Chapter 22: Respiratory Flashcards
(193 cards)
1
Q
The respiratory system consists of what?
A
A system of tubes that delivers air to the lungs
2
Q
What two systems work together to deliver oxygen to the tissues and remove carbon dioxide?
A
Respiratory and cardiovascular
3
Q
What two systems collaborate to regulate the body’s acid–base balance?
A
Respiratory and urinary systems
4
Q
List the 8 main functions of respiration
A
1) Gas exchange
2) Communication
3) Olfaction
4) Acid-Base balance
5) Blood pressure regulation
6) Blood and lymph flow
7) Blood filtration
8) Expulsion of abdominal contents
5
Q
Describe the purposes of the first 4 functions of respiration: gas exchange, communication, olfaction, and acid-base balance
A
1) Gas exchange: O2 and CO2 exchanged between blood and air
2) Communication: speech and other vocalizations
3) Olfaction: sense of smell
4) Acid-Base balance: influences pH of body fluids by eliminating CO2
6
Q
Describe the purposes of the last 4 functions of respiration: blood pressure regulation, blood and lymph flow, blood filtration, and expulsion of abdominal contents
A
1) Blood pressure regulation: help make angiotensin II
2) Blood and lymph flow: breathing creates pressure gradients
3) Blood filtration: lungs filter small clots
4) Expulsion of abdominal contents: breath-holding assists in urination, defecation, and childbirth(Valsalva maneuver)
7
Q
List and describe 4 main zones of the respiratory system
A
1) Conducting zone of respiratory system: Nostrils through bronchioles
2) Respiratory zone: consists of alveoli and other gas exchange regions
3) Upper respiratory tract: in head and neck
4) Lower respiratory tract: organs of the thorax
8
Q
Describe the conducting zone of the respiratory system
A
-Includes those passages that serve only for airflow
-No gas exchange
-Nostrils through major bronchioles
9
Q
What are the 3 functions of the nose?
A
1) Warms, cleanses, and humidifies inhaled air
2) Detects odors
3) Serves as a resonating chamber that amplifies voice
10
Q
Where does the nose begin and end? What is the nose shaped by?
A
1) Nose extends from nostrils (nares) to posterior nasal apertures (choanae)
2) Shaped by bone and hyaline cartilage
11
Q
What divides the nasal cavity?
A
Nasal septum
12
Q
What are the features of the nasal cavity?
A
Superior, middle, and inferior nasal conchae, each with a meatus beneath it
13
Q
Define meatus and describe its purposes
A
-Defined as a narrow air passage beneath each concha of the nasal cavity
-Its narrowness and turbulence ensure that most air contacts mucous membranes
-Cleans, warms, and moistens the air
14
Q
What type of tissue lines most of the nasal cavity?
A
Respiratory epithelium; specifically ciliated pseudostratified columnar epithelium
15
Q
Describe mucous formation and movement in the nose
(what creates it and what propels it)
A
Goblet cells secrete mucus and cilia propel the mucus posteriorly toward pharynx; then swallowed
16
Q
What are the 3 regions of the pharynx?
A
1) Nasopharynx
2) Oropharynx
3) Laryngopharynx
17
Q
Describe the nasopharynx (what is it, what does it contain, and what does it do?)
A
1) Posterior to nasal apertures and above soft palate
2) Receives auditory tubes and contains the pharyngeal tonsil
3) Passes only air, lined with pseudostratified columnar epithelium
18
Q
Describe the oropharynx (where is it, what does it contain, and what does it do?)
A
1) The space between soft palate and epiglottis
2) Contains lingual and palatine tonsils
3) Passes air, food, and drink and is lined by stratified squamous epithelium
19
Q
Describe the laryngopharynx (where is it, what begins there, what does it do?)
A
1) From the epiglottis to cricoid cartilage
2) Esophagus begins at that point
3) Passes air, food, and drink and is lined by stratified squamous epithelium
20
Q
What region(s) of the pharynx passes only air and is lined by pseudostratified columnar epithelium?
A
Nasopharynx
21
Q
What region(s) of the pharynx pass air, food, and drink and are lined by stratified squamous ?
A
Oropharynx and laryngopharynx
22
Q
Muscles of the pharynx assist in what two functions?
