Final Review - Personalized Pt 1 Flashcards
Adult larynx position
3rd - 6th cervical vertebre
larynx position at birth
C3-4
Normal A-O extension
35 degrees
Prognathism
protruding jaw/mandible
Narrowest portion of adult and child airway
adult - glotis
child - cricoid ring
cartilages of larynx
3 paired, 3 unpaired
paired - arytenoid, corniculate, cuniform
unpaired - epiglottis, thyroid, cricoid
Intrinsic Muscles (2 sets)
1 - alters size and shape - aryepliglottic, thyroepiglottic, arytenoid
2 - move true vocal cords
SLN
Internal - sensation causes spasm
External - motor innervation of cricothyroid muscle
cricothyroid muscle
innervated by external SLN
tensor of VC, elongates
Posterior cricoarytenoid
abductor
innervated by RLN
(please come apart)
thyroarytenoid
relaxor of VC
RLN
innervated all of larynx except cricothyroid muscle
-sensory information for below cords
Tracheal anatomy
20-25 c shaped cartilages
C6-T5, divides at T5-7 (~25 cm from teeth)
R mainstem
straighter, larger
Conducting Airways
anatomical deadspace, ventilation but no perfusion
-last site at terminal bronchiole which has gas no exchange
goblet cells
mucous producers, increase with injury
clara cells
in small bronchioles that do not have goblet cells, produce watery substance
Type 1 pneumocyte
increase surface area
cannot heal quickly
95% of wall
Type 2 pneumocyte
secrete surfactant
repairs epithelium
can regenerate to Type 1
usually mature at 24 weeks gestation
surfactant
decrease surface tension
prevent alveolar collapse/promotes stability
prevents transudation of fluid into alveoli
-DPPC, hydrophobic and hydrophillic opposing ends
Lung weight
1.5% of body weight
1 kg in 70 kg pt
Alveolar surface area
70 meters squared internal surface area
40 x external body surface area
short diffusion pathway
Inspiration
active phase
phrenic nerve (C3, 4, 5) innervates diaphragm
*negative pressure ventilation
Intercostal Nerves
T1-11, send signals to external intercostal muscles
Diaphragm
responsible for 75% of inspiratory effort
contraction - downward and forward movement
ribs lifted and moved outward
*down 1 cm during normal, can but up to 10 cm forced
-denervated = paradoxical chest movement
External Intercostals
- responsible for 25% respiration
- originate from ventral rami of T1-11
- contraction - ribs up and forward
- denervated causes feeling of dyspnea
Accessory Muscels
-assist forced inspiration
scalene muscles - elevated first 2 ribs
sternocleidomastoid - raise sternum
Expiration
passive
muscles - abdominal and internal intercostals
Transpulmonary pressures
pressure different between intrapulmonary and intrapleural
Recoil Pressure
elastic forces
Lung Pleura
visceral - thin, serosal that envelopes lungs
parietal - lines inner surface of chest wall
Pleura Pressure
-5 cm H20 at rest,
during inspiration -7.5
FRC
2.5 L
ERV + RV
What can spirometry not measure?
RV, so FRC and TLC cannot be determined this way. must use helium dilution or nitrogen washout
Compliance reduced
higher or lower lung volumes
venous congestion
atelectasis or fibrosis
Compliance increased
age, emphysema
old socks
Is inspiratory and expiratory compliance the same?
