L13- Pt 2 Flashcards
Gas transport has 2 mechanisms for…
Oxygen & carbon dioxide
Solubility of oxygen in blood
- Dissolved in plasma (2%)
- Bound to hemoglobin (HB) - 98%
Hemoglobin (Hb) is made up of
Globin - protein
Heme - contains Fe (iron)
Where does o2 and co2 bind to on hemoglobin of RBC?
O2 binds to Fe in heme
- co2 binds to protein (globin)
What are the 4 protein subunits of hemoglobin?
- 2 alpha & 2 beta chains
- 1 heme/ chain
- 1 Fe/ heme
- 02 binding to Fe
(4 o2/hb)
Where does O2 load and unload of hemoglobin
Load = lungs
Unload = tissues
Mechanism of o2 loading and unloading hb
O2 from lungs dissolves in plasma = RBC
- o2 from plasma binds to hemoglobin
- some o2 unloads from hemoglobin to tissues
Oxyhemoglobin dissociation curve is sigmoid shaped
TRUE or FALSE
True
Veins Po2 at rest is _______. Making its hemoglobin saturation ________
40 mmhg
Hb saturation = 75%
Arteries Po2 at rest is _______. With hemoglobin saturation of ________
100mmhg
Hb saturation = 97%
Hb saturation
Amount of oxygen in hemoglobin
Significance of high Hb saturation in venous blood at rest
- allows for holding breath
- being able to stop breathing and still live for 4-5 minutes
High hemoglobin (Hb) saturation in venous blood at rest indicates ….
There’s is an o2 reserve
- a supply of oxygen
Significance of flat portion of curve at a high po2’s
- acts as an o2 reservoir
- allow us to go to altitude w/o affecting saturation
The flat portion of the oxyhemoglobin curve at high po2 indicates
As po2 decreases, Hb saturation will remain high
Significance of the steep portion of the curve at tissues po2
- allows for increase unloading of o2 at tissues as tissues need it
- activity level
The steep portion of the curve at tissue pO2 indicates
Small change of po2 = large unloading of o2 from hemoglobin
Bohr effect is the effect of ____ on the curve
Ph
How is co2 transported in the blood (3 ways)
- Dissolved in plasma
- Bound to protein portion of hemoglobin
- As bicarbonate ion (hco3)
Bohr effect at rest vs during exercise
At rest:
- Tissue Ph = 7.4
Tissue po2 = 40mmHg
% HB saturation = 75%
During exercise:
- metabolism = acid = lower Ph
- curve shifts to right
- Tissue Po2 = 40 mmHg
% Hb saturation = 60%
During strenuous exercise how will the oxyhemoglobin dissociation curve look like
- increase temp + decrease pH
- shifting curve to right
- allowing greater unloading Hb = more o2 to muscles
- Decrease in muscle Po2
= greater unloading oh Hb = more o2 to muscles
CO2 release from RBC (hemoglobin) to lungs
- Three processes reverse allowing co2 to diffuse into alveoli and be exhaled
What causes the bicarbonate equation to be reversed?
Carbonic anhydrase
Carbonic anhydrase equation
CO2 + h2o ➡️ H2co3
h2co3 ➡️ Hco3+ H
Negative feedback for oxygen
Sensor
Integrated
Effector
Sensor = chemoreceptors- peripheral & central
(CO2, ph, o2)
Integrator = respiratory center in medulla oblongata
Effector = diaphragm
What are Peripheral chemoreceptors are found where and what do they sense?
In Carotid and aortic bodies
Sense: H+ ( as reflection of arterial Pco2)
Central chemoreceptors monitor what
Ph of CSF as reflection of arterial pco2
Central chemoreceptors are found and are stimulated by
In the medulla oblongata
Stimulated by: increase H+ in CSF
Peripheral chemoreceptors are stimulated by
Increase H+ in blood
