Respiratory System 8- Carriage Of Oxygen And Carbon In The Blood

Front 1

which 3 factors affect the transport

Back 1

(1) The oxygen diffusion gradients

(2) The carbon dioxide diffusion gradients

(3) Haemoglobin's oxygen dissociation relationship

Front 2

whats the PO2 in the alveoli

Back 2

104mm Hg

Front 3

PO2 in the blood in alveolar capillaries

Back 3

40 mm Hg

Front 4

since the PO2 in the alveoli is 104 mm Hg and PO2 of blood in alveolar capillaries 40mm Hg

Back 4

O2 diffuses into the blood until blood PO2 reaches 104mm Hg

Front 5

whats the PO2 of blood leaving the alveolar capilaries

Back 5

104 mmHg

Front 6

whats the PO2 of the blood leaving capillaries when it eaches pulmonary vein

Back 6

95 mmgH

Front 7

whats the pO2 of interstitial fluid

Back 7

40 mm Hg

Front 8

pO2 of cells

Back 8

20 mmgH

Front 9

What's the intracellular pCO2

Back 9

46mmHg

Front 10

interstitial fluid pCO2

Back 10

45mm hg

Front 11

whats the pCO2 of capillaries supplying tissues with blood ?

Back 11

40 mmHg

Front 12

pCO2 of alveoli

Back 12

40 mmHg

Front 13

in which way does CO2 of the alveoli diffuse and why ?

Back 13

from blood into alveoli because pCO2 of deoxygenated blood in Pulmonary artery is 45 mmgh and pCo2 of alveoli as about 40 mmHg.

Front 14

how much of a red blood cell's weight made up of haemoglobin

Back 14

1/3

Front 15

erythrocytes remove blood from where ?

Back 15

plasma and allow them to diffuse into blood

Front 16

how lond does erythropoesis take

Back 16

4 days

Front 17

where does erythropoesis take place

Back 17

bone marrow

Front 18

how is erythropoesis stimulated ?

Back 18

Low PO2 stimulates erythropoiesis by increasing the formation of the glycoprotein erythropoietin in the kidneys. Erythropoietin induces the bone marrow to make more erythrocytes.

Front 19

describe the structure of haemoglobin

Back 19

Each haemoglobin molecule is made up of 4 polypeptides, called globins, which each bind one heme (haem) molecule

Front 20

what molecule binds to heme

Back 20

1 iron molecule

Front 21

which molecule binds oxygen

Back 21

iron

Front 22

how many alpha and beta chains do aldult haemoglobin molecule consist of ?

Back 22

• Adult haemoglobin consists of 2 alpha chains and 2 beta chains

Front 23

whats oxygen rich haemoglobin called

Back 23

oxyhaemoglobin

(deoxyhaemoglobin when lacks oxygen)

Front 24

the rxn in which O2 binds to iron ions in haemoglobin (Hb) molecules to form oxyhaemoglobin (HbO2 ) is :

a) reversible

b) irreversible

Back 24

b) reversible.

Front 25

how many oxygens does a haemoglobin mol. bind ?

Back 25

4

(Each RBC has ~280 million Hb molecules, each binds 4 oxygen molecules)

Front 26

what percentage of O2 is carried by haemoglobin

Back 26

97%

Front 27

describe Hb's oxygen dissociation relationship

Back 27

-Hb carries 97% of oxygen, 3% is arried in plasma

-O2 binds to the Hb in the lungs and dissociates from the haemoglobin into the tissues

• The relationship between O2 and Hb is described by the oxygen dissociation curve

Front 28

How does CO poisoning occur

Back 28

CO binds strongly to Hb and takes up the place of O2 causing CO poisonig

Hydrogen cyanide (HCN) also binds to Hb

Front 29

what is Oxygen–Haemoglobin Saturation Curve

Back 29

Graph relating saturation of Hb to partial pressure of O2

Front 30

-------------- PO2 pressure results in greater Hb saturation

a. higher

b. lower

Back 30

Higher

Front 31

why is the Oxygen–Haemoglobin Saturation Curve a curve rather than a straigh line ?

