respiration Flashcards
what is the primary function of respiration?
gas exchange
where does gas exchange occur in mammals?
in the lung
what type of air gets inhaled during respiration?
o2 rich air
what type of air gets exhaled during respiration?
co2 rich air
what transports o2 and co2 in the body
blood
what happens to the air that flows through the nose?
cleaned of big dust particles and warmed
Through which parts of the nose air pass?
the nasal septum and the nasal turbinates
what is the trajectory of air flow after the nose?
- pharynx
- larynx
- trachea until it finally reaches the lungs via the main bronchi
what do the lungs and airways share the chest cavity with?
the heart, great vessels and esophagus
what do the airways consist of?
series of tube that branch and become narrower, shorter and more numerous as they penetrate into the lungs
what does the trachea divide into
2 main bronchi (one for each lung)
what does the main bronchi divide into?
lobar and segmental bronchi
how many lobar bronchi does the right lung have? why?
3 due to its 3 lobes
how many lobar bronchi does the left lung have? why?
2 due to its 2 lobes
what does the segmental bronchi divide into?
divide further into smaller branches
what is the smallest airway that does not contain alveoli?
terminal bronchioles
what is the pleura?
Thin cellular sheet attached to the thoracic cage interior and folds back upon itself, attached to the lung surface
what is the viscera pleura attached to?
surface of the lungs
what is the parietal pleura attached to?
interior throacic cage
wat is the pressure in the pleural space?
negative pressure
what are the airways divided into?
into 2 zones; conducitng and respiratory zones
what does the conducting airways consist of?
conducting airways consist of the airways from the mouth and nose openings, all the way down to the terminal bronchioles
what is conducted through the conducting airways?
air from the atmosphere to the respiratory part of the lungs
do the conductiive airways contribute to gas exchange
no
what is the condutive airways said to composed?
anatomical dead space
where does the repiratory part of the lungs begin?
begins where the terminal bronchioles divide into respiratory bronchioles,
what is found beyond the respiratory bronchioles?
the alveolar ducts lined with alveoli
what is the alveiolar region of the lungs for?
site of gas exchange
which zone takes makes up the greatest part of the lung?
respiratory zone due to high branching
what is The smallest physiological unit of the lungs
acinus
where is the acinus located?
distal to the terminal bronchioles
what are the 4 main functions of the conductive airways?
- defense against bacterial infection and foreign particles
- Warm and moisten inhaled air
- production of sound and speech by movement of passing air
- regulation of air flow
how can the conductive airways protect against bacteria?
the epithelial lining of the bronchi has hair-like projections and mucous is secreted to line the respiratory passage causing for foreign particles to stick to it and the cila sweeps mucous into the pharynx
what is the name given to the defense system of the conductive airways?
mucociliary defense system
how is airflow regulated in the conductive airways?
contaction or relaxation of the airwats to alter resistance to flow
how many alveoli are their in the human lung?
roughly 300 million
each alveolus may be associated with how many capillaries?
1000 capillaries
what type of blood is brought to the lungs via pulmonary circulation?
mixed venous blood
what happens to the mixed venous blood that comes to the lungs?
it gets oxygenated and then returns to the heart (left)
what does the broncial circulation involve?
supplies oxygenated blood from the systemic circulation to the tracheobroncial tree
what does the bronchiole circulation allow?
for the airways to get oxygenated
where does the pulmonary A. originate from?
from the Pulmonary trunk via the Right Ventricle
branches of the pulmonary A. run with what?
the airways
what happens when the pulmonary A. branches. reaches the alveoli?
arterioles divied into capillaries within the alveolar walls
what does the pulonary arteries constitute?
the respiratory surface of the lungs where the gas exhange takes place
where does the oxygenated blood in the lungs come from?
alveolar capillaries
by what does the oxygenated blood of the lung leave to return to the left heart?
pulmonary veins
what supplies the airway walls of the lungs?
bronchial A that branch off of the aorta
is the bronchiole ciruculation part of the systemic circulation?
yes
how many different types of alveolar cells are there?
3 types
what are the 3 types of alveolar cells?
