Respiratory Physiology Flashcards
What is cellular respiration
intercellular metabolic reactions that use o2 and produce co2 during ATP production
what is extracellular respiration
transfer of o2 and co2 between external environment and tissue cells
what is the main function of the respiratory system
provides o2 for tissues to metabolise
remove co2 and regulates pH (co2 is a byproduct of metabolism)
what are some accessory functions that the respiratory system does
endocrine functions - activates angiotensin II to
- increase fluid intake
- increase BP and plasma volume
immunological functions
- clearance of irritants/particles and potential pathogens
voice production
- via the larynx
- route for water loss
- route for heat elimination (hot breath)
components part of the upper and lower respiratory system
upper
- nasal passages
- pharynx
- larynx
lower
- trachea
- bronchi
- bronchioles
- alveoli
function of the respiratory airways
ventilation
gaseous exchange
protective mechanisms
structure of the lungs that allow perfusion
blood vessels and alveoli are always in close proximity, allowing perfusion with the blood and alveoli for gaseous exchange
list out step by step, as to how the respiratory and circulatory system helps takes deoxygenated blood from tissue, all the way till oxygenated blood being distributed
- deoxygenated blood travels via systemic circulation and into the heart
- heart pumps deoxygenated blood into lungs via pulmonary arteries
- oxygenation of blood and release of co2 in lungs
- blood re-enter heart from lung via pulmonary veins
- distributed to the rest of the body via aorta and branches
3 features of the pleura
visceral pleura (inner layer)
parietal pleura (outer layer)
pleura cavity (space inbetween both layers)
what is found within the pleural cavity, and what is the volume and purpose
intrapleural fluid, 5-15ml, lubricates pleural surfaces
3 important pressures in regards to the respiratory system to help with inspiration and expiration of air
atmospheric pressure
intra-alveolar pressure
intrapleural pressure
how do you determine the flow of air from atmosphere to lungs, or vice versa
air is always moving from a place of higher pressure, to lower pressure
how do you change your intra-alveolar pressure to create a pressure gradient to allow inspiration of air?
thorax and intercostal muscles help expand the chest cavity, intra-alveolar and intra-pleural pressure drops as the lungs are streched, resulting in a pressure gradient, allowing air to flow in
what is the transmural pressure gradient
different in intra-alveolar pressure and intra-pleural pressure
two conditions that may affect the pleural space, and what is the effect on respiration efficiency
pneumothorax - excess air within the pleural cavity
pleural effusion - excess fluids within the pleural cavity
both causes increased pressure within the pleural cavity, resulting in less efficiency in respiratory cycle
breaking airway generation into 23 division, where is the conducting zone and respiratory zone as well as what organs are within each zone
conducting zone 1-16 division
0 - trachea
2/3 - bronchi
4 - bronchioles
7/8 - terminal bronchioles
respiratory zone 17-23
18 - respiratory bronchioles
21 - alveolar duct
23 - alveolar sac
what are the two types of alveolar cells and there corresponding %
type I alveolar cells (90%) (respiratory epithelium)
type II alveolar cells (10%) (surfactant) (reduces surface tension, allowing for alveolar expansion)
how thick is the wall of the alveoli, and why so
0.5μm, thin barrier allows for instant gaseous exchange with blood vessels via diffusion
how does O2 and CO2 diffuse across the thin barrier
diffusion from high to lower concentration
CO2 rich blood > alveoli
O2 rich alveoli > blood vessels
what is the time taken for blood in capillaries and alveoli to diffuse
0.75 total, 0.25 for oxygenation and 0.5 for safety margin, in case there is a need for increase cardiac output/additional gaseous exchange
musculature of trachea, bronchi, bronchioles
trachea - mainly cartilage, little smooth muscles
bronchi - mainly cartilage, little smooth muscles
bronchioles - mainly smooth muscles
for trachea and bronchi, cartilaginous rings to help reinforce during pressure changes during respiration
protective mechanisms of airway
protection of respiratory epithelium (mucosa)
- humidifying air in upper passages for easy diffusion
- mucous secretion (prevent dust invasion)
protection of lungs
- mucocilliary trapping foreign matter
- ciliary escalator (flap foreign particles upwards)
- alveolar macrophages for particles
- airway reflexes such as coughing and sneezing
which part of the respiratory tract has cilia
epithelium to trachea, bronchi, bronchioles
what part of the body helps with inspiration and expiration of air
movement of chest wall and lungs
chest - skeleton and muscles
which set of intercostal muscles are responsible for inspiration of air, and how does it help
what about other muscles
external intercostal muscles help elevate the ribs, causing sternum to move up and out, increasing thoracic capacity
diaphragm contracts, pulling downwards to allow space for the thoracic cavity to expand
what changes to the air drawn/expelled happen during ventilation stimulation such as exercise
inspiration
- increase amount of air being draw into lungs per unit time
expiration
- increase amount of air being expelled from lungs per unit time
define anatomical dead space
space up to the respiratory bronchioles that do not have alveoli for gaseous exchange
what is alveolar ventilation and how do you calculate it
alveolar ventilation - amount of air that reach the alveolar per minute
AV = (TV - ADS) x breaths/min
what does effective oxygenation and co2 removal in lungs depend on
ventilation and gas exchange via diffusion
- enough fresh air per cycle?
