Respiratory System Flashcards
What is pulmonary ventilation?
- it is the exchange of air between atmosphere and lungs which is the result of pressure gradients caused by changes in the thoracic cavity volume?
What are the 3 processes involved in exchange of air? Where do they occur?
1) pulmonary ventilation = which include inspiration and expiration
- happens between atmosphere and lungs
2) external respiration = happens between lungs and blood
3) internal respiration = happens between blood and cell
How is Boyle’s Law related to pulmonary ventilation?
- Boyle’s Law states that gas volume is inversely proportionate to pressure
- when volume is increased during inspiration, pressure decreases,
- when volume is decreased during expiration, pressure increases
For the same number of molecules of air, what happens to the amount of gas?
- remains constant
When volume increases as we inhale, what happens to gas pressure?
- decreases
When volume decreases during expiration, what happens to pressure
- increases
What are the types of pressure involved in pulmonary ventilation?
1) atmospheric pressure
2) intrapulmonary pressure
3) intrapleural pressure
What is atmospheric pressure (Patm)?
- the normal pressure which is 760 mmHg (sea level)
What is the intrapulmonary pressure (Palv)
- air pressure inside the lungs
In between breaths, what type of pressure is present?
- atmospheric pressure
What is intrapleural pressure?
- the fluid pressure in the pleural cavity
The intrapleural pressure is at what mmHg?
about 4 mmHg less than atmospheric pressure (Patm) = 756 mmHG (at rest)
Which pressure is greater, intrapleural pressure or intrapulmonary pressure?
- intrapulmonary pressure
Why is intrapleural pressure negative?
because of the lungs tendency to recoil in while the thoracic wall wants to recoil out
What does pulmonary ventilation consist of?
- quiet inspiration
- forced inspiration
- quiet expiration
- forced expiration
At the start of quiet inspiration, where is the atmospheric pressure and intrapulmonary pressure at?
- they are equal since there is not movement of air. Therefore it is 760 mmHg
as soon as air movement happens, what happens in a quiet inspiration?
- the diaphragm and external intercostal muscles contract, which increases the thoracic volume cavity
- this causes the lung to resist because it wants to recoil in, which causes the intrapleural pressure to decrease from 756 mmHg to 754mmHg
- The higher pressure difference between the intrapleural pressure and intrapulmonary pressure causes the lungs to expand this decreasing the intrapulmonary pressure from 760 mmHg to 758 mmHg
- air moves down the pressure gradient until equal pressure between the atmospheric pressure and intrapulmonary pressure is established
During quiet inspiration, what happens to thoracic cavity volume? Why
increases due to the contraction of the diaphragm and external intercostal muscles
During quiet inspiration, what happens with the intrapulmonary pressure?
- at the start its equal to Patm which is 760 mmHg because theres no air movement
- but as soon as air movement occurs, it decreases to 758 mmHg due to lung expansion caused by the high pressure gradient between the Palv and Pip
During quiet inspiration, what happens with the intrapleural pressure?
- it decreases since the lung is resisting the expansion of the thoracic cavity caused by the contraction of the diaphragm and external intercostal pressure
What happens during forced inspiration?
- greater increase in thoracic cavity volume which increases the pressure gradient significantly so more air moves in
What muscles are involved in quiet inspiration?
- diaphragm and external intercostal muscles
What muscles are involved in forced inspiration?
- diaphragm, external intercostal muscles and sternocleidomastoid which work together to pull rib cage up
Are forced and quiet inspirations active processes? Why or why not?
Yes because muscle contractions are involved
During quiet expiration, what happens thoracic cavity volume?
- it decreases because muscles are relaxed which causes the lungs to go back to its resting size passively (no ATP is involved)
During quiet respiration, what happens to intrapleural pressure?
it increases from 754 mmHg back to 756 mmHg
During quiet expiration, what happens to intrapulmonary pressure?
- it increases from 760 mmHg to 762 mmHg
During quiet expiration, air moves in or out of its pressure gradient?
out
Describe the breathing during forced expiration?
- its impeded and laboured (eg. asthma)
Is forced expiration an active process? why or why not
yes because relax diaphragm, external intercostal muscles and internal intercostal muscles are ccotnracting
What muscles are working in a forced expiration?
