BMS130 (Physio) - Respiration (Week 6)
external, internal
(external/internal) exchange is between blood and lungs while (external/internal) exchange is between tissue and blood
local bronchoconstriction: decreased CO2; local bronchodilation: increased CO2
(increased/decreased) CO2 concentration is associated with local bronchoconstriction, while (increased/decreased) CO2 concentration is associated with local bronchodilation
increased
(increased/decreased) intrapleural pressure may lead to a pneumothorax
increased
(increased/decreased) size of the thoracic cavity correlates with decreased pressure in the lung
expiration
(inspiration/expiration) is usually a passive process during rest
males
(males/females) usually have larger lung capacity than the opposite sex
CO2 that enters the alveoli from the blood is derived from what two processes?
1. CO2 dissociates from HbCO2 in the cell 2. CO2 and water produced from carbonic acid via carbonic anhydrase
what are the two effects of DRG inspiratory neurons following signals from respiratory related mechanoreceptors and chemoreceptors via the ninth and tenth cranial nerves?
1. control the contraction of the diaphragm via the phrenic motor neurons 2. also inhibit expiratory neurons in the VRG and PRG, allowing inspiration to start
in systemic circulation, what are the 4 different fates of CO2 after it crosses the capillary wall from tissue into blood?
1. remains dissolved and travels in the blood (does not enter RBC) 2. CO2 enters RBC and remains dissolved in the ICF 3. CO2 reacts with H2O in the presence of carbonic anhydrase (ca) to form carbonic acid 4. CO2 reacts with Hb to form HbCO2 (carbaminohemoglobin)
PCO2 dependent activity of carotid body chemoreceptors is resposnible for what % of the hypercapnic ventilatory response? what is hypercapnia?
15-20%, hypercapnia: excess CO2 in arterial blood
how long is the delay between between increase in systemic PCO2 and increase activity in the central chemoreceptors?
90 seconds
what accounts for teh additional sensitivity of carotid body chemoreceptors, related to PCO2 dependent activity?
Because the sensitivity is to H+, H+ from other sources may also activate this receptor. For example, lactic acid from anaerobic respiration and ketone bodies from the metabolism of fatty acids.
what components of the CNS influence respiration?
CNS: hypothalamus and cerebral cortex
what is the Bohr effect?
Hb unloads O2 more readily with high H+ and CO2
what is the Haldane effect?
Hb without O2 binds H+ and CO2 with higher affinity
carotid body activity increases as PO2 (increases/decreases) or PCO2 (increases/decreases)
PO2 decreases, PCO2 increases
how does PO2 dependent activity of the carotid bodies change in response to low, normal, and high PO2? how does PCO2 dependent activity of the carotid bodies change in response to high PCO2?
PO2 dependent activity: low PO2: sharp increase in activity normal PO2: low activity high PO2: no activity PCO2 dependent activity: high PCO2: high activity
directly
PO2 of blood is (inversely/directly) proportional to % Hb saturation
high to low
air flow is always from areas of (high/low) pressure to (high/low) pressure
decreases
alveolar surface tension (increases, decreases) lung compliance
more
an increased PO2 is indicative of (more/less) dissolved O2
the (carotid/aortic) bodies have insignificant influence on breathing in humans
aortic
Apnea vs respiratory arrest
apnea: transient cessation of breathing respiratory arrest: permanent cessation of breathing
760 mmHg; atmospheric pressure decreases as elevation increases
at sea level, what is atmospheric pressure? how does this change as we increase elevation?
cyanosis
blueness of the skin resulting from insufficiently oxygenated blood in the arteries
CO2 reacts with H2O in the presence of carbonic anhydrase (ca) to form what product? what does this product dissociate into? what happens to the products of the dissociation?
carbonic acid; dissociates into H+ which bind to Hb and HCO3- which leaves the RBC
what peripheral chemoreceptors affect respiratory control?
carotid bodies and aortic bodies
how is membrane potential maintained within an RBC as HCO3- leaves the cell?
chloride shift: Cl- enters the cell as HCO3- leaves, replacing the lost charges
diffusion coefficient of CO2 is 20x greater than that of O2, allowing it to offset the smaller partial pressure gradient for CO2
compare the diffusion coefficient of CO2 to that of O2. what does this offset?
low changes in pressure, high changes in volume
compliant lungs occur when (low/high) changes in pressure result in (low/high) changes in volume
what is the role of the cerebral cortex in respiration?