A
Swallowing and speech
23
Q
Define the larynx (voice box) and its primary function
A
1) A cartilaginous chamber about 4 cm (1.5 in.) long
2) Its primary function is to keep food and drink out of the airway and sound production
24
Q
What are the two structures found in the larynx?
A
Epiglottis and vestibular folds of the larynx
25
Define the epiglottis
A flap of tissue that closes airway and directs food to esophagus behind it
26
What do the vestibular folds of the larynx do?
Play greater role in keeping food and drink out of the airway
27
How many cartilages make up the framework for the larynx?
9 (6 paired and 3 unpaired)
28
List and describe the 3 solitary and relatively large cartilages of the larynx
1) Epiglottic cartilage: spoon-shaped supportive plate in epiglottis; most superior one
2) Thyroid cartilage: largest, laryngeal prominence (Adam’s apple); shield-shaped
-Testosterone stimulates growth, larger in males
3) Cricoid cartilage: connects larynx to trachea, ring-like
29
List the 3 small pairs of cartilages found in the larynx
1) Arytenoid cartilages (2)
2) Corniculate cartilages (2)
3) Cuneiform cartilages (2)
30
Ligaments suspends larynx from the _____ and hold it together
hyoid
31
The interior wall of the larynx has two folds on each side; name them
1) Superior vestibular folds
2) Inferior vocal cords
32
Describe the superior vestibular folds
-Play no role in speech
-Close the larynx during swallowing
33
Describe the inferior vocal cords
-Produce sound when air passes between them
-Covered with stratified squamous epithelium
-Glottis: the vocal cords and the opening between them
34
Define glottis
the vocal cords and the opening between them
35
Describe sound production in the larynx (what causes it, what happens when cords are taut and slack?)
1) Air is forced between vocal cords, it vibrates them
-When cords are taut, high-pitched sounds
-When cords are slack, low-pitched sounds
36
Why do adult males have lower voices?
-Adult male vocal cords are usually longer and thicker
-Vibrate more slowly, which means lower-pitched sounds
37
What is loudness of a voice determined by?
The force of air passing between the vocal cords
38
Define and describe the trachea (what is it, where is it, what supports it?)
1) A rigid tube about 12 cm (4.5 in.) long and 2.5 cm (1 in.) in diameter
2) Anterior to esophagus
3) Supported by 16 to 20 C-shaped rings of hyaline (*) cartilage that prevent collapse
39
Describe why the C-shaped rings of the trachea are shaped the way they are
-The opening in the rings faces posteriorly toward esophagus
-This gap in the C allows room for the esophagus to expand as swallowed food passes by
40
What are the 3 layers of the trachea?
1) Mucosa
2) Middle tracheal layer (submucosa)
3) Adventitia
41
Describe the mucosa layer of the trachea
-Made of ciliated pseudostratified columnar epithelium
-Mucociliary escalator
42
What happens at the end of the trachea?
End of trachea forks into right and left main (primary) bronchi.
43
Define the base and apex of a lung
1) Base: broad concave portion resting on diaphragm
2) Apex: tip that projects just above the clavicle
44
Define the costal and mediastinal surfaces of the lungs
1) Costal surface: pressed against the ribcage
2) Mediastinal surface: faces medially toward the heart
45
Define the hilum and describe it (what surface is it on and what is it, and what does its general area make up?)
-A slit on the mediastinal surface through which the lung receives the main bronchus, blood vessels, lymphatics, and nerves
-These structures near the hilum constitute the root of the lung
46
Describe the shape of the right lung and list its lobes
1) Shorter than left lobe
2) Has three lobes: superior, middle, and inferior
-separated by horizontal and oblique fissure
47
Describe the shape of the left lung, name and describe its indentation, and list its lobes
1) Tall and narrow
2) Has an indentation called cardiac impression (cardiac notch is anterior portion of cardiac impression)
3) Has two lobes: superior and inferior
-separated by a single oblique fissure
48
List the order of airflow of the bronchial tree (8 steps)
1) Trachea
2) Primary (Main) Bronchi
3) Secondary (Lobar) Bronchi
4) Tertiary (Segmental) Bronchi
5) Bronchioles (smaller than 1 mm in diameter)
6) Terminal Bronchioles (end of conducting division)
7) Respiratory Bronchioles (start of respiratory division)
8) Alveolar ducts to Alveoli
49
Define the bronchial tree
A branching system of air tubes reaching from main bronchus to 65,000 terminal bronchioles
50
Describe the main (primary) bronchi and the differences between the right and left
-Main bronchi enter the lungs and are supported by C-shaped hyaline cartilage rings
-The right main bronchus slightly wider and more vertical than left
-Aspirated (inhaled) foreign objects are lodged in the right main bronchus more often than in the left
51
Describe the lobular (secondary) bronchi (what do they enter, what supports them, and how many right and left lobes?)