- epithelial type 1 and 2 cells
- endothelial cells
- alveolar macrophages
what do the alveolar epithelial cells form all together?
form a complete epithelial layer sealed by tight junctions
what is produced by alveolar epithelial type 2 cells?
pulmonary surfactant
what is the main function of pulmonary y surfactantf?
decreases the surface tension of the alveoli
what dot do the alveolar endothelial cells constitute?
constitute the walls of the pulmonary capillaries
what is the thickness of the endothelial cell walls?
as thin as 0.1 micron
what is the function of alveolar macrophages
These remove foreign particles that may have escaped the mucociliary defense system of the airways and found their way into the alveoli
how could the lung tissue be described?
elastic but unable to expand or contract by itself
how does air enter the lungs?
its sucked into the lungs
what allows to suck air into the lungs?
the respiratory muscles of the chest walls
what are the different types of respiiratory muscles?
inspiratory and expiratory muscles
what is the main inspiratory muscle?
the diaphragm
what innervated the diaphragm?
the phrenic n
C3-C5
What does contraction of the diaphragm cause?
its dome to descend and the chest to expand longitudinally and elevates the lower ribs because of the vertically oriented attachments of the diaphragm to the costal margins
the contraction of the external intercostal muscle allows what to happen?
raises the ribs during inspiration
what happens as the ribs elevate during inspiration?
the anterior-posterior and transverse dimensions of the chest enlarge
what muscles may assist in inspiration?
external intercostal diaphragm parasternal intercartilagenous mucle SCM scalenes
when do the accessory muscles of inspiration have the greatest involvement?
during ventilation
asthma
or in cases of obstructed airways
how are the neck muscles involved in inspiration?
elevate and fix the uppermost part of the rib cage, elevate the sternum, and slightly enlarge the anterio-posterior and longitudinal dimensions of the chest
is expiration active or passive during quite breathing?
passive
when does expiration become an active process?
higher levels of ventilation (exercise), or in pathological states when expiratory resistance increases and the movement of airflow out of the lungs is impeded
what are the muscles involved in active expiration?
internal intercostal muscles
abdominal muscles
what happens when expiratory muscle contract?
compress the abdominal content, depress the lower ribs, and pull down the anterior part of the lower chest
what happens to the diaphragm when expiratiory muscles are contracting?
gets pushed upwards
what are the muscles of expiration essential for?
- coughing
- singing
- talking
- vomiting
what can result in an enormous increase in pressure in the thoracic cage and abdomen?
Forced maximal contraction of the expiratory muscles against a closed glottis
what happens if valsalva’s maneuver is sustained?
this would lead to a decrease in venous return to the heart, thus a decrease in cardiac output due to constantly high pressure
summarize the events that happen in inspiration
- contraction of diaphragm and intercostal muscles
- expansion of throacic cage
- intrapleural pressure gets negative
- transpulmonary pressure increases
- expansion of lungs
- alveolar pressure < atmospherir
- air flows into the lungs
summarize the events that happen in expiration
- diaphragm and intercostal muscles stop contracting
- chest wall moves in
- intrapleural pressure returns to preinspiratory values
- transpulmonary pressure decreases
- lungs recoil
- air in lungs is compressed
- alveolar pressure > atmospheric pressure
- air flows out of the lungs
what does a spirometer measure?
measures volumes of inhaled or exhaled gas
what can the spirometer be used to measure?
measure tidal volume, vital capacity, inspiratory capacity, expiratory reserve volume, and inspiratory reserve volume
what cannot be measured using the spirometer?
It cannot be used to measure functional residual capacity, total lung capacity, or residual volume.
how does the spirometer function?
Basically a tube linked to a chamber with movable piston of known dimension.
○ We record the movement of the piston.
what does the vital capacity go from
super low to super high
what does the inspiratory capacity go from
low to super high
what does the functional residual capacity go from
hyper low to low
what does the total lung capacity go from
hyper low to super high
what does the tidal volume go from
normal low to normal high
what does the residual volume go from
super low to hyper low
what does the inspiratory reserve volume go from
high to super high
what does the expiratory reserve volume go from
low to super low
what is FRC?
functional residual capacity
how can FRC be measured?
measured by helium dilution
what does FRC involve?