conscious control over breathing and respiratory rates within limits; allows us to hold our breath, hyperventilate, or hypoventilate if we choose
does the ventral respiratory group (VRG) contain inspiratory or expiratory neurons? what are the functions of these neurons?
contain both; inspiratory neurons: activate the external intercostal and accessory muscles expiratory neurons: activates expiratory muscles (abdominal and internal intercostal), inhibits inspiratory neurons during expiration
what is the pre-botzinger complex of the botzinger complex?
contains the putative pacemaker neurons for respiration
how does increased PRG activity lead to increased rate of breathing?
decreases inspiratory neuron (medulla) activity leading to shortened inspiration and earlier expiration
intraplueral pressure increases, since air is allowed to enter via damage to the visceral or parietal pleura; intrapleural pressure now equal to intra-alveolar pressure, before it was slightly less; the lungs are no longer pushing against a lower pressure, and the force from elastic recoil overcomes the intrapleural fluid cohesiveness
describe how pressure changes in the lungs lead to a pneumothorax, or collapsed lung.
O2 is poorly soluble in bodily fluids, so most of it is carried by Hb
describe the solubility of O2 in bodily fluids
4 protein subunits, each with 1 heme
describe the structure of Hb
no, each lung has their own pleural sac
does collapse of the right lung affect the other lung?
what is the role of carbonic anhydrase (ac) in pulmonary circulation?
drives the reverse reaction seen in systemic circulation, and CO2 is produced from carbonic acid
increased resistance, decreased air flow rate
during an asthma attack, airways constrict leading to (increased/decreased) resistance and (increased/decreased) air flow rate
radius: decreases resistance to airflow: increases
during bronchoconstriction, how do the radius of airways and resistance to airflow change?
radius: increases resistance to airflow: decreases
during bronchodilation, how do the radius of airways and resistance to airflow change?
eupnea: 3% total energy exercise: 5% total energy poorly compliant lungs/obstructive lung disease: up to 30%
during eupnea, what % of our total energy is used for ventilation? how about during excercise? how about for poorly compliant lungs, or those with obstructive lung disease?
decreases
during heavy exercise, the time blood spends in the capillaries (increases/decreases)
deep, slow breathing: TV = 1200 mL/breath respiratory rate = 5 breaths/min alveolar ventilation = 5250 mL/min shallow, rapid breathing: TV = 150 mL/breath respiratory rate = 40 breaths/min alveolar ventilation = 0 mL/min
during quiet breathing at rest, TV = 500 mL/breath, respiratory rate = 12 breaths/min, and alveolar ventilation = 4200 mL/min. how do these values change during during deep, slow breathing and shallow, rapid breathing?
it is more difficult to inflate alveoli that have completely collapsed (no air) compared to partially inflated alveoli
during quiet breathing at rest, we only really move 0.5 L (500 mL) of air in and out of our lungs. why don't we want to expire all the air in our lungs?
inspiration: 2700 mL expiration:b 2200 mL
during quiet breathing, how much air (mL) is in the lungs following inspiration and expiration?
1 mmHg
during quite breathing, what pressure gradient is sufficient to move air into/out of the lungs?
the vocal folds come together, closing the glottis
during swallowing, how does the larynx change?
increased partial pressure gradient: increased rate of transfer increased SA: increased rate of transfer increased thickness: decreased rate of transfer increased diffusion coefficient: increased rate of transfer
each of the following factors is increased. how does each of them influence the rate of gas transfer across the alveolar membrane: partial pressure gradient SA of alveolar-capillary membrane thickness of the alveolar-capillary membrane diffusion coefficient
describe eupnea, dyspnea, and apnea
eupnea: normal breathing dyspnea: difficult or labored breathing, shortness of breath apnea: transient cessation of breathing
does the Botzinger complex contain inspiratory or expiratory neurons? what are the functions of these neurons?
expiratory neurons; inhibit the inspiratory neurons of the DRG and VRG
external: exchange between blood and lungs internal: exchange between tissue and blood
external vs internal respiration
carotid body chemoreceptors provide a much (faster/slower) response to increased PCO2 than central chemoreceptors
faster
alveoli
gas exchange between the lungs and the blood only occurs at the ""
what is the function of the neurons in the Pre-botzinger complex?
generate spontaneous action potential (no stimulus required) and are thought to be the pacemaker neurons for breathing
what is the role of the hypothalamus in respiration?
