Respiratory Physiology Flashcards
what is respiration
all components of the interchange of gases between the atmosphere and cells
what is ventilation
movement of air into and out of the lungs, alveoli
what is gas exchange
diffusion between air in lungs and blood; diffusion between blood and tissues
upper respiratory tract
nose, nasal cavity, pharynx larynx
lower respiratory tract
trachea, bronchi, lungs
the junction of bronchi is called
carina
the carina contains
irritant receptors that trigger the cough reflex
the conducting zone
trachea to terminal bronchioles
the respiratory zone
respiratory bronchioles to alveoli
tidal volume
volume of air inhaled in one breath
inspiratory reserve volume
volume between normal inhalation and maximal inhalation
expiratory reserve volume
volume between normal passive exhalation and maximal exhalation
residual volume
volume of air after maximal exhalation
inspiratory capacity
tidal + inspiratory reserve
vital capacity
tidal + inspiratory reserve + expiratory reserve
total lung capacity
total lung volume (including residual capacity)
minute ventilation (VE)
total volume of air breathed per minute; TVxf
clusters of alveoli are surrounded by (2)
elastic fibres and a capillary network
Type I vs Type II pneumocytes
Type I: gas exchange; 95% of surface
Type II: surfactant
larger alveoli have (more/less) surface tension
less
surfactant consists of
lipids and proteins
what is the role of surfactant
equalize PRESSURE between different alveoli
what contracts to allow inspiration
external intercostals, diaphragm (also serratus dorsalis cranialis)
quiet expiration is a result of
elastic recoil of the lungs and ribcage
active expiration is a result of
elastic recoil + internal intercostal muscles, rectus abdominis, external/internal oblique and transversus abdominis
elastic recoil of the lung is due to
elastic tissue, surface tension in alveoli
what is compliance
distensibility of the lungs (ease with which lungs and thorax expand)
conditions that decrease compliance
pulmonary fibrosis, pulmonary edema, respiratory distress syndrome
T/F pleural space is normally a virtual space
T
describe Ppl during breathing
subatmospheric at rest (-); becomes more - during inspiration, becomes less - (sometimes +) during expiration
if lung compliance decreases, ppl becomes more ____ on inhalation
negative (can damage the lung)
if airway resistance increases, ppl becomes more ______ on inspiration (especially with ____ airway obstruction), and more _______ on expiration (especially with ______ airway obstruction)
negative; upper; positive; lower
dead space
all ventilated parts of the respiratory system where gas exchange does not occur
T/F the conducting pathways are dead space
T
anatomic dead space + alveolar dead space =
physiologic dead space
if dead space ventilation increases, what often happens to alveolar ventilation
decreases
T/F you want to maximize dead space
F
________ flow tends to occur in larger airways whereas ______ flow tends to occur in smaller airways
turbulent; laminar
if turbulent flow develops in smaller airways, total gas movement is ______________ and lung sounds ___________
decreased; increase
T/F there is more resistance in the upper airways than the lower airways
T
histamine, leukotrienes, serotonin and TXA2 all promote (constriction/dilation) of airways
constriction
nitric oxide promotes (constriction/dilation) of airways
dilation
sympathetic receptors in the airways are primarily
β2 -> SM relaxation
common causes of inspiratory dyspnea
stenotic nares, dorsal displacement of soft palate, brachycephalic syndrome, laryngeal hemiplegia
common causes of expiratory dyspnea
physical narrowing of intrathoracic airways (ex. bronchoconstriction, edema), collapse of intrathoracic airways, pleural effusion, pneumothorax
T/F vascular pressures are lower in the pulmonary circulation than in the systemic circulation
T
T/F vessel walls of the pulmonary circulation are thicker walled and contain more smooth muscle than segments in the systemic circulation
F: other way around
T/F the lungs act as a blood reservoir during low demand
T
bronchial arteries are _________; bronchiolar arteries and alveolar duct arteries are called