no
Elastic forces of lung
elastic tissue - elastin and collagen, natural state is coiled
surface air-fluid interface - 2/3 of elastic force in lung
surfactant
Physiological dead space
anatomical + alveolar deadspace
anatomical deadspace = ~30% TV
Closing volume
volume of lung at which small airways close
CV > FRC, then small airways collapse during normal TV
*bernouli
Turbulence
directly proportional to density, velocity & resistance
Chief site of airway resistance
medium sized bronchi
Factors determining airway resistance
lung volume, bronchial smooth muscle & density/viscosty of inspired gas
Work, of breathing
W = pressure x volume
-hyperventilation increases o2 cost
Minute Ventilation
TV x frequency
amnt of air conducted into lungs per minute
Poiseulle’s Law
decreased radius by 16% = double resistance
decrease radius by 50% = increase resistance 16 fold
Pulmonary circulation
low pressure, low resistance system
PA is thin walled (1/3 thickness of aorta), very compliant
Fick’s Principle
determining CO, bloodflow through lungs/min
Extra-alveolar vessels
“store blood”
-not directly affected by lung pressures
bronchial vessels - oxygenated blood from systemic circulation (not for gas exchange), 1-2% of CO, empty into LA
Capillary Resistance
alveolar network dimensions are not regulated by autonomic or humoral control
alveolar capillary walls - contribute 40% of resistance
alveolar arterioles - contribute 50% resistance
Pulmonary Capillaries
70 ml volume at rest
200 ml maximal anatomical volume
Bronchial Circulation
blood flows at systemic pressures, 1-2% of CO
50% returns via azygos veins
rest returns via small anastamosis, normal R–>L shunt
Pulmonary Lymphatics
hydrostatic starling forces, ~20 ml/hr
Capillary recruitments
opening, increases capillary volume
chief mechanism for fall in PVR
capillary distention
expanding, compensates but can lead to lung congestion and heart failure
Pulmonary Vascular Resistance
minimal when lung volumes are close to FRC
increased with higher and lower lung volumes
Hydrostatic Pressure
zero point - R atrium and middle of lung
minimized in supine or prone
cause distention and recruitment in lung bases
What determines perfusion zones?
relationship between alveoli and blood pressure in pulmonary arteries and veins
-hydrostatic pressures, gravity, transmural pressure and lung volume
Vasconstrictors
increase PVR w/i pulmonary bed reduced PAO2 increased PCO2 thromboxane A2 alpha adrenergic catecholamines histamine
Vasodilators
decrease resistance increased PAO2 nitric oxide prostacyclin beta-adrenergic catecholamines acetylcholine
Thromboxane A2
vasoconstrictor
product of arachidonic acid metabolism
produced during acute lung damage
half life is seconds, effect is limited
Prostacyclin (Prostaglandin I2)
Vasodilator
inhibitor of platelet activation
product of arachidonic acid metabolism
Nitric Oxide
Vasodilator
localized effect, short half life
smooth muscle relaxation through synthesis of cGMP
higher affinity to hgb than oxygen
Hypoxic Pulmonary Vasoconstriction
adaptive response, shunts blood away from poorly oxygenated region
minimizes shunt
Pulmonary HTN
generalized alveolar hypoxia increases PVR, chronic high PVR
d/t vasoconstrictor activity
causes increased RV work –> RV hypertrophy, tricuspid regurg, cor pulmonae
Which portion of lung tends to be better ventilated?
apex
normal A-a PO2 difference
10-15 mmHg
larger indicates intrinsic pulmonary disease
true anatomical shunts
bronchopulmonary venous anastamosis
intracardiac thesbian veins
mediastinal veins
pleural veins
Mechanical Ventilation effects
increases zone 2
pos-press ventilation can decrease CO or increase VQ mismatch
Henry’s Law
solubility of a gas in a liquid depends on temperature, partial pressure and nature of solvent and gas
When dissolved molecules are attracted by water…
more can be accumulated without building excess pressure, highly soluble
How many times more soluble is carbon dioxide than oxygen?
20x
What determines rate of net diffusion
difference of partial pressures
Vapor pressure when gas is fully humidified?
47 mmHg
760 mmHg = __ mmHG air + __ mmHg water
713 mmHg air
47 mmHg water
Factors that effect gas diffusion rates
pressure differences gas solubility in fluid area of fluid distance which air must diffuse molecular weight of gas temp of fluid
Diffusion coefficient
directly proportional to solubility
inversely proportional to molecular weight
smaller molecules = faster diffusion rate
Alveolar air is expired at
end expiration
Fick’s Law of Diffusion
diffusion of gas through tissue membrane
factors - cross sectional area, driving pressure, gas coefficient and tissue thickness
Diffusing capacity of oxygen
21-65 mm/min/mmHg
Diffusing capacity of carbon dioxide
400-1200 mm/min/mmHg
*technically not measurable
PO2 and PCO2 in deoxygenated blood…
PO2 = 40 mmHg PCO2 = 45 mmHg
PO2 and PCO2 of inspired air….
PO2 = 150 mmHg PCO2 = O mmHg
Physiologic Shunt
VQ below normal, airway obstruction
blood not participating in gas exchange
Q, no V
Physiologic Dead Space
ventilated, not perfused
V, no Q