has control over other physiological processes which may affect breathing, such as body temperature and emotions; synthesizes releasing hormones, which can lead to the increase thyroid hormone and progesterone from other endocrine glands to increase respiratory rate
effect of high PCO2 on the peripheral and central chemoreceptors, and the direct effect on the medullary respiratory center
high PCO2 activates peripheral chemoreceptors and central chemoreceptors which stimulates ventilation and the elimination of CO2 gas. PCO2 higher than 50 mmHg (or PO2 lower than 60 mmHg) will inhibit the medullary respiratory center and cause respiratory failure
what activates PCO2 dependent activity of carotid body chemoreceptors?
high PCO2, detected by increases in H+ not CO2
type II pneumocytes can divide to create more type II pneumocytes or differentiate into type I pneumocytes
how are new type I and type II pneumocytes created in alveoli?
by removing excess air in the pleural cavity, decreasing the intrapleural pressure and allowing lungs to inflate
how can a pneumothorax be fixed?
adding the TV and IRV
how can inspiratory capacity (IC) be calculated?
require more energy/effort to stretch
how do noncompliant lungs differ from compliant lungs?
increase intrapleural pressure
how do penetrating injuries, lung disease, or medical procedures that allow air to enter the pleural cavity effect intrapleural pressure?
pulmonary arterioles: go to alveoli to get O2 - low O2: vasoconstriction since the alveoli don't have O2 to extract - high O2: vasodilation since need to get to the alveoli to extract the O2 systemic arterioles: go to tissues to drop off O2 -low O2: vasodilation, bc need to get O2 to the tissues since they don't have any -high O2: vasoconstriction, bc tissues have enough O2 and don't need more
how do pulmonary and systemic arterioles differ in their response to low O2 and high O2 conditions?
(1) diaphragm: contracts downwards (2) external intercostals: cause the ribs to elevate and the sternum to move up and out
how do the inspiratory muscles increase the size of the thoracic cavity during inspiration, creating an area of lower pressure in the lungs?
ventilation
how do the lungs allow for water loss and heat elimination?
unstretched: smaller than the thoracic cavity; stretched: fills the thoracic cavity
how do the lungs relate to the thoracic cavity when unstretched and stretched?
PO2: high in lungs, low in tissues; PCO2: low in lungs, high in tissues
how does PO2 differ in the lungs vs tissues? how about PCO2?
alveolar ventilation: volume of air exchanged between the atmosphere and alveoli per min, 4.2 L/min pulmonary ventilation: volume of air exchanged between lungs and the atmosphere per min, 6.0 L/min
how does alveolar ventilation differ from pulmonary ventilation?
passive diffusion down partial pressure gradients; never active transport
how does gas exchange of O2 and CO2 occur at the pulmonary and tissue capillaries?
all are signs of increased metabolic acitivty in tissues, and decrease O2 affinity of Hb
how does increased tempeature, BPG, acidity (decreasing pH) and PCO2 affect O2 affinity of Hb?
increased temperature = decreased O2 affinity; temperature increases as our tissues increase their metabolic activity, so it makes sense that we want decreased O2 affinity so Hb can drop O2 off to them
how does increased temperature affect the O2 affinity of Hb? what is the reasoning behind this?
increases during exercise, decreases under pathological conditions
how does the SA of the alveolar capillary membrane change during exercise and under pathological conditions
passage of air through the glottis cause the vocal folds to vibrate
how does the larynx allow for the creation of sound?
nitrogen: decreases oxygen: decreases carbon dioxide: increases water: increases
how does the partial pressure of the following gases change as it moves from the atmosphere (dry air) into the alveoli (wet air)? nitrogen oxygen carbon dioxide water
(1) faster rate of air leaving the lungs (2) more air leaving the lungs
how does the rate and amount of air leaving the lungs change during active/forced expiration?
(1) opposes the expansion of the alveolus (2) reduces alveolus size
how does the thin liquid film lining each alveolus lead to alveolar surface tension?
top of the lungs: more ventilation than perfusion bottom of the lungs: less ventilation than perfusion
how does ventilation-perfusion ratio differ between the top of the lung and the bottom of the lungs?
diffusion reserve: allows more gas exchange to take place if required, such as during heavy exercise; created because complete gas exchange occurs within 1/3 the length of the capillary, so the remaining 2/3 is a reserve
how is a diffusion reserve created within capillaries and what is its function?
the inspiratory muscles relax, decreasing the volume of the thoracic cavity and leading to increased pressure in the lungs
how is air forced out of the lung during passive expiration?
compliance = Δpressure/Δvolume; (1) alveolar surface tension (2) abundance of elastin fibers
how is elasticity of a lung calculated and what two factors is it dependent on?
by increasing the size of the thoracic cavity
how is pressure in the lungs decreased during inspiration?
by raising or lowering of the larynx and the stretching of vocal folds
how is the pitch of someone's voice controlled?
