CVP final Flashcards
What sets the basic drive of ventilation, activates the muscles of respiration, and has descending neural traffic to the spinal cord?
respiratory neurons in the brain stem
Pulmonary physiology includes the ventilation of alveoli coupled with perfusion of pulmonary capillaries and the exchange of _ and _ _?
oxygen, carbon dioxide
Which heart chamber has 100% of its’ output to the lungs via the pulmonary vessels?
right ventricle
Name the 3 centers for breathing in the respiratory control system.
- cerebral cortex & higher centers (like limbic system)
- mechanoreceptors
- chemoreceptors- monitor blood for mainly CO2 levels
Name 2 respiratory centers located in the medulla oblongata. Name 2 in the pons. Which of the 4 sets the drive of the ventilation at about 12-14 breaths/minute? Respiratory centers affect the _ & _ of ventilation?
medulla oblongata: dorsal & ventral medullary group
pons: pneumotaxic & apneustic centers
- dorsal medullary group sets the drive of the ventilation
- rate & depth of ventilation
The inspiratory muscles have what effect on the thoracic cage volume upon contraction? what about pressure? name some inspiratory muscles.
increase thoracic cage volume, decrease pressure;
inspiration: diaphragm, external intercostals, SCM, scaleni, levator costarum, ant & post superior serratus
Expiratory muscles have what effect on the thoracic cage volume upon contraction? pressure? Name some expiratory muscles. Are expiratory muscles normally active or passive?
decrease thoracic cage volume, increase pressure;
expiration: abdominals, internal intercostals, transversus thoracis, pyramidalis, post inferior serratus
- expiratory muscles are typically passive because the lungs have a natural recoil tendency
On inspiration, how much of the total body energy is used? Comment on how the diaphragm works upon inspiration.
3% used; the volume increases in the thoracic cage by dropping the floor out of the diaphragm
Which expiratory muscle is a stabilizer of the lumbar spine, and when weak, can result in low back pain?
transversus abdominis
What is it that keeps the lung inflated against the chest wall? What values does it vary between?
the pleural pressure-negative pressure between parietal & visceral pleura that keeps the lung inflated against the chest wall; varies between -5 and -7.5 cm H2O (inspiration to expiration)
In alveolar pressure, it is _ during inspiration and _ during expiration? When they’re equal, the flow is 0. This happens 2x per cycle, which is at the beginning and end of normal expiration.
subatmospheric during inspiration, supra-atmospheric during expiration
This pressure is a measure of the recoil tendency of the lung. It is the difference between alveolar pressure and pleural pressure. When does it peak?
transpulmonary pressure; peaks @ end of inspiration
Name the phenomenon being described. At the onset of inspiration, the pleural pressure changes at a faster rate than lung volume does.
hysteresis “slinky dog”
Is it easier to inflate an air-filled lung or a saline filled lung and why?
easier to inflate a saline filled lung because surface tension forces have been eliminated in the saline filled lung
As pleural pressure becomes more negative, what happens to transpulmonary pressure?
it increases (since transpulmonary pressure is difference between alveolar pressure & pleural pressure)
The compliance of a lung is its’ ability to expand and is figured by the change in lung volume divided by the change in _?
pleural pressure
What effect does the thoracic cage have on the lung?
It reduces compliance by about 1/2 around functional residual capacity (at the end of a normal expiration). Compliance is greatly reduced at either high or low lung volumes
In the work of breathing, what accounts for most of the work normally (roughly more than 90% of the work)?
compliance work (elastic work)
Besides the compliance (elastic) work of breathing, what are some other forms of work involved?
tissue resistance work (viscosity of chest wall & lung); airway resistance work; energy required for ventilation is about 3-5% of total body energy
During inspiration, comment on lung volume, size of airway caliber, and the amount of airway resistance.
increased LV, increased airway caliber, decreased airway resistance
During expiration, comment on lung volume, size of airway caliber, and the amount of airway resistance.
decreased LV, decreased airway chamber, increased airway resistance
This term for normal breathing is about 12-17 breaths/min, 500-600 ml/breath.
eupnea
This term is an increase in pulmonary ventilation matching increased metabolic demand (same CO2 levels), such as during exercise.
hyperpnea
This term is when an increased pulmonary ventilation exceeds metabolic demand (a decrease in CO2).
hyperventilation
This term is when a decreased pulmonary ventilation is less than metabolic demand (an increase in CO2).