-They enter the lobes and are supported by cartilage plates
-Three right lobar (secondary) bronchi: superior, middle, and inferior
-Two left lobar bronchi: superior and inferior
52
Name the left and right secondary bronchi
-Three right lobar (secondary) bronchi: superior, middle, and inferior
-Two left lobar bronchi: superior and inferior
53
Describe the segmental (tertiary) bronchi (what do they enter and are supported by, how many are there on each side, and what's a feature of these bronchi?)
1) They enter segments and are supported by cartilage plates
2) 10 on right, 8 on left
3) Bronchopulmonary segment: functionally independent unit of the lung tissue
54
Define the bronchopulmonary segment
A functionally independent unit of the lung tissue associated with the segmental (tertiary) bronchi
55
Describe all bronchi in general (what are they lined with, what do they all have, and what regulates their airflow?)
-All bronchi are lined with ciliated pseudostratified columnar epithelium
-Have MALT (mucosa-associated lymphoid tissue)
-Have a large amount of elastic connective tissue that contributes to the recoil that expels air from lungs
-Smooth muscle layer regulates airflow
56
What does the pulmonary artery do? What does the bronchial artery do?
1) Pulmonary artery branches follow the bronchial tree on their way toward (*) the alveoli
2) Bronchial artery from aorta services bronchial tree with systemic blood
57
Describe bronchioles
-1 mm or less in diameter
-Each bronchiole enter a Pulmonary lobule
-No cartilage support
-Divides into 50 to 80 terminal bronchioles
58
Describe terminal bronchioles
-Final branches of conducting zone
-Have no mucous glands or goblet cells but still have cilia
-Each terminal bronchiole gives off two or more smaller respiratory bronchioles
59
Describe the respiratory bronchioles and what they end in
-Have alveoli budding from their walls
-Considered the beginning of the respiratory zone
-Divide into 2 to 10 alveolar ducts
-End in alveolar sacs
60
There are ___ ________ alveoli in each lung, providing about ____ m2 of surface for gas exchange
150 million; 70m2
61
What are the 3 types of alveoli cells?
1) Squamous (type I) alveolar cells
2) Great (type II) alveolar cells
3) Alveolar macrophages (dust cells)
62
Describe squamous (type 1) alveolar cells
-Thin cells that allow for rapid gas diffusion between alveolus and bloodstream
-Cover 95% of alveolus surface area
63
Describe great (type II) alveolar cells
-Round to cuboidal cells that cover the remaining 5% of alveolar surface
-Repair the alveolar epithelium when the squamous (type I) cells are damaged
-Secrete pulmonary surfactant
64
Describe alveolar macrophages (dust cells)
-Wander the lumens of alveoli and the connective tissue between them
-Keep alveoli free from debris by phagocytizing dust particles
-100 million dust cells die each day as they ride up the mucociliary escalator to be swallowed and digested
65
Each alveolus surrounded by a basket of capillaries is supplied by the ________ artery
pulmonary
66
Define the respiratory membrane of alveoli and list the 4 things it's made of
-A thin barrier between the alveolar air and blood.
-Consists of:
1) Squamous alveolar cells
2) Endothelial cells of blood capillary
3) Their shared basement membrane
4) Very thin film of moisture inside the alveolus
67
What is important to prevent in alveoli?
-Important to prevent fluid from accumulating in alveoli
-Gases diffuse too slowly through liquid to sufficiently aerate the blood
68
In what 3 ways does the body prevent excess fluid from building up in the alveoli?
1) Low capillary blood pressure (and overall low pulmonary circuit blood pressure) results in low filtration; prevents rupture of delicate respiratory membrane
2) Excess liquid easily reabsorbed by blood capillaries
3) Lungs have a more extensive lymphatic drainage than any other organ in the body
69
What are the two pleurae of the lungs called and where are they? What is the potential space between them called?