0.75 seconds
how long does it take blood to travel through pulmonary capillary beds at rest?
4
how many O2 molecules can a single Hb molecule carry?
hypercapnia vs hypocapnia
hypercapnia: excess CO2 in the arterial blood hypocapnia: below normal CO2 in the arterial blood
hyperventilation vs hypoventilation
hyperventilation: increased ventilation, decreased CO2 in the blood, increase in blood pH hypoventilation: decreased ventilation, increase CO2 in the blood, decrease in blood pH
what activates the PO2 dependent activity of carotid body chemoreceptors?
hypoxemia (a low level of oxygen in the blood), not in response to anemia or increased CO bc O2 levels may still be high in these conditions
pulmonary capillaries: 100 mmHg, 96-99% Hb saturation; systemic capillaries: 40 mmHg, 75% Hb saturation
in a healthy individual at sea level, what is the normal PO2 at the pulmonary and systemic capillaries? what is the normal % Hb saturation?
alveolar dead space: approaches 0; physiological dead space: equal to the anatomic dead space (since physiological dead space = alveolar dead space + anatomic dead space)
in a healthy individual, what are the values for the alveolar dead space and therefore the physiological dead space?
low
in a healthy person resistance of airways (R) is (high/low)
30 mmHg
in normal individuals at sea level, what is P50?
lower, because air moves from high to low pressure
in order to bring air into the lungs during inspiration, the air pressure in the lungs must be (higher/lower) than that of the atmosphere
(1) production of mucus (2) immune system component including antibodies and macrophages
in what 2 ways do the lungs defend against foreign matter?
alveoli; thin walled and highly vascularized
in what structure of the respiratory system does gas exchange occur? what about this structure allows for this?
IRV decreases, ERV decreases
increasing the TV means that the IRV will (increase/decrease) and the ERV will (increase/decrease)
what does the pontine respiratory group (PRG) recieve input from and what is its function?
input from expiratory neurons found in the medial parabrachial nucleus and inspiratory neurons found in the lateral parabrachial nucleus and Kolliker-Fuse nucleus; influences the then influences the activity in the medullary respiratory center which is the primary respiratory control center and contains neurons that directly stimulate respiratory skeletal muscles
does the dorsal respiratory group (DRG) contain inspiratory or expiratory neurons? what do these neurons receive information from and what do they control?
inspiratory neurons that receive afferent information from respiratory related mechanoreceptors and chemoreceptors via the ninth and tenth cranial nerves; function: control the contraction of the diaphragm via the phrenic motor neurons and inhibit expiratory neurons int he VRG and PRG, allowing inspiration to start
what is hypoxia?
insufficient O2 at the cellular level
no, the volume of the intrapleural fluid is constant which is essential for breathing
is intrapleural fluid able to freely leave/enter the pleural cavity? how is this important?
a: tidal volume (TV) b: inspiratory reserve volume (IRV) c: expiratory reserve volume (ERV) d: vital capacity (VC) e: residual volume (RV) f: total lung capacity (TLC)
label all parts of this spirometer
describe the relationship between PCO2 and the central chemoreceptor activity
linear, increasing CO2 aligns with increasing central chemoreceptor activity
where are carotid bodies located and what innervates them?
located in the bifurcation of the common carotid artery; innervated by the carotid sinus nerve (a branch of the glossopharyngeal nerve, CNIX)
(1) pressure gradient is the primary factor in determining air flow rate (R) (2) small changes in pressure gradient are enough to move air in and out of the lungs
low resistance of airways, as seen in healthy people, allow for what 2 things related to air flow?
