Blood

Question 1

Composition of Blood

Answer 1

60% plasma, 40% cells – suspension

Question 2

Oxygen Solubility in Plasma

Answer 2

Oxygen INSOLUBALE in plasma – 0.003mL O2 in 100mL plasma per 1mmHg pp of oxygen (PO2)

Question 3

Hemoglobin

Answer 3

tetramer (MW 64kDa) – two α, two β chains, each containing a heme, central iron molecule that binds O2
o Hgb carries oxygen much more readily than plasma

Question 4

Oxygen Capacity

Answer 4

Each gram of hemoglobin can carry approximately 1.34mL of oxygen (oxygen capacity)
 Oxygen capacity does not include oxygen dissolved in plasma

Question 5

HB and Binding to Oxygen

Answer 5

Hb must be in reduced/ferrous state (Fe2+) to transport oxygen – 1.34mL oxygen – maintained in this state by NADH-methemoglobin reductase
o Methemoglobin – iron oxidized to Fe3+ ferric state – cannot bind oxygen

Question 6

Binding of Oxygen to Hemoglobin

Answer 6

Binding of O2 to Hb – important role in vasoregulation – promotes binding of NO to form S-nitrosohemoglobin
o Deoxygenation of Hb releases NO group – relaxes vessels to improve blood flow in this deoxygenated T structure (vs. oxygenated R structure)

Question 7

Consequences of Hemolysis

Answer 7

Free plasma hemoglobin maintained in ferrous (Fe2+) redox state: reacts with an O in near diffusion limited reaction to inhibit NO signaling

Oxidation of cell free hemoglobin from ferric (Fe3+) to ferryl (Fe4+) state acts as potent pro inflammatory agonist initiating oxidative cellular injury

When protective hemoglobin scavenging mechanisms saturated, levels of free hgb increases in plasma = consumption of NO

Question 8

Which species lack fetal hemoglobin?

Answer 8

pig, guinea pig, dog, horse, possum, mouse, rabbit