4-Transport in Blood

Question 1

dissolved O2

Answer 1

contrib to partial pressure

multiply 0.003 (solubility) by PAO2 to find
-so basically if PaO2 is normal dissolved O2 very small

Question 2

dissolved O2 when breathing 100% O2

Answer 2

dissolved contributes greater amount O2 transport (5 fold greater)

Question 3

Hb-Conjugated O2

Answer 3

majority of O2 in blood bound to Hg

O2 binding capacity of Hb = 1.34

Question 4

real Hb bound O2

Answer 4

20.1 x 0.97 = 19.5 mL O2/dL
amount of Hg present x percent saturation of Hg

Question 5

adult Hb

Answer 5

2 alpha + 2 beta bound to heme group

4 O’s can bind to each Hb (Fe binds reversible)
-positive cooperativity so affinity inc with bound O2

Question 6

Hb variants

Answer 6

1. methemoglobin- dec oxy content in blood, makes Hb bind O2 more tightly
2. fetal hemoglobin- y chains instead beta, higher affinity oxy than adult
3. hemoglobin S- sickle cell, abnormal betas so lower affinity and rods that occlude vessels

Question 7

O2 content

Answer 7

total amount of O2 per vol of blood

O2 binding cap x Hb present x SaO2 + dissolved O2
1.34 x 15 x 97% + 0.3 = 19.8 normally

Question 8

difference b/t arterial and venous O2 content

Answer 8

5

Question 9

PO2 influences what

Answer 9

dissolved component and hemoglobin bound O2

Question 10

O2 delivery to tissues

Answer 10

cardiac output x oxygen content

heart failure and anemia affect

Question 11

Hb dissociation curve

Answer 11

sigmoidal- shows affinity states
-flat upper part is high affinity, steep lower portion is low affinity

PO2 of 95 = 97% sat
PO2 of 40 = 75%

Question 12

P50 of O2

Answer 12

PO2 that Hb is 50% O2 saturated

inc/higher as shift right = weaker binding and releases to tissues more easily and v/v

Question 13

how body temp changes Hb-O2 binding

Answer 13

shifts curve right if inc temp
-metabolites from heat dec affinity binding

lower temp Hb binds more tightly, shift left to preserve O2

Question 14

pH on Hb-O2 binding

Answer 14

dec pH = shift right v/v
dec affinity

i.e. acidosis

Question 15

CO2 on binding

Answer 15

more CO2 = right shift curve
PCO2 inc

Question 16

2,3 DPG/BPG on binding

Answer 16

made in resp to low oxy levels/hypoxia

dec Hb affinity aka right shift

Question 17

anemia

Answer 17

SaO2 is normal but Hb % dec

Question 18

carbon monoxide

Answer 18

Hb preferentially binds over O2, higher affinity
-normal gas diffusion but content greatly reduced
PaO2 and SaO2 look normal

toxic effects > death, treat with hyperbaric oxy therapy

Question 19

transport of CO2

Answer 19

1. dissolved
2. conjugated to Hb
3. chemically modified as bicarb HCO3, mainly

Question 20

haldane effect

Answer 20

PO2 modulates Hb affinity for CO2
-higher PO2 dec affinity for CO2
-allows for loading CO2 in tissues at low PO2 and unload in lungs high PO2