- relaxed diaphragm, external and internal intercostal muscles
During forced expiration, whats happening with the intrepleural pressure?
- it increases due to the the decrease with the lung’s volume
What happens to the intrapulmonary pressure during forced expiration?
- it increases due which causes more air to move out
Stretch in lungs is determined by two factors. What are they?
compliance and recoil
What is compliance?
it refers to effort needed to stretch the lungs
A low compliance requires _____ effort.
much
a high compliance requires _____ effort
less
What is recoil?
the ability to return to resting size after being stretched. e
What causes recoiling and compliance?
the elastic CT and surfactant
What prevents lungs from collapsing?
- the fact that intrapleural pressure is always lower than intrapulmonary pressure
- the presence of surfactant
What is pneumothorax?
- air the in the pleural cavity which causes lungs to collapse
Why do the lungs collapse in pneumothorax?
- because the atmospheric pressure, intrapulmonary pressure and intrapleaural pressure are all equal, therefore lungs collapse and thoracic wall expands
what happens when Patm = Palv = Pip?
pneumothorax
= lungs collapse and thoracic wall expands
give an example of a surfactant?
lipoprotein/phospholipid mixture
What do lipoproteins/phospholipids mixture (surfactants) do?
- decreases surface tension on surface of watery film on alveoli
- prevents alveolar collapse
- allows easier stretch of lungs therefore compliance is high
What is respiratory distress syndrome?
it is the inadequate amount of surfactants in 7 month gestations to newborn babies
- this causes alveolar collapse and low compliance
- the low compliance requires much effort to stretch the lungs which leads to exhaustion and death
what is the formula for airflow?
F (airflow) = Pressure gradient/resistance
- *pressure gradient = Patm - Palv
- *resistance = airway resistance
what determines airway resistance?
the diameter of bronchi/bronchioles
How does asthma, bronchitis, emphysema affect airway resistance?
they increase it
What mechanism opens airway? Inspiratory or expiratory mechanisms?
inspiratory
What mechanism closes airway? inspiratory or expiratory?
expiratory
How does the SNS affect the diameter of bronchi/broncioles?
- it promotes bronchodilation (dilaltes bronchiolar smooth muscle)
How does PSNS affect bronchi/bronchioles diameter?
- it promotes bronchoconstriction (constricts bronchiolar smooth muschle)
How is respiratory volume measured?
by using a spirometer
1 respiration is equivalent to?
1 inspiration and 1 expiration
What are the different types of respiratory volume?
1) tidal volume
2) inspiratory reserved volume
3) expiratory reserved volume
4) residual volume
5) minute respiratory volume
6) forced expiratory volume in 1 minute
What is the tidal volume?
it is the volume of air inspired or expired in a quiet respiration
about how much air is inspired or expired in a tidal volume?
500 ml
What is the inspiratory reserved volume
it is the excess air on top of the tidal volume that can be inspired in a forced inspiration
How much air can be forcibly inspired usually?
3000 ml
What is the expiratory reserved volume?
the excess air on top of the tidal volume that can be forcible expired in a forced expiration
How much air can usually be expired in a forced expiration?
about 1200 ml
What is the residual volume
- it is the amount of air in lungs after max expiration
Generally, how much is in the lungs after max expiration?
about 1200 ml
What is minute respiratory volume?
- tidal volume x respiratory rate
- TV = ml
- respiratory rate = #ofbreaths/minute
On average what is the minute respiratory volume?
6L/min
What is the forced expiratory volume in 1 sec (FEV1)?
it is the volume expired in 1 sec with maximum effort followed by max inspiration
Respiratory capacities are always _________ volumes
2 or more
Respiratory capacities include?
- inspiratory capacity
- vital capacity
- total lung capacity
What is the inspiratory capacity
the total amount of air that can be inspired after a tidal expiration
How is IC calculated?
IC = TV + IRV
What is vital capacity?
- it is the largest volume of exchangeable air (in and out of lungs)
How is VC calculated?
VC = TV + ERV + IRV
What is total lung capacity?
it is the total amount of air the lungs can hold
How is TLC calculated?