(1) diaphragm (2) external intercostals (3) accessory inspiratory muscles (sternocleidomastoid and scalenus)
maximum contraction of which muscles is required to reach the full IRV?
what parts of the brain primarily controls breathing?
medulla and pons
are central chemoreceptors sensitive to changes in H+ produced from other physiological processes? why or why not?
no, H+ cannot cross the BBB so central chemoreceptors are activated by H+ in the CSF that arise due to high concentrations of CO2
oxyhemoglobin: hemoglobin w/ O2 deoxyhemoglobin: hemoglobin w/out O2
oxyhemoglobin vs deoxyhemoglobin
bronchoconstriction, bronchodilation
parasympathetic stimulation leads to (bronchoconstriction/bronchodilation) while sympathetic stimulation leads to (bronchoconstriction/bronchodilation)
parasympathetic stimulation vs sympathetic stimulation on airflow
parasympathetic: bronchoconstriction, low demand for air sympathetic: bronchodilation, high demand for air
bottom
perfusion and ventilation are both greater at the (top/bottom) of the lung
lungs and atmosphere
pulmonary ventilation includes exchange between what two things?
chloride shift in pulmonary vs systemic gas exchange
pulmonary: Cl- leaves the cell as HCO3- enters; systemic: Cl- enters the cell as HCO3- leaves;
eupnea
quite breathing at rest is referred to as
what influences the activity of the 3 major groups of respiratory neurons in the medullary respiratory center?
stimulation from the PRG
suffocation vs asphyxia
suffocation: 02 deprivation as a result of an inability to breath oxygenated air asphyxia: O2 deprivation of tissues caused by a lack of O2 in the air, respiratory impairment, or inability of the tissue to use O2
true
t/f: Hb bound O2 does not contribute to the PO2 of blood
true
t/f: lung capacity refers to the volume of air in all components of the respiratory system, including the alveoli, bronchi, and trachea
true
t/f: sound created by vibrations of vocal folds can be modified by the tongue, palate, and lips
true
t/f: the partial inflatedness of the lungs helps increase compliance
does not
the IRV (does/does not) include the TV
expiration
the abdominal muscles and internal intercostal muscles are muscles of (inspiration/expiration)
inspiration
the diaphragm and external intercostal muscles are muscles of (inspiration/expiration)
80%, decreases
the forced expiratory volume in 1 second (FEV1) is usally what portion of the vital capacity (VC)? how does this portion change as we get older?
less
the intrapleural pressure fluctuates with changes in the intra-alveolar pressure, but is always slightly (more/less)
thoracic
the lungs are housed within the "" cavity
extract O2, eliminate CO2
the major function of the respiratory system is to extract (O2/CO2) and eliminate (O2/CO2)
elastic recoil
the mechanics of passive expiration is referred to as ""
what would happen to breathing in the absence of PRG stimulation?
the medullary centers would generate breathing as slow, rhythmic gasping pattern
nitrogen, oxygen, carbon dioxide, water
the partial pressures of what 4 gases sum to equal the atmospheric pressure?
transmural (transpulmonary) pressure gradient
the pressure difference between the interpulmonary (intra-alveolar) pressure and the intrapleural pressure is referred to as the ""
what is the medullary respiratory center? what are the 3 major groups of respiratory neurons contained within it?
the primary respiratory control center and contains neurons that directly stimulate respiratory skeletal muscles; 1. Botzinger complex 2. ventral respiratory group 3. dorsal respiratory group
ventilation (airflow) and perfusion (blood flow) in various regions of the lungs
the relationship between what 3 things is represented by this graph?
where are central chemoreceptors located? what surrounds them?
the ventral surface of the medulla, surrounded by the ECF of the brain (aka CSF)
pressure
to move gas, differences in "" must be created
t./f: the carotid body is sensitive to both PO2 and PCO2
true
t/f: the left and right lungs are house separately and act as a separate sac within a sac
true
type I; type II
type (I/II) pneumocytes of the alveoli are simple squamous epithelial cells; type (I/II) pneumocytes secrete surfactant and synthesize ACE
type I and type II cells of carotid bodies
type I: chemoreceptor cells type II: support function
(1) decrease in compliance (2) increase in airway resistance (3) decrease in elastic recoil (4) need to increase ventilation
under what 4 circumstances does energy expenditure for ventilation increase?
1.5% dissolved, 98.5% carried by Hb; only dissolved O2 is reflected in PO2 values
what % of O2 is dissolve din the blood? what % is carried by Hb? which of these is reflected in blood PO2?
high surface area and low diffusion distance (thin walls)
what 2 characteristics of alveoli optimize the rate of gas exchange?
(1) thin walled to increase the rate of diffusion (2) highly vascularized, allowing diffused gas to enter the blood
what 2 characteristics of the alveoli allow for sufficient amounts of gas exchange?
(1) type I pneumocytes: simple squamous epithelium, 95% (2) type II pneumocytes: secretion of surfactant and synthesis of ACE, 5%
what 2 types of cells compose alveolar walls? what are their functions and what % of alveoli do they compose?
