Respiratory physiology 5 Flashcards
Calculate the patient’s arterial oxygen content from the data set:
Hgb 9 g/dL
HR: 100 bpm
Stroke volume: 70 mL
SaO2: 90%
PaO2: 60 mmHg
a. 10.641 mL O2/dL
b. 11.034 mL O2/dL
c. 11.894 mL O2/dL
d. 12.002 mL O2/dL
b. 11.034 mL O2/dL
CaO2= (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
Oxygen content is a measure of how much
oxygen is present in 1 deciliter (100 mL) of blood
What is the oxygen content equation?
CaO2= (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
Oxygen delivery tells us
how fast a quantity of O2 is delivered to the tissues
What is the oxygen delivery equation?
DO2= CaO2 x cardiac output x 10
Oxygen consumption is the
difference between the amount of O2 that leaves the lungs and the amount of O2 that returns to the luns
What is the oxygen consumption equation?
VO2= cardiac output x (CaO2-CvO2) x 10
After oxygen diffuses through the alveolar capillary membrane, it is transported by the blood in 2 ways:
- reversibly binds with hemoglobin (97%)
- dissolves in the plasma (3%)
Each gram of hemoglobin molecule can carry a theoretical maximum of
1.39 mL of molecular oxygen
VO2 equals
3.5 mL/kg/min
Vo2 is about ___________ in a 70 kg male
250 mL/min.
P50 is reduced by: (select 3) a. hgb f
b. hyperthermia
c. hypocarbia
d. increased 2,3 DPG
e. acidosis
f. carboxyhemoglobin
a. hgb F
c. hypocarbia
f. carboxyhemoglobin
P50 is the
PaO2 where hemoglobin is 50% saturated with oxygen
The oxyhemoglobin dissociation curve tells us the
tendency of hemoglobin to bind oxygen
A right-shifted oxyhemoglobin curve means
right= release
hemoglobin has a lower affinity for oxygen
A left-sided oxyhemoglobin curve means
left= love
hemoglobin has a higher affinity for oxygen
A lower P50 reflects
a left shift (left= love)
A higher P50 reflects a
right shift (right= release)
A left shift (decreased P50) is caused by
alkalosis, decreased temperature
decreased 2,3-DPG
A right shift (increased P50) is caused by
acidosis
increased temperature
increased 2,3-DPG
What hemoglobin species can cause a left shift?
fetal hemoglobin
methemoglobin
carboxyhemoglobin
The Bohr effect says that an increased partial pressure of Co2 and decreased pH cause
hemoglobin to release O2
Above a PaO2 of 100 mmHg,
hemoglobin is fully saturated with oxygen; increasing the FiO2 further will increase the amount of O2 dissolved in the blood
Increased hydrogen leads to
left shift of the oxyhemoglobin curve
2,3 DPG is produced during
RBC glycolysis (Rapoport-Leubering pathway)
___________ increases 2,3 DPG production
hypoxia; this increases O2 offloading
2,3 DPG is an important compensation mechanism during
chronic anemia
In banked blood, the concentration of 2,3 DPG
falls- shifts the oxyhemoglobin dissociation curve to the left
Identify the statement that BEST describes aerobic metabolism.
a. NADH is the final electron acceptor during electron transport
b. 1 molecule of glucose converts to 38 molecules ATP
c. Pyruvic acid is converted to lactate
d. Electron transport occurs in the cytoplasm
b. 1 molecule of glucose converts to 38 molecules ATP
_____________ is the energy currency in the body
Adenosine triphosphate (ATP)
________ is the primary substrate used for ATP synthesis.
Glucose
What are the 3 key processes involved in aerobic metabolism:
- glycolysis= net gain of 2 ATP
- Krebs cycle= net gain of 2 ATP
- oxidative phosphorylation= net gain of 34 ATP
The body’s enzymes tend not to function properly in
an acidic environment
In the absence of oxygen (anaerobic metabolism), pyruvate is converted to
lactic acid- this causes lactic acidosis
ATP cannot be
stored so the supply must continuously be replenished
Energy sources include
proteins, carbohydrates and fats
Energy usage is from
active transport
synthetic function
muscle contraction
cell division and growth
The more glucose molecules that go through glycolysis, the more ___________ is produced
2,3 DPG b/c the Rapoport-Luebering pathway occurs halfway through glycolysis
The Krebs cycle takes place in the
matrix of the mitochondria
The primary goal of the Krebs cycle is to
produce a large quantity of H+ ions in the form of NADH- these are used in electron transport
What is the primary goal of electron transport?
to produce a lot of ATP (energy)
What is the primary goal of glycolysis?
to convert 1 glucose to 2 pyruvic acid molecules
Importation of which ion maintains electroneutrality during the Hamburger shift?
Chloride
The primary by-product of aerobic metabolism is
carbon dioxide
The 3 primary ways that CO2 is transported (buffered) in the blood:
- as bicarbonate (70%)
- bound to hemoglobin (23%)
- dissolved in the plasma (7%)
Carbonic anhydrase is an enzyme that facilitates the formation of
carbonic acid (H2CO3) from H2O & CO2
To maintain electroneutrality, for every molecule of HCO3- that leaves the erythrocyte, one ________________ is transported in
Cl- ion- this is known as the chloride or Hamburger shift
A more acidic environment enhances O2 ______________ & ________________ CO2 loading into the blood
enhance O2 offloading from hemoglobin (Bohr effect) & increases CO2 loading into the blood (Haldane effect)
What is the carbonic anhydrase equation?
H2O+ CO2 <–> H2CO3 <–> H+ + HCO3-
In the lungs, the chloride shift operates
in reverse as CO2 is excreted from the body
Dissolved CO2 has a solubility coefficient of
0.067 mL/dL/mmHg
Solubility is a function of
Henry’s law