TV + IRV + ERV + RV
FEV1 is usually measured the same as _______
Vital capacity which is expressed in % VC
Usually, FEV1 = _____%VC
80
measurements of respiratory volumes allow diagnoses of?
obstructive disorders and restrictive disorders
what are examples of obstructive disorders?
- asthma, emphysema, and cystic fibrosis
in terms of obstructive disorders, which is more difficult, expiration or inspiration? Why is that
expiration due to increased airway resistance
Due to the increased airway resistance in obstructive disorders, what happens to RV, VC and the relation of FEV1 to VC?
- RV is increased since expiration is more difficult (more air remains in the lungs)
- VC decreases
- usually FEV1 is less than 80%VC
What are some examples of restrictive disorders
-scoliosis and pneumothorax
In restrictive disorders, what do they prevent?
expansion of lungs
In restrictive disorders, what is more difficult, inspiring or expiring?
inspiring
In terms of restrictive disorders, what happens to IC, VC, FEV1 and its relationship with VC
- IC goes down
- VC goes down
- FEV1 goes down
- but FEV1 = 80%VC
External respiration is an air exchange between?
lungs and blood
What happens to O2 and CO2 in external respiration?
O2 from alveoli travel to the blood and the CO2 from the blood travel to the alveoli
External expiration is aided by?
1) thin respiratory membrane which is composed 2 cells + basement membrane
2) large surface area in the capillaries and alveoli
3) slow blood velocity compared to gas diffusion
Regarding external respiration, how do the capillaries enlarge surface area?
- the rbc single file in the capillaries which maximizes rbc exposure to gases
What happens O2 and CO2 movement in internal respiration?
- O2 from blood moves to cells and CO2 from cells move to the blood
what is the partial pressure of gasses?
- the pressure exerted by a gas in a mixture of gasses
How is Partial pressure of a gas calculated
Partial Pressure = %ofGas x total pressure in mmHg
What promotes gas movements?
pressure gradients
What is the concentration gradient of pressure?
high to low pressure
How is O2 carried in the respiratory system?
- dissolved in the plasma
- bounded to the hemoglobin
Describe the movement of O2 in external expiration?
- It moves from high pressure in the alveoli to the low pressure in the capillaries which contains blood
What’s the reason behind O2 movement down the pressure gradient in external expiration?
- the PO2 in the alveoli which is 105 mmHg and the low PO2 in the capillaries which is 40 mmHg
What is the status of O2 transportation in internal expiration? Does it still move down its pressure gradient?
yes
How does O2 move down its concentration gradient in internal expiration?
- arterial PO2 is 95 mmHg and the Resting Venous + ISF PO2 is 40 mmHg and the ICF PO2 is less than 40 mmHg. This allows the O2 to move from high pressure to low pressure between the blood and cells
About what percentage of O2 is carried in dissolved plasma?
1.5%
What percentage of O2 is carried by hemoglobin?
98.5%
How many O2 can one hemoglobin carry?
4 (1 O2/Fe)
How is the relationship between O2 and Hemoglobin shown?
by using the O2-Hemoglobin dissociative curve
the plateau portion of the O2-Hb dissociation curve represents?
- the range of PO2 in the lungs when Hb picks up O2
under normal resting circumstances, how saturated is Hb?
97%
What happens to when PO2 in arteriole is lower than normal
- there is little change in Hb saturation
When does Hb carry normal amount O2?
- in a high altitude where PO2 in alveolar is higher than 60 mmHg
What does the steep portion of the O2-Hb dissociation curve represent?
Range of PO2 in tissues when O2 lives the hemoglobin
At rest what is the ISF PO2?
40 mmHg
If the ISF PO2 during resting conditions is 40 mmHg, how saturated is the Hg?
75%
If Hg is 75% at rest during O2, unloading. How much O2 is unloaded to to tissue cells? What does this allow the body to do?
22% - hold breathes
In a high metabolism or exercise, what is ISF PO2?
20 mmHg
How saturated is Hg during high metabolism like exercising?
40% saturated
During exercise or when metabolism is high, How much O2 is unloaded to tissue cells, percentage wise?
57% or more O2 is unloaded
When a shift to the right occurs in the the O2-Hg dissociation curve, what does this mean
- it means that Hg is getting more desaturated meaning unloading is easier than loading
What causes the O2-Hg dissociation curve to shift to the right?
