Respiratory-3 Flashcards
pao2 refers to
o2 dissolved in the plasma BEFORE gas exchange has occurred
how does o2 get from lung alveoli to become dissolved in plasma
by diffusion across the alveoli aka gas exchange
the diff between alveolar po2 & pao2 should be
5 mmHg
ventilation & perfusion should be
the same
low resistance, low pressure pathway
pulmonary circuit
blood flow must =
airflow
blood vessels feeding poorly ventilated areas of the lung __
constrict
blood vessels feeding well ventilated areas of the lung __
dilate
when do we see large mismatches of vq ratio
pneumonia, emboli, edema
in someone with pulmonary embolism, perfusion is impaired so vq ratio would be __ than 1
greater; bc lung better ventilated than they are perfused (perfusion is in denominator so if lowered, # goes up)
over 3 atmospheres of o2 =
o2 toxicity
2-3 atmospheres & for a short per of time; treat CO poisoning & anaerobic bacterial infections
hyperbaric 02 chamber
we must be conscious to breathe
f
respiratory rhythm regulated by
neurons in medulla aka rhythmic center
ventral respiratory group controls
muscles required for forceful inhalation & exhalation & inhibits the i neurons during exhalation
i neurons
activate interneurons that activate spinal motor neurons; assoc w accessory inspiratory muscles
accessory inspiratory muscles are responsible for
forced breathing
e neurons
inhibit motor neurons of phrenic n. during expiration + activates muscles for forced exhalation
in order to exhale, you have to inhibit the __ during exhalation
inspiratory neurons
chemoreceptors are sensitive to changes in
ph, pco2, & o2
__ ions stimulate chemoreceptors, but __ is driving the __ production
h; co2; h
chemoreceptors function to
maintain constant ph, pco2, & po2
peripheral chemo rs located in
aortic arch & carotid bodies
central chemo rs located in
medulla
stimulated by rise in blood h ions, but occurs as a result of co2 increase; they increase ventilation & respond quickly
peripheral chemo rs
normal blood ph
7.4
ph below 7.4
acidosis
ph above 7.4
alkalosis
most common cause of hypercapnia (elevated co2)
acidosis
most common cause of hypocapnia (low co2)
alkalosis
as H ion levels rise, __ increases
ventilation
central & peripheral chemo rs behave the same way except central slower to respond
t
how do co2 levels get back to normal
decreased ventilation -> don’t get rid of enough co2 so increased arterial pco2 -> stimulates peripheral & central chemo rs -> both activate inspiratory center to incr rate & depth of breathing -> helps get ride of co2 -> levels back to norm
why does hyperventilating give feeling of passing out?
when co2 levels decrease brain thinks ‘too much o2’ so constricts brain vessels hence not enough blood reaching brain
hyperventilation solution
breathe into bag -> co2 levels rise -> blood vessels to brain dilate -> increased flow to brain
better indicator of min-min changes in ventilation
co2
central chemo rs respond __ only
co2
peripheral chemo rs respond to __ but only at __
o2; o2 levels below 60 mm Hg
at what levels of Hg do peripheral chemo rs respond in a major way
less than 60 mm hg
low o2 __ ventilation
increases
high o2 __ ventilation
inhibits
under conditions of low o2, chemo rs are more sensitive to __ as well
co2
as co2 levels increase, respiratory rate
increases (to get rid of co2)
all chemo rs in presence of low o2 become MORE sensitive to co2
t
peripheral chemo rs normally respond to co2 but can also respond to low o2
t
both central & peripheral chemo rs respond to increases in __ by making you
co2; increase rate & depth of breathing
most healthy individuals will regulate breathing based on
co2 levels
individuals with cops always chronically elevated levels of
pco2 (because have trouble exhaling/getting rid of co2)
give no more than __ of o2
3L
each Hb can bind __ o2 molecules
4
how many hb molecules per rbc
280 mil
when bound to o2 even if 1 site occupied
oxyhemoglobin
if hb completely unoccupied
deoxyhemoglobin
where iron at center of heme group has +3 charge rather than +2
methemoglobin
methemoglobinemea
large amount of hb in methemoglobin form
all of us have some methemoglobin
t
iron with +3 charge can’t bind o2
t
when heme combines with CO (carbon monoxide) & not o2
carboxyhemoglobin
Hb prefers __ over __
CO; o2
why is carboxyhemoglobin dangerous?
hb won’t carry enough o2 -> can die
treatment for carboxyhemoglobin
hyperbaric o2 chamber
anything that reduced hb amount, reduces __ in major way
total blood o2 content (bc most o2 carried on hb)
sao2 aka
percent hb saturation
sao2 indication of
oxygenation
normal arterial blood is __% saturated hb
97%
each form of hb has slightly diff color depending on amount of o2 it carries & absorbs light differently
t
what determines o2 carrying capacity
hb concentration
what stimulates rbc & hb production
HYPOXIA which stimulates epo -> produces rbc’s -> hb rises & ANDROGENS
as a result of having higher androgens, males have
higher hct & hb
when o2 combines with hb aka
loading reaction
when o2 has released from hb
unloading reaction
where does loading occur
in lungs surrounding capillary alveoli (bc where o2 levels higher)
where does unloading occur
tissues
what dictates whether hb will bind to o2 or not
hb levels on environment
high po2 favors
loading
low po2 favors
unloading
what would happen if affinity of o2 for hb were too strong
o2 would not unload to tissues
the lower the po2 is, the __ affinity hb has for 02 & the __ it releases
less; more
why would a person with pneumonia that isn’t so bad still be able to do daily activities?
po2 doesn’t fall below 80