elastic; muscular
the bulk of gas exchange occurs
between inflation and deflation (decrease in pressure therefore blood rushes in)
most resistance to pulmonary blood flow is in
arterioles
pulmonary vascular pressure differences during cardiac and respiratory cycles are due in part to changes in
pulmonary vascular resistance
what are the passive influences of PVR and PVP
cardiac pressure, pulmonary inflation, capillary distension and recruitment, hematocrit, vascular anatomy and position
during exhalation, extra-alveolar arterioles/venules are _____________, but alveolar capillaries are _________(septa are _____)
compressed; dilated; not stretched
during inhalation, extra-alveolar arterioles/venules are _____________, but alveolar capillaries are _____________(septa are ______)
dilated; compressed; stretched tight
increased perfusion pressure results in what changed to pulmonary capillaries, which _______ PVR
increased distension and recruitment, which decreases PVR
as blood viscosity increases, PVR __________
increases
the ________ portion of the lung is preferentially perfused due to _______ resistance
dorsal; lower
what are the active influences of PVP and PVR
neural/hormonal factors, oxygen tension
most prostaglandins cause (vasoconstriction or vasodilation)
vasodilation
a decrease in oxygen concentration in a pulmonary arteriole causes (vasoconstriction or vasodilation)
vasodilation
what is the significance of bronchopulmonary anastamoses
provide collateral circulation to keep alveoli alive in the event that a bronchi or a vessel becomes occluded
T/F one of the factors that draws H2O back into capillaries is the HP of capillaries
F; surrounded by air therefore only capillary oncotic pressure works to bring H2O back in
oxygen comprises what % of the molecules in air
21%
in dry air, PO2 =
PB x FO2 (barometric pressure x fraction of oxygen, 21%)
T/F PO2 of inspired air is lower than the environmental PO2 because air is humidified
T (gets diluted by water vapour)
T/F to keep PACO2 constant, alveolar ventilation increases when CO2 production lowers
F; it increases when CO2 production increases (ex. during exercise)
T/F alveolar oxygen tension is lower than that of inspired air because oxygen is continuously diffusing out of the alveoli and into the blood
T
the respiratory exchange ratio (rate of CO2 production/rate of O2 consumption) is typically what value
0.8
O2 moves because of ________________ whereas CO2 moves because
large concentration gradient between PAO2 and PaO2; it is readily diffusible
T/F CO2 is 20x more effective at diffusion than O2
T
Diffusion depends on
- relative diffusion coefficient of gas (D)
- surface area for diffusion (A)
- distance between air and blood (X)
- pressure gradient
what happens to gas exchange in the lung during exercise
get higher cardiac output, so the velocity of blood flow is high; diffusion equilibrium does not occur in alveoli (less efficient) BUT is happening more frequently, so more O2 is overall delivered to tissues
what happens to gas exchange in tissues during exercise
blood vessels dilate -> blood flow slows -> more time for gas exchange; the distance the gas has to travel is also reduced
In normal, healthy animals, the V/Q ratio is
~0.8
what is a cause of normal, small V/Q mismach
gravity: some areas have lower V/Q than others
what happens to V/Q when the alveolus is supplied by an obstructed bronchiole
drops low
how to fix a low V/Q ratio due to airway obstruction
increase O2 administration
T/F V/Q mismatch due to a right-to-left shunt responds well to O2 therapy
F
what happens to V/Q when the alveolus is ventilated but has no blood? would this respond well to O2 therapy
becomes almost infinite; NO (because there is no blood to deliver any O2)
what happens to V/Q when there is a left-to-right-shunt
drops to 0
Hg structure
2α and 2β subunits surrounding a heme (C/N lattice with iron in the middle)
Hg can bind up to how many O2 at a time
4
Hg transports what % of O2 in blood
98
porphyria
a mutation in any of 8 genes that leads to a buildup of porphyrins in the body (heme is usually made from porphyrins and iron)
as heme enters lung and picks up oxygen, what happens
