in the lungs at a PO2 of 100 mm Hg?
98%.
262
What is the PO2 in the lungs at high altitude?
80 mm Hg.
263
What is the percent O2 saturation of hemoglobin in the lungs at a PO2 of 80 mm Hg?
95%.
264
At what PO2 in resting tissues is Hb 75% saturated?
40 mm Hg.
265
What percent of O2 carried by Hb is released in resting tissues?
23%.
266
At what PO2 in metabolically active tissues is Hb only 40% saturated?
20 mm Hg.
267
What percent of O2 carried by Hb is unloaded for tissue use at a PO2 of 20 mm Hg in metabolically active tissues?
35%.
268
What happens to Hb saturation with large changes in PO2 at high PO2?
Only small changes in Hb saturation occur.
269
What happens to Hb saturation with large changes in PO2 at low PO2?
Large changes in Hb saturation occur.
270
What ensures that oxygen is delivered where it is most needed in the body?
Hb's properties.
271
At what PO2 is Hb 95% saturated?
883 mm Hg.
272
Explain why breathing deeply increases both the alveolar and arterial blood PO2 but causes very little increase in the O2 saturation of hemoglobin.
Because the arterial blood is already nearly completely saturated with oxygen, and deep breathing only increases the amount of oxygen dissolved in plasma, not the amount bound to hemoglobin.
273
What factors influence hemoglobin saturation at a given PO2?
Temperature, blood pH, PCO2, and the amount of BPG in the blood all influence hemoglobin saturation at a given PO2.
274
What is BPG, and how does it affect hemoglobin saturation?
BPG is 2,3-bisphosphoglycerate produced by red blood cells as they metabolize glucose. BPG binds reversibly with hemoglobin, and its levels rise when oxygen levels are chronically low. It influences hemoglobin saturation by modifying hemoglobin's three-dimensional structure, thereby changing its affinity for O2.
275
How do temperature, PCO2, H+, and BPG levels in blood affect hemoglobin's affinity for O2?
An increase in temperature, PCO2, H+, or BPG levels in blood lowers Hb's affinity for O2, enhancing oxygen unloading from the blood. Conversely, a decrease in any of these factors increases hemoglobin's affinity for oxygen, decreasing oxygen unloading.
276
What is the Bohr effect?
The Bohr effect is a phenomenon where declining blood pH (acidosis) and increasing PCO2 weaken the Hb-O2 bond, enhancing oxygen unloading where it is most needed.
277
What are the three forms in which blood transports CO2 from the tissue cells to the lungs?
Dissolved in plasma (7-10%), chemically bound to hemoglobin (just over 20%) as carbaminohemoglobin, and as bicarbonate ions in plasma (about 70%).
278
How does carbon dioxide transport in RBCs differ from oxyhemoglobin transport?
Carbon dioxide transport in RBCs does not compete with oxyhemoglobin transport because carbon dioxide binds directly to the amino acids of globin (not to the heme).
279
How does the Haldane effect influence carbon dioxide loading and unloading?
Deoxygenated hemoglobin combines more readily with carbon dioxide than does oxygenated hemoglobin, as a result of the Haldane effect.
280
What reactions convert carbon dioxide to bicarbonate ions for transport, and where do they mostly occur?
When dissolved CO2 diffuses into RBCs, it combines with water, forming carbonic acid (H2CO3). H2CO3 is unstable and dissociates into hydrogen ions and bicarbonate ions. The reactions mostly occur inside RBCs.
281
Which enzyme catalyzes the conversion of carbon dioxide and water to carbonic acid?
Carbonic anhydrase.
282
What is the Bohr effect?
The triggering of O2 release due to the binding of H+ and CO2 to Hb.
283
How does CO2 loading enhance O2 release?
By triggering the Bohr effect.
284
What is the pH of blood under resting conditions?
7.4.
285
What is the pH of blood as it passes through the tissues?
7.34.
286
What is the ion exchange process that occurs to counterbalance the outrush of HCO3- from RBCs?
The chloride shift.
287
What is the role of chloride ions in the chloride shift?
To move from the plasma into the RBCs.
288
What is the purpose of the chloride shift?
To maintain the electrochemical balance of the RBCs.
289
What is the function of HCO3- in the transport of CO2?
To move quickly from the RBCs into the plasma and carry CO2 to the lungs.