1) Visceral pleura: serous membrane that covers lungs
2) Parietal pleura: adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm
-Pleural cavity: potential space between pleurae
70
Describe the pleural cavity
It's a potential space between the pleurae; normally no room between the membranes, but contains a film of slippery pleural fluid
71
Name and describe the 3 functions of pleurae and pleural fluid
1) Reduce friction
2) Create pressure gradient
-Lower pressure than atmospheric pressure; allows the two layers to stick to each other (assists lung inflation)
3) Compartmentalization
-Prevents spread of infection from one organ to another
72
Define a respiratory cycle
One complete inspiration (inhaling) and expiration (exhaling)
73
What are the two main types of respiration?
Quiet respiration vs. Forced respiration
74
Flow of air in and out of lung depends on there being what?
A pressure difference between air within lungs and outside body
75
What do respiratory muscles do? (2 things)
1) Change lung volumes
2) Create differences in pressure
76
Name the prime mover and synergists of inhalation
1) Prime mover: Diaphragm
2) Synergists: External intercostals and scalenes
77
What muscle is responsible for approximately 66-75% of inhalation?
Diaphragm
78
What 5 muscles are involved in forced inhalation?
1) Erector spinae
2) Sternocleidomastoid
3) Pectoralis major
4) Pectoralis minor
5) Serratus anterior muscles
79
Describe normal quiet expiration
1) A passive process of the relaxation of muscles
2) Elastic recoil of lungs and thoracic cage
80
What are the two muscles involved in forced expiration?
Rectus abdominis and internal intercostals
81
Define the valsalva maneuver and give 4 examples of when your body does it
-Consists of taking a deep breath, holding it by closing the glottis, and then contracting the abdominal muscles to raise abdominal pressure and push organ contents out
-Exs: Childbirth, urination, defecation, vomiting
82
The respiratory network in of the brain is located where?
Medulla
83
What are the two parts of the respiratory network of the medulla?
1) Ventral respiratory group (VRG)
2) Dorsal respiratory group (DRG)
84
Describe the ventral respiratory group (VRG)
-A group in the medulla that sets basic respiratory rhythm of 12 breaths per min
-In quiet breathing (eupnea), inspiratory neurons fire for about 2 seconds then expiratory neurons fire for about 3 seconds allowing inspiratory muscles to relax
85
What two things does the dorsal respiratory group (DRG) do?
1) Part of the medulla that modifies the rate and depth of breathing
2) Receives influences from external sources
86
What part of the pons is a respiratory center of the brain?
Pontine respiratory group (PRG)
87
Describe the Pontine respiratory group (PRG); what organ is it in and what two things does it do
-Located in the pons
-Modifies rhythm of the VRG by outputs to both the VRG and DRG
-Adapts breathing to special circumstances such as sleep, exercise, vocalization, and emotional responses
88
Name the locations of central and peripheral chemoreceptors
1) Central chemoreceptors: located in medulla
2) Peripheral chemoreceptors: located in the carotid and aortic bodies
89
What are the two types of chemoreceptors of the respiratory system?
Central and peripheral
90
Describe central chemoreceptors (where are they and what do they do)
-Located in medulla
-Responds to changes in the pH of cerebrospinal fluid, which reflects the CO2 level in the blood
-Not sensitive to O2 levels
91
Describe peripheral chemoreceptors (where are they and what do they do?)
-Located in the carotid and aortic bodies
-Respond to the O2 and CO2 content and the pH of blood
92
Describe the issue with respiratory chemoreceptors in chronic acidosis
-Accommodation in chronic acidosis (high CO2 levels) means that chemoreceptors no longer respond
-So breathing is NOT stimulated by high CO2 or acidosis; breathing is only stimulated by low O2 levels
93
Describe stretch receptors
Inflation (Hering-Breuer) reflex prevents over-inflation
94
What do irritant receptors do?
Respond to smoke, dust, pollen, chemical fumes, cold air, and excess mucus
95
What do cortical influences (cerebral control) do?
Voluntary control over breathing (bypasses brainstem centers)
96
What is respiratory flow similar to? Give 2 reasons why
-Respiratory airflow is similar to blood flow because:
1) The flow of air directly proportional to the pressure difference between two points
2) The flow of air is inversely proportional to the resistance
97
What drives respiration?
