Unit 3: Pulmonary Physiology Pt 1 Flashcards
What sets the basic drive for ventilation?
respiratory neurons in the brain stem, the Dorsal Respiratory Group
What are three things the Respiratory neurons in the brain stem, the Dorsal Respiratory Group, does?
- sets basic drive of ventilation
- descending neural traffic to spinal cord
- activation of muscles of inspiration
What does the alveolar pressure oscillate around?
atmospheric pressure
When does alveolar pressure = atmospheric pressure?
at the end of inspiration or expiration
When is alveolar pressure less than atmospheric pressure?
during inspiration
When is alveolar pressure greater than atmospheric pressure?
during expiration
What is transpulmonary pressure and when is it the greatest?
= a measure of the net collapsing force, or recoil pressure (diff b/w alveolar pressure and pleural pressure)
at the end of inspiration
When is pleural pressure more negative..during inspiration or expiration?
inspiration—> creates a negative pressure that creates a suction and keeps lungs pulled to wall
What sensory organ will detect changes in blood PCO2, PO2 and pH?
chemoreceptors
During Expiration what is happening to the levels of O2 and CO2?
What about inspiration?
O2 is decreasing and CO2 is increasing
O2 is increasing and CO2 is decreasing
Where are the respirator centers located?
in brain stem (MO)
- Dorsal and Ventral Medullary group
- Pneumotaxic and Apneustic centers
What three things are the respiratory centers influenced by?
- higher brain centers–> cerebral cortex
- peripheral mechanoreceptors
- peripheral and central chemoreceptors
What do the respiratory centers affect about ventilation?
affect rate and depth of ventilation
Do inspiratory muscles increase the thoracic cage volume or decrease it? What do expiratory muscles do?
inspiratory–> increase thoracic cage volume
expiratory –> decrease thoracic cage volume
What are the muscles of inspiration?
- Diaphragm
- External Intercostals
- SCM
- Ant. Serrratus
- Scaleni
- serratus posterior superior
- Levator Costarum
What are the muscles of Expiration?
- Rectus abdominus
- external and internal obliques
- transverse abdominis*
- internal intercostals
- serratus posterior inferior
- transversus thoracics
- pyramidal
What muscles drops the floor of the thoracic cage in order to increase thoracic cage volume?
diaphragm
What do all the muscles of inspiration have in common (except the diaphragm)?
they lift the rib cage
the diaphragm drops floor of thoracic cage
What percentage of the Total Body Energy do the muscles on inspiration use?
3%
T/F. Expiration is passive under resting conditions and is associated with recoil of the lungs.
True
What are the three considerations for the movement of air in and out of the lungs?
- Pleural Pressure
- Alveolar Pressure
- Transpulmonary Pressure
What is the negative pressure b/w the parietal and visceral pleura that keeps lulngs inflated against the chest wall?
Pleural presssure
What does the pleural pressure vary b/w?
-5 and -7.5 cm (inspiration to expiration)
What is the alveolar pressure compared to the atmospheric pressure during inspiration and expiration?
inspiration–> subatmospheric
experation–> supra-atmospheric
What is the difference called b/w alveolar P and pleural P and is the measure of recoil tendency of the lung called?
Transpulmonary pressure
When is the Transpulmonary Pressure increased? Decreased?
increased–> during inspiration
decreased–> during expiration
How do we max out or Transpulmonary pressure?
lungs fully inflated; so breath in as much air in as possible
What is the compliance of the lung “equation”?
change of volume / change of pressure
What is the term for the idea that at the onset of inspiration the pleural pressure changes at faster rate than lung volume?**
“hysteresis” –(slinky-dog affect)
Is it easier to inflate a saline filled lung or an air filled lung? Why?
saline filled lung b/c surface tension forces have been eliminated in the saline filled lung
How is the visceral pleura of the lung held to the parietal pleura?
by negative pleural pressure
What pleura is attached firmly to the rib cage and reflects back at the hilum to form the visceral pleura?
parietal pleura
What exists between the pleural that creates a suction such that visceral pleura will follow the parietal pleura?**
a negative pleural pressure*
–expansion of the thoracic cage will increase lung volume overriding the natural recoil tendency of the lung
When all respiratory muscles are relaxed, what does the volume in the lungs equal?
Functional Residual Capacity (FRC)
When are Chest wall forces (CWF) opposite but equal to Lung recoil forces (LRF)?**
at the end of normal expiration
How much does the effect of the thoracic cage on the lung, reduces compliance by around functional residual capacity?
(so at the end of normal expiration)
reduces by about 1/2
How is compliance affected at high or low lung volumes?
is it greatly reduced
What normally accounts for more of the work of breathing?**
compliance work (elastic work)
What three things are considered for the work of breathing?
- compliance work (most of it)
- Tissue resistance work (viscosity of chest wall and lung)
- Airway resistance work
What is the percentage of total body energy used by breathing, is it primarily inspiration or expiration?*
3-5% and it primarily inspiration*
During inspiration how is the airway resistance work in bronchioles impacted?
decreased during inspiration
increase lung vol–> decease airway caliber –> decrease airway resistance
During expiration how is the airway resistance work in bronchioles impacted?
increased during expatriation
decrease lung vol –> decrease airway caliber –> increase airway resistance
What is normal breathing called? and what is the normal rate of breaths per minute? What is the arteriol CO2 equal to?**
Eupnea (12-17 B/min)
Arterial CO2 = 40 mmHg*
What is it called when we increase pulmonary ventilation to match the increase in metabolic demand? What does Arteriol CO2 equal?