290
Define hypoxia.
Inadequate oxygen delivery to body tissues.
291
What causes cyanosis in fair-skinned people during hypoxia?
Hb saturation falling below 75%.
292
What is anemic hypoxia?
Poor O2 delivery due to too few RBCs or abnormal Hb.
293
What is ischemic hypoxia?
Impaired or blocked blood circulation.
294
What is histotoxic hypoxia?
Body cells are unable to use O2 even though adequate amounts are delivered.
295
What is hypoxemic hypoxia?
Reduced arterial PO2 due to disordered ventilation-perfusion coupling, pulmonary diseases, or breathing air containing scant amounts of O2.
296
What is carbon monoxide poisoning?
A unique type of hypoxemic hypoxia caused by CO outcompeting O2 for heme binding sites on Hb.
297
What is the Haldane effect?
The lower the PO2 and Hb saturation with O2, the more CO2 that blood can carry.
298
How does the bicarbonate buffer system help resist shifts in blood pH?
HCO3- generated in RBCs diffuses into plasma and acts as the alkaline reserve part of the blood's bicarbonate buffer system.
299
How can changes in respiratory rate or depth alter blood pH?
Slow, shallow breathing allows CO2 to accumulate in blood, increasing carbonic acid levels and lowering blood pH. Rapid, deep breathing flushes CO2 out of blood, reducing carbonic acid levels and increasing blood pH.
300
What is the Dorsal Respiratory Group (DRG)?
A cluster of neurons in the medulla oblongata that integrates input from peripheral stretch and chemoreceptors and communicates this information to the Ventral Respiratory Group (VRG).
301
What is the function of the Ventral Respiratory Group (VRG)?
It is a rhythm-generating and integrative center that contains groups of neurons that fire during inspiration and others that fire during expiration in a dance of mutual inhibition.
302
What is eupnea?
It is the normal respiratory rate and rhythm of 12-16 breaths per minute, with inspiratory phases lasting about 2 seconds followed by expiratory phases lasting about 3 seconds.
303
What is the role of the medulla in respiratory control?
The medulla sets the respiratory rhythm and contains clustered neurons in two areas, the VRG and DRG, that are critically important in respiration.
304
What happens during severe hypoxia?
VRG networks generate gasping, perhaps in a last-ditch effort to restore O2 to the brain.
305
What happens when a certain cluster of VRG neurons is completely suppressed?
Respiration stops, as by an overdose of morphine or alcohol.
306
What are the neural mechanisms involved in respiratory control?
Control of respiration primarily involves neurons in the reticular formation of the medulla and pons, with higher brain centers, chemoreceptors, and other reflexes all modifying the basic respiratory rhythms generated in the brain stem.
307
What are the two areas of the medulla oblongata that are critically important in respiration?
The Ventral Respiratory Group (VRG) and the Dorsal Respiratory Group (DRG).
308
What is the second hypothesis for normal respiratory rhythm?
Normal respiratory rhythm results from reciprocal inhibition of interconnected neuronal networks in the medulla.
309
How many sets of pacemaker neurons are there in the second hypothesis?
Two (or possibly three) sets.
310
What determines inspiratory depth?
How actively the respiratory centers stimulate the motor neurons serving the respiratory muscles.
311
What determines respiratory rate?
How long the inspiratory center is active or how quickly it is switched off.
312
What are the factors that influence breathing rate and depth?
Changing levels of CO2, O2, and H+.
313
What is the function of pontine respiratory centers?
To influence and modify the activity of medullary neurons.
314
What happens when lesions are made in the superior region of pontine respiratory centers?
Inspirations become very prolonged, a phenomenon called apneustic breathing.
315
What is the role of pontine respiratory centers during certain activities such as vocalization, sleep, and exercise?
To modify and fine-tune the breathing rhythms generated by the VRG of the medulla.
316
What is the hypothesis for the origin of the respiratory rhythm?
There are pacemaker neurons, which have intrinsic (automatic) rhythmicity like the pacemaker cells found in the heart.
317
What are the factors that influence brain stem respiratory centers?
Neural and chemical influences, including excitatory and inhibitory stimuli, peripheral and central chemoreceptors, receptors in muscles and joints, irritant receptors, stretch receptors in lungs, and other receptors and emotional stimuli acting through the hypothalamus.