Atmospheric pressure
98
What is the atmospheric pressure at sea level?
What are two ways to compare the pressure of something to atmospheric pressure?
-760 mm Hg at sea level, or 1 atmosphere (1 atm)
-“Positive” pressure and “negative” pressure are generally comparisons to atmospheric pressure
99
Define Boyle's law and apply it to lung pressure
-States that at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume
1) If the lung volume increases, their internal pressure (intrapulmonary pressure) falls
2) If the lung volume decreases, intrapulmonary pressure rises
100
1) If the pressure falls below atmospheric pressure, air moves ______ the lungs
2) If the pressure rises above atmospheric pressure, air moves _______ the lungs
1) If the pressure falls below atmospheric pressure, air moves into the lungs
2) If the pressure rises above atmospheric pressure, air moves out of the lungs
101
The unit for pressure used by respiratory physiologists is what?
cm H2O
102
Describe the cm H2O unit of pressure; what does it measure, is it more or less sensitive than mmHg, and how does it convert to mmHg?
1) This measures how far a column of water would be moved by a given pressure
2) This is more sensitive than mm Hg, since Hg (mercury) is a heavy liquid
3) 1 mm Hg is equal to about 1.4 cm H2O
103
What does inspiration require?
The two pleural membranes to stick together
104
What are the two reasons the pleural membranes of the lungs stick together?
1) Cohesion of water in the pleural cavity
2) Slightly negative Intrapleural pressure
105
Describe why the intrapleural pressure is slightly negative
1) Recoil of lung tissue and tissues of thoracic cage causes lungs and chest wall to be pulling in opposite directions
2) About −5 cm H_2 O of intrapleural pressure results
106
How far do the thoracic cage dimensions increase in quiet breathing? This increases its total volume by how much?
1) In quiet breathing, the dimensions of the thoracic cage increase only a few millimeters in each direction
2) Enough to increase its total volume by 500 mL; thus, 500 mL of air flows into the respiratory tract
107
Describe what happens during relaxed breathing (4 things)
1) Elastic recoil of thoracic cage compresses the lungs
2 )Volume of thoracic cavity decreases
3) Raises intrapulmonary pressure to about 1 cm H2O
4) Air flows down the pressure gradient and out of the lungs
108
How high does intrapulmonary pressure increase during forced breathing? What does this?
Accessory muscles raise intrapulmonary pressure as high as +40 cm H2O
109
List the two disorders of expiration
1) Pneumothorax
2) Atelectasis
110
Define and describe what happens during pneumothorax
-When the thoracic wall is punctured allowing air into pleural cavity
1) Lose negative intrapleural pressure
2) Lungs to recoil and collapse
111
Define atelectasis. What can it result from, and what happens during it?
-Defined as collapse of part or all of a lung
1) Can also result from an airway obstruction
2) Can’t re-inflate areas distal to the obstruction
112
Increasing resistance does what to airflow?
Decreases it
113
What are the two factors that influence airway resistance?
1) Bronchiole diameter
2) Pulmonary compliance
114
What two things control the diameter of the bronchioles?
Bronchodilation and bronchoconstriction
115
What two things control bronchodilation?
1) Epinephrine
2) Sympathetic stimulation
116
What can cause bronchoconstriction?
What happens when there's too much bronchoconstriction, and when does this happen?
1) Histamine, parasympathetic nerves, cold air, and chemical irritants lead to bronchoconstriction
2) Suffocation can occur from anaphylactic shock and asthma
117
Define pulmonary compliance
The ease with which the lungs or thoracic wall can expand
118
What two things reduce pulmonary compliance?
1) Degenerative lung diseases (TB, black lung disease) in which the lungs are stiffened by scar tissue
2) The surface tension of the water film inside alveoli
119
Describe how the surface tension of the water film inside alveoli can become disrupted (2 ways)
1) Surfactant disrupts hydrogen bonds between water molecules and thus reduces the surface tension
2) Infant respiratory distress syndrome (IRDS; premature babies lacking surfactant
120
What air is available for gas exchange? Does all inhaled air get there?
Only air that enters alveoli is available for gas exchange (not all inhaled air gets there)
121
Define anatomic dead space, and describe how it can be altered
-The conducting zone of the airway; relates to alveolar ventilation
-Can be altered somewhat by sympathetic and parasympathetic stimulation (sympathetic dilation increases dead space but allows greater flow)
122
In pulmonary diseases, some alveoli may be unable to exchange gases; what is it called when this happens?