- does the fresh air reach the alveoli?
- can the air diffuse effectively across to the capillaries?
- can co2 abundant air leave the lungs effectively?
perfusion of lungs
- does blood coming from heart reach alveoli?
- are all alveoli perfusing with blood
- is there sufficient time based on blood flow rate for proper perfusion
factors affecting gaseous exchange with alveoli
diffusion across alveolar-capillary barrier
- thickness of barrier
- partial pressure difference
- surface area
blood flow
- rate of blood flow through alveoli
- perfusion rate of alveoli
how do you calculate partial pressure of a specific gas? (example O2)
21% of atmospheric air is O2
21% x atmospheric air pressure to get = PO2 in air
what direction does gas exchange go to and fro? (pressure example)
high pressure > low pressure
equal pressure = no diffusion
is o2 soluble or insoluble? where does the insoluble o2 go to
relatively insoluble, approximately 98% will bind to hemoglobin
how does the surface area of alveoli affect gaseous exchange
large surface area promotes diffusion, if there is a reduction in surface area = no efficient gas exchange = lack of o2 to tissues, lack of co2 removal
how does rate of blood flow affect gaseous exchange
blood flow allows perfusion between alveoli and blood
blood flow slow down = slower rate of exchange
blood flow speed up = faster rate of exchange
gas exchange takes only 0.25 seconds (if u remember) so even if the blood flow’s fast, it’ll still diffuse properly
route for pulmonary circulation (from deoxygenated blood entering the right atrium)
right atrium > right ventricle > pulmonary artery to lungs > branches into multiple pulmonary arterioles > capillary bed around alveoli > small pulmonary veins > large pulmonary veins > left atrium
pulmonary artery pressure generated via the right ventricle is low/high? why so?
low pressure
- right ventricle relatively thin
- slow down blood flow to allow blood to go around each alveoli for gas exchange
compare the systemic and pulmonary circulation
pulmonary - low resistance low pressure, normally dilated
systemic - high pressure, normally constricted
how is blood flow within the lungs distributed
not uniform
what are some factors affecting the distribution of blood within the lungs
gravity
- upright position, more blood flow at the bottom
muscular tone of arterioles
- pulmonary arterioles can distend better than systemic arterioles
- vasoconstriction resulting in less blood flow to constricted location (etc the bottom, forcing blood upwards)
apex vs base of lungs
explain with levels of PO2 and PCO2, air and blood volume
why are the volumes as such
Apex
- more PO2, less PCO2
- more air, less blood
Base
- more PCO2, less PO2
- more blood, less air
base is closer to heart, thus blood reaches it more easily.
