Gas transport and electrolyte physio

Question 1

what is the composition of blood?

Answer 1

plasma (55%): water (mostly), proteins, other

ethryocytes (44%)

buffy coat (1%): wbc’s and platelets

Question 2

what are functions of erthrocytes?

Answer 2

1. carrying O2 from lungs to body
2. carrying CO2 from body to lungs
3. acid/base buffering

Question 3

what is the process of erthyropoiesis? what is it regulated by?

Answer 3

reticulocytes mature into erthrocytes and enter circulation based on O2 demand (hypoxia, anemia, decreased Hb, etc)

erthropoietin (EPO) is principle regulator and is controlled by HIF (transcription factor and when impaired can lead to erythrocytosis)

Question 4

when and where does erthyrocytes life cycle end?

Answer 4

after 120 days when they rupture in red pulp of spleen

Hb that is released is digested by macrophages

Question 5

what two ways is O2 transported?

Answer 5

1. dissolved: inadequate due to its low solubility (0.3 mL/ 100 mL) not keeping up with tissue demands
2. bound to hemoglobin

Question 6

what is the structure of Hb? what is its normal value?

Answer 6

4 heme sites so that 4 O2 can reversibly bind to it

globin has 2 alpha, 2 beta chains

adult form is hemoglobin A

fetal form is hemoglobin F

14.0 g/dL in female; 15.5 g/dL in male

Question 7

what is the correlation of % Hb saturation with PO2 and O2 concentration?

Answer 7

as PO2 increases, % Hb saturation (amount of binding sites being taken up by O2) increases, and O2 concentration increases

Question 8

how do you calculate normal oxygen concentration?

or just look at oxygen dissociation curve

Answer 8

(Hb * amount of O2 it can bind) = __ O2 /100mL blood

ex: (15 g Hb/100mL blood * 1.34 mL O2) = 20.1 O2 /100mL blood

Question 9

how do you calculate oxygen saturation?

what is the normal value in arteries?

what is the normal value in veins?

or just look at oxygen dissociation curve

Answer 9

O2 combined with Hb/ O2 capacity * 100

PaO2 is usually 100 mm Hg, therefore O2 saturation will be 97.5% in arteries

PvO2 is usually 40 mm Hg so O2 saturation will be 75% in veins

Question 10

what is p50?

what is normal value?

Answer 10

50% Hb saturation

normally 27 mm Hg

Question 11

at normal O2 levels (21 O2/dL) whats Hb doin?

what about PO2 at tissues?

Answer 11

O2 readily binds to Hb cause Hb wants it

O2 readibly jumps off and releases oxygen

Question 12

what happens when Hb conc dereases?

Answer 12

O2 carrying capacity decreases regardless of O2 saturaiton

Question 13

what happens when Hb conc increases?

Answer 13

O2 carrying capactiy increases regardless of O2 saturtion

Question 14

what does a left shift represent?

what disease associated with it?

Answer 14

increased affinity of Hb for O2

polycythemia and methemoglobinemia

*keeps O2

Question 15

what does right shift represent?

what disease associated with it?

Answer 15

decreased affinity of Hb for O2

associated with anemia

*helps release O2

Question 16

what kind of shift does excersice give?

what factors cause this?

Answer 16

right

• muscle is acidic (inc in H+)
• muscles is warm (Bohr effect)
• hypercarbic (CO2)
• 2,3-DPG (from metabolism of RBCs)- more during chronic hypoxia

Question 17

what is oxygen capacity?

normal value?

Answer 17

max oxygen that can be carried by Hb in blood

20.1 O2/ dL

Question 18

what is oxygen content?

normal value?

Answer 18

how much O2 is actually being carried by blood

19.5 mL o2/dL

Question 19

what is O2 saturation?

Answer 19

sites that are occupied by O2 on Hb out of total binding sites- given as %

Question 20

what are some red blood cell disorders? name 5

Answer 20

• anemia of blood loss
• anemia of chronic disease
• hemolytic anemias
• anemias of diminished erythropoiesis
• polycythemias

Question 21

what are the requirements for erythropoiesis?

Answer 21

1. adequate nutrition
2. vitamin B12- dna synthesis
3. folate- dna synthesis
4. iron availability- absorption, transport (ciculates as transferrin), storage—> needed for Hb to function and receive O2
   * need about 1 mg/d in men and 1.4mg/ day in women

Question 22

what does deficency in B12 or folate result in?