318
What is hypercapnia?
A condition where PCO2 levels rise in the blood and CO2 accumulates in the brain.
319
What happens when CO2 accumulates in the brain?
It is hydrated to form carbonic acid, which dissociates, liberating H+ and causing a drop in pH.
320
What is the response of the central chemoreceptors to an increase in H+ concentration in the brain?
They become excited and increase the depth and rate of breathing.
321
What is the most potent and closely controlled chemical influencing respiration?
CO2.
322
Where are the central chemoreceptors located?
Throughout the brain stem, including the ventrolateral medulla.
323
Where are the peripheral chemoreceptors located?
In the aortic arch and carotid arteries.
324
What is the effect of abnormally low PCO2 levels on respiration?
It becomes inhibited and slow, and periods of apnea may occur.
325
Why is hyperventilation dangerous during swim meets?
Strenuous hyperventilation can lower PCO2 so much that a lag period occurs before PCO2 rebounds enough to stimulate respiration again, causing oxygen levels to fall well below 50 mm Hg and potentially causing the swimmer to black out and drown.
326
What are the symptoms of hyperventilation?
Tingling and involuntary muscle spasms (tetany) in the hands and face caused by blood Ca2+ levels falling as pH rises, and dizziness or fainting due to reduced brain perfusion caused by hypocapnia.
327
How can the symptoms of hyperventilation be averted?
By breathing into a paper bag, which allows carbon dioxide to be retained in the blood.
328
Name the most important stimulus for breathing in a healthy person.
The body's need to rid itself of CO2.
329
What is the effect of rising CO2 levels on respiration?
Rising CO2 levels are the most powerful respiratory stimulant. Low PCO2 levels depress respiration.
330
How does blood PO2 affect breathing?
Under normal conditions, blood PO2 affects breathing only indirectly by influencing peripheral chemoreceptor sensitivity to changes in PCO2. Low PO2 augments PCO2 effects, and high PO2 levels diminish the effectiveness of CO2 stimulation.
331
When does arterial PO2 become the major stimulus for respiration?
When arterial PO2 falls below 60 mm Hg.
332
How do higher brain centers influence respiration?
Strong emotions and pain send signals to the respiratory centers, modifying respiratory rate and depth. The hypothalamus mediates this response.
333
Where are the main oxygen sensors located?
In the carotid bodies located at the bifurcation of the common carotid arteries and in the aortic bodies in the aortic arch.
334
What is the effect of arterial pH changes on respiration?
Changes in arterial pH due to CO2 retention or metabolic factors act through the peripheral chemoreceptors. The resulting changes in ventilation in turn modify arterial PCO2 and pH. Arterial pH does not influence the central chemoreceptors directly.
335
What is the role of the peripheral chemoreceptor system in maintaining ventilation?
The peripheral chemoreceptor system can maintain ventilation even though the brain stem centers are depressed by hypoxia.
336
What is the effect of a drop in blood pH on respiration?
As arterial pH declines, respiratory system controls attempt to compensate and raise the pH by increasing respiratory rate and depth to eliminate CO2 (and carbonic acid) from the blood.
337
Define hyperpnea and hyperventilation.
Hyperpnea is increased ventilation in response to metabolic needs during exercise, while hyperventilation is excessive ventilation characterized by low PCO2 and alkalosis.
338
What is the most widely accepted explanation for the abrupt increase in ventilation that occurs as exercise begins?
The interaction of three neural factors: psychological stimuli, simultaneous cortical motor activation of skeletal muscles and respiratory centers, and excitatory input reaching respiratory centers from proprioceptors in moving muscles, tendons, and joints.
339
Why is inhaling pure O2 by mask useless for panting athletes?
Because the shortage of oxygen is in the muscles, not the lungs.
340
What is the range of altitude where differences in atmospheric pressure are not great enough to cause healthy people any problems?
Between sea level and approximately 2400 m.
341
What happens to breathing when the blood concentration of CO2 reaches critical levels?
The brain stem respiratory centers automatically reinitiate breathing.
342
What is the inflation reflex?
A reflex that occurs when the lungs are inflated, causing stretch receptors to signal the medullary respiratory centers via afferent fibers of the vagus nerves, sending inhibitory impulses that end inspiration and allow expiration to occur.
343
What is the Hering-Breuer reflex?
