Transport of o2 and co2 in the blood (8)

Question 1

what are haemoglobin and myoglobin

Answer 1

respiratory pigments

Question 2

what is haemoglobin. What is its structure. where is it found

Answer 2

found in erythrocytes. its a large globular protein in RBCs, has quaternary structure (made of more than 1 polypeptide chain, 2 alpha, 2 beta) each polypeptide chain attached to a haem group (prosthetic group). cos of the prosthetic group haemoglobin is a conjugated protein. the haem groups have an affinity for oxygen, a haemoglobin can carry 4 o2 molecules

Question 3

What is a fully saturated haemoglobin

Answer 3

the haemoglobin is carrying the max amount of o2 molecules.

Question 4

what is loading/association

Answer 4

adding o2. happens in the lungs, o2 moves down conc gradient of the alveolar air space and into the erythrocytes
the hb has an affinity for o2 and so become associated - no bond between them

Question 5

what is unloading/dissociation

Answer 5

loss of oxygen. happens in respiring tissues, o2 moves down conc gradient from the erythrocytes into the tissues where o2 is used in ar and its concentration remains low.
as the hb releases the o2 it dissociates.

Question 6

what is myoglobin (beyond syllabus, helps w applied Qu’s)

Answer 6

a protein, an o2 store in muscle cells. 1 haem group. forms oxymyoglobin when it picks up o2 from oxyhaemoglobin, releases o2 when levels fall (in muscles after exercise).
-has higher affinity for o2 than hb, so will pick up o2 when oxyhaemoglobin is releasing it

Question 7

summary - transport of o2

Answer 7

-loads onto hb in lungs - oxyhaemoglobin
-travels in blood as oxyhaemoglobin to muscles
-dissociates from oxyhb to associate w myoglobin - oxymyoglobin
-stored in muscles as oxymyoglobin
-is released when the muscles are working hard to allow aerobic resp to continue for longer before switching to anaerobic resp.

Question 8

What is the composition of the air

Answer 8

78.5%nitrogen 20%o2 0.04%co2 1%argon

Question 9

what happens to density of air the further above sea level you are

Answer 9

the density decreases (as the number of molecules above you decreases as you go higher up)

Question 10

what does partial pressure of gases measure

Answer 10

the concentration of each particular gas present

Question 11

what is po2 (partial pressure of o2)

Answer 11

the pressure the o2 exerts in a gas mixture. units kPa. The concentration of oxygen.

Question 12

what is co operative binding

Answer 12

it is difficult for the the o2 to bind to the hb at 1st, but then the haemoglobin shape distorts - allosteric effect. this allows more o2 molecules to bind easier

Question 13

at low po2 (concentration of o2) does the HB offload oxygen easier or not

Answer 13

easier

Question 14

what does co operative binding ensure

Answer 14

that haemoglobin is very good at delivering large amounts of o2 to tissues if required

Question 15

At low oxygen concentration what is haemoglobin able to do

Answer 15

the haemoglobin offloads its oxygen easier (the HB dissociate w the o2, so it has 3, 2,2 or no o2 associated w it)

Question 16

what does the number of o2 molecules offloaded depend on

Answer 16

it depends on the rate of aerobic respiration, the rate of o2 consumption, and the diffusion gradient for o2.

Question 17

what causes saturated haemoglobin to release most of its o2

Answer 17

a low affinity for o2 in the low po2 conditions of respiring muscles.

Question 18

What does the sigmoid (s) curve shape indicate

Answer 18

Cooperative binding between haemoglobin and oxygen

Question 19

Why does myoglobin have a greater affinity for oxygen than haemoglobin

Answer 19

The haem group has a higher affinity for oxygen than the haem group of haemoglobin

Question 20

On an oxygen dissociation curve graph, why does the myoglobin curve lie left of the haemoglobin curve, and why is it a steeper curve

Answer 20

Myoglobin will pick up and store oxygen at much lower concentrations than haemoglobin does.Myoglobin holds onto its oxygen for longer. Myoglobin has a greater affinity for oxygen

Question 21

Oxymyoglobin is an oxygen store, When does oxymyoglobin release its oxygen

Answer 21

When the muscles are working hard, it may be using o2 for respiration faster than oxyhaemoglobin can supply it. The o2 concentration will get lower and lower until the oxymyoglobin then releases its o2

Question 22

Why does oxymyoglobin only release o2 when levels of it are low

Answer 22

Oxymyoglobin holds onto its o2 so it can provide extra o2 to the muscle and allow it to keep respiring aerobically for abit longerbefore it ahs to switch to anaerobic respiration.