Back 31

because Hb changes shape each time a molecule of O2 is bound

Front 32

each time an O2 is bound to Hb it makes it easier for next O2 to bind, why is this an advantage

Back 32

• Allows Hb to bind O2 when O2 levels are low

Front 33

whats Hb saturation

Back 33

the percentage of heme units in a haemoglobin molecule that contains bound oxygen

Front 34

Environmental Factors Affecting Hb

Back 34

PO2 of blood,

Blood pH,

Temperature,

Metabolic activity within RBCs

Front 35

what happens to the The Oxygen–Haemoglobin Saturation Curve when temp rises

Back 35

more o2 is released

curve shifts right

Front 36

what happens to the The Oxygen–Haemoglobin Saturation Curve when temp drops

Back 36

less O2 releases

curve shifts left

Front 37

at what PO2 is Hb in erythroytes nearly 100% saturated

Back 37

Haemoglobin in the erythrocytes is nearly 100% saturated with oxygen at PO2 of 80 mm Hg and above, thus the blood in the alveolar capillaries is saturated

Front 38

what is the O2 saturation percentage at pO2 of blood capillaries (4o mmhg)

Back 38

• The PO2 of blood in the capillaries of the tissues is about 40mm Hg. At PO2 of 40mm Hg, haemoglobin is about 75% saturated, so about 25% of the O2 carried by the erythrocytes can dissociate into the interstitial fluid

Front 39

describe the relationship between pO2 in IF in skeletal muscle and Hb during exercise

Back 39

• During exercise, the PO2 of the interstitial fluid in skeletal muscle can drop to 15 mm Hg. At PO2 of 15 mm Hg, haemoglobin gives up 75% of its O2

Front 40

what is the effect of low ph on Hb O2 binding

Back 40

•The ability of haemoglobin to bind O2 at any PO2 declines with decreasing pH • Decreases i

Front 41

what causes the pH to decrease

Back 41

increase of H+ ions

Front 42

what happens as PCO2 increases ?

Back 42

•As PCO2 increases, the CO2 combines with water to form carbonic acid. Carbonic acid dissociates into H+ ions and bicarbonate ions

•The hydrogen ions then bind to the protein part of the haemoglobin molecule causing a conformational change, decreasing the affinity of haemoglobin for O2

Front 43

whats the bohr effect?

Back 43

a decrease in pH and an increase in the CO2 concentration mean that a greater PO2 is required to saturate the haemoglobin - the oxygen dissociation curve shifts to the right.

Front 44

effects of pH on oxygen-hb curve

Back 44

When the pH drops below normal levels, more oxygen is released; the oxygen–haemoglobin saturation curve shifts to the right. When the pH increases, less oxygen is released; the curve shifts to the left.

Front 45

Role of temperature on O2-Hb curve

Back 45

• Increases in temperature shift the oxygen dissociation curve to the right, as does the accumulation of acidic by products such as lactic acid

• Temperature effects are significant only in active tissues that are generating large amounts of heat, e.g., active skeletal muscles

• In heavy exercise, CO2 and lactic acid accumulate in the tissues and the temperature increases, resulting in as much as 85% of the O2 being released from the haemoglobin

• However, in the lungs, because of an increased respiration rate, PCO2 in the lungs decreases and the oxygen dissociation curve shifts further towards the left allowing the haemoglobin to saturate more readily

Front 46

effects of low and high temp on o2-Hb curve

Back 46

When the temperature rises, more oxygen is released; the oxygen–haemoglobin saturation curve shifts to the right 2,3-bisphosphoglycerate (B

Front 47

2,3-bisphosphoglycerate (BPG)

Back 47

• Erythrocytes generate ATP by glycolysis, forming lactic acid and BPG

• BPG levels rise when pH increases or when stimulated by certain hormones

• BPG directly affects O2 binding and release: It decreases the affinity of haemoglobin for O2 . If BPG levels are too low, haemoglobin will not release O2

• People in high altitudes have high concentrations of BPG in the blood and this is thought to increase oxygen delivery to the tissues at high altitudes

• BPG levels in stored blood decrease with tim

Front 48

In what way does BGP directly affect o2 binding and release ?

Back 48

It decreases the affinity of haemoglobin for O2 . If BPG levels are too low, haemoglobin will not release O2

Front 49

• Foetal Haemoglobin structure

Back 49

-different from adult

- Foetal Hb binds more O2 than adult Hb • This allows foetus to take O2 from maternal blood

Front 50

what 3 ways is CO2 transported in the blood?

Back 50

(1) In the form of bicarbonate ions (72%)

(2) Combined with blood proteins (20%) – bound to Hb

(3) As carbon dioxide dissolved in the plasma (8%)

Front 51

what are blood proteins which bind to CO2 called ?

what is formed when they bind to hb?