Another name for the inflation reflex, which is thought to be more a protective response to prevent the lungs from being stretched excessively than a normal regulatory mechanism.
344
What is the purpose of the pulmonary irritant reflexes?
To promote reflex constriction of air passages or stimulate a cough or sneeze in response to accumulated mucus, inhaled debris, or noxious fumes.
345
What is the effect of exercise on ventilation?
Ventilation can increase 10- to 20-fold during vigorous exercise, a response called hyperpnea.
346
What is the effect of high altitude on breathing?
At high altitude, where atmospheric pressure and PO2 are lower, breathing can be stopped or become difficult due to the lack of oxygen.
347
What is the cause of the rise in lactic acid levels during exercise?
Anaerobic respiration, not inadequate respiratory function.
348
What is the cause of allergic asthma?
Active inflammation of the airways controlled by a subset of T lymphocytes.
349
What triggers allergic asthma?
Allergens from dust mites, cockroaches, cats, dogs, and fungi.
350
What is the prevalence of asthma in North America?
About one in ten people.
351
What is the leading cause of cancer death in North America?
Lung cancer.
352
What is the primary cause of lung cancer?
Smoking.
353
What is the cure rate for lung cancer?
Notoriously low, with most people dying within one year of diagnosis.
354
What is emphysema?
A condition where the alveolar walls disintegrate, leading to hyperinflation and reduced ventilation efficiency.
355
What is chronic bronchitis?
A condition where inhaled irritants lead to chronic production of excessive mucus, obstructing airways and impairing lung ventilation and gas exchange.
356
What are the two clinical patterns associated with COPD?
Pink puffers and blue bloaters.
357
How is COPD treated?
With inhaled bronchodilators and corticosteroids, and oxygen use in severe cases.
358
What are the symptoms of asthma?
Episodes of coughing, dyspnea, wheezing, and chest tightness, accompanied by a sense of panic.
359
Is the obstruction in asthma reversible?
Yes, it is reversible.
360
Name two chronic illnesses that can result from disrupted sleep.
Hypertension and heart disease, stroke, and diabetes.
361
What is obstructive sleep apnea and how is it treated?
Obstructive sleep apnea is a disorder characterized by the temporary cessation of breathing during sleep. It is often treated using a continuous positive airway pressure (CPAP) device.
362
How does smoking lead to lung cancer?
Smoking paralyzes the cilia that clear mucus from the airways, allowing irritants and pathogens to accumulate. The cocktail of free radicals and other carcinogens in tobacco smoke eventually translates into lung cancer.
363
What are the three most common types of lung cancer?
Adenocarcinoma, squamous cell carcinoma, and small cell carcinoma.
364
What is central sleep apnea and how is it caused?
Central sleep apnea is caused by a reduced drive from the respiratory centers of the brain stem during sleep rather than by obstruction of the airway.
365
How does the respiratory system develop in embryos?
The upper respiratory structures appear first, followed by the epithelium of the lower respiratory organs. The lungs are filled with fluid during fetal life, and at birth, the respiratory passageways fill with air.
366
What is infant respiratory distress syndrome?
Infant respiratory distress syndrome is a condition resulting from inadequate surfactant production in premature infants.
367
What is the key to survival in lung cancer?
Early detection and complete removal of the diseased lung before metastasis.
368
What are the consequences of metastatic lung cancer?
Radiation therapy and chemotherapy are the only options, but these have low success rates.
369
What is the cause of obstructive sleep apnea?
Obstructive sleep apnea is caused by the collapse of the upper airway due to the relaxation of the muscles of the pharynx during sleep, which allows the soft tissues of the pharynx to sag and obstruct the airway.
370
Which age group has the highest respiratory rate?
Newborn infants.
371
What is the respiratory rate in adults?
Between 12 and 16 breaths per minute.
372
How much does VO2max decline per decade in inactive people beginning in their mid-20s?
About 9%.
373
What is the maximum amount of oxygen we can use during aerobic metabolism?
VO2max.
374
What is the most common lethal genetic disease in North America?
Cystic fibrosis.
375
What is the root cause of cystic fibrosis?
A faulty gene that codes for the CFTR protein.
376
What is the function of the CFTR protein?
To control Cl- flow in and out of cells.
377
What happens when CFTR lacks a critical amino acid?
