4. Gas Transport and Erythrocyte Phys

Question 1

what is the fxn of blood

Answer 1

1. deliver nutrients and O2
2. remove waste products
3. maintain homeostasis
4. circulation

Question 2

what is the normal level of hematocrit for women, men, newborn and 2 month old

Answer 2

women - 40%

men- 45%

newborn- 55%

2 month 35%

Question 3

what are the fxn of erythrocytes

Answer 3

carrying O2 from lungs to body

carry CO2 from body to lungs

acid/base buffering

Question 4

what are reticulocytes

Answer 4

precursors of erythrocytes

mature into erythrocytes entering circulation and these mature based on O2 demand

Question 5

what is eryhtropoietin (EPO) and when is it produced

Answer 5

principle regulator

produced by kidneys in response to: anemia, low Hb, decreased RBF, central hypoxia (pul disease, altitude)

Question 6

what regulates EPO

Answer 6

hypoxia inducible factor (HIF)

Question 7

what happens to genetic deletion of HIF?

what about impaired regulations?

Answer 7

genetic deletion –> anemia, mutations in polycythemia

impaired regulation –> erythrocytosis

Question 8

where do RBCs rupture

Answer 8

spleen, liver and bone marrow

Question 9

When RBCs death and phagocytose - they break down into:

Answer 9

1. globin –> AA –> reuse for protein synthesis
2. heme –> Fe3+ bound to transferrin –> store in liver as ferritin –> recycle Fe3+ for more RBC formation

–> heme also converted to bilirubin –> liver –> SI –> kidney and Large intestine & excreted as urine and feces, respectively

Question 10

how is O2 transported in blood

Answer 10

dissolved in plasma

bound to Hb (majority)

Question 11

how do Hb and O2 bind

Answer 11

4 O2 molecules to 1 Hb

contain 4 heme sites - 2 alpha and 2 beta subunits for adults

Question 12

what is normal O2 concentration

Answer 12

20 mL

15 g Hb/100 mL blood

Question 13

what is the difference btn arterial and venous O2 saturation

Answer 13

arterial - 100 mm Hg - 97.5%

venous - 40 mm Hg - 75%

Question 14

what are tissue PO2 levels and what do they mean

Answer 14

lower (steeper curve)

-O2 readily released from Hb to deliver O2 to tissue

Question 15

what happens to O2 carrying capacity if Hb concentration decreases

Answer 15

O2 carrying capacity decreases (regardless the O2 saturation)

& vice versa

Question 16

what is a left shift on the O2 dissociation curve

Answer 16

=increased affinity of Hb for O2

polycythemia & methemoglobinemia

Question 17

what is right shift on a O2 dissociation curce

Answer 17

decreased affinity for Hb for O2 (advantage for unloading O2)

anemia, exercising, acidic, hypercarbic, 2,3 BPG

Question 18

why does exercise favor a right shift

Answer 18

let go of O2 more –>

more to myoglobin for ETC, increase H+ concentration & hypercarbic

Question 19

what does chronic hypoxia form

Answer 19

2,3 DPG

(2,3 DRG = end point of RBC metabolism)

Question 20

what is required for erythropoiesis

Answer 20

adequate nutrition

Vit B12 & B9 (for DNA synthesis)

iron availability (absorption, transport and storage)

Question 21

what do you get with folate or B12 deficient

Answer 21

megaloblastic macrocytic anemia

Question 22

what occurs with poor B12 absorption

Answer 22

pernicious anemia

Question 23

what do you get with iron deficiency

Answer 23

microcytic anemia

Question 24

what do you get when you have deficient transport of transferrin to developing RBCs

Answer 24

hypochromic anemia

Question 25

how does ATP contribute to iron and its regulation

Answer 25

iron has no mitochondria - so need energy to convert Fe3+ to Fe2+ to bind to Hb

• maintain Fe2+
• ion transport
• prevent oxidative damge (which can occur if you cant change Fe3+ to Fe2+)

Question 26

what does iron overload lead to

Answer 26

liver cirrhosis

skin pigmentation

DM

Question 27

what happens to Hb concentration, blood O2 content and O2 % saturation with anemia

Answer 27

Hb -decreased (halved)

blood oxygen content - decreased (halved)

O2 % saturation doesnt change

Question 28

what can cause primary polycythemia

Answer 28

genetic (low EPO)

extra RBCs - increased total blood vol & viscosity

Question 29

what can cause secondary polycythemia

Answer 29

hypoxia (high EPO)

extra RBCs

CO maybe abnormal

Question 30

what can cause physiologic polycythemia

Answer 30

high altitude adaption

extra RBCs

normal CO

Question 31

what happens with methemoglobinemia

Answer 31

increased met-Hb

Fe3+ form - not converted or enzyme isn’t working

-decreased O2 available to tissues

–> Left shift - hold onto O2

blood = chocolate color & skin = blue

Question 32

what happens to A-V O2 difference during exercise

Answer 32

lower

shows increased demand

increase CO2 production

Question 33

what is respiratory quotient determined by

Answer 33

fuel being used (fat vs carb)

carb = 1 CO2 to 1 O2 –> RQ = 1

fat = 7 CO2 to 10 O2 –> RQ = 0.7

protein = 9 CO2 to 10 O2 –> RQ = 0.9

Question 34

what does exercise do to respiratory quotient

Answer 34

increases it

Question 35

how does CO2 get transported

Answer 35

dissolved (not enough alone)

carbamino compounds

as HCO3- (major)

Question 36

what is the haldane shift

Answer 36

presence of O2 reduces affinity of amine chain for CO2 binding to Hb

carbamino compounds - transport CO2 by binding Hb via amine group

Question 37

what happens to CO2 in RBC

Answer 37

converted to H2CO3 by carbonic anhydrase and then dissociates into HCO3- & H+

H+ is buffered in RBC by deoxyHb - carried in venous blood

HCO3- exchanged for Cl- across RBC and carries to lungs

Question 38

what happens to HCO3- in the lungs

Answer 38

HCO3- converted back to CO2

CO2 - moves down gradient in alveoli