Hyperpnea
Arterial CO2 = 40 mmHg (still same as Eupnea)
What is it called when increased pulmonary ventilation is greater than metabolic demand? What is the Arterial CO2?
Hyperventilation
decrease arteriol CO2 to less than 40 mmHg
What is it called when decreased in pulmonary ventilation is less than metabolic demand? What is the Arterial CO2 equal?
Hypoventilation
increase arteriol CO2 to more than 40 mmHg
What is the term for increased blood levels of CO2?
Hypercapnia
abnormal high levels of CO2 in blood
What is the term for increase in frequency of respiratory rate?
Tachypnea
What is the term for absence of breathing?
Apnea (e.g. Sleep Apnea)
What is the term for difficulty or labored breathing?
Dyspnea
What is the term for when one has dyspnea when recumbent (lying down), and is relieved when upright?
Orthopnea
Ex: congestive heart failure, asthma, lung failure
T/F. Lungs have a natural tendency to collapse.
True
What is normally responsible for 2/3 of the collapse tendency of the lung? What is the other 1/3?
Surface tension forces
1/3 elastic fibers
What will happen when the pleural space communicates with the atmosphere?
lung will collapuse
i.e. pleural pressure = atmospheric pressure
What could cause a lung to collapse?
- Puncture of parietal pleura
- Erosion of visceral pleura
- Major airway is blocked, the air trapped distally will be absorbed by blood and segment of lung will collapse
How many bronchopulmonary segments does each lunch have?
10
How many lobes does the right lung have? left?
right = 3 lobes left = 2 lobes
What occurs when there is a loss of negative pleural pressure?
lung collapses!
- separation of parietal and visceral pleura
- chest wall expands and diminished Chest Wall Force and Lung Recoil Force
(pleural cavity will increase in space)
What is in the pleural cavity?
pleural fluid = thin layer of mucoid fluid
What does the Pleural Fluid in the pleural cavity provide? What is it made of? How much is the total amount?
- lubrication
- transudate (interstitial fluid + protein)
- total amount is only a few ml’s
How is excess pleural fluid removed? Why is this good?
by lymphatics on:
- mediastinum
- superior surface of diaphragm
- lateral surfaces of parietal pleura
~ helps create negative pleural pressure
What is the collection of large amounts of free fluid in pleural space called?
Pleural Effusion
- edema of pleural cavity
What are possible causes of Pleural Effusion?
(collection of large amounts of free fluid in pleural space)
- blockage of lymphatic drainage
- cardiac failure
- reduced plasma colloid osmotic pressure
- infection/inflam of pleural surfaces–> breaks down membranes
What reduces the surface tension forces by forming a monomolecular layer b/w aqueous fluid lining alveoli and air and preventing a water-air interface?
Surfactant
What produces surfactant?
type II alveolar epithelial cells
What is surfactant made up of?
complex mix of phospholipids, proteins, and ions
– dipalmitoyl lecithin, surfactant apoproteins, Ca++ ions
What is the term for the size of one alveoli determined in part by surrounding alveoli?
Interdependence (can’t expand unless rest of alveoli around it decrease in size)
What does the Law of Laplace have to do with in the lungs? What is the equation for it?
the role of surfactant
P = 2T/r
P = collapse pressure T = surface tension r= radius
(think about blowing up a balloon and how it gets easier once larger, but when smaller it collapses easier)
Without surfactant what would happen to the smaller alveoli that have increased collapse pressure?
they would tend to empty into larger alveoli
Law of Laplace
How does surfactant offset the physical tendency of what the Law of Laplace proves?
as the alveolar size decreases, surfactant is concentration –> which will decrease surface tension forces–> off-setting the decrease in radius
What is the amount of air moved in or out each breath?*
Tidal Volume (500ml) –> (smallest number of static lung volumes**
What is the maximum volume one can inspire above normal inspiration?*
Inspiratory Reserve Volume (3000ml) –> (largest number of static lung volumes)
What is the maximum volume one can expire below normal expiration?*
Expiratory Reserve Volume
What is the volume of air left in the lungs after maximum expiratory effort?*
Residual Volume
What cannot be determined with basic spirometry?**
- Residual volume (air can never get ride of)
- Functional Residual Capacity
- Total Lung Capacity
(anything that contains RV_
What is the volume of air left in the lungs after a normal expiration, and is the balance point of lung recoil and chest wall forces?**
Functional Residual Capacity
Residual Volume + Expiratory Reserve Volume
What is the maximum volume one can inspire during an inspiration effort?
Inspiratory Capacity
Tidal Volume + Inspiratory Reserve Volume
What is the maximum volume one can exchange in a respiratory cycle?
Vital Capacity
IRV + TV + ERV
What is the air in the lungs at full inflation?
Total Lung Capacity
IRV + TV + ERV + RV
What three volumes of the lungs will decrease with restrictive lung conditions?
- VC (vital capacity)
- IRV (inspiratory reserve volume)
- IC (inspiratory capacity)
slide 33-34
How are Pulmonary Flow Rates compromised?
with obstructive conditions
slide 35 ??