Gas exchange- how are gases transported?

Question 1

What is a red blood cell?

Answer 1

main function is to carry oxygen
biconcave discs, so can bend and twist
contain plasma membrane protein, section and other proteins
major factor contributing to blood viscosity

Question 2

What is haemoglobin?

Answer 2

oxygen combines with iron
2 alpha polypeptide chains
2 beta polypeptide chains
each chain forms a protein subunit with a single heme molecule

Question 3

Oxygen transportation

Answer 3

combined with haemoglobin
dissolves in plasma
carried in the blood

Question 4

oxygen transport by haemoglobin

Answer 4

combines reversibly by oxygen
deoxyhaemoglobin
when it picks up oxygen it releases hydrogen ions
the amount of oxygen bound to Hb is known as saturation
pulse oximeter measures this

Question 5

Carbon dioxide transport at the tissues

Answer 5

co2 moves from the tissues to the plasma
most enters the RBCs and combines with Hb and the rest combines with water to form hydrogen and HC03
HCo3 combines with Hb02 to release oxygen and form HHb
oxygen moves into tissues

Question 6

Carbon dioxide transport in the lungs

Answer 6

oxygen moves from alveoli into ciruculating plasma
most moves into RBC and forms Hb02 and H is released from the Hb
h combines with HC03 to form water and C02. The co2 moves to alveoli
co2 dissolves in plasma moves into the alveoli and HB releases Co2 as well

Question 7

Acid/Base balance

Answer 7

hydrogen ions are being continually produced through metabolism, they are regulated by hydrogen ion excrete by the kidneys and C02 excretion by the lungs
hydrogen in body if kidneys don’t work
accumulation of Co2 leads to an increase in hydrogen ion production and fall in blood ph causing respiratory acidosis
then can’t exhale C02, so over ventilating of lungs

Question 8

release of oxygen at the tissues

Answer 8

dissociation curve is steep between 20 and 40 mmHg

a small decrease in oxygen within the tissues results in substantial unloading of oxygen from the blood

Question 9

Factors affecting dissociation

Answer 9

temperature
partial pressure of C02
pH
anaemia and carbon monoxide

Question 10

How does temperature affect dissociation?

Answer 10

> > temperature moves curve to the right and dissociates oxygen more deadly
&laquo_space;temperature holds on haemoglobin

Question 11

How does partial pressure of C02 affect dissociation?

Answer 11

shift curve to left

hydrogen ins make more acidic

Question 12

How does pH affect dissociation?

Answer 12

acidotic moves curve to right

Question 13

How does anaemia and carbon monoxide affect dissociation?

Answer 13

anaemia,which is a lack of 02 decrease exercise tolerance

carbon monoxide combines with haemoglobin more readily than o2 so blood can’t pick up 2,3 BPG
shifts curve to right

Question 14

Bohr effect

Answer 14

effect of pH on the 02 dissociation curve
excess of H irons leads to a low ph
deoxyhaemoglobin more readily accepts hydrogen ions
shifts the curve to right

Question 15

Effect of pH on haemoglobin

Answer 15

a decreased pH causes greater release of oxygen from haemoglobin

acidotic, septic, released more o2 into tissues

saturation drops from 75-60 %
in peripheral tissue Hb will release 20% more oxygen

Question 16

oxygen dissociation curve

Answer 16

mixed venous blood has a partial pressure of 02 of 40mmHg
haemoglobin is 75% saturated at this level with 02
at 100mmHg partial pressure of 02 Hb is 97.4% saturated with oxygen
70mmHg, curve has flattened out

haemoglobin picks up 1 molecules which changes configuration of haem chains
picks up 2 readily
difficulty with first and last