L21-Blood gases-DONE

Question 1

How do partial pressures relate to amount of gas transport?

Answer 1

-Diffusion occurs down the partial pressures of gases to support metabolism.
- O2 carrying around is needed in the cells and in the mitochondria. short diffusion distance easily diffusible through membranes.

Question 2

What does metabolism depends on? and what are the measures of metabolism?

Answer 2

-Metabolism as a cell is how much ATP each cell uses per time.

Measures of metabolism:-
-ATP generation.
-oxidative phosphorylation
-O2 consumption per minute.

Question 3

Define Metabolic rate?

Answer 3

VO2 , Oxygen consumption of mils per minute, along with VCO2, generation of CO2 in mils per minute.

Question 4

What is done to support the metabolism of tissues?

Answer 4

A certain amount of O2 is delivered per minute and transport away certain amount of CO2 in order to KEEP A STEADY STATE

Question 5

What are the 3 determinants of how much gas is transported?

Answer 5

1). how much O2 nad CO2 in a litre of blood?
i). Gas transported in solution(dissolved).
ii). Gas transport bound to carrier molecules so doesn’t affect the pH.

2). Factors that can modulate/change gas content of O2 or CO2 in the blood.
i). Bohr effect & Haldane effects

3). How much blood is transported?
i). Cardiac output

Question 6

Explain the 3 determinants of how much gas is transported in more detail.

Answer 6

1). How much O2 or CO2 dissolved in a litre of blood. H+ ions are bounds to Proteins(no longer free in solution) so not affecting pH. O2 and CO2 has the ability to bind to carrier molecules so it no longer contributes to the partial pressure> therefore doesn’t affect the pH.

2).2 effects that are modulating or changing are called Bohr’s effect and Haldane’s effect.

3).Blood flow to the specific tissue depends on the delivery to the tissue
Cardiac output is all about delivering O2 and moving CO2.

Question 7

Define Henry’s law about gas in solution.

Answer 7

Amount of gas dissolved in solution is proportional to its partial pressure.

Question 8

When is the equilibrium reached when O2 is diffusing into the blood(via Fick’s law)

Answer 8

It will reach equilibrium when the partial pressure in gas and the partial pressure in the liquid are the same.

Question 9

What is the equation associated with Henry’s law? for amount dissolved?

Answer 9

Amount dissolved = partial pressure x solubility coefficient (apha)

Question 10

Difference between CO2 and O2 solubility.

Answer 10

CO2 is 20x more soluble than O2.

Question 11

What’s the relationship between arterial partial pressure and O2 content?

Answer 11

-There is a linear relationship as the PO2 gets to 13kPa, there’s only 3mL of O2 per litre inn blood in that dissolved solution.
-The slope of this graph = solubility.

Question 12

Why is there alot more OC2 dissolved in solution?

Answer 12

There is a lot more CO2 dissolved in
per litre of blood because it’s much more soluble ,even though CO2’s partial pressure from the outside is less than half.

Question 13

What does the proportionality constant equal to?

Answer 13

Solubility of the gas

Question 14

Can we survive on just the dissolved O2 or are there other ways?

Answer 14

No and there are other ways.

Question 15

Describe the structure of gas carrier molecules?

Answer 15

• 4 haem + globin chains
• each4 moiety allows 4 bindings of O2.
  -peptide chains/globin chains.
  -a & B chains will bind to both CO2 & H+ ad changes its shape and change in property.
  -B chains only bind 2,3-DPG(later slide)

Question 16

What does a gas carrier molecule carry?

Answer 16

Carry both O2 and CO2

Question 17

What does the shape of a protein gives it ? example?

Answer 17

It gives its property(cell-surface receptors)

Question 18

How is there variability when Hb binds to O2?Give me an example of the saturation.

Answer 18

Hb bind for O2 in each molecule.
Hb has a different number of O2 bound to them and that depends on the equilibrium and the partial pressure of the O2. W can measure it in plasma but not in red blood cells.
O2 bound to 16 of the binding sites in the red circle. there’s continuous variability of the saturations in everyone. its not the same in everyone > 50% saturated.

Question 19

Describe the cooperative nature of O2 binding to Hb?

Answer 19

Binding of the 1st O2 causes a shape change in the Hb AND that makes it easier for the next 2nd & 3rd O2 to bind. Now its congested and it’s not easy for the 4th O2 to bind hence the plateau.

This shape of the curve in Hb & O2 transport is called Cooperative nature.

Question 20

What is this cooperativity nature due to ….? and why?

Answer 20

Allosteric changes, because shape of the protein determines its property.

Question 21

What is the equation for saturation(%)?

Answer 21

( O2 bound / O2 capacity-number of binding sites in total ) x 100

Question 22

What would happen if all of the Hb proteins are in the plasma? and what does it mean and lead to ?

Answer 22

viscosity would be high, blood would be thicker and more resistance to flow. Normally Hb is packed tightly inside the red blood cells. If not it can lead to impaired blood flow.

Question 23

Therefore why Hb is isolated from the plasma?

Answer 23

1. Increase the plasma viscosity
2. Will get excreted by the kidney
3. expose to enzymatic attacks in the plasma

Question 24

What does the partial pressure and the saturation graph tell us?

Answer 24

For a certain partial pressure of Oxygen, it will determine how many binding sites are actually occupied.

Question 25

How do we support the local metabolism using Bohr's effect? and what does this allow?

Answer 25

We have to desaturate the Hb. ie:- During exercise, if the skeletal muscles in the legs are generating heat, generating more CO2, generating more Hydrogen metabolism, I can deliver more O2 there, compared to the gut where the there is no increase in CO2. This allows local regulation of O2 delivery.