1. temperature 2. 2,3-BPG 3. CO2 4. acidity (pH); despite these four factors, PO2 is still the main determinant of Hb saturation
what are 4 factors that affect the affinity of O2 to Hb? aside from these 4 factors, what is the main factor in determining the % Hb saturation?
1. partial pressure gradients of O2 and CO2 2. SA of the alveolar-capillary membrane 3. thickness of the alveolar-capillary membrane 4. diffusion coefficient
what are 4 major factors that influence the rate of gas transfer across the alveolar membrane?
(1) smell (2) acid-based balance (3) venous returns (4) vocalization (5) route for water loss and heat elimination (6) enzyme synthesis (7) defends against foreign matter
what are 7 functions of the lung, other than gas exchange?
thin walled capillaries made of a single layer of endothelial cells that form a continuous sheet around alveoli and maximize diffusion by providing constant blood flow that maintains a consistent concentration gradient
what are pulmonary capillaries and where are they found?
1. pulmonary ventilation: aka breathing, exchange between lungs and the atmosphere 2. external respiration: exchange between blood and lungs 3. internal respiration: exchange between tissue and blood 4. transport of respiratory gases: movement of O2 (from lungs to tissues) and CO2 (from tissues to lungs) via blood
what are the 4 processes of respiration? what are they?
sternocleidomastoid and scalenus muscle; only contract during forceful inspiration
what are the accessory muscles of inspiration? when do they contract?
males: 5700 mL females: 4200 mL
what are the average lung capacity values for males and females?
inspiration: diaphragm, external intercostal expiration: abdominal muscles, internal intercostal
what are the muscles of inspiration (2) and expiration (2)?
(1) lungs can expand more readily because pushing against a lower pressure (2) prevention of outwards expansion of the thoracic cavity because easier for atmospheric pressure to push the thoracic wall inwards, against a lower pressure
what are the two effects of the lower intrapleural pressure caused by the natural inward pull of the lungs and outward pull of the thoracic cavity?
created by a thin water-based film that lines each alveolus that opposes the expansion of the alveoli and reduces the size of the alveoli; important for elastic recoil
what creates alveolar surface tension? what property of the lung is this important for?
angiotensin-converting enzyme (ACE): converts angiotensin I to angiotensin II to regulate blood pressure
what enyzme is made in the lungs? what is the function of this enzyme?
(1) age (2) obstructions to the respiratory system, such observed in chronic obstructive pulmonary disease (COPD)
what factors may cause a decrease in the forced expiratory volume in 1 second (FEV1)?
epinephrine
what hormone causes bronchodilation?
the percent of oxygen-saturated hemoglobin relative to total hemoglobin in blood; >95%
what is a SPO2 measurement? what is this value for a normal individual?
collapse of the lungs, due to air being allowed to enter the pleural cavity and the intrapleural pressure equilibrating with atmospheric pressure and intra-alveolar pressure
what is a pneumothorax? what causes it?
ventilated alveoli that do not participate in gas exchange with blood; occurs due to the sphere shape of alveoli, making it so that only air near the surface of the alveoli is being exchanged and the volume of air in the middle isn't
what is alveolar dead space? what gives rise to this?
the volume of air exchanged between the atmosphere and the alveoli per minute; alveolar ventilation = (tidal volume - physiological dead space) x respiratory rate
what is alveolar ventilation? how is it calculated?
the total volume from the nose/mouth to the terminal bronchioles (conducting airways); the air here is not available for gas exchange
what is anatomic dead space?
an enzyme made in the lungs that converts angiotensin I to angiotensin II to regulate blood pressure
what is angiotensin-converting enzyme (ACE)? where is it made and what is its function?
intrapleural fluid
what is contained within the pleural cavity?
the mechanics of passive expiration
what is elastic recoil?
quiet breathing at rest, during which we move about 0.5 L (500 mL) in and out of the lungs
what is eupnea? how much air is moved in and out of the lungs during this?
vital capacity (VC): the maximum volume of air that can be moved out during a single breath
what is labeled by the asterisk? what is its definition?
blue arrow: visceral pleura red arrow: parietal pleura black line: pleural cavity w/ intrapleural fluid
what is labeled by the blue arrow, red arrow, and black #3?
expiratory reserve volume (ERV): the volume of air expired by maximum contraction of the expiratory muscles, beyond expiration at the end of the tidal volume (TV)
what is labeled by the letter c? what is its definition?
