Ventilatory system Flashcards
What is the carina?
- bifurcation of primary bronchi
- produce cough reflex
What are the three branches of the bronchi and what do they supply?
- primary: supply lungs
- Secondary: supply lobes
- Tertiary: supply lobules
What are the inspiratory muscles?
- diaphragm
- ext. intercostal muscles
- sternomastoids
- serratus anterior
- scalene
What are the expiratory muscle?
- abdominal and internal costals produce forceful expiration.
- generally passive at rest.
What are the branchings of the bronchioles?
- terminal and respiratory
- with smooth muscle but no cartilage
At what point in the respiratory tract do we begin to gain control of the amount of air we can take in?
The area of where we start to gain control of how much air is being passed for respiration.
Define total lung capacity.
-maximum volume of gas the lungs can hold
What helps to form the total lung capacity?
-non overlapping compartments form lung volumes
Tidal volume is what and what volume?
500mL
volume inspired and expired with breathing
Inspiratory reserve volume?
- 3000mL
- amount of air that can be inspired in addition to tidal volume
- requires forced inspiration to do so
Expiratory reserve volume?
- 1100mL
- amount of air expired at end of tidal volume by forced expiration
Residual volume?
1200mL
-amount of air remaining in the pulmonary system after forced expiration
Vital capacity?
4600mL
- sum of all air inspired/expired
- max inspiration to max expiration
Total lung capacity
sum of all volumes.
- includes vital capacity + residual volume
Inspiratory capacity?
sum of volume above resting capacity
-therefore is tidal volume + inspiratory reserve volume
Functional residual capacity
-expiratory reserve volume + residual volume
the sum of volume below resting capacity
Describe minute volume and the equation to describe it.
- volume of gases moved in or out of lungs per minute
- V= breath per minute * tidal volume
What is alveolar ventilation and the equation to describe it?
- volume of gases that enter spaces participating in gas exchange per minute
- (bpm)*(TV-DS)
What is anatomic dead space?
-the space where air remains in the trachea, bronchi, bronchioles
What is physiological dead space?
-anatomic dead space+ventilated alveoli with poor perfusion
What is pleural pressure?
-fluid between parietal and visceral pleura
What is alveolar pressure?
-pressure inside the alveoli
The transpulmonary pressure?
-difference between the alveolar pressure and the pleural pressure
Total tidal volume is 0.5L so what is the amount of respirated and perfused alveoli in normal individual with dead space of .15L?
-0.35L
The amount of CO2 in the arterial blood will be equal to what?
arterial CO2 level equals the amount of CO2 in the lungs
How can we verify that dead space is the eqaution that is used?
- dead space air does not participate in exchange and has negligible CO2
- blood gases equilibrate during gas exchange in capillaries, therefore blood CO2 equals the CO2 in region of the lungs
What happens to the pressure in the alveoli during inspiration/ expiration?
- inspiration: decrease of pressure
- expiration: increase of pressure
What is the compliance of the lungs?
-the extent to which lungs will expand for each unit incrase in transpulmonary pressure
Compliance is a measure of what?
-the expansibility of the lungs and the trachea
What is a major component that allows the lungs to function normally in air, and not at all in water?
Saline helps to reduce the amount of surface tension that opposes the movement of the lungs
What component is similar to saline in the lungs that reduce surface tension and improve the ventilatory efficiency?
-surfactant
Surfactant contains what three components secreted by what cells?
- dipalmitoylphosphatidylcholine
- surfactact apoproteins
- Ca ions
- produced by type II alveolar cells.
What is the equation for surface tension on the pressure?
pressure= 2* surface tension/ alveolar radius
By how much does surfactant reduce the surface tension in the lungs?
-reduces by 4.5 times.
What cells, muscles and cartilage are in the trachea?
- pseudostratified ciliated columnar with goblet cells
- cartilaginous rings
- trachealis muscle
What are the high pressure/ low flow areas?
thoracic aorta, bronchial arteries, trachea, bronchial tree, adventitia, CT
What are the low pressure/ high flow areas of the lungs?
pulmonary artery and branches to the alveoli
What is the pressure gradient in the pulmonary system?
7 mmHg
True False:
There is 9% of total blood volume of the body in the lung, where 70mL is in the pulmonary calillaries
True
What happens if the left side of teh heart were to undergo a failure?
- will increase pulmonary circulation, and BP
- there will be little effect in the systemic, due to the vast amount of fluid in that system
True, False:
2% of the blood in the systemic arteries is blood that bypasses the pulmonary capillaries, and therefore contains less oxygen per deciliter than blood in equilibrium with alveolar air.
True
Where does the blood in the physiologic shunt come from?
-this blood is supplied from the lung parenchyma and the left side of the heart
What component contributes to the fact that arteriole blood has less oxygen per liter than in the alveolar capillaries?
-the physiologic shunt
When oxygen concentration is at 73mmHg or lower what happens to the vasculature in the lungs?
- blood vessels constrict by unknown method
- the poorly ventilated alveoli increase the blood to higher functioning alveoli
What are the different zones of blood flow to the lungs and what can affect this distribution?
- zone 1: when standing there is no blood flow, and alveolar pressure is higher than capillary pressure (pathological)
- Zone 2: intermittent flow only during systole
- Zone 3: continuous blood flow
In a normal individual what type of zone can the lungs be divided into while standing?
- apices have zone 2, and lower 2/3 will be a zone 3.
- strenuous exercise can convert all lobes/sections into zone 3
What happens when one lungs blood supply is obstructed and what feature contributes to allow this?
- unobstructed lung increases blood flow 2x
- this is due to passive dilation based on high level of capacitance of the pulmonary vessels
What hormones constrict the pulmonary arterioles?