It gets stuck in the endoplasmic reticulum, is marked for degradation, and never reaches the plasma membrane to perform its normal role.
378
What is the consequence of less Cl- secretion in cystic fibrosis?
Less water follows, resulting in the thick mucus typical of CF.
379
What is the conventional therapy for CF?
Mucus-dissolving drugs, 'clapping' the chest to loosen the thick mucus, and antibiotics to prevent infection.
380
What is the goal of CF research?
To restore normal salt and water movements.
381
What are some approaches to restore normal salt and water movements in CF patients?
Introducing normal CFTR genes into respiratory tract mucosa cells, prodding another channel protein to take over the duties of transporting Cl-, developing techniques to free the CFTR protein from the ER, and using hypertonic saline to osmotically move water.
382
What is the function of the respiratory system in relation to the integumentary system?
The respiratory system provides oxygen and disposes of carbon dioxide, while the skin protects respiratory system organs by forming surface barriers.
383
How does the skeletal system relate to the respiratory system?
The bones protect lungs and bronchi by enclosure, while the respiratory system provides oxygen and disposes of carbon dioxide.
384
What is the role of the muscular system in relation to the respiratory system?
The respiratory system provides oxygen needed for muscle activity and disposes of carbon dioxide. The activity of the diaphragm and intercostal muscles is essential for producing volume changes that lead to pulmonary ventilation, and regular exercise increases respiratory efficiency.
385
How does the nervous system relate to the respiratory system?
The respiratory system provides oxygen needed for normal neuronal activity and disposes of carbon dioxide. The medullary and pontine centers regulate respiratory rate and depth, while stretch receptors in lungs and chemoreceptors provide feedback.
386
What is the role of the endocrine system in relation to the respiratory system?
The respiratory system provides oxygen and disposes of carbon dioxide. Angiotensin converting enzyme in lungs converts angiotensin I to angiotensin II. Epinephrine dilates the bronchioles, testosterone promotes laryngeal enlargement in pubertal males, and glucocorticoids promote surfactant production.
387
How does the cardiovascular system relate to the respiratory system?
The respiratory system provides oxygen and disposes of carbon dioxide. Carbon dioxide present in blood as HCO3- and H2CO3 contributes to blood buffering. Blood is the transport medium for respiratory gases.
388
What is the role of the lymphatic system/immunity in relation to the respiratory system?
The respiratory system provides oxygen and disposes of carbon dioxide. Tonsils in pharynx house immune cells. The lymphatic system helps to maintain blood volume required for respiratory gas transport, while the immune system protects respiratory organs from bacteria, bacterial toxins, viruses, protozoa, fungi, and cancer.
389
How does the urinary system relate to the respiratory system?
The respiratory system provides oxygen and disposes of carbon dioxide to provide short-term pH homeostasis. The kidneys dispose of metabolic wastes of respiratory system organs (other than carbon dioxide) and maintain long-term pH homeostasis.
390
What is the function of the respiratory system in relation to the digestive system?
The respiratory system provides oxygen and disposes of carbon dioxide, while the digestive system provides nutrients needed by respiratory system organs.
391
What is the function of the respiratory system in relation to the reproductive system?
The respiratory system provides oxygen and disposes of carbon dioxide.
392
What are the effects of aging on the respiratory system?
Protective mechanisms become less effective, mucosal cilia are less active, and the number of glands in the nasal mucosa decreases, resulting in a dry nose and thick mucus production.
393
What is adult respiratory distress syndrome (ARDS)?
A dangerous lung condition that can develop after severe illness or injury to the body, where neutrophils leave the body’s capillaries in large numbers and then secrete chemicals that increase capillary permeability, causing the lungs to fill with fluid and the patient to suffocate.
394
What is aspiration?
Inhaling or drawing something into the lungs or respiratory passages, or withdrawing fluid by suction during surgery to keep an area free of blood or other body fluids.
395
What is bronchoscopy?
The use of a viewing tube inserted through the nose or mouth to examine the internal surface of the main bronchi in the lung, with forceps attached to the tip of the tube to remove trapped objects or take samples of mucus for examination.
396
What is pneumonia?
An infectious inflammation of the lungs, in which fluid accumulates in the alveoli, with most of the more than 50 varieties of pneumonia being viral or bacterial.
397
What is sudden infant death syndrome (SIDS)?