FRC involves going from Low (normal exhale) to Hyper Low (Zero Volume)
why can FRC not be measured directly? what method is used instead?
impossible to fully colapse a lung thus use C1xV1=C2x(V1+FRC)
what does the chamber contain when trying to measure FRC?
known V1 and C1
how is C2 measured?
after the person exhales, breathes from tube to mix gases, helium content can then be measured
what is ventillation?
amount of air inspired into the lungs over some period of time
what is another name given to ventilation?
minute ventilation (Ve) since its often calculated over aperiod of a minute
what is Ve?
the amount of air inspired or expired during a minute
Ve-Vtxf
what is the normal tidal volume and frequency of breathing in a normal adult male?
Vt= 500ml f= 12 breathes/min
what would Ve be if Vt= 500ml
f= 12 breathes/min
6000ml/min
does all the inhaled air reach the respiratory zone? why or why not?
no, some air remains in the conductive airways (Deadspace)
what is the volume of air that gets trapped in the conductive airways?
~150mL
How much air would actually reach the respiratory zone of the lungs?
Va=(500-150)x122=4200ml/minute
what are the primary muscles of inspiration?
intercostals and diaphragm
what are the acessory muscles of inspiration?
scalenes and SCM
what are the accessory muscles of expiration?
internal intercostal
abdominal muscles
what is the alveolar deadspace?
when a certain amount of inspired air doesn’t enter the respiratory zone thus doesnt take part in gas exchange and will cause either for decreased blood or no blood at all to the alveoli
what is the difference between minutes and alveolar ventillation?
the deadspace ventilation that is wasted from the gas exchange point
VD=VE-VA
what are the characteristics of normal alveolar ventilation?
Va matches CO2
PaCO2 is maintained at a constant level
when does alveolar hyperventilation occur?
when more O2 is supplied and more CO2 is removed that the metabolic rates require
what happens when VE exceeds the body’s need?
alveolar hyperventilation
what happens to the alveolar partial pressures in alveolar hyperventilation?
alveolar partial pressures of O2 (PAO2) rises and that of CO2 (PACO2) decreases
what is alveolar hypoventilation?
fall in the overall ventilation
what happens to the partial pressures during alveolar hypoventilation?
alveolar partial pressure of O2 (PAO2) falls and PACO2 rises
what is an effect/ consequence of alveolar hypoventilation?
the blood in the pulmonary capillary is less oxygenated, and PaO2 falls below normal values
when does alveolar hypoventilation occur?
Alveolar hypoventilation may occur during severe disorders of the lungs (e.g. chronic obstructive lung disease), or when there is damage to the respiratory muscles, injury to chest cage or CNS is depressed
what happens to the partial pressures when breathing air with low PO2?
PO2 decreases and no changes to PCO2
what happens to the partial pressures when INCREASE ALVEOLAR VENTILATION AND UNCHANGED METABOLISM?
P02 INCREASES
PCO2 DECREASES
what happens to the partial pressures when decrease alveolar ventilation and unchanged metabolism
PO2 DECREASES
PCO2 INCREASES
what happens to the partial pressures when metabolism increases but unchanged alveolar ventilation
PO2 DECREASES
PCO2 INCREASES
what happens to the partial pressures when metabolism decreases but unchanged alveolar ventilation
P02 INCREASES
PCO2 DECREASES
what happens to the partial pressures when proprtional increase in metabolism and alveolar ventilation?
PO2: NO CHANGE
PCO2: NO CHANGE
How is oxygen transferred across the alveolar-capillary membrane?
via passive diffusion
what law governs diffusion rates?
fick’s law
what does fick’s law state?
rate of diffusion of a gas through a tissue is proportional to the tissue are and difference in gas partial pressures between the 2 sides, inversely proportional to tissue thickness
how do the pressures of O2 and CO2 compare between the venous blood and the alveoli?
PO2 is lower and PCO2 is higher than in the alveoli
in what direction will O2 diffuse between venous blood and alveoli?
O2 diffuses from the alveolar gas to the blood
in what direction will CO2 diffuse between venous blood and alveoli?
CO2 diffuses from blood to alveoli
in what direction does diffusion take place?
from high concentration to low concentration
how does O2 diffuse through a liquid?
