O2 Transport and Regulation

Question 1

What are the four steps for successful breathing?

Answer 1

1. Bring oxygen from outside into the lung (aka breathing)
2. Oxygen from lung to blood through simple diffusion (affected by: concentration gradient, surface area, and distance)
3. Cardiovascular system (heart disease can affect this step)
4. Oxygenated blood goes to peripheral tissues (profusion)

Question 2

What is the PO2 at sea level?

Answer 2

160 mmHg

Question 3

What is the PO2 and CO2 level for oxygen rich blood?

Answer 3

100 mmHg (oxygen)
40mmHg (co2)

Question 4

What is the PO2 and CO2 level in your tissue?

Answer 4

40 mmHg (oxygen poor)
46 mmHg (co2)

Question 5

What are the directions of CO2 and Oxygen in your body?

Answer 5

-Oxygen goes from lung to the blood (PO2 level higher in the lung to diffuse to the blood)
-CO2 goes from the blood to the lung (PCO2 level higher in the blood to diffuse to the lung)
simple diffusion

Question 6

Emphysema

Answer 6

-Destruction of alveoli means less surface area for gas exchange
-High compliance (easy to expand, difficult to recoil)
-body short of oxygen

Question 7

Fibrotic lung disease

Answer 7

-thickened alveolar membrane slows gas exchange (due to lung tissue turning into scar tissue). Loss of lung compliance may decrease alveolar ventilation.
-PO2 could be normal in the first step but everything after that will be lower
-increased distance (less diffusion)

Question 8

Pulmonary Edema

Answer 8

-Fluid in interstitial space increases diffusion distance. Arterial PCO2 may be normal due to higher CO2 solubility in water.
-affects step two (levels will be lower)
-increased diffusion distance

Question 9

Asthma

Answer 9

-Increased airway resistance decreases alveolar ventilation
-narrow airway
-affects to step one

Question 10

Hematocrit

Answer 10

A way to measure the amount of RBC with a small tube
Total Blood O2 = O2 dissolves in plasma (PO2) + O2 bound to hemoglobin (HbO2)
-most red blood cell is 42% of complete blood count

Question 11

How is oxygen transported in the blood?

Answer 11

-only 2% of oxygen is dissolved in plasma
-98% of oxygen is bound to hemoglobin in red blood cells
-When the PO2 level is low the binding affinity is low and they dissociate -> when they dissociate the oxygen is free and will follow the concentration gradient, going to the tissue

Question 12

How is CO2 transported in blood?

Answer 12

-7% is dissolved in the plasma
-93% goes into the plasma but only 23% binds with hemoglobin.
-the rest of CO2 is turned into carbonic acid (acts as a good buffer) and dissociates into bicarbonate (want) and hydrogen -> chloride shift happens when Cl- is used to make bicarbonate to get out of plasma.
-when transported into lungs, turns back into CO2

Question 13

How many binding sites do hemoglobin have?

Answer 13

four

Question 14

How does hemoglobin affect oxygen transport?

Answer 14

-when there is a PO2 level of 100 mmHg every binding site on the hemoglobin is taken and results in 99% saturation
-When PO2 level is really low, not all binding sites will be taken and you will have low oxygen saturation.

Question 15

What does the normal HbO2 saturation curve show?

Answer 15

-It shows the relationship between the PO2 levels and percent O2 saturation of hemoglobin.
-The difference in y-axis is how much oxygen has been released.
-binding affinity of hemoglobin to oxygen is mainly based on PO2 level.
(100% saturation if all four binding sites are taken, 75% for three taken, 50% for two taken, and 25% for one taken)

Question 16

What causes a right shift in saturation curve?

Answer 16

-Increased CO2
-Temperature increase
-increase in 2,3-DPG (metabolizes molecule)

Question 17

What is the difference between normal and right shift saturation curve?

Answer 17

-Now instead of one oxygen being released you release three when PO2 level is 40 mmHg
-this can happen when you’re exercising
-Release more oxygen for your tissues

Question 18

How does pH levels affect saturation curve?

Answer 18

Decreased- right shift
Increased- left shift

Question 19

How does temperature affect saturation curve?

Answer 19

Decreased- left shift
Increased- right shift

Question 20

How does PCO2 affect saturation curve?

Answer 20

Decreased- left shift
Increased- right shift

Question 21

How does 2,3-DPG 9 (metabolic compound) affect saturation curve?

Answer 21

Decreased- left shift
Increased- right shift

Question 22

Why is CO poisoning so deadly?

Answer 22

-it affects hemoglobin
-hemoglobin binding affinity to CO is 200x higher than oxygen so it will take the “seat” that is supposed to be left for oxygen
-so your body lacks oxygen

Question 23

What is hypoxia?

Answer 23

-response to high altitude
-have to compensate low oxygen level by producing more RBC (produce more EPO)

Question 24

Where is the respiratory control center?

Answer 24

It is in the pons/medulla

Question 25

What does the medulla do?

Answer 25

-initiates respiration
-> Dorsal resp group (DRG), (quiet breathing, inspiration)
->Ventral Resp group (VRG), (forced breathing, expiration)

Question 26

What is pons responsible for?

Answer 26

-modulates respiration
-receives input

Question 27

Peripheral Chemoreceptor response

Answer 27

-chemoreceptor sends CO2, pH, and oxygen
-stimulates peripheral chemoreceptors in carotid and aortic bodies
-responds when plasma PO2 level is less than 60 mmHg
-triggers RCC and forces ventilation, also increases PO2

Question 28

Central chemoreceptor response

Answer 28

-molecules need to go to the brain (through blood-brain barrier) in order to be picked up by central detector
-only molecule that can go through and reach brain is CO2
-force ventilation (breathing) and increases PO2 levels