Physiologic (total) dead space
123
Define physiologic (total) dead space
-The sum of anatomic dead space and any pathological alveolar dead space
-Occurs with disease
124
Define spirometer
A device that measures rate and depth of breathing, speed of expiration, and rate of oxygen consumption
125
What are the 4 respiratory volumes (know definitions from lab)
1) Tidal volume
2) Inspiratory reserve volume
3) Expiratory reserve volume
4) Residual volume
126
Define vital capacity
The total amount of air that can be inhaled and then exhaled with maximum effort
127
How is vital capacity calculated, and why does it matter?
1) VC = ERV + TV + IRV
2) It's an important measure of pulmonary health
128
Name 4 variations in respiratory rhythm
1) Eupnea
2) Apnea
3) Hyperventilation
4) Hypoventilation
129
Define eupnea and what it's characterized by (what's its tidal volume and respiratory rate?)
-Defined as relaxed, quiet breathing
-Characterized by tidal volume 500 mL and the respiratory rate of 12 to 15 bpm
130
Define apnea
Temporary cessation of breathing
131
Define hyperventilation and hypoventilation
1) Hyperventilation: increased pulmonary ventilation in excess of metabolic demand
2) Hypoventilation: reduced pulmonary ventilation leading to an increase in blood CO2
132
What are the 3 most common elements in air, and what percentages of air do they make up?
1) 78.6% nitrogen
2) 20.9% oxygen
3) 0.04% carbon dioxide
133
What are some less common things in air?
0% to 4% water vapor, depending on temperature and humidity, and minor gases argon, neon, helium, methane, and ozone
134
Define Dalton's Law
Total atmospheric pressure is the sum of the contributions of the individual gases
135
Define partial pressure
The separate contribution of each gas in a mixture
136
At sea level 1 atm of pressure = ______ mm Hg
760
137
Define alveolar gas exchange
The swapping of O2 and CO2 across the respiratory membrane
138
Describe alveolar gas exchange
1) Air in the alveolus is in contact with a film of water covering the alveolar epithelium
2) For oxygen to get into the blood (load) it must dissolve in this water, and pass through the respiratory membrane
3) For carbon dioxide to leave the blood (unload) it must pass the other way, and then diffuse out of the water film into the alveolar air
139
Gases diffuse down their own gradients until what?
The partial pressure of each gas in the air is equal to its partial pressure in water
140
Define Henry's Law
For a given temperature, the amount of gas that dissolves in water is determined by its solubility in water and its partial pressure in air
141
1) CO2 is ____ times more soluble than O2
2) ____ is practically insoluble in plasma
20; N2
142
What does PO2 normally equal in air and blood during oxygen exchange?
104 mm Hg in alveolar air versus 40 mm Hg in blood
143
What allows for rapid diffusion in oxygen exchange (between alveoli and blood) ?
Steep oxygen partial pressure gradient allows rapid diffusion
144
What does PCO2 normally equal in blood and air during carbon dioxide exchange?
46 mm Hg in blood versus 40 mm Hg in alveolar air
145
Describe the steepness of the gradient of carbon dioxide diffusion (between the alveoli and blood cells). Is carbon dioxide more or less soluble than oxygen?
The gradient is not as steep as oxygen, but CO2 is more soluble
146
Compare the amounts of oxygen and carbon dioxide exchanged between the alveoli and blood during carbon dioxide exchange
Equal amounts of O2 and CO2 are exchanged
147
What 4 things can affect the rate of gas exchange (between the blood and alveoli)?
1) Pressure gradient
2) Respiratory membrane surface area
3) Respiratory membrane thickness
4) Ventilation-perfusion coupling
148
Name 3 conditions of the membrane surface, and describe what they do to gas exchange
Emphysema, lung cancer, and tuberculosis decrease surface area for gas exchange
149
How thick is the respiratory membrane? What happens if it thickens?
-Only 0.5 micrometers thick
-Slows down diffusion if membrane thickens
150
How can the respiratory membranes thicken?
Pneumonia, pulmonary edema (left ventricular heart failure), etc.