Question 23

once oxymyoglobin has released its store of o2 when does it gain back its o2

Answer 23

when the oxygen debt has been repaid, the myoglobin is converted back to oxymyoglobin by taking o2 from oxyhaemoglobin.

Question 24

how does myoglobin become oxymyoglobin

Answer 24

myoglobin takes o2 from oxyhaemoglobin, its able to do this due to its greater affinity for o2 than haemoglobin

Question 25

what is the structure of fetal haemoglobin

Answer 25

its made up of 2 beta chains and 2 gamma chains. (while adult haemoglobin is made up of 2 alpha and 2 beta chains)

Question 26

why does fetal haemoglobin have a higher affinity for o2 than adult haemoglobin

Answer 26

the developing fetus needs to be able to take o2 from the maternal blood at the placenta. this woiud not be as efficient if the fetal and maternal haemoglobin had the same affinity for oxygen. the blood offloads o2 easier to blood of a higher o2 affinity.

Question 27

which has a higher affinity for oxygen: myoglobin or fetal haemoglobin

Answer 27

myoglobin trumps all

Question 28

does blood offload o2 easier to blood of a higher affinity

Answer 28

yes

Question 29

what affects the ability of haemoglobin binding with o2

Answer 29

oxygen concentration and co2 concentration

Question 30

how much co2 dissolves straight into the plasma

Answer 30

5%

Question 31

how is the compound carbaminohaemoglobin formed

Answer 31

co2 combines with the amino groups in the polypetide chains of haemoglobin.

Question 32

how much co2 combines w amino groups to make carbaminohaemoglobin

Answer 32

10-20%

Question 33

what does the majority 75-85% of the co2 do

Answer 33

it diffuses into te RBCs for conversion into hydrogencarbonate

Question 34

what enzyme do RBCs contain

Answer 34

carbonic anhydrase

Question 35

what does carbonic anhydrase do with the co2 in the blood

Answer 35

it catalyses a reaction in which co2 forms a weak acid called carbonic acid

Question 36

what does the carbonic acid then do

Answer 36

some of the acid dissociates producing hydrogen ions and hydrogencrabonate ions

Question 37

what do the hydrogencarbonate ions then do

Answer 37

they diffuse out out of the RBC and into the plasma (this is how majority of co2 is carried in the blood)

Question 38

what do the hydrogen ions then do

Answer 38

they combine with haemoglobin molcules inside the RBCs, forming a compound called haemoglobinic acid.

Question 39

if a haemoglobin molecule is binded to an co2 molecule what can it then not do

Answer 39

it cannot then bind to a o2 molecule, as the hydrogen ions make it drop its o2

Question 40

hydrogen iions + haemoglobin=?

Answer 40

haemoglobinic acid

Question 41

by accepting hydrogen ions the haeomglobin acts as a buffer, what does this prevent

Answer 41

it prevents a drop in pH and the conditions becoming too acidic

Question 42

what is the chloride shift

Answer 42

chloride ions moving into the RBCs

Question 43

what is the point of the chloride shift

Answer 43

it happens to maintain charge in RBC

Question 44

what happens to oxyhaemoglobin when its underthe influence of hydrogen ions

Answer 44

the oxyhaemoglobin dissociates, loses all o2

Question 45

what is the Bohr effect

Answer 45

the percentage saturation of haemoglobin is lower when co2 concentration is high

Question 46

co2 + haemoglobin = ?

Answer 46

carbaminohaemoglobin