residual volume (RV): volume of air that remains in the respiratory system after maximum expiration, air that is trapped in the alveoli and air ways after the maximum ERV has been expired
what is labeled by the letter e? what is its definition?
total lung capacity (TLC): the maximum volume of air the respiratory system can hold; TLC = VC + RV ~5.7 L
what is labeled by the letter f? what is its definition and how is it calculated?
inspiratory capacity (IC): the maximum volume of air that can be inspired, calculated by adding the TV and IRV
what is labeled by the number 5? what is its definition?
functional residual capacity (FRC): the volume of air in the respiratory system at the end of normal passive expiration
what is labeled by the number 7? what is its definition?
the volume of air in the respiratory system, including the alveoli, bronchi, trachea, etc.
what is lung capacity?
compliance: the amount of effort required to stretch or distend the lungs compliance = Δvolume/Δpressure
what is lung compliance and how is it calculated?
compliance: the amount of effort required to stretch or distend the lungs; elastic recoil: how readily the lungs rebound after stretching
what is lung compliance? what is elastic recoil?
alveolar dead space + anatomic dead space
what is physiological dead space?
composition: mixture of lipids and proteins; mechanism: decreases cohesion between water molecules
what is pulmonary surfactant composed of and how does it function to reduce alveolar surface tension?
offers information about respiratory rates and expiration/inspiration durations
what is the clinical significance of a spirometer?
F = ΔP/R where.. F = air flow rate ΔP = pressure gradient R = resistance of airways
what is the equation for air flow rate (F)?
the volume of air expired during the first second of expiration in determining VC, usually 80% of VC; indicates the maximum airflow rate of the lungs
what is the forced expiratory volume in 1 second (FEV1)? what does it indicate?
reduce alveolar surface tension, allowing for greater lung compliance; without surfactants, inspiration would become more difficult
what is the function of pulmonary surfactants released by type II pneumocytes? what would happen in the absence of these surfactants?
functional residual capacity (FRC): the volume of air in the respiratory system at the end of normal passive expiration; FRC = ERV + RV
what is the functional residual capacity (FRC) and how is it calculated?
the pressure within the pleural sac; fluctuates with changes in the intra-alveolar pressure but is always slightly less
what is the intrapleural pressure and when does it fluctuate?
756 mmHg
what is the intrapleural pressure when the intra-alveolar pressure is 760 mmHg?
the partial pressure gradients of O2 and CO2
what is the major determinant of the rate of gas transfer across the alveolar membrane?
purpose: allows us to breath naturally generated by the inward pull of the lungs and visceral pleura and the outward pull of the thoracic wall and parietal pleura
what is the purpose of the intrapleural pressure and how it is naturally generated?
humidifies, warms, and filters ambient air before it reaches the lungs
what is the purpose of the nose/nasal cavity in the respiratory system?
the pressure difference between the interpulmonary (intra-alveolar) pressure and the intrapleural pressure; transmural pressure gradient = intrapulmonary - intrapleural
what is the transmural (transpulmonary) pressure gradient? how is calculated?
760 mmHg; the sum of the partial pressures of all gases
what is the value of atmospheric pressure at sea level and what composes it?
tidal volume (TV): the volume of air entering/leaving the respiratory system during a single breath at rest; a small portion of the lung's capacity that can fluctuate in correspondance to demand in oxygen
what is tidal volume (TV)? what causes it to fluctuate?
vital capacity (VC): the maximum volume of air that can be moved out during a single breath; VC = IRV + TV + ERV ~ 4.5 L
what is vital capacity (VC) and how is it calculated?
contraction of the abdominal and internal intercostal muscles to flatten the ribs and sternum, and push the diaphragm up further
what occurs during active/forced expiration?
tidal volume (TV): the volume of air entering/leaving the respiratory system during a single breath at rest
what part of the spirometer is labeled by the asterisk? what is its definition?
inspiratory reserve volume (IRV): the maximum volume of air that can be inspired over the tidal volume (TV)
what part of the spirometer is labeled by the letter b? what is its definition?
physiological control factors: parasympathetic stimulation, decreased CO2 concentration; pathological factors: allergies or physical blockage of the airways
what physiological and pathological factors lead to bronchoconstriction?
physiological control factors: sympathetic stimulation, increased CO2 concentration, release of epinephrine; pathological factors: none
what physiological and pathological factors lead to bronchoconstriction?
