module 3 - 8.4 transport of oxygen and carbon dioxide in the blood

Question 1

what does affinity mean?

Answer 1

tendency to bind to oxygen

Question 2

what is the affinity of haemoglobin for oxygen?

Answer 2

high

Question 3

at high partial pressures of oxygen, what happens to the haemoglobin?

Answer 3

it will bind to the oxygen forming oxyhaemoglobin

Question 4

what happens to oxygen at high/ low concentration?

Answer 4

high conc. - oxygen binds to haemoglobin
low conc. - oxygen dissociates to haemoglobin

Question 5

what is the equation for oxyhaemoglobin?

Answer 5

——————————affinity————————————->
Hb + 4O2 ⇌ Hb(O2)4
haemoglobin + oxygen ⇌ oxyhaemoglobin
<—————————dissociation———————————

Question 6

what is partial pressure?

Answer 6

measuring concentration of gas when mixed with another gas

Question 7

what is haemoglobins oxygen dissociation curve?

Answer 7

it is a sigmoid curve and plateau’s when all haemoglobin is oxyghaemoglobin

Question 8

at respiring tissue or capillary beds, what is pO2?

Answer 8

low, so haemoglobin dissociates its oxygen to 20-25% saturation

Question 9

what happens as oxygen binds to one monomer of Hb?

Answer 9

molecules shift from tense to relaxed state

Question 10

what does the shift from tense to relaxed state promote?

Answer 10

promotes the binding of oxygen to remaining 3 monomer’s haem group thus saturating the Hb molecule with oxygen

Question 11

what is cooperative binding?

Answer 11

the first oxygen molecule binds and changes structure of haemoglobin molecule, makes it easier for each successive oxygen molecule to bind

Question 12

what happens when oxygen starts binding to the haemoglobin?

Answer 12

the alpha bonds start breaking

Question 13

when does the dissociation from oxyghaemoglobin to haemoglobin occur?

Answer 13

doesn’t happen until capillaries

Question 14

where is the highest concentration of oxygen?

Answer 14

lungs

Question 15

where is oxygen concentration low?

Answer 15

in capillaries - its used for respiration

Question 16

what is deoxygenated haemoglobin?

Answer 16

haemoglobin without the bound oxygen

Question 17

how is the difference of absorption between oxy & deoxyhaemoglobin?

Answer 17

oxy - lower
deoxy - higher
measured with pulse oximeter

Question 18

what is the Bohr effect?

Answer 18

• helps oxyhaemoglobin to dissociate and get oxygen more easily
• it describes how high pCO2 affects Hb’s affinity for oxygen

Question 19

what does CO2 in the plasma form?

Answer 19

carbonic acid, this lowers pH of blood, causes oxyHb to dissociate its oxygen

Question 20

what happens in respiring tissue? (to do with Bohr effect)

Answer 20

where pCO2 is high, Hb releases O2 more easily

Question 21

what happens in the lungs? to do with Bohr effect)

Answer 21

• decrease in CO2 causes increase in blood pH (Hb releases O2 more easily)
• where pCO2 is low, Hb binds to oxygen more easily

Question 22

where is CO2 the highest and what does this cause?

Answer 22

• highest in cells/respiring tissue
• diffuses down conc. gradient to lungs then to air

Question 23

what molecules trigger the Bohr effect?

Answer 23

• carbon dioxide
• lactic acid

Question 24

why does lactic acid trigger the Bohr effect?

Answer 24

• lactic acid is produced when cells don’t have enough oxygen
• this increases acidity of blood more than CO2
• cells need more oxygen

Question 25

what produces carbonic acid?

Answer 25

when CO2 is dissolved in plasma

Question 26

how do you know how strong the Bohr effect is?

Answer 26

steeper gradient, stronger Bohr effect

Question 27

why do marine animals need to have a strong Bohr effect?

Answer 27

they need to dive down deep and allows for nearly all oxygen to dissociate and supply the body

Question 28

where is fetal haemoglobin found?

Answer 28

red blood cells and is involved in transporting oxygen from mothers bloodstream to organs and tissues in foetus

Question 29

fetal haemoglobin has a different composition from adult haemoglobin, what does this allow?

Answer 29

allows oxygen to bind more strongly, higher affinity for O2
- developing foetus is able to retrieve oxygen from mothers bloodstream

Question 30

what does the structure and behaviour of lugworm enable for the organism?

Answer 30

to thrive in low-oxygen environment

Question 31

what is the water flow like through the burrow when submerged by tide?

Answer 31

continuous

Question 32

how does oxygen diffuse in a lugworm?

Answer 32

through the gills and body surface

Question 33

what are the differences between human and lugworm haemoglobin?

Answer 33

• lugworm reaches a high saturation at much lower partial pressure to that of man
• dissociation curve is shifted to the left and lugworm has very high affinity for O2
• lugworm haemoglobin shows no Bohr shift

Question 34

what is myoglobin?

Answer 34

an oxygen-binding protein found in skeletal muscle tissue of vertebrates and mammals

Question 35

what is the difference in functions between haemoglobin and myoglobin?

Answer 35

haemoglobin - transports oxygen
myoglobin - store oxygen

Question 36

what does high concentrations of myoglobin in muscle cells allow?

Answer 36

allows organisms to hold their breath for a longer period of time
- diving mammals have muscles with high abundance of myoglobin

Question 37

what 3 ways can carbon dioxide be transported?

Answer 37

1. dissolved in plasma as CO2
2. combined with amino groups of haemoglobin to form CARBAMINOHAEMOGLOBIN
3. converted to hydrogen carbonate ions (HCO3-) in cytoplasm of RBCs and then transported to plasma as HCO3-

Question 38

what is the Haldane Effect?

Answer 38

• oxygenation of blood in the lungs displaces CO2 from haemoglobin which increases removal of carbon dioxide from blood
• this means oxygenated blood has a reduced affinity for carbon dioxide

Question 39

where does most carbon dioxide diffuse into?

Answer 39

the cytoplasm of erythrocytes

Question 40

what does carbonic anhydrase do?

Answer 40

converts carbon dioxide and water into carbonic acid which then dissociates into hydrogen carbonate and hydrogen ions

Question 41

what is the chloride shift?

Answer 41

• HCO3- ions leave the erythrocytes and enter plasma by diffusion
• to maintain electrochemical balance, chloride ions are imported into erythrocytes

Question 42

what is haemoglobonic acid?

Answer 42

• H+ producsed by dissociation of carbonic acid bind with haemoglobin in RBCs - this forms heamoglobonic acid
• haemoglobin acts as a buffer to maintain blood pH