The unexpected death of an apparently healthy infant during sleep, commonly called crib death, believed to be a problem of immaturity of the respiratory control centers, with most cases occurring in infants placed in a prone position to sleep.
398
What is tracheotomy?
The surgical opening of the trachea, done to provide an alternate route for air to reach the lungs when more superior respiratory passageways are obstructed.
399
Define expiration.
Expiration is the process of air leaving the lungs, which is largely passive and occurs as the inspiratory muscles relax and the lungs recoil.
400
What causes gases to flow from the lungs during expiration?
Gases flow from the lungs during expiration when intrapulmonary pressure exceeds atmospheric pressure.
401
What is the greatest resistance to air flow in the respiratory system?
The midsize bronchi offer the greatest resistance to air flow in the respiratory system.
402
What is surfactant and what is its role in the respiratory system?
Surfactant is a substance that reduces the surface tension of alveolar fluid, preventing alveolar collapse and helping to keep the lungs inflated.
403
What is infant respiratory distress syndrome (IRDS)?
IRDS is a condition in premature infants where their lungs cannot stay inflated due to a lack of surfactant in their alveoli.
404
What are the four respiratory volumes and capacities?
The four respiratory volumes are tidal, inspiratory reserve, expiratory reserve, and residual. The four respiratory capacities are vital, functional residual, inspiratory, and total lung.
405
What is anatomical dead space?
Anatomical dead space is the air-filled volume of the conducting passageways, which is about 150 ml.
406
What is alveolar ventilation and why is it important?
Alveolar ventilation is the best index of ventilation efficiency because it accounts for anatomical dead space.
407
What is external respiration?
External respiration is the process of gas exchange that occurs in the lungs, where oxygen enters the pulmonary capillaries and carbon dioxide leaves the blood and enters the alveoli.
408
What is the larynx and what is its function?
The larynx, or voice box, contains the vocal folds and provides a patent airway. It also serves as a switching mechanism to route food and air into the proper channels.
409
What is the trachea and what is its function?
The trachea extends from the larynx to the main bronchi and reinforces the airway with C-shaped cartilage rings. Its mucosa is ciliated.
410
What are the respiratory structures in the respiratory zone?
The respiratory zone structures include respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, where gas exchange occurs across the respiratory membrane.
411
What is the function of the pleurae and pleural fluid?
The parietal pleura lines the thoracic wall and mediastinum, while the visceral pleura covers external lung surfaces. Pleural fluid reduces friction during breathing movements.
412
What is intrapulmonary pressure and intrapleural pressure?
Intrapulmonary pressure is the pressure within the alveoli, while intrapleural pressure is the pressure within the pleural cavity, which is normally negative relative to intrapulmonary pressures.
413
What is the process of inspiration and what muscles are involved?
Inspiration occurs when the diaphragm and external intercostal muscles contract, increasing the dimensions and volume of the thorax. As the intrapulmonary pressure drops, air rushes into the lungs until the intrapulmonary and atmospheric pressures are equalized.
414
Name two major respiratory disorders and their characteristics.
Chronic Obstructive Pulmonary Disease (COPD) is characterized by an irreversible decrease in the ability to force air out of the lungs. Emphysema is characterized by permanent enlargement and disintegration of alveoli, loss of lung elasticity, and active expiration. Chronic bronchitis is characterized by excessive mucus production in the lower respiratory passageways, which severely impairs ventilation and gas exchange.
415
What is asthma and what causes it?
Asthma is a reversible obstructive condition caused by an immune response that causes its victims to wheeze and gasp for air as their inflamed respiratory passages constrict. It is marked by acute episodes and symptom-free periods.
416
What is tuberculosis and how does it affect the body?
Tuberculosis is an infectious disease caused by an airborne bacterium that mainly affects the lungs. Although most infected individuals remain asymptomatic by walling off the bacteria in nodules (tubercles), symptoms appear when immunity is depressed. Some patients’ failure to complete drug therapy has produced multidrug-resistant TB strains.
417
What is sleep apnea and what causes it?
Sleep apnea is usually caused by obstruction of the pharynx during sleep.
418
How is oxygen transported in the blood?
Molecular oxygen is carried bound to hemoglobin in the red blood cells. The amount of oxygen bound to hemoglobin depends on the PO2 and PCO2 of blood, blood pH, the presence of BPG, and temperature. A small amount of oxygen gas is transported dissolved in plasma.