hypoventilation (common during druggies taking depressants)
This term means an increased frequency of respiratory rate.
tachypnea
This term means an absence of breathing. Give an example.
apnea (sleep apnea)
This term means difficult or labored breathing.
dyspnea
This term is dyspnea when recumbent, and is relieved when one stands upright. aka “positional dyspnea”. Which diseases exhibit it?
orthopnea; CHF, asthma, lung failure
Lungs have a natural tendency to _ as the surface tension forces are 2/3 and the elastic fibers are 1/3. However, the lungs are kept against the chest wall by negative pleural pressure “suction”.
collapse
If the pleural space communicates w/the atmosphere (pleural pressure =atmospheric pressure), the lung will collapse. What are some causes of collapsed lungs?
puncture of the parietal pleura (sucking chest wound), erosion of visceral pleura (allows air in pleural cavity), and also if a major airway is blocked the air trapped distal to the block will be absorbed by the blood & that segment of the lung will collapse
This is a thin layer of mucoid fluid that provides lubrication, is a transudate (ISF + protein), and the total amount is only a few mL’s. Excess is removed by _ from which areas?
pleural fluid; excess is removed by lymphatics from mediastinum, superior diaphragm surface, lateral surfaces of the parietal pleura, al helping to create negative pleural pressure “suction”
T/F: lymphatic drainage will decrease with increased venous pressure?
TRUE
What is a collection of large amounts of free fluid in the pleural space? aka edema of pleural cavity. What are some possible causes?
pleural effusion; causes-blockage of lymphatic drainage, cardiac failure (resulting in increased capillary filtration pressure), reduced plasma colloid osmotic pressure (starving people), and infection/inflammation of the pleural surfaces which break down capillary membranes
T/F: surfactant = pleural fluid?
False. surfactant is a detergent, not equivalent to pleural fluid.
This substance reduces tension forces by forming a monomolecular layer between aqueous fluid lining alveoli & air, preventing a water-air interface.
surfactant
Surfactant is produced by what cells? it is a complex mix composed of which substances?
produced by type II alveolar epithelial cells; complex mix of phospholipids, proteins, & ions
Briefly describe the role of surfactant using the Law of Laplace.
Without surfactant, smaller alveoli have increased collapse pressure & would tend to empty into larger alveoli, making the big bigger and the small smaller. Surfactant automatically offsets this physical tendency: as the alveolar size decreases, surfactant is concentrated, which decreases surface tension forces, offsetting the decreased radius size.
In the stabilization of alveolar size, the size of one alveoli is determined in part by surrounding alveoli. what is this term?
interdependence
This static lung volume is the amount of air moved in or out each breath (from peak-trough).
tidal volume (TV)-roughly 500 mL
This static lung volume is the maximum volume one can inspire above normal inspiration.
inspiratory reserve volume (IRV)- roughly 3,000 mL
This static lung volume is the maximum volume one can expire below normal expiration.
expiratory reserve volume (ERV)-roughly 1,100 mL
This static lung volume is the volume of air left in the lungs after maximum expiratory effort, and is the hardest to measure.
residual volume (RV)- roughly 1,200 mL
This static lung capacity is the volume of air left in the lungs after a normal expiration; the balance point of lung recoil & chest wall forces. a combination of ERV & RV.
functional residual capacity (FRC)- combo of ERV & RV.
-FRC is typically about 93% in the alveoli
This static lung capacity is the maximum volume one can inspire during an inspiratory effort.
inspiratory capacity (IR)- combo of TV + IRV
This static lung capacity is the maximum volume one can exchange in a respiratory cycle.
vital capacity (VC)- a combo of IRV + TV + ERV (maximum to minimum)
This static lung capacity is the air in the lungs at full inflation?
total lung capacity (TLC)- a combo of IRV, TV, ERV, RV
Of the static lung volumes & capacities, which 3 cannot be determined by basic spirometry. What then are they determined by?
RV, FRC, TLC; determined by helium delution method
What is the helium delution method solving for? What is the formula used?
solving for FRC;
FRC= (helium initial/helium final)-1, then multiplied by the initial volume in the jar
Restrictive lung conditons will reduce which lung volumes/capacities? What happens w/a restrictive lung condition? how does one happen?
VC, IRV, IC; an inability to expand the chest wall to get breath in; can happen w/subluxated ribs, black lung, or too tight of a corset
What is a determination of how fast you can get rid of the vital capacity from your lungs and is compromised w/obstructive conditions resulting in decreased air flow?
pulmonary flow rates
Name 4 pulmonary flow rates.
