gas transport by blood Flashcards
The most abundant gas in the atmosphere
nitrogen
Air sum of all the partial pressures is approx.
760 mmHg
air composition at sea level-partial pressure of oxygen
160 mmHg
percent of oxygen of air
21%
how to calculate partial pressure of O2
Pp Oxygen = % composition of air x P total
What happens at altitude?
air becomes less dense, O2 composition remains the same partial pressure of O2 changes , exerting less pressure
diffusion occurs due
partial pressure gradient
partial pressure of O2 is higher in pulmonary capillaries or in alveoli?
aveoli
t/f pressure force for diffusion of CO2 is lower than O2
true
henry’s law
Amount of gas dissolved in a liquid is directly proportional to its partial pressure at a constant temperature
Partial pressure of O2 in arterial blood
100mmHg
t/f at higher pressure more gas will dissolve
true
t/f at lower gas pressure less gas will dissolve
true
oxygen transport in blood
dissolved in blood
bound to hemoglobin
percent of O2 dissolved in blood
3% dissolved in plasma
percent of o2 bound to hemoglobin
97%
t/f the o2 dissolved in blood plasma are the ones that exert partial pressure of O2
true
once bound to hemoglobin O2
does not exert pressure
O2 pressure in blood cannot be used to
determine quantity of O2 in blood
what do you need to now to calculate quantity of O2 in blood?
Hb concentration
Oxygen saturation in arterial blood
t/f oxygen saturation depends on partial pressure of oxygen
true
Hb structure
Quaternary protein: 2 ⍺ chains and 2 β chains
Each chain is bound to a red pigment: Heme
Ferrous iron (Fe2+) which combines with O2
Each molecule of Hb combine with 4 molecules of O2
OxyHg-Dissociation curve
Describes the relationship between SaO2 and oxygen tension
t/f Oxygen affinity for the heme group depends on the oxygenation of the others
true
p50 is the PaO2 pressure at which
50% of the Hb is saturated
t/f Each specie has a specific p50
true
Oxygen transport: OxyHg-Dissociation curve = curve to the right
affinity O2-Hb decreased
Oxygen transport: OxyHg-Dissociation curve = curve to the left
Increased O2 – Hb binding affinity
Causes of Oxygen transport: OxyHg-Dissociation curve = curve to the left
Metabolic alkalosis with low PaCO2 and pH increased
Low temperatures: Hypothermia
diphosphoglycerate decreased: old RBC transfusions
O2 binding affinity increased: it is more difficult for the Hb to offloading O2
Causes of Oxygen transport: OxyHg-Dissociation curve = curve to the right
Metabolic acidosis, ph. is low, and CO2 is high – Metabolic active tissues
Increased of Temperature
Increased in the concentration of 2.3DPG
O2 binding affinity for the Hb decreases: Hb releases easily the O2
forms of hemoglobin transport : physiological
Deoxy-hemaemoglobin
Oxy-hemoglobin
HbF: fetal Hg (2 ⍺ and 2 γ)
forms of hemoglobin transport : pathological
HbS: people with sickle cell diseases (abnormal β chain)
MetHb- Methemoglobin
COHb – Carbon monoxide hemoglobin
Methemoglobin
Fe2+ gets oxidized to Fe3+
form of the Hb does not bind to O2 – Oxygen capacity is decreased
treatment for Methemoglobin
methylene blue
t/f CO and O2 bind the same sites on the Hb- they compete each other
true
t/f Direct relation between amount of oxygen and Hb
true
Hufner’s Constant
1g of Hb can combine to 1.34ml O2
3 forms of blood transport of CO2
Dissolved - 5% in arterial blood
Reacting with H2O and producing Bicarbonate – Effect of Carbonic Anhydrase
In reaction with Hb and plasma proteins as carbaminohemoglobin
The majority of CO2 in arterial blood is transported reacting
Co2 + H2O, inside the RBC as carbonic acid
t/f Pathological forms of the Hb can altere the bounding reaction with O2
true