its affinity for O2 increases and it starts to pick it up more rapidly
as heme enters tissue and releases oxygen what happens
its affinity for O2 decreases and release becomes more rapid
hg is most fully saturated at what oxygen tension
70-80 mmHg
as temperature rises, Hg affinity for O2
falls
as pH decreases, Hg affinity for O2
decreases
as DPG levels rise, Hg affinity for O2
decreases
as Hg is depleted of O2, it changes colour to; this is called
reddish-blue; cyanosis
what can cause cyanosis (2)
reduced O2 uptake; reduced blood flow
oxy-Hb absorbs more (red or infrared) in pulse oximetry
infrared light
deoxy-hb absorbs more (red or infrared) in pulse oximetry
red
active tissues produce CO2, carbonic acid, and lactic acid, lowering pH and facilitating the release of O2 from Hg via what effect
Bohr effect
how does O2 delivery increase during exercise (3)
- 5-fold increase in CO
- 50% increase in Hb due to splenic contraction
- marked increase in the O2 gradient between capillaries and tissue
CO poisoning produces what colour in mucous membranes and skin
cherry red
what is the Haldane effect
deoxygenated blood has increased affinity for CO2
most CO2 is carried in the blood as
HCO3 (via carbonic anhydrase)
T/F CO2 rides on Hg bound to the heme
F; bound to the globin
fetal adaptations to low O2 includes (3)
higher Hb affinity for O2; higher Hb; higher CO
describe fetal Hb
2α and 2γ
control of ventilation come from centers in the
cerebrum, brainstem and spinal cord
T/F fetal hemoglobin affinity for oxygen is greater than adult hemoglobin
T
what monitors changes in blood gas tensions and pH
peripheral and central chemoreceptors
T/F multiple inputs regulate the rhythm of breathing
T
breathing is adjusted to
activity level, metabolism, posture, and non-respiratory behaviours (sniffling, vocalizing, eating)
what are SARs and what is their role
Slowly Adapting Stretch Receptors; sense increase in airway volume and terminate the inspiration
sustained stimulation of SARs causes
activation of expiratory neurons -> active breathing
what innervates SARs
vagus (parasympathetic)
irritant receptors are innervated by
vagus
activation of irritant receptors triggers
bronchoconstriction, increased mucous production, coughing
where are J receptors (C-fiber receptors) and what is their role
in pulmonary interstitium near capillaries; monitor the blood composition and interstitial volume and alter RR
what is responsible for increasing RR when interstitial pressure rises during infectious, allergic or vascular disease
J receptors (C-fiber receptors)
what is the job of sensory input from skeletal muscles
monitor force of muscle contraction and inhibit if too great
what is the job of chemoreceptors in the carotid and aortic bodies
sense changes in PaO2 and PaCO2, pH and change the rate and depth of breathing
where is the carotid body located
bifurcation of carotid arteries
T/F carotid bodies are the only structures monitoring PaO2 in adults
T
what are the biggest stimuli for the carotid bodies to trigger an AP and significant increases in ventilation
small drop in pH or increase in PaCO2
what are the central chemoreceptors
located in the medulla (pons and ventricles) and respond to changes in CO2 by sensing the drop in pH
T/F stimulation of pain receptors increases RR and depth
T
large particles tend to deposit where in the respiratory tract
in the nasopharynx - impaction
medium particles tend to deposit where in the respiratory tract
small airways - sedimentation
small particles tend to deposit where in the respiratory tract
alveoli - diffusion
what are the sources of mucous for the respiratory tract
goblet cells (in larger airways); submucosal bronchial glands (in the bronchi); Clara cells (in respiratory bronchioles)
secretion of mucous in the respiratory tract is under what regulation
autonomic
changes in the sol layer alter ________________ whereas changes in the gel layer alter _________________
ciliary function; clearance rates
T/F the lungs can uptake/convert/degrade hormones/chemicals/toxins in the mixed venous blood
T
macrophages, bradykinin, histamine, serotonin, PGE2, PGF2, heparin are all released by the pulmonary tissue/cells into
systemic blood
