carriage of oxygen in the blood

Question 1

what are the roles of the cardiovascular system?

Answer 1

supply oxygen and metabolic fuel to tissues
remove metabolic waste from tissues
defence against pathogens

Question 2

what is oxidation?

Answer 2

loss of electrons

Question 3

what is an oxidising agent?

Answer 3

a substance that is reduced so that it can oxidise another molecule

Question 4

give examples of oxidising agents in anaerobic bacteria

Answer 4

sulphate
nitrate
sulphur

Question 5

what does oxidation do to a substrate?

Answer 5

simplifies the electronic structure

releases energy

Question 6

what is reduction?

Answer 6

gain of electrons

Question 7

what does reduction do to substrates?

Answer 7

allows complex molecules to be made from simple ones

requires energy

Question 8

when are oxidation reactions irreversible?

Answer 8

when they release a large amount of energy

Question 9

what does NAD stand for?

Answer 9

nicotinamide adenine dinucleotide

Question 10

how is NAD used in the body?

Answer 10

NADH gives electrons

NAD can store electrons

Question 11

give an equation for NAD to NADH

Answer 11

NAD+ + H+ + 2e- –> NADH

Question 12

what is microcytic anaemia?

Answer 12

smaller than usual RBCs

Question 13

what is microcytic anaemia?

Answer 13

larger than usual RBCs

Question 14

what are reticulocytes?

Answer 14

immature RBCs that have just left the bone marrow

Question 15

what % of RBCs are reticulocytes?

Answer 15

1-2%

Question 16

how long does it take for reticulocytes to turn into mature RBCs?

Answer 16

1 day after being in circulation

Question 17

how is the rRNA arranged in reticulocytes?

Answer 17

reticular, mesh-like structure

Question 18

what does a blood smear with high levels of reticulocytes show?

Answer 18

lots of haemolysis

Question 19

why can RBCs not repair themselves?

Answer 19

they don’t have a nucleus or organelles

Question 20

how long do RBCs survive in the bloodstream?

Answer 20

120 days

Question 21

why do RBCs require a small amount of ATP?

Answer 21

maintain the Na+ pumps in the cell membranes

actin filaments

Question 22

how do RBCs make ATP?

Answer 22

glycolysis

Question 23

what is the glucose uptake system in RBCs?

Answer 23

glut1 - works by facilitated diffusion

Question 24

what is the pH of RBCs?

Answer 24

low - acidic

Question 25

why do RBCs contain antioxidants? name an antioxidant

Answer 25

to protect haemoglobin against oxidative stress vitamin C

Question 26

describe the process of an RBC being destroyed?

Answer 26

ageing RBC undergoes changes to its plasma membrane recognised by phagocytes undergoes phagocytosis in the spleen, liver and bone marrow

Question 27

what is a haem group?

Answer 27

porphyrin ring with a ferrous iron centre

Question 28

what does hexavalent mean?

Answer 28

can form 6 bonds with surrounding atoms

Question 29

how many electrons does ferrous iron have in its outer shell and how are they arranged?

Answer 29

6 d electrons 4 in one plane held to nitrogen atoms in the porphyrin ring one bound to a histidine group underneath the porphyrin ring one sticking out

Question 30

why does oxygen form a weak reversible bond to haemoglobin?

Answer 30

oxygen cannot get close enough to remove the electron fully because of steric hindrance

Question 31

what causes steric hindrance in a haemoglobin molecule?

Answer 31

3D folding of the subunit

Question 32

what makes up a haemoglobin molecule?

Answer 32

4 subunits each with a haem group attached | 4 polypeptide chans connected by salt bridges, hydrogen bonds and hydrophobic interactions

Question 33

what is methaemoglobin?

Answer 33

haemoglobin with ferric iron

Question 34

when is methaemoglobin made?

Answer 34

over time, RBCs gradually accumulate methaemoglobin so they can no longer carry oxygen

Question 35

what does methaemoglobin reductase do?

Answer 35

converts methaemoglobin back to haemoglobin

Question 36

what does methaemoglobin reductase rely on?

Answer 36

NADH

Question 37

what percentage of people's haemoglobin is methaemoglobin?

Answer 37

1-2%

Question 38

what is methaemoglobinemia and what causes it?

Answer 38

abnormally high Methaemoglobin genetics or exposure to chemicals

Question 39

how does a high level of methaemoglobin lead to the death of a RBC?

Answer 39

markers on the surface of the RBC change change is detected by the cells of the liver and spleen they signal to dendritic cells and macrophages

Question 40

how do individuals with methaemoglobin reductase deficiency compensate for the defect?

Answer 40

make more RBCs than normal polycythemia

Question 41

what are the subunits of adult haemoglobin?

Answer 41

2 alpha | 2 beta

Question 42

what are the subunits of fetal haemoglobin?

Answer 42

2 alpha | 2 gamma

Question 43

what is an advantage of fetal haemoglobin having a higher affinity for oxygen?

Answer 43

can remove it more easily from placental blood

Question 44

what does 2,3 DPG stand for and what does it do?

Answer 44

2-3 diphosphateglycerate enhances ability of RBCs to release oxygen in hypoxic tissue binds to beta subunit as it starts to deoxygenate and increases steric hindrance

Question 45

define percent saturation

Answer 45

proportion of haemoglobin bound to oxygen

Question 46

how can % Hb be measured?

Answer 46

pulse oximeter uses a laser to detect the colour of blood which is a good indicator of levels of venous blood

Question 47

what should be the levels of % Hb in healthy individuals?

Answer 47

96-99%

Question 48

what is hypoxaemia?

Answer 48

arterial oxygen saturation below 90%

Question 49

what shape is the oxygen/haemoglobin curve?

Answer 49

sigmoid shape

Question 50

how does heat shift the oxygen/haem curve?

Answer 50

heat shifts curve to the right

Question 51

how does pH shift the oxygen/haem curve?

Answer 51

low pH shifts the curve to the right

Question 52

describe the structure of myoglobin

Answer 52

single subunit with haem group on it

Question 53

how does myoglobin act as an oxygen store?

Answer 53

loads O2 as Hb unloads it | only releases O2 when pO2 is very low and Hb cannot supply O2 fast enough

Question 54

where does the myoglobin curve lie with respect to the HbA curve?

Answer 54

to the left - has a higher affinity for oxygen

Question 55

what is rhabdomyolysis?

Answer 55

the process of myoglobin being released from damaged muscle tissue

Question 56

how can myoglobin cause acute kidney failure?

Answer 56

rhabdomyolysis occurs myoglobin is filtered by the kidneys toxic to the renal tubular epithelium causes acute renal failure

Question 57

what controls haematocrit levels?

Answer 57

erythropoietin (EPO)

Question 58

where is EPO released from?

Answer 58

interstitial cells in the kidneys

Question 59

what part of the body does EPO act on?

Answer 59

bone marrow

Question 60

describe the negative feedback loop of EPO raising haematocrit levels

Answer 60

``` normal haematocrit = 45% haematocrit falls renal hypoxia EPO increases stimulates RBC production in the bone marrow haematocrit levels restored ```

Question 61

how is CO2 carried in red blood cells?

Answer 61

CO2 converted to bicarbonate via carbonic anhydrase bicarbonate diffuses out of RBC chloride moves in to maintain the electrical neutrality (chloride shift)

Question 62

how is CO2 removed from the blood in the lungs?

Answer 62

venous blood containing bicarbonate brought to the lungs bicarbonate re-enters RBC and converted back to CO2 CO2 diffuses into alveoli air space chloride leaves the RBC to balance the electrical charge of bicarbonate entering