O2 from a gaseous medium diffuses through the alveolar-capillary membrane to a liquid plasma in the pulmonary capillaries
how can a gas diffuse through a liquid?
needs to be soluble in the liquid
which gas between O2 and CO2 is more soluble?
co2
how much faster does CO2 diffuse into blood than O2?
20x faster
how is the pressure difference at the beginning of the pulmonary capillaries?
large pressure difference for P02 on either side of the alveolar capillary membrane
what does the large pressure difference on either side of the alveolar capillary membrane cause?
results in a large pressure gradient
what happens to the pressure difference as blood flows through the lungs?
the pressure difference becomes smaller and thus the O2 gradient across the capillary becomes less
what happens to the rate of diffusion as the pressure gradient decreases?
rate of diffusion also decreases
what is the PCO2 at the beginning of the capillaries and alveolar?
capillaries: 46 mm Hg
alveolar gas: 40 mm Hg
how much smaller is the pressure difference at the alveolar-capillary membrane for CO2 than for O2
10x smaller
which substance has a greater rate of diffusion between O2 and CO2
CO2
what is the result of a faster diffusion rate for CO2 and the pressure differences for CO2 and O2 across the alveolar capillary membrane?
the time required for equilibrium between alveolar air and capillary blood is approximately the same for the two gases.
what is the transit time of blood through pulmonary capillaries at rest?
0.75seconds
during transit time of blood, what is it in contact with?
blood in the capillaries is in contact with the air in the alveoli
In a normal lung, diffusion of both O2 and CO2 is accomplished within what proportion of RBC transit time?
1/3 RBC transit time
what happens to the Pressures of O2 and CO2 in a resting patient with impaired rate of diffusion?
PO2 and PCO2 may be normal due to diffusion
what happens to the Pressures of O2 and CO2 in a patient with impaired rate of diffusion when blood flow increases?
transit time will become shorter and may cause for arterial PO2 may decrease and arterial PCO2 may increase
what is the surface of the thin walled vessels in the pulmonary capillaries?
100m^2 of 40x body’s surface area
which has a lower BP, systemic or pulmonary circulation?
pulmonary circulation
which has thicker vessels; systemic or pulmonary circulation?
systemic
what is the pressure developed by the right evntricle suring systole?
~25 mm Hg
where does blood from RV get transmitted to?
pulmonary A.
what happens tot he pressure in the right ventricle when systole falls?
goes back to atmospheric pressure (0)
what happens to BP of pulmonary circulation during diastole?
it decreases gradually as blood flows through pulmonary capillaries
what is the Mean pulmonary arterial pressure?
~15 mm Hg
what is the mean left atrial pressure?
~5 mm Hg
what is the MAP of the systemic circulation?
~100 mm Hg
what does blood flow depend on?
vascular resistance
what is the equation for flow?
flow=pressure/resistance
what is the total pressure drop from pulmonary artery to left atrium
~ 10 mm Hg
what is the pressure drop between systemic artery to RA?
~100 mm Hg
what is resitance of the pulmonary circulation compared to the systemic one?
1/10 of the systematic one
what does the low vascular resistance in pulmonary circulation rely on?
the thin walls of the vascular system
is the compliance of the pulmonary circulation high or low?
high compliance
how many folds of increase of CO can the pulomary circulation accomodate?
2-3 folds without changing pulmonary A pressures
what does The increase in blood flow with little changes in driving pressure indicate?
pulmonary blood flow increases, pulmonary resistance falls
how does vascular resistance drop?
increasing cross-sectional area of the vascular bed
what may happen to vessels that were previously closed to accomodate for increase blood flow?
may open as the cardiac output rises (recruitment)
what is the effect of drugs such as serotonin, histamine and norepinephtrine on pulmonary blood vessels?
which cause the contraction of smooth muscle increase pulmonary vascular resistance in the larger pulmonary arteries.
what is the effect of drugs such as ACh and isoproteranol on pulmonary blood vessels?
relax smooth muscle may decrease pulmonary vascular resistance.
what type of reflex occurs in poorly oxygenated parts of the lungs?
vasoconstriction reflex
what is the effect of NO produced by endothelial cells?
relaxes vascular smooth muscle leading to vasodilation.
what may affect pulmonary blood flow?
gravity and body posture
how does blood flow change in an upright position?
blood flow will increase
how does blood flow increase when in an upright position?