151
Define ventilation–perfusion coupling
The ability to match air flow and blood flow to each other
152
How does ventilation–perfusion coupling relate to gas exchange?
Gas exchange requires both good ventilation of alveolus and good perfusion of the capillaries
153
What does ventilation-perfusion coupling require in gas exchange, and what two things allow this to happen?
-Gas exchange requires both good ventilation of alveolus and good perfusion of the capillaries
1) Pulmonary blood vessels change diameter depending on air flow to an area of the lungs
2) Bronchi change diameter depending on blood flow to an area of the lungs
154
When do pulmonary blood vessels constrict and dilate?
1) If an area is poorly ventilated, pulmonary vessels constrict
2) If an area is well ventilated, pulmonary vessels dilate
155
When do the bronchi constrict and dilate?
1) If an area is well perfused, bronchodilation occurs
2) If an area is poorly perfused, bronchoconstriction occurs
156
Bronchi dilation depends on the ________ aka _________ of an area, whereas pulmonary vessel dilation depends on the _______ aka ________ of an area.
Blood flow aka perfusion; air flow aka ventilation
157
What are the two ways in which oxygen is transported, and what percent of oxygen transport do they each make up?
1) 98.5% bound to hemoglobin
2) 1.5% dissolved in plasma
158
What is hemoglobin called when oxygen is bound to it? What is hemoglobin called without oxygen?
1) Oxyhemoglobin (HbO2): O2 bound to hemoglobin
2) Deoxyhemoglobin (HHb): hemoglobin with no O2
159
What are the three ways in which carbon dioxide is transported, and what percent of carbon dioxide transport do they each make up?
1) 90% is hydrated to form carbonic acid (dissociates into bicarbonate ions)
2) 5% is bound to proteins
3) 5% is dissolved as a gas in plasma
160
During gas exchange, where does the carbon dioxide come from, and what percent does each source make up? Why?
1) 70% of CO2 comes from carbonic acid
2) 23% comes from proteins
3) 7% comes straight from plasma
-Blood gives up the dissolved CO2 gas and CO2 from the carbamino compounds more easily than CO2 in bicarbonate
161
Describe the transport of CO2 as carbonic acid
-90% of CO_2 is hydrated to form carbonic acid
-CO2+H2O → H2 + CO3 → HCO3− + H+
-Then dissociates into bicarbonate and hydrogen ions
162
Describe the transport of carbon dioxide
1) 5% binds to protein part of hemoglobin (& plasma proteins)
2) Creates carbaminohemoglobin (HbCO2)
3) Carbon dioxide does not compete with oxygen ; they bind to different moieties on the hemoglobin molecule
163
Explain how carbon dioxide doesn't compete with oxygen for hemoglobin
They bind to different moieties on the hemoglobin molecule
164
Define systemic gas exchange
The unloading of O2 and loading of CO2 at the systemic capillaries
165
Describe the process of CO2 loading (systemic gas exchange) (4 steps)
1) CO2 diffuses into the blood
2) Carbonic anhydrase in RBC catalyzes the reaction of carbon dioxide and water into HCO3- and H+
3) H+ binds to hemoglobin (makes hemoglobin release O2)
4) HCO3− diffuses out of RBC into the plasma
-Causes chloride shift (exchanges HCO3− for Cl−)
166
List the reaction that takes place during CO2 loading (systemic gas exchange)
CO_2+H_2 O→H_2 CO_3→HCO_3^−+H^+
167
Define alveolar gas exchange
The loading of O2 and unloading of CO2
168
Describe the process of CO2 unloading (alveolar gas exchange) (5 steps)
1) As Hb loads O_2 its affinity for H^+ decreases, H^+ dissociates from Hb and binds with HCO_3^−
2) The exact opposite of the loading reaction happens
3) Reverse chloride shift: HCO3^− diffuses back into RBC in exchange for Cl^−, free CO2 that is generated diffuses into alveolus to be exhaled
169
What 3 factors adjust the rate of oxygen unloading to match need?
1) Ambient PO2
2) Ambient pH (Bohr effect)
3) Temperature
170
Describe how ambient PO2 affects the rate of oxygen unloading
Active tissue has a decreased PO2, therefore O2 is released from Hb
171
Describe how ambient pH (Bohr effect) affects the rate of oxygen unloading
Active tissue has increased CO2, which lowers pH of blood; therefore it promotes O2 unloading
172
Describe how temperature affects the rate of oxygen unloading
Active tissue has an increased temperature, therefore it promotes O2 unloading
173
1) Rate and depth of breathing adjust to maintain arterial blood levels of what 3 things? (list these in order of most to least significant)
2) What should these levels be?