419
What are the three ways in which carbon dioxide is transported in the blood?
CO2 is transported in the blood dissolved in plasma, chemically bound to hemoglobin, and (primarily) as bicarbonate ions in plasma.
420
What is hypoxia and what are its symptoms?
Hypoxia occurs when inadequate amounts of oxygen are delivered to body tissues. When this occurs, the skin and mucosae may become cyanotic.
421
What are the factors that influence breathing rate and depth?
Important chemical factors modifying baseline respiratory rate and depth are arterial levels of CO2, H+, and O2. An increasing arterial PCO2 level (hypercapnia) is the most powerful respiratory stimulant. It acts (via formation of H+ in brain tissue) on central chemoreceptors to cause a reflexive increase in the rate and depth of breathing. Hypocapnia depresses respiration and results in decreased ventilation and, possibly, apnea. Arterial PO2 levels below 60 mm Hg strongly stimulate peripheral chemoreceptors. Decreased pH and a decline in blood PO2 act on peripheral chemoreceptors and enhance the response to CO2. Emotions, pain, body temperature changes, and other stressors can alter respiration by acting through hypothalamic centers. Respiration can also be controlled voluntarily for short periods. Dust, mucus, fumes, and pollutants initiate pulmonary irritant reflexes. The inflation (Hering-Breuer) reflex is a protective reflex initiated by extreme overinflation of the lungs it acts to terminate inspiration.
422
1. What is the cause of cystic fibrosis?
Abnormal CFTR protein that fails to form a chloride channel.
423
2. What is the result of thick mucus in cystic fibrosis?
Clogging of respiratory passages and inviting infection.
424
3. What are the age-related changes in the respiratory system?
Thorax becomes more rigid, lungs become less elastic, vital capacity declines, sleep apnea becomes more common, and respiratory system protective mechanisms are less effective.
425
4. How does the mucosa of the nasal cavity develop?
From the invagination of the ectodermal olfactory placodes.
426
5. What is the function of the pharynx and lower respiratory passageways?
To develop from an outpocketing of the endodermal foregut lining.
427
6. What forms the walls of the respiratory conduits and the lung stroma?
Mesoderm.
428
7. What happens when the phrenic nerves are cut?
Paralysis of the diaphragm.
429
8. Which of the following laryngeal cartilages is/are not paired?
Epiglottis.
430
9. What initiates the inflation reflex under ordinary circumstances?
Overinflation of the alveoli and bronchioles.
431
10. What provides the greatest surface area for gas exchange?
Alveolar sacs.
432
11. Which of the following statements are correct about mouth-to-mouth artificial respiration?
All of these.
433
12. What happens when a baby holds its breath?
Automatically starts to breathe again when the carbon dioxide levels in the blood reach a high enough value.
434
13. Which of the following would most likely result in cessation of breathing?
The pontine respiratory group.
435
14. How is the bulk of carbon dioxide carried?
As the ion HCO3- in the plasma after first entering the red blood cell.
436
15. How is it possible to change the pitch of our voice from high to low?
By changing the tension of the vocal cords.
437
16. What is the difference between minute ventilation and alveolar ventilation rate?
Minute ventilation is the total volume of air moved into and out of the respiratory system per minute, while alveolar ventilation rate is the volume of air that reaches the alveoli per minute. Alveolar ventilation rate provides a more accurate measure of ventilatory efficiency because it takes into account the dead space volume.
438
17. What is hyperventilation?
Hyperventilation is breathing that is deeper and more rapid than normal. It can lead to a decrease in carbon dioxide levels in the blood and cause respiratory alkalosis.
439
18. What are the age-related changes in respiratory function?
The thorax becomes more rigid, the lungs become less elastic, vital capacity declines, sleep apnea becomes more common, and respiratory system protective mechanisms are less effective.
440
19. Why did only one lung collapse in the case of pneumothorax?
Because each lung is surrounded by its own pleural cavity, and the pleural cavities are separate from each other. Therefore, a pneumothorax can occur in only one lung.
441
20. What is the route of air from the nares to an alveolus?
Air enters the nares, passes through the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and finally reaches the alveoli. The respiratory system can be divided into the conducting zone (nasal cavity to bronchioles) and the respiratory zone (respiratory bronchioles to alveoli).
