Erythrocytes

Question 1

What are features of a mature erythrocyte

Answer 1

Packed with haemoglobin
no nucleus or mitochondria
no DNA / RNA / cell division
120 day life span
old fragile RBC's removed by spleen
generated in red bone marrow

Question 2

What happens to old erythrocytes

Answer 2

phagocytic cells in liver and spleen engulf old RBC
Haemoglobin proteins broken down into amino acids
Haem group converted to bilirubin
bilirubin is taken to liver and is secreted into bile
iron binds to transferrin in blood and is recycled

Question 3

What hormone controls erythropoiesis and what organ secretes it

Answer 3

Erythropoietin

secreted by kidney

Question 4

What is main site of erythropoiesis

Answer 4

bone marrow

Question 5

What is haematocrit

Answer 5

percentage of blood that is RBC

Question 6

How does erythrocyte generate ATP

Answer 6

glycolysis

Question 7

NADH is product of glycolysis, what does NADH do to iron?

Answer 7

helps maintain iron as its Fe2+ ionic state

Question 8

How is ionic homeostasis maintained in an erythrocyte

Answer 8

Na / K ATPase transporters

Question 9

what are the products of Glyoclysis

Answer 9

requires 2 ATP

generates 4 ATP and 2 NADH

(can also produce NADPH)

Question 10

How is NADPH formed in glycolysis

Answer 10

when fructose-6-phosphate is redirected to Hexose monophosphate, pentose phosphate pathway

Question 11

What is oxidative stress

Answer 11

imbalance in production of free radicals and bodies ability to detoxify them with antioxidants

leads to cell damage

Question 12

What is glutathione

Answer 12

Tripeptide containing glutamate, cysteine, glycine

Question 13

What does reduced glutathione do

Answer 13

combats oxidative stress

maintains normal reduced state in cell

Question 14

How does glutathione combat oxidative stress

Answer 14

detoxifies H2O2 (hydrogen peroxide) which is primary intermediate of oxidative damage

Question 15

What does NADPH do

Answer 15

Keeps iron as ferrous ion (Fe2+)

reduces glutathione

Question 16

insufficiency of production of NADPH from pentose pathway can lead to what

Answer 16

cell damage via oxidative damage from free radicals

Question 17

How is CO2 transported in blood?

Answer 17

dissolved in solution 10%
bound to Hb 30%
Bicarbonate ion 60%

Question 18

Once CO2 has dissolved into RBC, how is it converted to bicarbonate

Answer 18

CO2 + H20 H2CO3 H+ + HCO3-

Question 19

What enzyme facilitates the conversion of CO2 to bicarbonate in RBC?

Answer 19

carbonic anhydrase

Question 20

What happens to bicarbonate in RBC once formed?

Answer 20

transported out of cell and into plasma via
HCO3- / Cl- transporter

Cl- comes in to cell to maintain cell membrane potential

Question 21

What are hydrogen ions (biproduct of bicarbonate formation) buffered by?

Answer 21

deoxygenated haemoglobin

Hb - + H+ = HHb

Question 22

As bicarbonate is driven out of cell, and Cl- is transported in to cell to compensate, what happens to cell?

Answer 22

Cell swells (at tissue)

Question 23

As bicarbonate is transported into cell and chloride is transported out of cell to compensate, what happens to cell

Answer 23

cell shrinks (at lungs)

Question 24

What are the constituents of adult haemoglobin

Answer 24

4 globin (protein) subunits each containing a single haem
4 Haem groups total
Each haem group contains one Fe2+ ion
each haem group binds one O2 molecule

Question 25

What is the haem group

Answer 25

porphyrin ring

Question 26

What subunits of globin exist in haemoglobin molecule in adults

Answer 26

2 alpha and 2 beta

2 alpha and 2 gamma in fetus

Question 27

Describe basic mechanism by witch oxygen is transported along placenta to fetus

Answer 27

Fetal haemoglobin has higher affinity for oxygen than adult haemoglobin

therefore oxygen will transport from adult haemoglobin to fetal haemoglobin

Question 28

explain G6PD deficiency

Answer 28

G6PD is an enzyme in the pentose phosphate pathway which is how NADPH is manufactured. If you have a deficiency in this enzyme then you cannot produce NADPH and therefore cannot combat oxidative stress