apex is further from heart, so less blood but more air
air carries O2, blood carries CO2
how does the body help balance blood and airflow balance in the apex of the lungs
low co2
- contraction of local airway smooth muscles (force air to go elsewhere)
- constriction of local airways
- increased airway resistance
- reduction in airflow
high o2
- relaxation of pulmonary arteriolar smooth muscles
- dilation of local blood vessels (more blood from base to apex)
- reduce in vascular resistance
- increase blood flow
how does the body help balance blood and airflow balance in the base of the lungs
high co2
- relaxation of local airway smooth muscles
- dilation of local airways
- reduced airway resistance
- increase airflow
low o2
- constriction of local pulmonary arteriolar smooth muscles
- constriction of local blood vessels
- increase vascular resistance
- reduce blood flow
what is tidal volume
total amount of air entering and leaving lungs while on rest
what is inspiratory reserve volume
extra air entering lungs during maximal inspiration (ontop of TV)
what is expiratory reserve volume
extra air leaving the lungs during maximum expiration (ontop of passive expiration)
what is residual volume
volume of air left in lungs after maximum expiration
what is vital capacity
amount of air that can mobilize in and out of the lungs (total lung capacity - residual volume)
what is functional residual capacity
air that maintains in the lungs after quiet expiration
formula for minute ventilation
Tidal volume x Respiratory rate (breaths per minute)
two type of chemoreceptors that help control respiration
medullary chemoreceptor (central) and carotid/aortic body chemoreceptors (peripheral)
what does the medullary chemoreceptors sense
drop in pH and increase in CO2 levels
what does the aortic/carotid body chemoreceptors sense
decrease in O2 levels
three ways the co2 is broken down to be transported in blood
- dissolved directly into plasma
- bind to hemoglobin
- turned into bicarbonate
how does co2 turn into bicarbonate to be excreted by the erythrocyte? (mention the entire chemical equation as well as what comes in after bicarbonate goes out)
CO2 + H2O + enzyme carbonic anhydrase = H2CO3 = break down further into H+ and HCO3-
HCO3- leaves the erythrocyte and takes in a Cl- ion to balance. (Chlorine shift to maintain electrical neutrality)
What stimulates the medullary chemoreceptor
the H+ ion that was broken down from carbonic acid (H2CO3) within the cerebral spinal fluid binds to the chemoreceptor to increase respiratory rate
Note
- Normal H+ ions cannot stimulate the central chemoreceptor because its not very soluble!!! only the H+ from the H2CO3 that’s already WITHIN the cerebral spinal fluid can
what stimulates the peripheral chemoreceptors
O2 and H+ ions
where are the carotid and aortic bodies found
carotid artery’s bifurcation, near to the carotid sinus and aorta
local control mechanism to match ventilation and perfusion (two alveoli, one cmi)
blood flow to the malfunctioning alveoli will have its arteriole constricted to allow blood to flow to more well-oxygenated alveoli for diffusion
what are some local factors affecting gas exchange at alveoli
- surface area of alveoli
- thickening of alveoli membrane
- increase diffusion distance due to excess fluid
- increase airway resistance to the alveoli
what are some factors affecting the efficiency of diffusion of gases
- partial pressure of gas between alveoli and blood
- diffusion barrier thickness
- diffusion property of gas
- area for diffusion
what is compliance of the chest wall and lungs
how readily they are stretched/inflated
what is the formula for compliance
Change in lung volume/change in pleural pressure
what can cause a lack of compliance
- scarring of the lung tissues
- lack of surfactant
- edema of alveolar wall
how does surface tension of alveoli influence the lungs’ compliance
surface tension causes alveoli to contract, by pulling each other together, resulting in increase pressure within alveoli (smaller = more pressure, higher tendency to collapse)
as a result, the smaller alveoli will empty into the bigger alveoli
relationship between pressure and radius
pressure and radius are inversely proportional
pressure and surface tension are proportional
what is something that can help prevent collapsing of the alveoli
presence of surfactant, reduces alveolar surface tension = lower tendency to collapse
what is the surfactant made up of, and where does it recide
mixture of phospholipids, lipids, and proteins
it lines the inner surface of alveolar epithelium
some situations where there will be an increase in resistance to the flow of air
- bronchoconstriction
- reduced lung volume
- mucus accumulation
all results in increase work of breathing
FEV1 and FVC
forced expiratory volume exhaled in 1 second after full inspiration
forced vital capacity - total volume expired forcefully after full inspiration
why measure FEV1 and FVC for spirometry
picks up changes in
- resistance to airflow
- elasticity of lungs
what two systems (and one other thing) is utilised to transport o2 to tissue
respiratory system
- perfusion, diffusion, ventilation
cardiovascular system
- vascular constriction, cardiac output
blood
factors affecting amount of o2 carried by HB
- partial pressure of O2 in blood (higher PO2, more O2 binding)
- concentration of HB in blood (more HB, more O2 can bind)
- Affinity of HB for O2
factors affecting affinity of HB for O2
- temperature
- pH level
- 2,3 disphosphoglycerate (DPG)
pH influence on HB saturation curve
higher pH = acidic = high CO2 content = oxygen more readily released = curve moves to the right
lower pH = alkaline = high O2 content = oxygen not needed in excess = curve move to the left
temperature influence on HB saturation curve
low temperature = colder = less energy used = no need excess O2 = hold onto O2 = graph moves left
high temperature = hot = more energy used/needed = O2 more readily let go = graph moves right
what is 2,3 DPG?
2,3 diphosphogylcerate is a by-product of RBC glycolysis
how does 2,3 DPG influence the HB saturation graph
no 2,3 DPG = not working/not working hard = no excess O2 needed = graph moves left