-norepinephrine
-einephrine
angiotensin II
-prostaglandins
What agents help dilate the pulmonary arterioles?
- isoproterenol
- acetylcholine
What agents cause venule constriction of the pulmonary system?
- serotonin
- histamine
- E coli endotoxin
The sympathetic vasoconstrictor nerve fibers outflow from the cervical sympathetic ganglia and have what effect on vasculature?
-this decreases the pulmonary blood flow by 30% and mobilizes the blood from the pulmonary reserve to restore blood flow
What happens to allow for increased blood flow through the pulmonary system during exercise?
- opening of previously closed capillaries
- distension of the capillaries
- -overall this prevents large increases of pressure in the alveolar capillaries
What are the benefits for the heart of opening new alveolar capillaries and improving there distensibility?
-prevents increased afterload of the heart, and therefore preventing pulmonary edema.
What is the normal left atrial pressure?
6 mmHg
If the left atrial pressure is 40-50 mmHg, what is likely to occur?
left sided heart failure
An increase of 8mmHg in the left atria, is enough to cause what effect?
-increase the pulmonary arterial pressure
The pulmonary capillaries are leaky to protein molecules and contribute to what type of colloid osmotic pressure difference when compared to the peripheral tissue?
-the pulmonary interstitial tissue is 2 times higher than peripheral due to higher levels of colloid osmotic pressure
When does pulmonary edema occur within a matter of minutes that the lymphatic vessel are unable to compensate for?
- left sided heart failure or mitral valve disease
- damage to pulmonary blood capillary membranes
What happens when capillary pressure remains chronically elevated for 2 or more weeks?
- the compensatory mechanisms have time to adjust and prevent death.
- acute mechanisms will not be able to compensate as well.
What are the most common causes of pleural effusion?
- block lymphatic drainage from the pleural cavity
- cardiac failure
- reduced plasma colloid osmotic pressure
- infection/inflammation
Pleural effusion is also know as?
lung collapse when pleural space pressure elevates above -4mmHg
True or False:
Hypoxia increases pressure in the pulmonary artery which is possibly due to release of prostaglandin.
True
If blood flow to a section of the lung, what are the following effects that will occur?
- alveolar PCO2 is decreased
- this causes constriction of the bronchi to that section of the lung
What are the main components of air?
- 09% N
- 95% Oxygen
- 93% Ar
- 03% Carbon Dioxide
What are is the only gas that exists in equilibrium between the atmosphere and the alveoli?
carbon dioxide
The total pressure exerted by the mixture of non-reactive gasses is equal to the sum of the partial pressures of individual gasses?
Dalton’s Law
Pressure and Volume are inversely proportional when an ideal gas is kept at a constant amount and constant temperature.
Boyle’s Law
What contributes to the drop of gas concentrations in the alveoli compared to the atmosphere?
the alveoli contain water vapor and offset the ‘equilibrium’ between atmosphere and alveolar gas concentration
At constant temperature, the amount of a given gas dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
Henry’s Law
What is the ideal gas law?
P=nRT/V
P= pressure n= moles R= gas constant T= temperature in Kelvin V=volume
Henry’s Law is really mostly concerned with the solubility coefficient, which contributes to the ability of the gas to diffuse when it is dissolved in a liquid.
Class presentation
Why will carbon dioxide exert less partial pressure than oxygen?
-carbon dioxide has a higher solubility and will therefore have a lower exertion of partial pressure
The functional residual capacity of the lungs on average is 2300mL, and only has how much air inspired and expired?
350mL of air is brought into the alveoli
What controls the oxygen concentration in the alveoli and its partial pressure?
- rate of absorption of oxygen into the blood
- rate of new oxygen that enters into the lungs
Why will alveolar ventilation not increase above 149mmHg?
The highest amount of oxygen partial pressure is 149mmHg in the atmosphere. Therefore it is the maxmimum amount that could be absorbed
What is the partial pressure of carbon dioxide concentration in the alveoli controlled by?
- if excretion increases in tissues then PCO2 increases
- PCO2 decreases as ventilation rate increases
How thick should a membrane have to be in order to infere with gas exchange rates?
2-3X the normal thickness based on factors like edema, or fibrosis
What is the primary reason people with COPD has poor gas exchange?
Membrane thickness has increased 2-3X the normal thickness
What is Va/Q ratio?
-alveolar ventilation/ blood flow
What is the normal range for Va/Q?
Va/Q= 0.8= 4/5
Where in the capillary system is gas exchange considered complete?
- initial third of the capillary
If there is a pulmonary obstruction what happens to the Va/Q ratio?
-becomes 0 as Va=0 and therefore the blood gas composition remains the same. No gradient being created to drive exchange of gases
What happens to the Va/Q when there is a vascular obstruction like an embolism?
- Va/Q= infinity as Q=0
- this prevents gas exchange, as no blood can contact the gases
- this is considered a physiological shunt
With a vascular obstruction what happens to the alveolar partial pressures of CO2 and O2?
- PCO2= 0.0
- PO2 =149
During normal alveolar perfusion PCO2 and PO2 are able to reach what levels?
- PCO2= 40mmHg
- PO2= 104mmHg
What is the best way to describe shunted blood?
-a certain amount of venous blood in the pulmonary capillaries that does not get oxygenated, normally occurring when Va/Q is below normal (0.8)
The thin descending loop of henle is highly permeable to which components?
water
Aldosterone is important for sodium reabsorption and potassium secretion, what does it target to do so?
principal cells
The macula densa is found in what part of the renal tubule?
distal convoluted tubule