Question 26

What is 2-3,-DPG ? examples of where?

Answer 26

-side chain product from glycolysis. -mature RBCells have no mitochondria so no oxidative phosphorylation to generate ATP(instead they do anaerobically) so the production of this 2,3-DPG is related to the metabolic activity of the RBCells. - ONLY binds to beta chains

Question 27

What happens to the graph of Hb in increase and decrease of 2,3-DPG?

Answer 27

INCREASE - In chronic hypoxia(low O2 levels) and blood alkalosis - altitudes ->shifts the Hb curve right counteracting the left shift of hypocapnia(low CO2 levels) & alkalosis - helps maintaining O2 delivery to tissues. -more 2,3-DPG, Hb releases more O2 easily and shifts the curve right. DECREASE - under storage (blood banks) or chronic acidosis(too much in tissues) - decreases O2 availability in transfused blood. -less 2,3-DPG, Hb holds onto O2 tightly and Hb is less wiling to release O2 so sifts the curve left.

Question 28

What is a Haematocrit ?

Answer 28

Measure of the red blood cell volume.

Question 29

Define O2 capacity

Answer 29

It is the capacity of Hb to bind O2 ( if 100% saturated)

Question 30

What's the relationship between O2 content and O2 consumption? What is the equation for how much O2 have consumed in tissues ?

Answer 30

The rate at which O2 is consumed by the periphery = the difference between the O2 content in arterial blood leaving the heart and in mixed venous blood returning to the heart. VO2 = (CAO2-CvO2) x Cardiac Output

Question 31

How do we increase or change the VO2?

Answer 31

Cant change the CA, but can change CV. We can take out more blood so less is left in the venous. We can extract more O2 which would lead the Hb being less saturated in the venous blood. SO a lower PO2 in the venous blood.

Question 32

What is the 3rd way that Co2 is transported ? hint:-carbonic anhydrase.

Answer 32

CO2 +H2O = H2CO3 = H+ + HCO3- Carbonic anhydrase speeds up the formation of H2CO3. Transport CO2 in the form of Bicarbonate. We can both isoforms of carbonic anhydrase in the lumen of proximal tubule and within the epithelial cells. H2CO3 is carbonic acid HCO3- is carbonate ion

Question 33

Explain the steps in which the O2 is delivered to the tissues.

Answer 33

1. Transport Oxygen and Hb into the tissues via diffusion. 2. Then CO2 from the tissues are transported into the plasma down a concentration gradient. either:- (i) dissolved to increase pp of CO2 in the plasma or (ii) binding to a (protein) transport molecule. ie- Albumin or (iii) bicarbonate ion - very slow reaction.

Question 34

Is oxyhaemoglobin or deoxyhaemoglobin better at picking up CO2?

Answer 34

deoxyhaemoglobin

Question 35

Explain Chloride shift or the hamburger effect?

Answer 35

To stop the build up the end products(bicarbonate ions) of the bicarbonate reaction. We transport the HCO3- ions out of the rbc into the plasma and swap that with a -ve charge of Cl- ions coming into the rbc.

Question 36

How important are the different types of CO2 transport?

Answer 36

1.largest CO3 store is the HCO3- 2. Hb is important for CO2 flux - Flux here is the difference between arterial and venous is mainly about the change in the bicarbonate and the change in the role of Hb in transporting CO2.

Question 37

What is Haldane effect?

Answer 37

The graph with CO2 content (ml/L blood) with PCO2. -Allows dual ways to transport O2 and CO2 between lungs and tissues. -Hypoxia increase Hb affinity for CO2 and H+ ions. -When we have a reduction in PO2, more deoxyhaemoglobin for the same partial pressure from the previous line, there would be more CO2 content in the blood because it moved up. > shift in the curve

Question 38

Explain the significance of Haldane effect in TISSUES.

Answer 38

Oxygenated Hb delivers O2 to the tissues, we get more of the deoxyHb. So CO2 diffuse in to the rbc from the plasma. and CO2 binds directly to those deoxyHb in the rbc. Then carbonic anhydrase forms bicarbonate and chloride shift. and to stop the build up of H+ ions( which would buffer the pH), H+ ions bind to the deoxyHb. That buffering of the pH allows us to form more bicarbonate ions which is pumped out into the plasma, enabling us to transport more CO2. Getting rid of the O2 and picking up CO2.

Question 39

Explain the significance of Haldane effect in LUNGS.

Answer 39

Diffusion of CO2 from the blood into the alveoli. from deoxyHb to H+ is going backwards here. and the reaction from CO2 to H+ is going backwards too. we pick more O2 from the lungs into the rbc, there is more oxyHb. There is a reciprocal arrangement as O2 is picked, the CO2 is getting rid of.

Question 40

Why is Hb a stronger base?

Answer 40

Able to accept a proton/H+ proton acceptor DexoyHb is 3,1/2 times stronger base than the OxyHb.

Question 41

Compare both Haldane and Bohr curves.

Answer 41

- Hb content curve and CO3 content curve. - arterial CO2 and venous CO2 in 2 curves. - gives the difference in the arterial content and difference in venous content which are VCO2 and VO2.

Question 42

Summary...

Answer 42

- Gases only give partial pressure when dissolved in solution. -1. O2 is carried:- i) in solution(producing PO2) ii) bound to Hb -2. CO2 is carried :- i) in solution (producing pCO2 ) ii) bound to proteins (mainly Hb) iii) as HCO3- - link between partial pressure and Hb. - Bohr effect - changes in O2 affinity causing changes in O2 content. - Haldane effect - changes in CO2 content.