Answer 22

megaloblastic macrocytic anemia

Question 23

what does poor absorption of B12 result in?

Answer 23

pernicious anemia

Question 24

what does deficiencey in iron result in?

Answer 24

microcytic anemia (most common)

Question 25

what does defiency in the transport of transferrin to developing erthyroblasts result in?

Answer 25

hypochromic anemia

Question 26

what functions do ATP and iron contribute to in a RBC?

Answer 26

ATP- membrane flexibitly, gives energy (because no mitochondria), ion transport (ATPase)

iron- maintains FE2 (ferrous state) rather than FE3 (ferric state), prevents oxidative damage

Question 27

what is hemachromatosis?

what can it lead to?

what are the three types and what are each caused by?

Answer 27

iron overload

liver cirrohosis, skin pigmentation, diabetes mellitus

1. primary
2. secondary

** both caused by blood transfusions, ineffective erythropoiesus, increased iron intake

3. neonatal- develps in utero with unknown cause

Question 28

how do Hb conc, PO2, %Hb saturaton change in anemia?

Answer 28

half the Hb content–> half blood oxygen content (they are proportional)

BUT % Hb saturation does not change

Question 29

for primary polycythemia, what is its:

cause?

effect on # of RBC’s

total blood volume

viscosity

cardiac output

Answer 29

genetic–> low EPO

extra RBCs

increase in total BV (2x)

increase in viscosity

normal (kinda) CO

Question 30

for secondary polycythemia, what is its:

cause?

effect on # of RBC’s

cardiac output

Answer 30

hypoxia–> high EPOs

extra RBCs

CO may be abnormal

Question 31

for physiologic polycythemia, what is its:

cause?

effect on # of RBC’s

cardiac output

Answer 31

high altitude adaption

extra RBCs

normal CO

Question 32

what are characteristics of methemoglobinemia?

shift is ODC?

Answer 32

increase met-hemoglobin

iron is in ferric form

decreased O2 to tissues

blood is brown

skin is blue

leftward shift is ODC

Question 33

how do you describe oxygen consumption in a tissue?

how do you figure it out?

Answer 33

a-v O2 content difference (how much O2 tissues consumed)

20mL (going into tissue)- 15 mL(out of the tissue)= 5 mL O2 (that tissues consumed)

Question 34

how does exercise effect a-v O2 difference?

Answer 34

tissues consume more O2 (due to increase of CO2 being produced by them)–>

less venous O2 (only now about 5 mL vs 15)–>

bigger a-v difference

Question 35

how do you use the a-v difference to calculate RQ?

what is the normal values?

Answer 35

volume CO2 produced/ volume O2 consumed—>

VdotCO2/VdotO2

200 mL CO2 produced/ 250 mL O2 consumed = 0.8

Question 36

how is RQ determined (real world wise, not equation)?

Answer 36

the type of fuel being used by body

carbs- 1:1 ratio

fat- 7:10 ratio

protein- 9:10 ratio

(__ CO2 produced for every __ O2 consumed)

Question 37

how is RQ affected by exercise?

Answer 37

increases with # of calories burned

Question 38

what are the three ways CO2 is transported?

Answer 38

1. dissolved CO2- not enough on its own
   * travels down its conc gradient into alveoli
2. carbamino compounds- bound to plasma proteins or Hb (not heme, but amine group)
   * once in lungs, dissociates from the proteins
3. as HCO3 (most)- a lot more on that in another card

Question 39

what is the Haldane shift?

Answer 39

presence of O2 reduces affinity of amine chain (on Hb) for CO2

Question 40

how is CO2 converted to HCO3?

how is it exported from cell?

what kind of shift does HCO3 cause?

Answer 40

converted by carbonic anhydrase

exported by chloride

causes “chloride shift” or “hamburger shift”

Question 41

what are the 5 steps of how CO2 is carried to lungs in the blood as HCO3?

Answer 41

1. Co2 produced and exits tissue
2. CO2 hydrates into H2CO3 by carbonic anhydrase in RBCs
3. H2CO3 dissociates into H+ and HCO3-
4. H+ is buffered by deoxyhemoglobin in RBC’s and carried to venous blood
5. HCO3- is exchnaged for Cl- across RBCs and carried to lungs

once HCO3 is in lungs—> converted back to CO2