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Glossary of Respiratory Physiology week 1

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conducting zone
brings air into and out of the lungs; warms, filters, and humidifies air
respiratory zone
site of gas exchange, lined with alveoli
what structures does the conducting zone include?
nose, nasopharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
what structures does the respiratory zone include?
respiratory bronchioles, alveolar ducts, and sacs
trachea
- cilia, smooth muscle, cartilage?
YES YES YES
bronchi
- cilia, smooth muscle, cartilage?
YES YES PATCHY
bronchioles
- cilia, smooth muscle, cartilage?
YES YES NO
respiratory bronchioles
- cilia, smooth muscle, cartilage?
SOME SOME NO
alveolar ducts
- cilia, smooth muscle, cartilage?
NO SOME NO
alveolar sacs
- cilia, smooth muscle, cartilage?
NO NO NO
what type of stimulation of is involved in dilating the airways?
sympathetic adrenergic neurons activate B2 receptors on smooth muscle (also activated by circulating catecholamines and by B2 agonists)
why type of stimulation is involved in constricting the airways?
parasympathetic cholinergic neurons activate muscarinic receptors on smooth muscle
Type II alveolar cells
synthesize surfactant, which is required to reduce surface tension of alveoli and prevent their collapse
residual volume
the volume remaining in the lungs following maximal expiration (not measured by spirometry)
functional residual capacity
(FRC) volume remaining in lungs following a normal tidal expiration; expiratory reserve volume + residual volume
alveolar gas
air that had been in the alveoli
minute ventilation
Vt x breaths/minute
alveolar ventilation
(Vt - Vd) x breaths/minute
in normal persons, what percentage of the vital capacity is expired in the first second of forced expiration?
80%

i.e. FEV1/FVC is 0.8
list two examples of obstructive disease
asthma, COPD
obstructive disease
obstruction of the airways, increases the resistance to airflow
obstructive disease
- what happens to FEV1/FVC?
FEV1 is dec more than FVC such that FEV1/FVC is dec
restrictive disease
- e.g.
fibrosis
restrictive disease
increased stiffness and elastic recoil of lung tissues
restrictive disease
- what happens to FEV1/FVC?
because the elastic recoil of lung structures is inc, FEV1 is dec less than FVC, thus FEV1/FVC is inc (or normal)
Dalton's law of partial pressures
the partial pressure of a gas in a mixture of gases is the pressure that gas would exert if it occupied the whole volume of the mixture
if equilibration has occured, what is the partial pressure of a gas in the liquid phase equal to?
the partial pressure of the gas in the gas phase
do bound or chemically modified forms a gases contribute to the partial pressure of the gas?
NO!
what is an important example of a chemically modified gas?
conversion of CO2 to HCO3- in red blood cells
what is the driving force for gas diffusion?
the partial pressure difference of the gas (delta P) across the membrane or capillary wall
how is the diffusion coefficient related to the MW and solubility of a gas?
D is inversely correlated with the MW of the gas and directly correlated with the solubility of the gas
diffusion-limited gas exchange
total amount of gas transferred is limited by the diffusion process; partial pressure gradient for the gas IS maintained
diffusion-limited gas exchange examples
O2 transport during exercise, emphysema, fibrosis, CO transport
perfusion-limited gas echange
total amount of gas transferred is limited by blood flow; partial pressure gradient for the gas IS NOT maintained (e.g. normal transfer of O2)
what type of gas exhange is exhibited in fibrosis, and why?
diffusion-limited process, b/c of thickening of the alveolar membranes, which dec D(L)
what is the most important muscle of inspiration?
diaphragm
during exercise, what additional muscles are used for inspiration?
external intercostal and accessory muscles
during normal tidal breathing what muscles are involved in expiration?
none -- it's passive
during exercise what muscles are involved in expiration?
abdominal muscles and the internal intercostal muscles
compliance eqn
dV/dP
how does compliance relate to elasticity?
compliance is the inverse of elasticity
hysteresis
the inspiration (filling) limb of the lung's pressure-volume loop has a different slope (compliance) than the expiration limb
is the intrapleural pressure normally negative or positive?
negative
asthma
obstructive

inc airway resistance
COPD
obstructive

(1) dec elastic fibers in alveoli (inc compliance)

(2) inc airway resistance
fibrosis
restrictive

inc elastic (stiffness) dec compliance
surfactant
reduces surface tension of alveoli, thus reducing the collapsing pressure of small alveoli
what is the most important constituent of surfactant?
DPPC
how does the ANS cause constriction of the airways?
parasympathetic stimulation, via muscarinic receptors, causes constriction of the bronchial smooth muscle, dec radius, and inc resistance to airflow
how does the ANS cause dilation of airways?
sympathetic stimulation, via Beta-2 receptors, causes dilation of bronchial smooth muscle, inc radius, and dec resistance to airflow
dissolved O2 constitutes what percentage of total O2 content of the blood?
2%
to bind O2 in what state must iron be in?
Fe2+
P50
the PO2 that corresponds to 50% saturation
right shifts of the O2-Hg dissociation curve occur when? produce what?
occur when there is a dec affinity of Hg for O2, produce an increase in P50
3 factors that cause a right shift?
(1) inc in PCO2 and dec in pH

(2) inc in temp

(3) inc in [2,3-DPG]
left shifts of the O2-Hg dissociation curve occur when? produce what?
occur when there is inc affinity of Hg for O2, produces a dec in P50
5 factors that cause a left-shift
(1) dec PCO2 and inc pH

(2) dec temp

(3) dec 2,3-DPG

(4) HbF

(5) CO
CO poisoning
dual evil:

(1) binds to hemoglobin with 250 x the affinity that of O2

(2) inc affinity of remaining units for O2, so this O2 isn't released to tissues that need it!
Dissolved O2 eqn
Dissolved O2 = PO2 x solubility
O2 bound to hemoglobin depends on what three things?
(1) Hb concentration

(2) O2-binding capacity

(3) % saturation
what are the three forms CO2 is found in blood, and which is major?
HCO3- (major), dissolved, bound to proteins such as Hb
chart the path of CO2 generation to expiration
CO2 generated --> added to venous blood --> in RBCs: CO2 + H2O yields H2CO3 (carbonic anhydrase catalyst) which then yields H+ + HCO3- --> H+ remains in RBCs, buffered by deoxyhemoglobin --> HCO3- exchanges with Cl- to get to plasma --> travels to lungs --> reverse process occurs --> expiration
Haldane effect
greater binding of CO2 to hemoglobin in its deoxygenated form

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