Lab 2 Questions

Question 1

What is the Law of Mass Action?

Answer 1

If the concentration on one side of a reversible rxn increases, the reaction is driven towards the opposite side

Question 2

What is the principal factor determining the extent of Hb saturation?

Answer 2

PaO2 (also PAO2 but hardly mentioned)

Other factors include, PCO2, H+ concentration, & temperature

Question 3

What does Beer’s Law state?

Answer 3

Concentration of a substance in solution is directly proportional to the amount of light absorbed by the solution

Concentration increases & absorbance of light for that concentration increases too

Question 4

What is the formula for the proportion method which involves absorbance and concentration?

Answer 4

Concentration of known/absorbance of known = concentration of unknown/Absorbance of unknown

This will tell you the concentration of Hb in a given sample
* Absorbance and concentration are directly proportional to one another

Question 5

What is Drabkin’s reagent? What are the two chemicals within it and what do they do?

Answer 5

Drabkin’s reagent is a solution where we dissolve our blood in
* Contains: Potassium cyanide & potassium ferricyanide
* Potassium ferricyanide converts all Hb molecules into a single form (methemoglobin)
* Methemoglobin reacts with Potassium cyanide to form a stable cyanmethemoglobin structure whose absorbance we can measure

Question 6

The proportion of Hb that is bound to O2 is referred to as what? What is the value in both arterial blood and venous blood?

Answer 6

• Percent oxyHb saturation (%SO2)
• Arterial blood = 97.5%
• Venous blood = 75%

Question 7

How does a finger pulse oximeter work?

Answer 7

Estimates % of SaO2 by passing through two wavelengths of low intensity light (one red and one infrared), and oxygen saturation is determined because blood saturated with oxygen absorbs less red light than oxygen-depleted blood

Question 8

What is the formula for total O2 content of blood?

Answer 8

O2 bound to Hb + O2 dissolved in plasma

Question 9

What are you multiplying to get total amount of O2 dissolved in plasma?

Answer 9

0.003ml O2/100mL blood/mmHg

• Multiply by how many mmHg of PO2 is given
• i.e. 100mmHg (PO2) ==> 0.003mL O2/100mL blood/mmHg x 100mmHg = 0.3 mL O2/100mL blood

Question 10

What do you multiply to get O2 bounded to Hb

Answer 10

Hb concentration x 1.34 mL O2/g Hb x %SpO2 level

I.e. 13g Hb/100mL blood (Hb concentration) x 1.34 mL O2/g Hb x 0.98 (%SpO2)

Question 11

Clinical significance of Hb?

Answer 11

Hb is closely tied to its molecular structure; changes in molecular structure impacts function (sickle cell anemia)

Question 12

What does sickle cell anemia do?

Answer 12

• It causes a point mutation which then will cause the cells to clump together and obstruct blood flow through capillaries
• Cells can easily rupture causing reduce in Hb concentration of the blood

Question 13

What is iron-deficiency anemia?

Answer 13

• Iron is required for heme-synthesis, & diet deficient in iron impairs Hb production
• Hb not as abundant; but saturation can be fully achieved (blood O2 content reduced)

Question 14

What is polycythemia?

Answer 14

• Abnormal increase in RBC production, Hb concentration increases.
• By increasing RBC’s, blood becomes more viscious, thus increasing resistance to blood flow

Heart works harder to pump blood and can lead to cardiac failure or death

Question 15

Major functions of Hb?

Answer 15

1. Transport O2
2. Transport CO2
3. Buffering H+

Question 16

Describe the structure of Hb. What is a possible cause of anemia?

Answer 16

• Hb is a tetramer made up of 4 molecules (2 alpha & 2 beta subunits)
• Each subunit contains an iron-containing heme; heme is the molecule interacting with O2 to allow transport
• Anemia can be caused by point mutation in B-globin gene, low iron stores, or dietary intake

Heme is the pigment that imparts red colour to blood

Question 17

Would it be advantageous for a football player to breathe in 100% O2 while resting on the sidelines between plays?

Answer 17

• Firstly breathing in more O2 when you are 100% saturated doesn’t make a difference
• Secondly, sideline players, their muscles are not exercising, so ATP demands dramatically drop
• Even though metabolism might stay elevated, when the player is relaxed the consumption of O2 is pointless
• Plus if the player is sitting down between plays they are likelier to use their anaerobic respiration over aerobic

Question 18

Significance of plateau and steep portion of O2-Hb dissociation curve?

Answer 18

• 40mmHg represents the systemic circulation & Hb saturation changes a lot with relatively low changes in PO2 (steep curve)
• 100mmHg which is reflective of pulmonary circ., plateau means that changes in PO2 won’t impact %Hb Sat.