Lecture 27 Flashcards
Gas Transport
Why is partial pressure equal but concentration is not?
CO2 is 20X more soluble than O2 in plasma
How is O2 transported?
it binds to hemoglobin inside the red blood cell
4 binds to hemoglobin at a time
When oxygen is bonded to hemoglobin, what is it called?
Oxyhemoglobin
How does hemoglobin increase O2 carrying capacity?
Since the partial pressure of the alveoli and the capillaries are the same, only 2 percent of the oxygen dissolves into plasma. the hemoglobin allows 98% of the oxygen to be in the blood
Where is O2-Hb binding saturation plateau?
At the lungs (60-100mm Hg)
where is the O2-Hb binding saturation steep?
at the tissues (0-40mm Hg)
Why is the O2-HB dissociation curve sigmoidal?
hemoglobin is cooperative, the more O2 binds, the greater the affinity for O2 grows
when the dissociation curve moves to the right, it means..
Affinity decreases (P50 increases meaning it takes longer and more O2 to reach 50%)
when the dissociation curve moves to the left, it means..
Affinity increases (P50 decreases meaning it takes shorter and less O2 to reach 50%)
an increase of acidity…
decreases the affinity of hemoglobin cause it makes it go into the T state therefore increasing the P50
an increase of PCO2…
decreases affinity cuz it increases the acidity therefore increases the P50
2 ways of O2 Transport
98%- Oxyhemoglobin
2% - dissolved O2 in plasma
3 ways of CO2 transport
- 7% transported as dissolved gas in plasma
- 23% transported as HbCO2
- 70% transported as bicarbonate dissolved in plasma
What is the bicarbonate equation?
CO2 + H2O ——-> H2CO3 ——> H+ + HCO3-
where does carbonic anhydrase fit in the equation?
to turn CO2 + H20 to carbonic acid
What happens when there’s too much H+ in the blood
acidosis
How does CO2 get transported out of tissues
The CO2 diffuses into he plasma and into the red blood where it binds to Hb
More CO2 and binds to water beaconing carbonic acid with the help of Carbonic anhydrase. It then turns into bicarbonate and the H+ binds to the Hb
How does CO2 get transported out of the lungs
the dissolved CO2 diffuse out (7%)
the 23% bonded to the Hb diffuse out
this makes the opposite reaction occur and more bicarbonate goes into the blood to drive the production of CO2 (70%)
how is ventilation regulated?
medulla oblongata receives input from the
- medullary chemoreceptors
- carotid & aortic chemoreceptors
- limbic system
How is CO2 levels detected
medulla chemoreceptors
how is O2 and pH levels detected?
the carotid and aortic chemoreceptors
What type of feedback is regulation of ventilation
negative feedback loop
What system controls the medulla receptors
central nervous
what system controls the aortic and carotid arch
peripheral nervous
