O2 & CO2 Flashcards
why does O2 & CO2 matter to dentistry?
Understanding the basic fundamentals of gas exchange in the lungs and tissue is the foundation for understanding sedation
Dental anesthesia in toxic doses can cause respiratory depression: toxicity is more common in children (they weigh less)
The process of metabolism requires oxygen and creates CO2, therefore all tissues need oxygen and all tissues need to expel CO2
the respiratory system is composed of:
naso- oro- and laryngo-pharync, trachea, bronchi, bronchioles, and lungs
breathing in and out movement of the diaphragm
sinuses do what?
warm and humidify the air that we breath
trap pathogens from the air
where are the sinuses?
in dentistry, what procedures can interact with sinuses?
extractions/implants
root canals
dentures
epiglottis prevents ____ and ____ from getting into the respiratory system (aspiration/chocking)
food and drink
vocal cords are located…
right at the top of trachea (below epiglottis)
epiglottis is ____ when swallowing
depressed
intubation tube is placed…
in trachea past the epiglottis
alveoli is where _____ ________ happens
gas exchange
flow of O2 of respiratory system
breathe in O2
oral cavity
trachea
bronchi
bronchiole
alveolar sacs
crosses alveolar membrane and capillary membrane
blood
blood is our _____ ____ to transport gasses for and from metabolism
freeway system
O2 goes ___ the blood while CO2 comes ______ the blood at the lungs
O2 into blood
CO2 out of blood
*at lungs
O2 goes ___ the blood while CO2 comes ______ the blood at the tissues
O2 out of blood
CO2 into blood
*at tissues
what does each letter represent?
D: rate of diffusion
delta P: change in partial pressure
A: surface area
S: solubility constant
d: distance of diffusion
MW: molecular weight
limiting factors of diffusion of O2
CO2 is ____ soluble in blood than O2
more
*readily allows exchange at the tissues that need O2
oxygen delivery is the product of ___ ____
cardiac output
- carries through Hb on RBCs
- each RBC has many Hb molecules
Hb has __ subunits containing ___ with ferrous iron atom
Hb has 4 subunits containing heme with a ferrous iron atom
Hb is a protein
Hb: iron can reversibly bind to ___
O2
always diatomic oxygen (O2 not O)
“oxygenation”
diatomic oxygen
O2
As O2 binds, the affinity for the other 3 subunits to bind ____
increases
“cooperative binding”
each binding increases affinity for binding more
aka peer pressure
hemoglobin/oxygen dissociation curve
hemoglobin/oxygen dissociation curve: small changes in pO2 at the beginning results in _____ changes in SaO2
large
affinity of Hb: 3 factors that change
- pH
- temperature
- concentration of 2,3 - diphosphoglycerate
affinity of Hb: shifting right will ____ affinity
decrease affinity
right = decrease affinity = release
affinity of Hb: shifting left will ____ affinity
increase
left = increase affinity = bind
_____ in metabolic demand will decrease O2 in the blood
increase demand = decrease O2 blood
Bohr Effect
drop in pH causes a decrease in affinity (shift right)
- high levels of CO2 causes decreased pH therefore need O2 to be released
what is 2,3 - diphosphoglycerate?
product of glycolysis
increases 2,3-bip and the curve shifts right
increased metabolic load gives off more ____ into the blood
CO2
Haldane Effect
deoxygenated blood has a higher capacity to bind CO2
ie: venous blood caries more CO2 than arterial blood
CO2 is about __ x more soluble than O2 in the blood
20x more soluble
Hb can bind __ CO2
4
*like O2
vasodilation = _____ perfusion
increased
if no blood is perfusing the alveoli, then…
no gas exchange occurs
high levels of CO2 in the blood _____ pH
decreases
more H+
acidic
bicarbonate buffer system
CO2 is converted to carbonic acid from carbonic anhydrase in RBs
how can kidneys assist in buffering blood when there is too much CO2?
H+ excretion by kidneys
CO2 is discharged into alveoli and expired
Bohr effect vs Haldane effect
Bohr: acidic blood and lowers the affinity
Haldane: deoxy RBsC have increased affinity for CO2
ph of arterial blood is
7.4
hypoxia
O2 deficiency at the level of the tissues
causes of hypoxia
- Decreased PO2 of arterial blood
- Decreased amount of Hb to carry oxygen (anemia)
- Low blood flow to a tissue (cutting off circulation)
- Toxic product not allowing O2 to do its job (CO poisoning)
hypoxia symptoms
the brain is affected first causing confusion, headache, impaired judgment
loss of consciousness
death
respiratory complications
fluid in alveoli
inflammation in any part of the respiratory tract
—-asthma: bacterial, fungal, viral infections
spasms of the muscles
—-asthma and bronchospasm
COPD
—-emphysema and chronic bronchitis
Who do we monitor oxygen levels in?
Ways to measure safe oxygen levels in your
patients:
capnography: measuring levels of CO2 expired, not an exact measure for dentistry
pulse oximeters: measuring levels of O2 in blood
respiratory rate: Make sure your pt is breathing
respiratory rate b/m (infant to adult
sleep apnea
A serious breathing condition where breathing is irregular and will stop for a period of time while asleep
- obese
- large tongue
- skeletal class II (no prominent chin)
CO2 changes during CPR
CPR: rescue breaths is on ___-___% oxygen flow
16-17% O2 flow
gasses move ___ through the concentration gradient
downhill
from high to low pressure
Hb _____ binds four O2 molecules through _____ binding to deliver O2 through the body to the tissues
Hb reversibly binds 4 O2
through Cooperative binding
what three factors impact the dissociation of O2 and Hb
- pH
- temperature
- 2,3-biphosphoglycerate
