Gas Transport in the Blood

Question 1

What do erythrocytes do?

Answer 1

maxmises the surface area to volume ration, 1/3 of RBC made up of haemoglobin

Question 2

what are haemoglobin molecules made up of?

Answer 2

4 polypeptides called globins , each bind one heme molecules

Question 3

What does each heme molecule have?

Answer 3

a red colour and binds one iron molecules

Question 4

What molecule bind oxygen?

Answer 4

iron molecules

Question 5

What does adult haemoglobin have?

Answer 5

2 alpha chains and 2 beta chains

Question 6

What is oxygen rich haemoglobin called?

Answer 6

Oxyhaemoglobin

Question 7

What is oxygen defficient haemoglobin?

Answer 7

Deoxyhaemoglobin

Question 8

What is lifespan of erythrocytes?

Answer 8

M 120days F 110 days

Question 9

How long does erythropoiesis take?

Answer 9

takes 4 days and occurs in bone marrow

Question 10

What stimulates erythropoiesis?

Answer 10

low PO2 increases formation of glycoprotein erythropoeitin in the kidney, induces bone marrow to make more erythrocytes

Question 11

What are 3 factors of transport respiratory gases?

Answer 11

Oxygen diffusion gradients
Carbon dioxide diffusion gradients
Haemoglobins oxygen disassociation relationship

Question 12

What is po2 in alveoli and capillary?

Answer 12

104mmhg, po2 in alveolar capillaries is 40mmhg - o2 diffuses following its po2 into blood untill 104mmhg

Question 13

What does blood leaving the alveolar capillaries have a po2 of?

Answer 13

104mm, by the time reaches pulmonary vein will be 95mm -pulmonary vein recieves some deoxygenated blood from bronchial veins - transported to tissues

Question 14

What will interstitial fluid have a po2 of?

Answer 14

40mmhg and cells 20mmhg - oxygen flow from the blood capillaries into the interstitial fluid and then into cells

Question 15

what do cells produce and why?

Answer 15

CO2 and results in intracellular pco2 of 46mmHg but intersitital fluid has a PCO2 of 45mm hg and capillaries supplying the tissues with blood will have PCO2 of 40mm Hg

Question 16

Where does CO2 diffuse into?

Answer 16

blood so that by the time deoxygenated blood pumped back to lungs through pulmonary artery it has a PCO2 of 45mmHg

Question 17

What is PCO2 of alveoli?

Answer 17

40mmHg so CO2 diffuses from blood into alveoli - blood passes into pulmonary vein now a PCO2 of 40mmHg

Question 18

How much oxygen does haemoglobin carry?

Answer 18

87% in oxygen and 3% in solution of blood plasma. the binding of 02 with haemoglobin is reversible - o2 binds to haemoglobin in lungs disassociates from haemoglobin in the tissues - relationsip described by oxygen disassociation curve

Question 19

When is haemoglobin in erythrocytes 100% saturated with oxygen?

Answer 19

Po2 of 80mmHg and above the blood in alveolar capillaries is saturated

Question 20

What is the PO2 of blood in capillaries?

Answer 20

Of tissues is 40mmHg and at PO2 40mm haemoglobin is 75% saturated and 25% of o2 carried to disassociate into the interstitial fluid

Question 21

During exercise the PO2 of interstitial fluid is what?

Answer 21

In skeletal muscle drop to 15mmHg and at PO2 haemoglobin gives up 75% of its o2

Question 22

When does haemoglobin decline?

Answer 22

with decreasing PH when haemoglobin bind O2 at ny PO2

Question 23

What is an Decrease in PH caused by?

Answer 23

increase in concentration of hydrogen ions

Question 24

How is carbonic acid formed?

Answer 24

as PCO2 increases CO2 combines with water to form.

Question 25

What does carbonic acid disassociate into?

Answer 25

carbonic acid disassociates into H and bicarbonate ions

Question 26

What do hydrogen ions bind to?

Answer 26

Protein part of haemoglobin molecule causing a comformational change decreasing the affinity of haemoglobin for O2

Question 27

What does a decrease in PH cause?

Answer 27

an increasing in the CO2 concentration means a greater PO2 is needed to saturate the haemoglobin - curve shifts to the right

Question 28

What causes oxygen curve to the right?

Answer 28

Increases in temperature as accumulation of acidic products such as lactic acid

Question 29

What happens in heavy exercise?

Answer 29

CO2 and lactic acid accumulate in tissue and temp increases so 85% of o2 released from haemoglobin

Question 30

IN lungs what happens with increased RR?

Answer 30

PCO2 decreases oxygen curve to left so haemoglobin saturates

Question 31

What modifies affinity of haemoglobin for O2?

Answer 31

BPG - produced by erythrocytes and decreases the affinity of haemoglobin for 02 - people in high altitudes have high conc of BPG in the blood and increases oxygen delivery to tissues at high altitudes - BPH levels in stored blood decrease with time

Question 32

How is CO2 transported in blood?

Answer 32

As CO2 in plasma, combined with blood proteins and in form of bicarbonate ions

Question 33

What are blood proteins that bind CO2 called?

Answer 33

Carbamino compounds - CO2 binds to form carbaminoheamoglobin- the affinity of haemoglobin for CO2 is greate if haemoglobin gives up oxygen this is haldane effect in tissue giving up O2 binds to CO2 in alveoli its opposite

Question 34

How does CO2 form carbonic acid?

Answer 34

Diffuses into erythrocytes and reacts with water

Question 35

Where does negative bicarb ions diffuse?

Answer 35

Out of erythrocytes into blood plasma as a result negative cholride ions move into erythrocytes - maintains electrical balance between in and out of cell

Question 36

What is chloride shift?

Answer 36

Exchange of negative chloride ions for negative bicarb ions

Question 37

What happens to hydrogen ions that diffuse out of erythrocytes?

Answer 37

PH of plasma would drop and prevented by most hydrogen ion binding

Question 38

When deoxygenated blood reaches alveoli what happens?

Answer 38

CO2 in blood diffuses into alveoli and co2 to blood proteins go to alveoli - pco2 blood decreases bicarb bck in erythrocytes and haemoglobin releases hydrogen ions - cholirde ions move out of erythrocytes

Question 39

What causes blood ph increase?

Answer 39

Movement of hydrogen ions into erythrocytes and increaseuptake of oxygen by haemoglobin