- increased PCO2
- low pH which relates to the the increase of CO2 which is a lactic acid
- increased temperature
Why does a low pH make it more difficult for the O2 to bind to the Hb?
- because H+ ions bind to globin (Bohr model)
When does Hb release more O2 which means a shift to the right in the O2-Hg dissociation curve?
- increased metabolism (exercise)
When there’s a shift to the left in the O2-Hg dissociative curve, what does this mean?
- it means that Hg is more saturated meaning it’s easier to load more O2 than unload O2
What causes left shifting in the O2-Hg dissociative curve?
- low PCO2
- “normal” pH
- low temp
Where does left shifting in O2-dissociation curve usually occur in the body? Why
lungs because of low temp due to evaporating and cooling
How do you calculate Partial pressure of CO2?
PCO2 = %ofCO2 in air x 760mmHg(atm)
How is CO2 carried in the respiratory system?
1) Dissolving in plasma
2) Binding to the Hg
3) As bicarbonate ions
What percentage of CO2 is dissolved in plasma?
8%
In terms of CO2 transportation, during external expiration, CO2 moves from?
from the blood to the lungs
What makes it possible for CO2 move down its pressure gradient (high to low) in external respiration?
the higher resting venous PCO2 which is 45 mmHg which moves to the lower arterial PCO2 which is 40 mmHg which moves to the alveolar PCO2 of 40 mmHg
CO2 diffuses from what to during external respiration?
capillaries to alveolus
In terms of internal respiration, describe the movement of CO2. Where does it come from and where does it go?
From cell —> ISF –> capillaries
What makes CO2 possible to move down its pressure gradient (high to low) in internal expiration. (talk about pressures)
the ICF PCO2 is higher than 45 mmHg which moves to the ISF PCO2 of 45 mmHg which moves to resting venous PCO2 pressure of 45 mmHg into the capillary
O2 and CO2 transport is done with diffusion. True of False
True
CO2 also gets carried by binding to Hg. CO2 is carried as?
carboaminohemoglobin
what percentage of CO2 is carried by the hemoglobin
20%
does CO2 bind better with deoxygenated blood or oxygenated blood? what does this say?
deoxygenated blood.
- that CO2 are readily available for binding or transport at tissue cells
CO2 can also carried in the respiratory system as?
bicarbonate
Inside the red blood cells at tissues, how does CO2 become bicarbonate?
it enters the RBC where it combines with H2O to produce H2CO3 (carbonic acid) this is aided by the carbonic anyhdrase which makes the reaction faster. But because H2CO3 is very unstable, it dissociates to produce H+ and HCO3- (bicarbonate)
what makes production of bicarbonate faster inside the RBC?
carbonic anhydrase enzyme
The H+ ions released by H2CO3 binds with what? What does it do?
binds with Hg and slight lowers the pH (acidic) but it can’t cause a significant difference because Hg is a buffer
Why cant the free H+ released by the carbonic acid inside the RBC change the pH drastically
because Hg is a buffer
The bicarbonate HCO3- created by the RBC goes to what? What does this mean?
it’s released in exchanged of Cl- to make more HCO3-
- it means that there is more Cl- present in the venous blood rbc
The exchange of HCO3- and Cl- in the RBC is called?
chloride shift
Inside the rbc at lungs, is the process of CO2 transportation still the the same? If not, what happens in this area then?
- no
- either the haldene effect
- or reversed chloride shift
What happens in the haldane effect
the O2 binds with deoxyHb (which could HbH and/or HbCO2) this creates HbO2 which binds with CO2 + H+ poorly therefore releasing CO2 and H+
What happens in the reverse chloride shift at the lungs? What does this say about concentration of HCO3 inside the rbc in the lungs and Cl- as well?
HCO3 re enters the RBC where it binds with H+ to create carbonic acid (H2CO3) via carbonic anhydrase enzyme which makes CO2 and H2O.
- its low. so HCO3 moves down its gradient (high to low) in exchange for Cl- (high to low)
For CO2 to get out, where does it originate
rbc –> plasma –> alveolar air –> out
What controls respiration in the body?