Back 51

• The blood proteins that bind CO2 are called carbamino compounds

• CO2 binds to form carbaminohaemoglobin

Front 52

whats the haldane effect

Back 52

• The affinity of Hb for CO2 is greater if that Hb molecule has just given up oxygen

(The affinity of Hb for CO2 is greater if that Hb molecule has just given up oxygen)

Front 53

Exchange of O2 and CO2 in pulmonary and systemic capillaries

Back 53

Front 54

describe the transportation of CO2 as bicarb ions (chloride shift)

Back 54

• CO2 diffuses into the erythrocytes and reacts with water to form carbonic acid • This then dissociates into hydrogen ions and bicarbonate ions

• The negative bicarbonate ions diffuse out of the erythrocytes into the blood plasma

• As a result of this movement out of bicarbonate ions, negative chloride ions move into the erythrocytes from the blood plasma - this maintains the electrical balance between the inside and the outside of the cells

• This exchange of negative chloride ions for negative bicarbonate ions is called the chloride shift

Front 55

whats the chloride shift in general terms

Back 55

exchange of negative chloride ions for negative bicarbonate

Front 56

H+ ions

Back 56

• Hydrogen ions also form from the carbonic acid. Most of these hydrogen ions bind to Hb (reducing it). If hydrogen ions were to diffuse out of the erythrocytes, the pH of the plasma would drop

• When the deoxygenated blood reaches the alveoli, the CO2 in solution in the blood diffuses into the alveoli and CO2 bound to the blood proteins dissociates and also diffuses into the alveoli • As the PCO2 of the blood decreases, bicarbonate ions diffuse back into the erythrocytes and Hb releases the hydrogen ions

• The bicarbonate ions then bind with the hydrogen ions to form carbonic acid. During this process, the chloride ions move out of the erythrocytes

• The carbonic acid then dissociates into water and CO2 and the CO2 diffuses towards the alveoli. Associated with this movement of hydrogen ions into the erythrocytes is a slight increase in blood pH and an associated increase in the uptake of oxygen by the Hb

Front 57

pO2 in alveoli and alveolar capillaries, which way does O2 diffuse ?

Back 57

alveoli: 104

alveolar capillaries: 40

o2 diffuses from alveoli into capillaries

Front 58

pO2 in interstitial fluid and cells

Back 58

interstitial fuild: 40

cells: 20

blood diffuses from IF into cells

Front 59

pO2 from alveolar capillaries by the time it reaches pulmonary vein

Back 59

104mmg

pulmonary vein: 95mmhg

Front 60

cells PCO2

Back 60

46mmhg

Front 61

interstitial fluid pco2

Back 61

44mmhg

Front 62

cappilaries supplying tissue PCO2

Back 62

45mmgh

Front 63

what fraction of RBC is Hb

Back 63

1/3

Front 64

lifespan of RBC in men and women

Back 64

120 and 110

Front 65

how long does erythropoesis take ?

Back 65

4 days

Front 66

what stimulates erythropoesis

Back 66

stimulated by low PO2 in the kindeys which leads to the formation of glycoprotein which stimulates eruthropoesis in the RBM

Front 67

why is the o2-hb graph curve

Back 67

hb changes shape each time o2 molecule is bound

Front 68

what is a o2bh curve

Back 68

graph relating to saturation of hb to partial pressure of o2

Front 69

what results in higher hb saturation

Back 69

higher po2

Front 70

what is hb saturation

Back 70

% of heme in a hb molecule which contains bound o2

Front 71

what happens to the curve when PH drops or Temp rise

Back 71

more O2 is released

curve shifts to the right

Front 72

what happens to the curve as ph drops

Back 72

shifts to the right

more o2 released

Front 73

what happens when ph rises and temp drops

Back 73

less o2 released

curve shifts left

Front 74

what happens to O2 Hb binding with increasing pH?

Back 74

declines

Front 75

how does increasing pH decrease Hb O2 affinity

Back 75

caused by increased pCO2 this causes CO2 to react with water forming carbonic acid which dissociated into h+ and bicarb ions

H+ ions increase pH

H+ ions bind to protein part of Hb causing conformational change decreasing affinity Hb for O2

Front 76

what happens to curve as temp increases

Back 76

shifts to the right

more o2 released

Front 77

in what tissues is the effect of temp significant on the curve

Back 77

active tissue that generate large amounts of heat e.g active skeletal muscle

Front 78

describe effect of BPG on Hb and O2 binding affinity

Back 78

released in glycolysis with lactic acid

BPG rise with temp in pH

increase in BGP increases Hb affinity for O2

low levels of BGP cause o2 to stay bound to Hb

Front 79

describe foetal Hb

Back 79

binds more o2 than adult

allows it to take up o2 from maternal blood

Front 80

haldane effect

Back 80

affinity of hb for co2 is greater if hb has just given up o2

Front 81

chloride shift

Back 81

maintains electrolyte balance

cl- moves into rbc as HCO3 diffuses out if the rbc