1) pH: 7.35 to 7.45
2) PCO2: 40 mm Hg
3) PO2: 95 mm Hg
174
Brainstem respiratory centers receive input from what?
Central and peripheral chemoreceptors that monitor composition of CSF and blood
175
Most potent stimulus for breathing is ___, followed by ______, and least significant is _____
pH, CO2, O2
176
Pulmonary ventilation is adjusted to maintain what?
pH of the brain
177
What two things affect pulmonary ventilation? They each produce what percent of the change in respiration induced by pH shift?
1) Central chemoreceptors in medulla produce about 75% of the change in respiration induced by pH shift
2) Peripheral chemoreceptors produce 25% of the respiratory response to pH changes
178
Define acidosis and alkalosis. List each of their most common causes
1) Acidosis: blood pH lower than 7.35
-Hypercapnia
2) Alkalosis: blood pH higher than 7.45
-Hypocapnia
179
Define hypocapnia and hypercapnia (exact numbers)
1) Hypocapnia: PCO2 less than 37 mm Hg (normal 37 to 43 mm Hg); associated with alkalosis
2) Hypercapnia: PCO2 greater than 43 mm Hg; associated with acidosis
180
Define respiratory acidosis and respiratory alkalosis; what do they result from?
pH imbalances resulting from a mismatch between the rate of pulmonary ventilation and the rate of CO2 production
181
What can be a corrective homeostatic response to acidosis? Why does this work?
-Hyperventilation, because:
1) “Blowing off” CO2 faster than the body produces it
2) Pushes reaction to the left (i.e. produces are CO2 (expired) and H2O)
-This reduces H^+ (reduces acid), raises blood pH toward normal
182
What can be a corrective homeostatic response to alkalosis? Why does this work?
-Hypoventilation, because:
1) Allows CO2 to accumulate in body fluids faster than we exhale it
2) Shifts reaction to the right (i.e. creates HCO3^− + H^+)
-This raises the H^+ concentration, lowering pH to normal
183
PO2 usually has little effect on respiration, but when can it significantly stimulate ventilation (i.e .what is this disorder called)?
Chronic hypoxemia, PO2 less than 60 mm Hg, can significantly stimulate ventilation
184
Define chronic hypoxemia and describe when it can happen
-Defined as PO2 less than 60 mm Hg; can significantly stimulate ventilation
-Causes hypoxic drive: respiration driven more by low PO2 than by CO2 or pH
-Can be caused by emphysema, pneumonia
-High elevations after several days
185
Define hypoxic drive
Respiration driven more by low PO2 than by CO2 or pH
186
Define chronic obstructive pulmonary disease (COPD)
-Defined as a long-term obstruction of airflow and substantial reduction in pulmonary ventilation
187
Name two major COPDs, describe what causes them, and name other risk factors for them
1) Chronic bronchitis and emphysema
2) Almost always associated with smoking
3) Other risk factors include: air pollution, occupational exposure to airborne irritants, hereditary defects
188
Describe chronic bronchitis
-A severe, persistent inflammation of lower respiratory tract
-Excessive mucus produced; develop chronic cough
-Symptoms include hypoxemia and cyanosis
189
Describe emphysema (describe its causes, progression, and symptoms)
1) Alveolar walls break down reducing surface area
2) Lungs fibrotic and less elastic
3) Air passages collapse (obstructs outflow of air)
-Air trapped in lungs; person becomes barrel-chested
4) Weaken thoracic muscles
-Spend three to four times the amount of energy just to breathe
190
What aspect of breathing does COPDs reduce?
Vital capacity
191
What do COPDs cause?
-Hypoxemia, hypercapnia, and respiratory acidosis
-Hypoxemia stimulates erythropoietin release from kidneys, and leads to polycythemia
192
Define Cor pulmonale
Hypertrophy and potential failure of right heart due to obstruction of pulmonary circulation
193
What accounts for more deaths than any other cancer, and what is its main cause?
-Lung cancer
-Most important cause is smoking (at least 60 carcinogens)