1) respiratory centres in medulla
2) pontine respiratory receptors
3) lung stretch receptors
4) voluntary control
5) chemical control (chemoreceptors)
What do the respiratory centres in the medulla do?
they set rhythm, depth and rate of breathing
What are the two groups of neurones present in the respiratory centres of medulla?
the ventral respiratory group (VRG) and the dorsal respiratory group (DRG)
What does the ventral neurone group do?
generates the rate of the inspiratory and expiratory neurones
What does the dorsal respiratory group do?
receives input from chemoreceptors and modifies VRG output
the inspiratory neurones of the respiratory centre in the medulla impulses down the spinal cord to which nerves? What do these nerves innervate
- phrenic nerve to innervate the diaphragm
- thoracic nerve to innervate the external intercostal muscle
The expiratory neurones found in the respiratory centres of the medulla do what?
they fire up to inhibit inspiratory neurones and allow expiration passively
In a quiet breathing, how long do inspirations and expirations last?
inspiration = about 2 secs expiation = about 3 secs
Are the VRG active during forced respiration? Yes or No? Why?
Yes to get more muscles moving
In the presence of alcohol or morphine or damage of VRG, what happens to respiration?
it may cease
What do the pontine respiratory centres do in respiration?
works with medullary centres to smoothen breathing
if pontine respiratory centres are damaged, what happens?
- breathing may become irregular and gasping
what do lung stretch receptors do in terms of respiration?
cause the hering-breuer reflex
where are stretch lung receptors found?
bronchi and bronchioles
What is the hering-breuer reflex?
- caused by the lung stretch receptors
- when they detect over stretching during inspiration —> they impulse via vagus nerve —> inhibit inspiratory neurone —> relaxes muscle resulting to expiration to prevent over inflation
What is working in voluntary control of respiration
primary motor cortex to skeletal muscle (corticospinal pathway) which bypasses medulla
If medulla is damaged, what does the primary motor cortex need to do?
remember breathing
When you hold in your breath voluntary, PCO2 increases, will medulla act up or not?
will act up
what are the two chemoreceptors working in respiration?
peripheral chemoreceptors & central chemoreceptors
Where are peripheral chemoreceptors found?
- carotid and aortic bodies
What are peripheral chemoreceptors sensitive to?
free H+ ions that affect pH
Peripheral chemoreceptors are not that sensitive too?
PCO2
If H+ Ions increases then ph lowers down which results to increase or decrease of ventilation rate ?
increase
can blood pH just change easily? why
no because blood is buffered
What stimulates the peripheral chemoreceptors?
when PO2 reaches about 50-60 mmHg and ends there, (emergency situation)
What does a low PO2 indicate?
a lung problem, low atm PO2
Where are central chemoreceptors found?
in the medulla oblangata
central chemoreceptors are dominant control. True of False?
True
central chemoreceptors respond indirectly to?
arterial PCO2
what is the resting arterial PCO2 at? What is it’s sent point?
40 mmHg
37 to 43 mmhg
What do central chemoreceptors detect in CSF?
H+ ions
CSF is poorly buffered. Yes or no? what does this mean about Central chemoreceptors?
- yes
- that small changes can stimulate central chemoreceptor response
how does temp affect ventilation?
- increased temp = increases ventilation
- decreased temp = decreases ventilation
how does increased emotion affect ventilation?
it increases it
What does increased proprioreceptor discharge do to ventilation?
it increases it
How does Blood pressure affect ventilation?
sudden increase in BP = increased vent
sudden decrease in BP = decreased vent
sudden pain causes what in ventilation?
stop vents
chronic pain does what to ventilation?
increases vent
sudden cold causes what in ventilation
temporarily stops it
stretch and anal sphincter causes what in ventilation?
increased vent
What causes hyperventilation
decreased PCO2 causes cerebral vasoconstriction therefore PO2 to brain decreases too which causes dizziness
What is hypoventilation
increase in arterial PCO2 causes increase in H+ which causes acidosis
What does CO poisoning do?
it decrease total number of O2 since CO binds 210x more strongly to Fe of Hg than O2
Binding of CO to Hb is called?
carboxyHb
Is there a change in PO2 and PCO2 in CO poisoning? What does this mean
no
- no change in ventilation