The vessels are more distended toward the bottom of the lungs because gravity increases vascular pressure. Near the top of the lungs, the pulmonary capillaries may be completely compressed if alveolar pressure is greater than blood pressure in the capillaries
how can we measure distribution of blood flow in the uprigth human?
using radioactive xenon
what happens to the dissolved xenon when measuring distribution of blood flow in the lungs?
evolved into alveolar gas from the pulmonary capillaries
what is the lower blood flow at the bottom of the lungs due to?
extra-alveolar vessels being less expanded at low lung volumes
what does the hydrostatic pressure of the blood cause?
an uneven distribution of blood flow from the top to bottom of the lung
how is the pressure in the top portion of the lung when confronted with gravity?
pulmonary arterial pressure< alveolar pressure
what happens to the capillaries in the top part of the lung?
they are compressed
when does the pulmonary arterial pressure< alveolar pressure occur?
only in cases of low arterial pressure or positive ventilation.
how is the pressure in the middle portion of the lung when confronted with gravity?
pulmonary arterial pressure> alveolar pressure > venous pressure
in the middle portion of the lung, what does flow depend on?
on the difference between arterial and alveolar pressures
how is the pressure in the bottom portion of the lung when confronted with gravity?
pulmonary arterial pressure> venous pressure> alveolar pressure
in the bottom portion of the lung, what does flow depend on?
the flow depends on the arterio-venous pressure difference
changes in lung volume affects pulmonary resistance based on what?
whether the blood vessels are surrounded by alveoli (alveolar vessels) or not (extra-alveolar vessels)
how are the alveolar vessels stretched above FRC?
stretched longitudinally
what happens to the vascular resistance of the alveolar vessels above FRC?
increase of vascular resistance due to decrease of diameter
what happens to the extra-alveolar vessels below FRC?
vessels collapse because they are not stretched by the pulmonary tissues
In an upright lung at rest, in normal gravity, how do the top and bottom alveoli differ?
the alveoli at the top of the lungs are more opened than the bottom ones
how do the bottom and top alveoli differ when breathing?
alveoli from the bottom of the lungs are opened wider than those at the top
how can the distribution of ventilation be measured?
while inhaling Xenon
how is the ventilation-perfusion ratio of the lungs?
it is abnormally high at the top and much lower at the bottom.
O2 consumption per minute is equal to what?
its equal to the o2 taken up by the blood in the lungs in one minute
what is the [o2] in the blood that enters the lungs?
CvO2
what is the [o2] in the blood that leaves the lungs?
CaO2
what is VO2
measured by comparing [O2] in the expired gas collected in a large spirometer and [O2] in inspired gas;
what is CaO2 measured from?
from artery
what is CvO2 measured from?
via catheter in pulmonary A.
what is the amount of gas dissolved in the blood proportional to?
directly
proportional to the partial pressure of the gas,
what is stated by Henry’s Law?
Henry’s Law states that the number of gas molecules dissolved in
a liquid is proportional to the partial pressure of the gas above the
liquid
is the amount of 02 dissolved in blood high or small?why?
small, because o2 is relatively insoluble in H20
how much O2 is found in 100 ml of plasma?
0.3 ml of O2
what would happen is 02 was only found in the plasma?
the tissue demand for O2 would never be met.
where is hemoglobin found in?
RBC
what is the function of Hemoglobine?
permits whole blood to take up to 65 times as much O2 as plasma
hemoglobin contributes to what portion of the weight of RBC?
1/3 of the weight
what is the structure of hemoglobin?
consists of a heme (iron porphyrin) joined to a protein globin which consists of 4 polypeptide chains, each containing an Fe++ ion that can bind to 1 molecule of O2
how much Hb is found in a L of blood?
147g of Hb
what is Hb essential for?
essential for the transport of O2 by blood
what is the total amount of 02 in arterial blood?
~20% volume
does the O2 bound to Hb contributes to Po2
No
what does the PO2 of the plasma determine?
it determines the amount of O2 that combines with Hb