- minute respiratory volume (RR * TV)
- forced expiratory volumes (FEV’s)- timed; FEV/VC
- peak expiratory flow
- maximum ventilatory volume
How many generations of branching are there considered in the lung? Name the chain from the trachea down to the 300 million alveoli.
20 generations of branching; trachea (2cm squared)–bronchi (first 11 generations of branching)-bronchioles, which lack cartilage (next 5 generations of branching)-respiratory bronchioles, where some gas exchange can take place (last 4 generations of braching)-alveolar ducts give rise to alveolar sacs which give rise to 300 million alveoli (SA 50-100 meters squared)
What is the area where gas exchange cannot occur, which includes most of the larger airways?
dead space
what is the anatomical dead space, and how much?
the airways; 150 mL (75 mL per lung)
What is the physiological dead space?
anatomical dead space & non-functional alveoli
At the end of a normal expiration most of the FRC is at the level of the _? What is the typical turnover of alveolar air?
alveoli; 6-7 breaths typical turnover of alveolar air
What is the typical rate of alveolar ventilation (air flowing to alveoli)? What is the typical pulmonary blood flow (cardiac output)? What is the ventilation/perfusion ratio typically?
4L/min; 5L/min; 4/5 = .8 ventilation/perfusion ratio
In terms of the autonomic efferent control of the airways, the SNS has beta receptors that cause dilatation. Does the direct/indirect effect predominate?
the direct effect is WEAK due to sparse innervation; the indirect effect predominates via circulating norepinephrine
What effect does parasympathetic muscarinic effects cause?
constriction
What are NANC nerves? Inhibitory ones release what, resulting in which effects? stimulatory NANC nerves cause what?
non-adrenergic, non-cholinergic nerves; inhibitory NANC nerves-release VIP & NO, causing bronchodilitation; stimulatory-bronchoconstriction, mucous secretion, vascular hyperpermeability, cough, vasodilation “neurogenic inflammation”
In terms of the autonomic Afferent nerves, what are the slow-adapting receptors associated with? Which receptors are senstive to mechanical stimulation, protons, low chloride solutions, histamine, cigarette smoke, ozone, serotonin, and PGF?
slow-adapting receptors: associated w/smooth muscle of proximal airways & stretch receptors (involved in reflex control of breathing & cough reflex); rapidly adapting receptors
In the autonomic control of the airways, these contain neuropeptides (like substance P, neurokinin A, calcitonin gene-related peptide), is selectively stimulated by capsaicin (red pepper), and is also activated by bradykinin, protons, hyperosmole solutions & cigarette smoke.
C-fibers (high density)
Locally, histamine binds preferentially to which receptors and facilitates constriction? Which prostaglandin series is for constriction?
H1 receptors; Prostaglandin F series
Environmental pollution, like smoke, dust, sulfur dioxide, and some acidic elements in smog will elicit what effect on the airways? What is this mediated by?
constriction; mediated by parasympathetic reflex & local constrictor responses
What is the normal level of bicarbonate (HCO3-)? Metabolic acidosis will stimulate what? What regulates bicarbonate?
24 mEq/L; metabolic acidosis (HCO3- < 24) stimulates ventilation; kidney regulates bicarbonate
What is the normal level of CO2? Respiratory acidosis will have what effect on ventilation? What regulates CO2?
40 mmHg; respiratory acidosis(CO2 > 40) will stimulate ventilation; Lung regulates Co2
An accumulation of CO2 leads to _ (a _ pH)?
acidosis; decreased pH
Compared to the aorta, how thick is the pulmonary artery? What about the RV compared to the LV? Which has a larger lumen; systemic or pulmonary arteries? why?
pulmonary artery wall 1/3 as thick as aorta; RV 1/3 as thick as LV; all pulmonary arteries have larger lumens, making them more compliant, operable under a lower presure, and can accomodate 2/3 of the stroke volume from the right ventricle
How do pulmonary veins compare to systemic veins?
pulmonary veins are shorter, but have a similar compliance compared to systemic veins
How much blood volume is found in the pulmonic system? _ stenosis can increase the pulmonary volume 100%? Shifts in blood volume have the greatest effect on which circulation system?
450 ml (9% of total blood volume); Mitral stenosis (going into LV) can increase the pulmonary volume 100%; shifts have a greater effect on pulmonary circulation by virtue of size