spirometer: measures the volume of air in the lungs over time x-axis: time (s) y-axis: volume of air in lungs (mL)
what type of graph is shown and what does it measure? what is the x-axis and y-axis labeled?
the forced expiratory volume in 1 second (FEV1)
what value indicates the maximum airflow rate for the lungs?
inspiratory and expiratory reserve volumes (IRV and ERV)
what volumes are available when oxygen demands are increased above the TV requirement?
respiratory rate increases, TV increases
when demand for oxygen increased, the respiratory rate (increases/decreases) and the TV (increases/decreases)
complete gas exchange occurs by 1/3 of the way through a capillary (within 0.25s); this means that the partial pressures of gases are equilibriated with alveolar partial pressure
when has complete gas exchange occurred between the blood and air in the alveoli? what does this mean about the partial pressures of the air in both these places?
at the end of inhalation and exhalation, when the size of the thoracic cavity is not changing and air is not moving in or out of the lungs
when is intra-alveolar (interpulmonary) pressure equilibrated with atmospheric pressure (760 mmHg)?
(1) intrapleural fluid cohesiveness (2) transmural pressure gradient
when the lungs are stretched, what two factors contribute to it being held in close apposition to the thoracic cavity?
R = resistance of airways; determined by radius
when using the following equation to determine air flow rate, what is represented by R and what determines its value? F = ΔP/R
ΔP = pressure gradient; ΔP = atmospheric pressure - intra-alveolar pressure
when using the following equation to determine air flow rate, what is represented by ΔP and how is it calculated? F = ΔP/R
decrease airflow: low concentrations of CO2 induce contraction of local airway smooth muscles, causing bronchoconstriction and increased airway resistance increased blood flow: high concentrations of O2 relax the local pulmonary arteriolar smooth muscle, causing vasodilation and decreasing vascular resistance
when ventilation is high and perfusion is low, CO2 concentration is low while O2 concentration is high. how is airflow decreased and blood flow increased to help balance this?
decreased CO2, increased O2
when ventilation is high and perfusion is low, how do CO2 and O2 concentrations within the lungs change?
increase airflow: high concentrations of CO2 cause relaxation of local-airway smooth muscles, causing bronchodilation, and decreased airway resistance decrease blood flow: low concentrations of O2 increase contraction of local pulmonary arteriolar smooth muscle, causing vasoconstriction, and increasing vascular resistance
when ventilation is low and perfusion is high, CO2 concentration is high while O2 concentration is low. how is airflow increased and blood flow decreased to help balance this?
high pCO2, low pO2
when ventilation is low and perfusion is high, how do CO2 and O2 concentrations within the lungs change?
the blood
where does transport of gases between the lungs and tissues occur?
located between the vocal folds, involved in creation of sound
where is the glottis located? what is it involved in?
located at the entrance of the trachea; composed of a glottis (laryngeal opening) between vocal folds
where is the larynx located and what is it composed of?
dead space volume (150 mL) and pulmonary ventilation (6000 mL/min)
which of the following stay constant regardless of breathing pattern (quiet breathing at rest; deep, slow breathing; shallow, rapid breathing): tidal volume respiratory rate dead space volume pulmonary ventilation alveolar ventilation
type II pneumocytes; corona viruses
which pneumocyte expresses ACE receptors on its surface? this receptors are binding targets for what specific virus?
the residual volume (RV), because it does not leave the respiratory system
which volume represented in a spirogram cannot be measured and why?
O2 is needed as the final electron acceptor during oxidative phosphorylation
why is O2 extraction via the respiratory system important?
we are only moving air in and out of the dead space, so the alveoli are always exposed to the same air
why is alveolar ventilation during shallow, rapid breathing 0 mL/min?
the nose/nasal cavity humidifies, warms, and filters ambient air before it reaches the lungs
why is breathing through the nose more advantageous than breathing through the mouth?
it includes physiological dead space (alveolar dead space + anatomic dead space) while alveolar ventilation doesn't take into account alveolar dead space
why is pulmonary ventilation greater than alveolar ventilation?
small airways may collapse before all the air can be removed from the alveoli
why isn't it possible for individuals to expire all the air in the lungs?
because lung compliance makes inspiration easier and exhalation harder, but elasticity makes inspiration harder and exhalation easier
why must there be a balance between lung compliance and elasticity?
why are the neurons of the medullary respiratory center are classified as the major respiratory neurons?
without them, involuntary respiration would not occur
are central chemoreceptors sensitive to changes in H+ like carotid body chemoreceptors?
yes
